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Unformatted text preview: Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply April 2005 U.S. Department of Energy Foreword The United States Department of Agriculture (USDA) and the United States Department of Energy (DOE) both place high importance on developing resources and conversion technologies for producing fuels, chemicals and power from biomass. The two departments are working together on several aspects of bioenergy. This report is the third to be produced from joint collaboration. This and other reports can be found at: http://www.eere.energy.gov/biomass/publications.html. The website for biomass feedstock research sponsored by the DOE’s Office of Energy Efficiency and Renewable Energy Office of the Biomass Program (OBP) can be found at: http:// bioenergy.ornl.gov/. More general information about OBP’s feedstock research program can be found at: http://www.eere.energy.gov/biomass/ biomass_feedstocks.html. The website for research and development sponsored by the USDA Forest Service can be found at: http://www.fs.fed.us/ research/. The website for bioenergy research sponsored by the USDA Agricultural Research Service can be found at: http:// www.ars.usda.gov/research/programs/ programs.htm?NP_CODE=307. Notice This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, or any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at: http://www.osti.gov/bridge Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:[email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm Acknowledgements The authors would like to acknowledge the support of the Office of the Biomass Program and in particular, John Ferrell and Sam Tagore. The authors gratefully acknowledge the valuable contributions of Robert Guida, Rajita Majumdar, Borys Mararytsya, and Adam McCann of BCS, Incorporated in the review of the final draft and preparation of the print copy. BIOMASS AS FEEDSTOCK FOR A BIOENERGY AND BIOPRODUCTS INDUSTRY: THE TECHNICAL FEASIBILITY OF A BILLION-TON ANNUAL SUPPLY Robert D. Perlack Lynn L. Wright Anthony F. Turhollow Robin L. Graham Environmental Sciences Division Oak Ridge National Laboratory Bryce J. Stokes Forest Service U.S. Department of Agriculture Donald C. Erbach Agricultural Research Service U.S. Department of Agriculture A Joint Study Sponsored by U.S. Department of Energy U.S. Department of Agriculture Prepared by: Oak Ridge National Laboratory P.O. Box 2008 Oak Ridge, Tennessee 37831-6285 Managed by: UT-Battelle, LLC for the U.S. Department of Energy under contract DE-AC05-00OR22725 DOE/GO-102995-2135 ORNL/TM-2005/66 Contributors Howard Brown Biomass Program Communications National Renewable Energy Laboratory Golden, CO Marilyn A. Buford National Program Leader USDA Forest Service Washington, DC Frederick J. Deneke Coordinator USDA Forest Service Cooperative Forestry Washington, DC Achim Dobermann Project Leader Department of Agronomy and Horticulture University of Nebraska Lincoln, NE James L. Easterly P.E. Principal Easterly Consulting Fairfax, VA Thomas Foust Biomass Program Technology Manager National Renewable Energy Laboratory Golden, CO Dennis M. May Program Manager USDA Forest Service North Central Research Station St. Paul, MN David B. McKeever Research Forester USDA Forest Service Forest Products Laboratory Madison, WI James E. McMurtrey III Research Agronomist (retired) USDA, Agricultural Research Service Hydrology and Remote Sensing Lab Beltsville, MD Patrick D. Miles Research Forester USDA Forest Service North Central Research Station St. Paul, MN John R. Mills Research Forester USDA Forest Service Pacific Northwest Research Station Portland, OR Ralph Overend Research Fellow National Renewable Energy Laboratory Golden, CO Michael Pacheco Director, National Bioenergy Center National Renewable Energy Laboratory Golden, CO Robert B. Rummer Project Leader USDA Forest Service Southern Research Station Auburn, AL Hosein Shapouri Agricultural Economist Office of Energy Policy and New Uses USDA Office of the Chief Economist Washington, DC Kenneth E. Skog Project Leader USDA Forest Service Forest Products Laboratory Madison, WI Shahab Sokhansanj Biomass Supply Systems Logistics Environmental Sciences Division Oak Ridge National Laboratory Oak Ridge, TN Marie Walsh Adjunct Associate Professor Bio-Based Energy Analysis Group University of Tennessee Knoxville, TN Contents Executive Summary ................................................................................................................................................................ i 1. 2. 2.1 2.2 2.3 3. 3.1 3.2 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.4 4. 4.1 4.2 4.3 4.3.1 4.3.2 4.3.3 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 Introduction ............................................................................................................................................................. 1 The Biomass Feedstock Resource Base ............................................................................................................... 3 Land Resource for Biomass Production ..................................................................................................................... 3 Biomass Feedstock Consumption .............................................................................................................................. 3 Composition of the Current Resource Base .............................................................................................................. 3 Forest-Derived Biomass Resource Assessment ................................................................................................... 5 Forestland Resource Base .......................................................................................................................................... 5 Forest Resources ......................................................................................................................................................... 6 Increasing Biomass Resources from Forests ............................................................................................................ 9 Logging Residues and Other Removals from the Forest Inventory .......................................................................... 9 Forest Residues from Fuel Treatment Thinning ........................................................................................................ 9 Forest Products Industry Processing Residues ...................................................................................................... 14 Urban Wood Residues .............................................................................................................................................. 15 Forest Growth and Increase in the Demand for Forest Products .......................................................................... 16 Forest Resources Summary .................................................................................................................................... 16 Agriculture-Derived Biomass Resources ........................................................................................................... 18 Agricultural Land Resource Base ............................................................................................................................ 18 Agricultural Resources ............................................................................................................................................. 19 Evaluating the Biomass Potential of Agriculture .................................................................................................... 21 Scenario 1: Current Sustainable Availability of Biomass from Agricultural Lands ............................................... 21 Scenario 2: Technology Change with Conventional Crops Only (No Land Use Change) ...................................... 22 Scenario 3: Technology Change with Perennial Crops and Land Use Change ..................................................... 23 Factors Increasing Biomass Resources from Agriculture ...................................................................................... 24 Crop Yields ................................................................................................................................................................ 24 Residue-to-Grain or -Seed Ratios ............................................................................................................................ 25 Residue Collection Technology for Annual Crops ................................................................................................... 26 Cropland Tillage ........................................................................................................................................................ 27 Allocation of Cropland Acres to Perennial Crops .................................................................................................... 28 4.4.6 4.4.7 4.5 5. 5.1 5.2 6. Grain to Ethanol or Bioproducts and Soybeans to Biodiesel ......................................................................... 30 Secondary Processing and Other Residues ................................................................................................... 30 Agricultural Resources Summary .................................................................................................................... 32 Potential Concerns and Impacts ................................................................................................................ 34 Forest-Derived Biomass Resources ................................................................................................................ 34 Agriculture-Derived Biomass Resources ........................................................................................................ 36 Summarized Findings .................................................................................................................................. 38 References ....................................................................................................................................................................... 39 Glossary ....................................................................................................................................................................... 44 Appendix A: Forest Resource Analysis ........................................................................................................................... 48 Appendix B: Agriculture Resource Analysis ................................................................................................................... 54 List of Figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Annual biomass resource potential from forest and agricultural resources ............................................... 2 Summary of biomass resource consumption ................................................................................................ 4 The biomass resource base ............................................................................................................................ 5 Ownership break-up of U.S. forestland by region .......................................................................................... 5 Projections of timber removals, growth, and inventory ................................................................................. 6 Total timberland biomass and forest residue inventory ................................................................................ 8 Estimate of the sustainably recoverable forest biomass .............................................................................. 8 Forest utilization relationships .................................................................................................................... 10 Logging and other removal residues ........................................................................................................... 10 Fire suppression cost and acres burned .................................................................................................... 11 Total treatable biomass resource on timberlands and other forestlands ................................................ 12 Fuel treatments on timberland and other forestland ................................................................................. 13 Summary of potentially available forest resources .................................................................................... 16 Summary of cropland uses, idle cropland, and cropland pasture in the contiguous United States ............................................................................................................................. 18 Harvested acres of oats and soybeans, 1900–2000 ................................................................................ 19 Agricultural productivity, 1948–1996 ......................................................................................................... 20 Current availability of biomass from agricultural lands ............................................................................. 21 Availability of biomass under increased crop yields and technology changes ........................................ 22 Availability of biomass under increased crop yields, technology changes, and inclusion of perennial crops ......................................................................................................................... 23 Average corn yields, 1900–1999 ................................................................................................................ 24 Breeding of new giant soybean cultivars for forage production ................................................................ 26 Soybean residues from large biomass (top) and conventional soybeans (bottom) ................................. 26 Crops under no-till cultivation ...................................................................................................................... 27 Summary of the allocation of agricultural land under alternative scenarios ........................................... 29 Summary of potentially available agricultural resources ........................................................................... 32 Summary of potential forest and agricultural resources ........................................................................... 35 List of Tables Table A.1. Table A.2 Table A.3 Table A.4 Table A.5 Table A.6 Table A.7 Table A.8 Table A.9 Table B.1 Table B.2 Table B.3 Table B.4 Table B.5 Table B.6 Current availability of logging residue and other removals ........................................................................ 48 Availability factors for logging residue and other removals under current recovery conditions ...................................................................................................................................... 48 Availability of logging residue and other removals under current recovery conditions ............................ 49 Availability of logging residue and other removals under future growth and recovery conditions ...................................................................................................................................................... 49 Total fuel treatment thinnings resource ...................................................................................................... 50 Assumed availability factors for fuel treatment thinnings ......................................................................... 50 Availability of fuel treatment thinnings ........................................................................................................ 51 Forest products industry processing residues ............................................................................................ 51 Summary of availability of urban wood residues ........................................................................................ 52 Comparison of USDA baseline for major crops with change scenarios .................................................... 54 Current availability of biomass from agricultural lands – baseline summary .......................................... 55 Summary of biomass from agricultural lands under moderate crop yield increases without land use change .............................................................................................................................. 56 Summary of biomass from agricultural lands under high crop yield increase without land use change ........................................................................................................................................... 57 Summary of biomass from agricultural lands under moderate crop yield increase with land use change ........................................................................................................................................... 58 Summary of biomass from agricultural lands under high crop yield increase with land use change ........................................................................................................................................................... 59 Abbreviations and Acronyms CAFO .............................................................................................................. confined animal feeding operation CRP ................................................................................................................ Conservation Reserve Program DOE ................................................................................................................ U.S. Department of Energy EERE .............................................................................................................. Energy Efficiency and Renewable Energy FIA .................................................................................................................. Forestry Inventory and Analysis (USDA program) FTE ................................................................................................................. Fuel Treatment Evaluator HFRA .............................................................................................................. Healthy Forest Restoration Act LBS ................................................................................................................ large biomass soybean MSW .............................................................................................................. municipal solid waste NCGA ............................................................................................................. National Corn Growers Association OBP ................................................................................................................ Office of the Biomass Program quad............................................................................................................... quadrillion (1015) BTUs R&D ............................................................................................................... research and development RMR ............................................................................................................... residue maintenance requirement RUSLE ............................................................................................................ Revised Universal Soil Loss Equation SCI ................................................................................................................. Soil Conditioning Index TPO ................................................................................................................ Timber Product Output (USDA) USDA .............................................................................................................. U.S. Department of Agriculture Executive Summary The U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) are both strongly committed to expanding the role of biomass as an energy source. In particular, they support biomass fuels and products as a way to reduce the need for oil and gas imports; to support the growth of agriculture, forestry, and rural economies; and to foster major new domestic industries — biorefineries — making a variety of fuels, chemicals, and other products. As part of this effort, the Biomass R&D Technical Advisory Committee, a panel established by the Congress to guide the future direction of federally funded biomass R&D, envisioned a 30 percent replacement of the current U.S. petroleum consumption with biofuels by 2030. Biomass — all plant and plant-derived materials including animal manure, not just starch, sugar, oil crops already used for food and energy — has great potential to provide renewable energy for America’s future. Biomass recently surpassed hydropower as the largest domestic source of renewable energy and currently provides over 3 percent of the total energy consumption in the United States. In addition to the many benefits common to renewable energy, biomass is particularly attractive because it is the only current renewable source of liquid transportation fuel. This, of course, makes it invaluable in reducing oil imports — one of our most pressing energy needs. A key question, however, is how large a role could biomass play in responding to the nation’s energy demands. Assuming that economic and financial policies and advances in conversion technologies make biomass fuels and products more economically viable, could the biorefinery industry be large enough to have a significant impact on energy supply and oil imports? Any and all contributions are certainly needed, but would the biomass potential be sufficiently large to justify the necessary capital replacements in the fuels and automobile sectors? The purpose of this report is to determine whether the land resources of the United States are capable of producing a sustainable supply of biomass sufficient to displace 30 percent or more of the country’s present petroleum consumption – the goal set by the Advisory Committee in their vision for biomass technologies. Accomplishing this goal would require approximately 1 billion dry tons of biomass feedstock per year. The short answer to the question of whether that much biomass feedstock can be produced is yes. Looking at just forestland and agricultural land, the two largest potential biomass sources, this study found over 1.3 billion dry tons per year of biomass potential (Figure 1) — enough to produce biofuels to meet more than one-third of the current demand for transportation fuels. The full resource potential could be available roughly around mid-21st century when large-scale bioenergy and biorefinery industries are likely to exist. This annual potential is based on a more than seven-fold increase in production from the amount of biomass currently consumed for bioenergy and biobased products. About 368 million dry tons of sustainably removable biomass could be produced on forestlands, and about 998 million dry tons could come from agricultural lands. Forestlands in the contiguous United States can produce 368 million dry tons annually. This projection includes 52 million dry tons of fuelwood harvested from forests, 145 million dry tons of residues from wood processing mills and pulp and paper mills, 47 million dry tons of urban wood residues including construction and demolition debris, 64 million dry tons of residues from logging and site clearing operations, and 60 million dry tons of biomass from fuel treatment operations to reduce fire hazards. All of these forest resources are sustainably available on an annual basis. For estimating the residue tonnage from logging and site clearing operations and fuel treatment thinnings, a number of important assumptions were made: all forestland areas not currently accessible by roads were excluded; all environmentally sensitive areas were excluded; equipment recovery limitations were considered; and recoverable biomass was allocated into two utilization groups – conventional forest products and biomass for bioenergy and biobased products. From agricultural lands, the United States can produce nearly 1 billion dry tons of biomass annually and still continue to meet food, feed, and export demands. This projection includes 428 million dry tons of annual crop residues, 377 16 million dry tons of perennial crops, 87 million dry tons of grains used for biofuels, and 106 million dry tons of animal manures, process residues, and other miscellaneous feedstocks. Important assumptions that were made include the following: yields of corn, wheat, and other small grains were increased by 50 percent; the residue-to-grain ratio for soybeans was increased to 2:1; harvest technology was capable of recovering 75 percent of annual crop residues (when removal is sustainable); all cropland was managed with no-till methods; 55 million acres of cropland, idle cropland, and cropland pasture were dedicated to the production of perennial bioenergy crops; all manure in excess of that which can applied on-farm for soil improvement under anticipated EPA restrictions was used for biofuel; and all other available residues were utilized. The biomass resource potential identified in this report can be produced with relatively modest changes in land use, and agricultural and forestry practices. This potential, however, should not be thought of as an upper limit. It is just one scenario based on a set of reasonable assumptions. Scientists in the Departments of Energy and Agriculture will explore more advanced scenarios that could further increase the amount of biomass available for bioenergy and biobased products. Forest resources 368 Agricultural resources 998 Total resource potential 1366 0 200 400 600 800 1000 1200 1400 Million dry tons per year Figure 1: Annual biomass resource potential from forest and agricultural resources 17 1. Introduction Feedstock Resource Vision Goals Established by the Biomass Research & Development Technical Advisory Committee (Source: BTAC, 2002a) Biopower — Biomass consumption in the industrial sector will increase at an annual rate of 2% through 2030, increasing from 2.7 quads in 2001 to 3.2 quads in 2010, 3.9 quads in 2020, and 4.8 quads in 2030. Additionally, biomass consumption in electric utilities will double every 10 years through 2030. Combined, biopower will meet 4% of total industrial and electric generator energy demand in 2010 and 5% in 2020. Biobased Transportation Fuels — Transportation fuels from biomass will increase significantly from 0.5% of U.S. transportation fuel consumption in 2001 (0.0147 quad) to 4% of transportation fuel consumption in 2010 (1.3 quads), 10% in 2020 (4.0 quads), and 20% in 2030. Biobased Products — Production of chemicals and materials from biobased products will increase substantially from approximately 12.5 billion pounds or 5% of the current production of target U.S. chemical commodities in 2001, to 12% in 2010, 18% in 2020, and 25% in 2030. Biomass is already making key energy contributions in the United States, having supplied nearly 2.9 quadrillion Btu (quad) of energy in 2003. It has surpassed hydropower as the largest domestic source of renewable energy. Biomass currently supplies over 3 percent of the total energy consumption in the United States — mostly through industrial heat and steam production by the pulp and paper industry and electrical generation with forest industry residues and municipal solid waste (MSW). In addition to the many benefits common to any renewable energy use, biomass is particularly attractive because it is the only current renewable source of liquid transportation fuel. This, of course, makes it an invaluable way to reduce oil imports — one of our nation’s most pressing energy and security needs. Biomass also has great potential to provide heat and power to industry and to provide feedstocks to make a wide range of chemicals and materials or bioproducts. The overall mission of the U.S. Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy (EERE) is to strengthen the nation’s energy security, environmental quality, and economic vitality in public-private partnerships that enhance energy efficiency and productivity; bring clean, reliable and affordable energy technologies to the marketplace; and make a difference in the everyday lives of Americans by enhancing their energy choices and their quality of life. Consistent with this mission, DOE-EERE’s Biomass Program supports a research agenda to develop biomass feedstock production and conversion technologies capable of providing for significant fractions of domestic demands for transportation fuels, electric power, heat, chemicals and materials. The U.S. Department of Agriculture (USDA) through its agencies and offices has similar goals of reducing foreign oil dependence, improving the environment through the development of new sources of energy, increasing the use of agricultural crops and forest resources as feedstocks for bioenergy and bioproducts, and creating jobs and enhancing income in America’s rural sector. The Biomass Research and Development Act of 2000 created the Biomass R&D Technical Advisory Committee to provide advice to the Secretaries of Agriculture and Energy on program priorities and to facilitate cooperation among various federal and state agencies, and private interests. The Technical Advisory Committee also established a national vision for bioenergy and biobased products. Included in its vision was the setting of a very challenging goal: biomass will supply 5 percent of the nation’s power, 20 percent of its transportation fuels, and 25 percent of its chemicals by 2030. The goal is equivalent to 30 percent of current petroleum consumption and will require more than approximately one billion dry tons of biomass feedstock annually — a fivefold increase over the current consumption (DOE, 2003). The purpose of this report is to assess whether the land resources of the United States have the potential to produce a sustainable supply of biomass that can displace 30 percent of the country’s current petroleum consumption. This report does not attempt to outline R&D and policy agendas to attain this goal, nor does it attempt to assess the economic competitiveness of a billion-ton bioenergy and bioproducts industry, and its potential impacts on the energy, agriculture (food and feed production), and forestry sectors of the economy. Many of these issues are partially addressed in the roadmap that accompanied the biomass vision (BTAC, 2002b). The roadmap explores the technical research, development, and demonstrations needed to achieve advances in biomass systems and outlines the institutional and policy changes needed to remove the barriers to economically and environmentally sound 1 18 development of sustainable biomass systems. To provide some perspective, the next section of this resource assessment report summarizes current biomass consumption and the biomass feedstock resource base. The biomass feedstock resource base from forests and agricultural lands are then discussed in more detail in the main body of the report. 2 19 2. The Biomass Feedstock Resource Base 2.1 Land Resources for Biomass Production The land base of the United States encompasses nearly 2,263 million acres, including the 369 million acres of land in Alaska and Hawaii. About 33 percent of the land area is classified as forest land, 26 percent as grassland pasture and range, 20 percent as cropland, 8 percent as special uses (e.g., public facilities), and 13 percent as miscellaneous uses such as urban areas, swamps, and deserts (Vesterby and Krupa, 2001; Alig et al., 2003). About one-half of this land has some potential for growing biomass. This percentage is nearly 60 percent without Alaska and Hawaii. Currently, slightly more than 75 percent of biomass consumption in the United States (about 142 million dry tons) comes from forestlands. The remainder (about 48 million dry tons), which includes biobased products, biofuels and some residue biomass, comes from cropland. 2.2 Biomass Feedstock Consumption In 2003, biomass contributed nearly 2.9 quadrillion BTU (quad) to the nation’s energy supply, nearly 3 percent of total U.S. energy consumption of about 98 quads (EIA, 2004a). At 47 percent of total renewable energy consumption, biomass is the single largest renewable energy resource, recently surpassing hydropower (Figure 2). More than 50 percent Coal, 23% Natural gas, 24% Biomass, 47% Renewable energy, 6% Nuclear, 8% Hydroelectric, 45% Geothermal, 5% Wind, 2% Solar, 1% Petroleum, 39% Biomass Consumption Million dry tons/year Forest products industry Wood residues 44 Pulping liquors 52 Urban wood and food & other process residues 35 Fuelwood (residential/commercial & electric utilities) 35 Biofuels 18 Bioproducts 6 Total 190 Forestlands and agricultural lands contribute 190 million dry tons of biomass - 3% of America's current energy consumption. Source: EIA, 2004a & b Figure 2: Summary of biomass resource consumption 3 20 of this biomass comes from wood residues and pulping liquors generated by the forest products industry. Currently, biomass accounts for approximately 13 percent of renewably generated electricity, nearly all (97 percent) the industrial renewable energy use, nearly all the renewable energy consumption in the residential and commercial sectors (84 percent and 90 percent, respectively), and 2.5 percent of transport fuel use. A relatively significant amount of biomass (~6 to 9 million dry tons) is also currently used in the production of a variety of industrial and consumer bioproducts that directly displace petroleum-based feedstocks (Energetics, 2003). The total annual consumption of biomass feedstock for bioenergy and bioproducts together currently approaches 190 million dry tons (Figure 3). Forest Resources Primar y Primary Logging residues from conventional harvest operations and residues from forest management and land clearing operations Removal of excess biomass (fuel treatments) from timberlands and other forestlands Fuelwood extracted from forestlands Secondary Secondar y Primary wood processing mill residues Secondary wood processing mill residues Pulping liquors (black liquor) ertiar tiary Ter tiar y Urban wood residues — construction and demolition debris, tree trimmings, packaging wastes and consumer durables Agricultural Resources Primary Primar y Crop residues from major crops — corn stover, small grain straw, and others ·Grains (corn and soybeans) used for ethanol, biodiesel, and bioproducts Perennial grasses Perennial woody crops Secondary Secondar y Animal manures Food/feed processing residues ertiar tiary Ter tiar y MSW and post-consumer residues and landfill gases The resource base includes a wide range of primary resources, and secondary and tertiary residues. This report emphasizes primary resources. 2.3 Composition of the Current Resource Base The biomass resource base is composed of a wide variety of forestry and agricultural resources, industrial processing residues, and municipal solid and urban wood residues (Figure 3). The forest resources include residues produced during the harvesting of forest products, fuelwood extracted from forestlands, residues generated at primary forest product processing mills, and forest resources that could become available through initiatives to reduce fire hazards and improve forest health. The agricultural resources include grains used for biofuels production, animal manures and residues, and crop residues derived primarily from corn and small grains (e.g., wheat straw). A variety of regionally significant crops, such as cotton, sugarcane, rice, and fruit and nut orchards can also be a source of crop residues. Municipal and urban wood residues are widely available and include a variety of materials — yard and tree trimmings, land-clearing wood residues, wooden pallets, packaging materials, and construction and demolition debris. Figure 3: The biomass resource base The remainder of this report addresses the potential availability of biomass feedstock projected over a long term — roughly around mid-21st century when large-scale bioenergy and biorefinery industries are likely to exist. The report emphasizes primary sources of forest- and agriculture-derived biomass such as logging residues, fuel treatment thinnings, crop residues, and perennially grown grasses and woody crops. These primary sources have the greatest potential to supply large, sustainable quantities of biomass. While the primary sources are emphasized, secondary and tertiary (or residue) sources of biomass are also addressed in the report. The amount of forest-derived biomass is based on an analysis of extant resources and trends in the demand for forest products. The biomass resource potential from agricultural land is based on creating scenarios that extrapolate from current agriculture and research and development trends. While the forestland area is much larger, agricultural land has a greater biomass resource potential due to a much higher level of management intensity. Forestlands, especially those held publicly, will always be managed less intensively than agricultural lands because forests are expected to provide multiple-use benefits including wildlife habitat, recreation, and ecological and environmental services. By contrast, active cropland and, to a lesser extent, idle cropland and cropland pasture are intensively managed, with crops and management practices changing on a year-to-year basis and land moving in and out of active production. 4 21 3. Forest-Derived Biomass Resource Assessment 3.1 Forestland Resource Base The total forestland in the United States is approximately 749 million acres — about one-third of the nation’s total land area. Most of this land is owned by private individuals or by the forest industry (Figure 4). Two-thirds of the forestland (504 million acres) is classified as timberland which, according to the Forest Service, is land capable of growing more than 20 ft3 per acre of wood annually (Smith et al., 2004). Although timberland is not legally reserved from harvesting, much of it is inaccessible or inoperable by forestry equipment. In addition, there are 168 million acres of forestland that the Forest Service classifies as “other.” This “other” forestland is generally incapable of growing 20 ft3 per acre of wood annually. The lower productivity is due to a variety of factors or site conditions that adversely affect tree growth 120 100 Million acres 80 60 40 20 0 r th No st ea rth l No ntra Ce u th So st ea u th l So ntra Ce t ea Gr ins Pla u mo nta in ic e s t cif Pa r thw No ic est cif Pa uthw So sk Ala a Int er Public ow nership Industrial ow nership Private ow nership Of the 504 million acres of U.S. timberland, about 29% is publicly owned, 13% is owned by the forest industry, and the remaining 58% is privately owned. Timberland ownership varies considerably among regions of the country. The East United States tends to be dominated by private ownership and the West by public land ownership. Source: Alig et al., 2003 Figure 4: Ownership break-up of U.S. forestland by region (e.g., poor soils, lack of moisture, high elevation, and rockiness). As a result, this land tends to be used for livestock grazing and extraction of some non-industrial wood products. The remaining 77 million acres of forestland are reserved from harvesting and are intended for a variety of non-timber uses, such as parks and wilderness. The total forestland base considered for this resource analysis includes the 504 million acres of timberland and the 168 million acres of other forestland. The timberland acreage is the source of nearly all current forest-derived bioenergy consumption and the source of most of the potential. The other forestland is included because it has accumulated excess biomass that poses wildland fire risks and hazards. Much of this excess biomass is not suitable for conventional wood products but could be used for a variety of bioenergy and biobased product uses. 22 5 3.2 Forest Resources The processing of harvested forest products, such as sawlogs and pulpwood, generates significant quantities of mill residues and pulping liquors. These secondary forest residues constitute the majority of biomass in use today (Figure 3). Secondary residues generated in the processing of forest products account for 50 percent of current biomass energy consumption. These materials are used by the forest products industry to manage residue streams, produce energy, and recover important chemicals. Fuelwood extracted from forestlands for residential and commercial use and electric utility use accounts for about 35 million dry tons of current consumption. In total, the amount of harvested wood products from timberlands in the United States is less than the annual forest growth and considerably less than the total forest inventory (Figure 5), suggesting substantial scope for expanding biomass resource base from forestlands. In addition to these existing uses, forestlands have considerable potential to provide biomass from two primary sources: residues associated with the harvesting and management of commercial timberlands for the extraction of sawlogs, pulpwood, veneer logs, and other conventional products; and currently non-merchantable biomass associated with the standing forest inventory. This latter source is more difficult to define, but generally would include rough and rotten wood not suitable for conventional forest products and excess quantities of smaller-diameter trees in overstocked forests. A large amount of this forest material has been identified by the Forest Service as needing to be removed to improve forest health and to reduce fire hazard risks (USDA-FS, 2003; Miles, 2004). These two categories of forest resources constitute what is defined as the primary source of forest residue biomass in addition to the fuelwood that is extracted for space heating applications in the residential and commercial sectors and 1200 1000 Billion cubic feet 800 600 400 200 0 1997 2010 Removals 2020 2030 Inventory 2040 2050 Net annual growth Removals from the forest inventory are a small fraction of the total standing inventory. Current removals are also less than net annual forest growth. Forest inventories are projected to increase relative to removals despite a loss of about 3% (23 million acres) of U.S. forestland by the year 2050. The projected loss is expected as a result of land conversion to urban and developed uses driven primarily by population and income growth (Alig et al., 2003). Source: Haynes, 2003 Figure 5: Projections of timber removals, growth, and inventory 23 6 for some feedstocks by electric utilities. Perennial woody crops (also referred to as short-rotation woody crops) are also a potential primary biomass resource. Because these woody crops would be grown on agricultural lands, they are discussed in the agricultural resources section that follows (Section 4.0). There is also a relatively large tertiary, or residue, source of forest biomass in the form of urban wood residues — a generic category that includes yard trimmings, packaging residues, discarded durable products, and construction and demolition debris. All of these forest resources can contribute an additional 226 million dry tons to the current forest biomass consumption (approximately 142 million dry tons) – an amount still only a small fraction of the total biomass timberlands inventory of more than 20 billion dry tons (Figure 6). Specifically, these forest resources include the following: The recovered residues generated by traditional logging activities and residues generated from forest cultural operations or clearing of timberlands. Currently, about 67 million dry tons of residues are generated annually from these activities (Smith et al., 2004; USDA-FS, 2004a). About 41 million dry tons of this biomass material is potentially available for bioenergy and biobased products after consideration of equipment recovery limitations (Tables A.1 to A.3, Appendix A). The recovered residues generated from fuel treatment operations on timberland and other forestland. Well over 8 billion dry tons of biomass has been identified for fuel treatment removal (Miles, 2004). The amount of this biomass potentially available for bioenergy and biobased product uses is estimated at 60 million dry tons annually. This estimate takes into consideration factors affecting forest access, residue recovery, and the merchandizing of the recoverable biomass into higher-value fractions (conventional wood products) and lowervalue fractions (the biomass suitable for bioenergy and biobased product uses) (Tables A.5 to A.7, Appendix A). The fraction that could be available for bioenergy and biobased products is less than 1 percent of the total size of the fuel treatment biomass resource. The direct conversion of roundwood to energy (fuelwood) in the residential, commercial, and electric utility sectors. Thirty-five million dry tons of biomass is currently extracted by the residential and commercial sectors and by the electric power sector. Most of the fuelwood used by the residential and commercial sectors is used for space- and process-heating applications. Forest products industry residues and urban wood residues. Utilization of unused residues generated by the forest products industry (8 million dry tons); urban wood residues discarded from construction and demolition activities (20 million dry tons); and residues from the disposal of tree trimmings, packaging residues, and wood-based consumer durables (8 million dry tons) can annually provide 36 million dry tons to the current 108 million dry tons currently used. Forest growth and increase in the demand for forest products. In the long term, a continuation of current trends in the demand and supply of forest products could increase the potential contribution of forest biomass by another 89 million dry tons annually. The additional 89 million dry tons result from a combination of sources and changing circumstances. An increase in the harvest of traditional forest products will create additional logging residues, and more efficient equipment will allow the recovery of a greater fraction of the logging residue. However, this increase will be offset somewhat by more efficient logging practices that will generate less wood residue per unit volume of the harvested forest products (Haynes, 2003). Demand growth for conventional forest products will create additional mill residue, and pulping liquor and urban wood residues. However, the rate of increase in these secondary and tertiary forest residue sources will be tempered by product substitution, recycling and reuse, and more efficient manufacturing processes. A summary of the amounts of biomass available annually and on a sustainable basis from forest resources is summarized in Figure 7. The approximate total quantity is 368 million dry tons annually. As noted, this includes about 142 million dry tons of biomass currently being used primarily by the forest products industry, as well as the 89 million dry tons that could result annually from a continuation of demand and supply trends in the forest products industry. 7 24 25 20 Billion dry tons 15 10 5 0 Nat'l forest Other public Private All ownerships Ownership group Merchantable wood for traditional forest products Forest residues for bioenergy & biobased products 69% 70% 60% 50% 40% 30% 21% 20% 8% 10% 2% Source: Smith et al., 2004 0% Merchantable wood (boles) Tops Saplings Sound dead wood The merchantable wood or the conventional forest products component includes the boles and sound dead wood. The forest residue fraction suitable for bioenergy and biobased products includes the tops and some fraction of saplings considered to be overstocked. The total forest residue resource is about 6.7 billion dry tons. Figure 6: Total timberland biomass and forest residue inventory Logging & other residue Fuel treatments (forestlands) Fuelwood Forest products industry wastes Urban wood residues Forest growth 0 41 60 35 106 37 89 20 40 60 80 100 120 Figure 7: Estimate of the sustainably recoverable forest biomass 8 25 3.3 Increasing Biomass Resources from Forests 3.3.1 Logging Residues and Other Removals from the Forest Inventory A recent analysis shows that the annual removals from the forest inventory totaled nearly 20.2 billion ft3. Of this volume, 78 percent was for roundwood products, 16 percent was logging residue, and slightly more than 6 percent was classified as “other removals” (Smith et al., 2004). The total annual removals constitute about 2.2 percent of the forest inventory of timberland and are less than net annual forest growth (Figure 5). The logging residue fraction is biomass removed from the forest inventory as a direct result of conventional forest harvesting operations. This biomass material is largely tree tops and small branches left on site because these materials are currently uneconomical to recover either for product or energy uses (Figure 8). The remaining fraction, other removals, consists of timber cut and is burned in the process of land conversion or cut as a result of cultural operations such as precommercial thinnings and timberland clearing. Data on the total amount of logging residue and other removals are available from the USDA Forestry Inventory and Analysis (FIA) program’s Timber Product Output (TPO) Database Retrieval System (USDA-FS, 2004a). This database provides volumetric information on roundwood products (e.g., sawlogs, pulpwood, veneer logs, and fuelwood), logging residues, other removals, and mill residues. For the United States, total logging residue and other removals currently amount to nearly 67 million dry tons annually: 49 million dry tons of logging residue and 18 million dry tons of other removal residue (Table A.1, Appendix A). Forest Inventory and Analysis The Forest Inventory and Analysis (FIA) program of the Forest Service is the nation’s forest census and has been in continuous operation since 1930 under various names (Forest Survey, Forest Inventory and Analysis). Its mission is to “make and keep current a comprehensive inventory and analysis of the present and prospective conditions of and requirements for the renewable resources of the forest and rangelands of the United States.” FIA reports on status and trends in forest areas and locations; on the species, size, and health of trees; on total tree growth, mortality, and removals by harvest; on wood production and utilization rates by various products; and on forest land ownership. FIA is the only program which provides consistent, credible, and periodic forest data for all forest lands (public and private) within the United States. FIA covers all U.S. forestlands, including Alaska, Hawaii, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific territories. The FIA program is managed by the R&D organization within the USDA Forest Service in cooperation with state and private forestry and national forest systems. More information can be found at http://www.fia.fs.fed.us/. This analysis uses data from the FIA databases. Not all of this resource is potentially available for bioenergy and biobased products (Figure 8). Generally, these residues tend to be relatively small pieces consisting of tops, limbs, small branches, and leaves. Stokes reported a wide range of recovery percentages, with an average of about 60 percent potential recovery behind conventional forest harvesting systems (Stokes, 1992). With newer technology, it is estimated that the current recovery is about 65 percent. Other removals, especially from land-clearing operations, usually produce different forms of residues and are not generally as feasible or as economical to recover. It is expected that only half of the residues from other removals can be recovered. Of course, not all of this material should be recovered. Some portion of this material, especially the leaves and parts of tree crown mass, should be left on site to replenish nutrients and maintain soil productivity. Since many forest operations involve the construction of roads that provide only temporary access to the forest, it is assumed that these residues are removed at the same time as the harvest or land clearing operations that generate the residues. Limiting the recoverability of logging and other removal residue reduces the size of this forest resource from about 67 million to 41 million dry tons (Tables A.2 and A.3, Appendix A). About three-fourths of this material would come from the logging residue. Further, because of ownership patterns most of the logging residue and nearly all residues from other sources (e.g., land clearing operations) would come from privately owned land (Figure 9). 3.3.2 Forest Residues from Fuel Treatment Thinning Vast areas of U.S. forestland are overstocked with relatively large amounts of woody materials. This excess material has built up over years as a result of forest growth and alterations in natural fire cycles. Over the last ten years, federal agencies have spent more than $8.2 billion fighting forest fires, which have consumed over 49 million acres (Figure 10). The cost of fighting fires does not include the costs of personal property losses, ecological damage, loss of valuable forest products, or the loss of human life. The Forest Service and other land management agencies are currently addressing the issue of hazardous fuel buildups and looking at ways to restore ecosystems to more fire-adaptive conditions. The removal of excess woody material would also improve forest health and productivity (Graham, et al., McCaffrey, and Jain, 2004). 26 9 In August 2000, the National Fire Plan was developed to help respond to severe wildland fires and their impacts on local communities while ensuring sufficient firefighting capacity for future fires. The National Fire Plan specifically addresses firefighting capabilities, forest rehabilitation, hazardous fuels reduction, community assistance, and accountability. Recently, the Healthy Forest Restoration Act (HFRA) of 2003 was enacted to encourage the removal of hazardous fuels and utilization of the material, and protect, restore and enhance forest ecosystem components. HFRA is also intended to support R&D to overcome both technical and market barriers to greater utilization of this resource for bioenergy and other commercial uses from both public and private lands. Removing excess woody material has the potential to make available relatively large volumes of forest residues and small-diameter trees for bioenergy and biobased product purposes. The Forest Service has identified timberland and other forestland areas that have tree volumes in excess of prescribed or recommended stocking densities that require some form of treatment or thinning operation to reduce fire risks and hazards, and are in close proximity to people and infrastructure (USDA-FS, 2003b). For timberlands, this was accomplished using the Fuel Treatment Evaluator or FTE (USDAFS, 2004c; Miles, 2004), an assessment tool developed to identify, evaluate, and prioritize fuel treatment oppor tunities and facilitate the implementation of HFRA on all timberland areas. The FTE uses a stand density index approach to identify stands that are minimally fully stocked. Stands that exceed this threshold are identified as potential candidates for thinning Pulpwood, Fuelwood, and Other Products Growing-stock Top (4-inch) Sawtimber (9 or 11-inch) Growing-stock volume (cu.ft.) Sawtimber volume (bd.ft.) Sawlogs, Veneer Logs, and Other Products Residual Volume Utilized Top (variable) Utilized Product Volume Stump Height (1-foot) Inventory Tree Sawlog portion Upper-stem portion Unmerchantable stem, branches, cull, saplings Removals from growing stock Removals from non-growing stock Utilized Tree Utilized Stump (variable) Foliage Stump Excluded from both growing stock and non-growing stock Logging residue includes the unmerchantable tops and small branches. Source: Northeastern Forest Inventory & Analysis Program Figure 8: Forest utilization relationships 50 40 Million dry tons 28.9 30 20 8.5 10 0.7 0 0.3 2.1 0.4 Private National Forest Other public Forest ownership Logging Other removals 41 million dry tons of logging and other removal residue is currently available annually for recovery. Most of this resource would come from privately owned timberland Figure 9: Logging and other removal residues 270 1 treatment. Treatable land areas are then sorted into fire regime condition classes to measure the extent a given area has departed from natural wildfire conditions. The condition classes range from minimally altered areas to areas that are significantly altered from historical norms and pose significant fire risks due to the heavy fuel loadings. The FTE program requires individual tree data. Because this information was not collected for all “other forestland” areas prior to 1998, Forest Service personnel implemented FTE procedures manually for other forestland areas where individual tree data were available. The results for these areas were then extrapolated to similar areas, based on forest type and ecoregion, where individual tree data were not available. Since 1998, the FIA program has been collecting individual tree data on all forestland nationwide. The FTE identified nationwide about 7.8 billion dry tons of treatable biomass on timberland and another 0.6 billion dry tons of treatable biomass on other forestland (Figure 11; Table A.5, Appendix A). Only a fraction of this approximately 8.4 billion dry tons is considered potentially available for bioenergy and biobased products on a sustainable annual basis. Many factors reduce the size of this primary biomass resource (USDA-FS, 2003). The first of these limiting factors is accessibility to the material from the standpoint of having roads to transport the material and operate logging/collection systems (Table A.6, Appendix A). This is rarely a technology-limited factor since there is equipment for nearly any type of terrain and for removing wood a long distance, even without roads (e.g., via helicopters, two-stage hauling, or long-distance cableways). However, there are usually economic and political constraints that inhibit working in roadless areas and more difficult terrain. Estimates of operational accessibility assume conventional types of operations by limiting the areas for consideration to roaded forestland. About 60 percent of the North American temperate forest is considered accessible (not reserved or high-elevation and within 15 miles of major transportation infrastructure) (FAO, 2001). The Forest Service’s final environmental impact statement for roadless area conservation indicates that about 65 percent of Forest Service acreage falls within roaded or nonrestricted designations (USDA-FS, 2004b). Road density is much higher in the eastern United States, and in most cases, the topography is more accessible. 9 1600 1400 8 7 Million dollars 1200 1000 800 600 400 200 0 1992 1994 1996 1998 2000 2002 Burnt acres 5 4 3 2 1 0 2004 Fire suppression costs On average, nearly 5 million acres have been burned each year over the last 10 years. Fire suppression costs average nearly $170 per acre burned. Figure 10: Fire suppression cost and acres burned 28 11 Million acres 6 Operational accessibility is further limited by the need to avoid adverse impacts to soil and water. Steep slopes, sensitive sites, regeneration difficulty, or lack of adequate resource information may exclude an area from operational treatments. A summary of national forest land management plans from 1995 indicated about 60 percent of the western national forest timberland base to be “suitable” for timber production operations (Timko, 2003). This would be a conservative estimate for other landowners as well, and an even more conservative estimate for eastern U.S. timberlands. A more significant restriction is economic feasibility. Operating in steep terrain, in unroaded areas, or with very low-impact equipment is expensive. The value of the biomass (in its broad sense, meaning a combination of product value and treatment value) has to be weighed against the cost of removing the material. For example, May and LeDoux (1992) compared FIA data for hardwood inventory with economic modeling of the cost of harvest and concluded that only 40 percent of the inventory volume in Tennessee was economically available. Biomass, with a lower product value, would be even less available if the biomass has to cover the entire cost of the operation. If the biomass were to be produced as part of an integrated operation, it would be at most 40 percent available in the eastern hardwood example. The primary economic factor is the cost of transportation to processing mills. The recoverability (i.e., the fraction of standing biomass removed offsite) of wood for bioenergy and biobased products is a function of tree form, technology, and timing of the removal of the biomass from the forests. In most cases, merchantable wood is removed, and the forest residues — in the form of limbs and tops, and small non-merchantable trees — remain scattered across the harvest area. This practice reduces recoverability when the biomass is removed in a second pass. However, when all biomass is harvested and processed using an integrated system, recovery is usually greatly improved, even greater than 90 percent. For example, a study by Stokes and Watson (1991) found that 94 percent of the standing biomass could be recovered when using a system to recover multiple products if the biomass from in-woods processing was actually utilized for bioenergy. 310 Private lands 5175 158 Other public lands 770 147 National forests 1849 0 Other forestlands Timberland 1000 2000 3000 4000 5000 6000 Million dry tons About 8.4 billion dry tons of treatable biomass is potentially available for bioenergy and biobased products. Figure 11: Total treatable biomass resource on timberlands and other forestlands 29 12 There is a concern about removal of large quantities of biomass from stands because of reduced long-term site productivity and loss of diversity and habitat associated with down-wood debris. Although the consequences are very site-specific, most negative impacts can be eliminated or minimized by leaving leaves, needles, and a portion of the woody biomass on site (Burger 2002). The 8.4 billion dry tons of treatable biomass that is potentially available for bioenergy and biobased products was reduced by the following factors (Table A.6, Appendix A): • To allay any concerns about site impacts, recovered material using an integrated system is limited to 85 percent. • Only 60 percent of the identified treatable areas are assumed to be accessible. • Fuel treatment material is recovered on a 30-year cycle before any sites are re-entered. • Harvested fuel treatment biomass is allocated into two utilization groups: (1) merchantable trees suitable for conventional or higher-value forest products as well as rotten trees, brush and understory, small saplings, and polewood trees; (2) the residues (e.g., tops, limbs, and branches) from the harvested larger trees suitable for bioenergy and biobased product uses. The conventional forest products fraction assumed is 70 percent, and the residue or bioenergy and biobased product fraction is 30 percent (USDA-FS, 2003). The combination of these factors significantly reduces the amount of fuel treatment biomass that can be sustainably removed on an annual basis. About 49 million dry tons can potentially be removed annually from timberlands, and about 11 million dry tons can be removed annually from other forestlands (Figure 12; Table A.7, Appendix A). Most of the fuel treatment biomass from timberlands would come from privately owned lands; slightly less than 20 percent of the material would come from national forests. In contrast, proportionately more of the fuel treatment biomass allocated to bioenergy and biobased products on other forestland land would come from publicly held lands. Most of 50 40 35.2 Million dry tons 30 20 9.4 10 2.2 0 National forest Other federal State & local Private 1.1 2.0 2.8 0.4 6.3 Forest Ownership Timberland Other forestland About 60 million dry tons can be removed from timberlands and other forestlands for fuel treatments. Figure 12: Fuel treatments on timberland and other forestland 30 13 these lands are located in the western regions of the country. The 60 million dry tons of fuel treatment biomass assumes that a relatively large percentage (70 percent) goes to higher-valued products. If feedstock prices for biomass were to increase relative to conventional forest products, the amount of biomass available for bioenergy and biobased products could increase substantially. 3.3.3 Forest Products Industry Processing Residues 3.3.3.1 Primary Wood Processing Mills The Forest Service classifies primary mill residues into three categories — bark, coarse residues (chunks and slabs), and fine residues (shavings and sawdust). In each of these categories, residues are further segmented into hardwoods and softwoods. Data on residue quantities are reported at any user-specified spatial scale, ranging from data of individual counties to state and national totals. Primary mill residues are desirable for energy and other purposes because they tend to be clean, uniform, and concentrated and have a low moisture content (< 20 percent). These desirable physical properties, however, mean that nearly all of these materials are currently used as inputs in the manufacture of products or as boiler fuel. Very little of this resource is currently unused. According to Forest Service estimates, about 80 percent of bark is used as fuel and about 18 percent is used in low-value products such as mulch (USDA-FS, 2004a). For coarse residues, about 85 percent is used in the manufacture of fiber products and about 13 percent is used for fuel. About 55 percent of the fine residues are used as fuel and 42 percent used in products. Primary timber processing mills (facilities that convert roundwood into products such as lumber, plywood, and wood pulp) produced 91 million dry tons of residues in the form of bark, sawmill slabs and edgings, sawdust, and peeler log cores in 2002 (USDA-FS, 2004a). Nearly all of this material is recovered or burned, leaving slightly less than 2 million dry tons available for other bioenergy and biobased product uses (Table A.8, Appendix A). 3.3.3.2 Secondary Wood Processing Mills Residues are also generated at secondary processing facilities — mills utilizing primary mill products. Examples of secondary wood processing mill products include millwork, containers and pallets, buildings and mobile homes, furniture, flooring, and paper and paper products. Since these industries use an already processed product, they generate smaller quantities of residues. In total, the secondary mill residue resource is considerably smaller than the primary mill resource (Rooney, 1998; McKeever, 1998). The types of residues generated at secondary mills include sawdust and sander dust, wood chips and shavings, board and cut-offs, and miscellaneous scrap wood. At the larger secondary mills, most of the residue produced is used on site to meet energy needs (such as heat for drying operations) or is recycled into other products. This is in contrast to practices at the smaller mills where much of the residue material goes unused (Bugelin and Young, 2002). The recovery of residue at smaller mills is more constrained because it may be generated seasonally and may be more dispersed. Neither the Forest Service nor any other federal agency systematically collects data on secondary mill residue. One of the few estimates of the amount of secondary mill residue available is provided by Fehrs (1999). He estimates that 15.6 million dry tons is generated annually, with about 40 percent of this potentially available and recoverable. The remaining fraction is used to make higher-valued products and is not available (Table A.8, Appendix A). 31 14 3.3.3.3 Pulp and Paper Mills In the manufacture of paper products, wood is converted into fiber using a variety of chemical and mechanical pulping process technologies. Kraft (or sulfate) pulping is the most common processing technology, accounting for over 80 percent of all U.S.-produced pulp. In Kraft pulping, about half the wood is converted into fiber. The other half becomes black liquor, a by-product containing unutilized wood fiber and valuable chemicals. Pulp and paper facilities combust black liquor in recovery boilers to produce energy (i.e., steam), and, more importantly, to recover the valuable chemicals present in the liquor. The amount of black liquor generated in the pulp and paper industry is the equivalent of 52 million dry tons of biomass (Table A.8, Appendix A). Because the amount of black liquor generated is insufficient to meet all mill needs, recovery boilers are usually supplemented with fossil and wood residue–fired boilers. The pulp and paper industry utilizes enough black liquor, bark, and other wood residues to meet nearly 60 percent of its energy requirements. Currently, the forest products industry along with DOE are looking at black liquor gasification to convert pulping liquors and other biomass into gases that can be combusted much more efficiently. 3.3.4 Urban Wood Residues There are two principal sources of urban wood residues: MSW and construction and demolition debris. MSW consists of a variety of items ranging from organic food scraps to discarded furniture and appliances. In 2001, nearly 230 million tons of MSW was generated (EPA, 2003). Wood and yard and tree trimmings are the two sources within this residue stream that are potentially recoverable for bioenergy and biobased product applications. The wood component includes discarded furniture, pallets, containers, packaging materials, lumber scraps (other than new construction and demolition), and wood residuals from manufacturing. McKeever (2004) estimates the total wood component of the MSW stream at slightly more than 13 million dry tons (Table A.9, Appendix A). About 55 percent of this material is either recycled as compost, burned for power production, or unavailable for recovery because of excessive contamination. In total, about 6 million dry tons of MSW wood is Additional Potential from Commercial Forest Thinnings in the U.S. South potentially available for recovery for bioenergy and This analysis does not include wood that is currently merchantable at the lower size biobased products. The other component of the and quality specifications for conventional products, such as pulpwood and small MSW stream — yard and tree trimmings — is sawlogs. Depending on local market conditions, i.e., low-price wood and/or highestimated at 9.8 million dry tons. However, only price oil markets, this resource could move between these markets and be an 1.7 million dry tons is considered potentially additional potential resource for bioenergy and biobased products. As an example, the southern U.S. has vast acreages of forests that are being commercially thinned to available for recovery after accounting for what is improve stand quality. Most of the wood goes to pulpwood, while some is used to currently used and what is unusable. The other principal source of urban wood residue is construction and demolition debris. These materials are considered separately from MSW since they come from much different sources. These debris materials are correlated with economic activity (e.g., housing starts), population, demolition activity, and the extent of recycling and reuse programs. McKeever (2004) estimates annual generation of construction and demolition debris at 11.6 and 27.7 million dry tons, respectively. About 8.6 million dry tons of construction debris and 11.7 million dry tons of demolition debris are considered potentially available for bioenergy and biobased products (Table A.9, Appendix A). Unlike construction debris, which tends to be relatively clean and can be more easily source-separated, demolition debris is often contaminated, making recovery much more difficult and expensive. make lumber and composite boards. It is projected that approximately 8 million dry tons could be available annually from such thinnings in the South. Forest Stand Type Planted pine Natural pine Oak-Pine Lowland Hardwood Upland Hardwood Total Million Dry Tons 6.7 1.1 <0.01 0.1 <0.001 7.9 Notes: Volumes are merchantable bole wood to a 4-inch top, inside bark. Residues from thinning, including tops and small-diameter trees are already accounted for in other sections of this report. For pine, it was assumed that 50% of the output would be pulpwood and that this material could possibly be used for energy (Clark and Shiver 2005). For the hardwood, 70% of the volumes were assumed to be the potentially available for bioenergy and biobased products. Source: Mills (2005) 32 15 All these sources of urban wood residue total 28 million dry tons. As noted by McKeever (1998), many factors affect the availability of urban wood residues, such as size and condition of the material, extent of commingling with other materials, contamination, location and concentration, and, of course, costs associated with acquisition, transport, and processing. 3.3.5 Forest Growth and Increase in the Demand for Forest Products The Fifth Resources Planning Act Timber Assessment projects the continued expansion of the standing forest inventory despite the estimated conversion of about 23 million acres of timberland into more developed uses (Haynes, 2003). The size of the standing forest inventory will increase because annual forest growth will continue to exceed annual harvests and other removals from the inventory. The forest products industry will continue to become more efficient in the way it harvests and processes wood products. The demand for forest products are also projected to increase. However, the increase will be less than historical growth owing to a general declining trend in the use of paper and paperboard products relative to GNP and the relatively stable forecast of housing starts (Haynes, 2003). The increase in the consumption of forest products will be met by an increase in timber harvests; an increase in log, chip, and product imports; and an increase in the use of recovered paper. Further, consumers will become more efficient in the use of wood products by generating fewer wood residues and increasing recycling rates. These changes and trends will affect the availability of forest residues for bioenergy and biobased products. An overall increase in the amount of biomass available due to changes in the demand and supply of forest products will increase the availability and use of forest residues by about 89 million dry tons annually by mid-21st century. Specifically, the availability of logging and other removal residues could increase by about 23 million dry tons over the current annual resource estimate of 41 million dry tons. Fuelwood harvested for space- and process-heat applications could increase by another 16 million dry tons over current levels. Wood residues and pulping liquors generated by the forest products industry could increase by about 16 and 22 million dry tons, respectively. And, the amount of urban wood waste generated could increase by 11 million dry tons over currently available amounts. 33 16 3.4 Forest Resources Summary Biomass derived from forestlands currently contributes about 142 million dry tons to the total annual consumption in the United Sates of 190 million dry tons. Based on the assumptions and conditions outlined in this analysis, the amount of forestland-derived biomass that can be sustainably produced is approximately 368 million dry tons annually — more than 2.5 times the current consumption. The distribution of this resource potential is summarized in Figure 13. This estimate includes the current annual consumption of 35 million dry tons of fuelwood extracted from forestland for residential, commercial and electric utility purposes, 96 million dry tons of residues generated and used by the forest products industry, and 11 million dry tons of urban wood residue. As discussed previously, there are relatively large amounts of forest residue produced by logging and land clearing operations that goes uncollected (41 million dry tons per year) and significant quantities of forest residues that can be collected from fuel treatments to reduce fire hazards (60 million dry tons per year). Additionally, there are some unutilized residues from wood processing mills and unutilized urban wood. These sources total about 36 million dry tons annually. About 48 percent of these resources are derived directly from forestlands (primary resources). About 39 percent are secondary sources of biomass from the forest products industry. The remaining fraction would come from tertiary or collectively from a variety of urban sources. 80 Million dry tons per year 60 16 8 16 22 40 15 11 49 20 32 35 8 9 0 F u el treatm en ts (T im b erlan d ) F u el treatm en ts (O ther forestlan d ) O th er rem oval resid ue L o gg in g residu e 46 52 28 11 W oo d resid ues (forest p ro du cts) P ulp in g liq u ors (forest p ro du cts) Fu elw o od 8 U rb an w o od resid u e 13% G ro w th U n exp lo ited E xistin g u se 13% 5% 13% 3% 14% 19% 20% Quantities shown do not add to 368 million dry tons due to rounding Figure 13: Summary of potentially available forest resources 34 17 4. Agriculture-Derived Biomass Resources 4.1 Agricultural Land Resource Base Agriculture is the third largest single use of land in the United States. In 1997, the year of the most recent complete land inventory, agricultural land totaled some 455 million acres — 349 million acres of land in active use to grow crops, 39 million acres of idle cropland (including land enrolled in the Conservation Reserve Program or CRP), and 67 million acres of cropland used as pasture (Figure 14) (USDA-NRCS, 2003a). The amount of agricultural land actively used to grow crops has varied from 330 to 380 million acres over the last 30 years. Cropland tends to move in and out of active production because of soil and weather conditions at planting time, expected crop prices, and the presence of government programs. Some cropland is also permanently converted to other nonagricultural uses. Between 1997 and 2001, seven million acres of active cropland were lost to other uses (USDA-NRCS 2003a). The agricultural land base considered for this resource analysis includes 342 million acres of active cropland, 39 million acres of idle cropland, and 67 million acres of cropland used as pasture (448 million acres total). All cropland acres are assumed to be potential contributors to agriculturally derived biomass feedstocks. Permanent pasture land might be another potential resource, but it is not considered in this analysis. 80 70 60 50 Million acres 40 30 20 10 0 Cro CR P pla nd pas tur e Un acc oun ted Ric e Oth er cro ps Fa llow &f aile d Co rn gra in Sm all gra ins So ybe an s Ha y Co fto n Sil age Corn grain, small grains (primarily wheat), and soybeans account for 60% of cropland use. Figure 14: Summary of cropland uses, idle cropland, and cropland pasture in the contiguous United States Source: Vesterby and Krupa, 2001 35 18 4.2 Agricultural Resources Grains and oilseeds are the primary feedstocks used to produce most of the ethanol, biodiesel, and bioproducts consumed today. Food and feed processing residues and tertiary post-consumer residues are also used to generate a modest amount of electricity. These agriculture-derived biomass resources account for nearly 25 percent of the current biomass consumption. This amount of biomass, however, is small relative to currently available agricultural biomass resources and tiny relative to agriculture’s full potential. With appropriate economic incentives, and improved cropping practices and technologies, such as higher-yielding plants and more efficient harvest equipment, significant amounts of agricultural crop residues, and food and feed processing residues could be sustainably produced. Moreover, the amount of sustainable biomass derived from agricultural land could be increased further by dedicating some land to the production of perennial grass and woody crops. U.S. agriculture has changed considerably since the early part of the 20th century (USDA-NASS, 2003a). The key technological drivers of this change were mechanization and dramatically increased yields of major grain and fiber crops. Mechanization dramatically reduced the need for horses for “horsepower,” and consequently oat production (for animal food) greatly declined. In the same time frame, soybean production increased but for different reasons (Figure 15). Increased crop yields were a direct result of research such as corn and wheat hybridization, and governmental price support policies. Agriculture also became more productive in the use of inputs to grow crops (Figure 16). A substantial increase in livestock production, especially cattle and poultry, also occurred. Driven by a need to reduce erosion, maintain soil structure and nutrients, and build soil carbon levels, agriculture adopted sounder environmental and conservation practices. For example, no-till cultivation, the most environmentally friendly production system, is now practiced on more than 62 million acres, and another 50 million acres are part of another conservation tillage system (CTIC, 2004). Crop rotation is also much more common. In the mid-1990s for instance, the practice of rotating corn with soybeans increased from nearly half to about two-thirds of the planted corn acreage. 80 70 60 Million acres 50 40 30 20 10 0 1900 1920 Oats 1940 1960 Soybeans 1980 2000 Major changes in crop use allocations have occurred over the past 60 years. Source: USDA-NASS, 2003a Figure 15: Harvested acres of oats and soybeans, 1900-2000 36 19 1.4 Relative ratio of output to input 1.2 1.0 0.8 0.6 0.4 0.2 0.0 1948 1958 Output 1968 Input 1978 Productivity 1988 1998 Agricultural productivity - a measure of output to input - has increased steadily over the last half century. Source: USDA-NASS, 2003a Figure 16: Agricultural productivity, 1948-1996 Agriculture is expected to continue to change and adapt to new technologies and circumstances. Biotechnology, for example, is transforming agriculture by making available genetically altered varieties of corn and soybeans. Biotech hybrids of corn now account for 40 percent of the total planted acreage (National Corn Growers Association, 2004). The future could also see agriculture becoming a more important supplier of bioenergy and biobased products to the U.S. economy. The production of ethanol from corn and other grains is projected to continue to grow (USDA-OCE, 2004, 2005). Biodiesel production has also grown significantly and could increase substantially in the future under an EPA mandate to reduce sulfur in diesel fuel (Stroup, 2004). The demand for new biobased products is also expanding. For example, innovative carbon-based technologies, such as the development of carbon-annotate fibers, could provide new markets for biomass. 4.3 Evaluating the Biomass Potential of Agriculture To assess the potential biomass contribution from agriculture, a number of scenarios were evaluated. These scenarios include various combinations of changes in the following: yields of crops grown on active cropland, crop residue-to-grain or -seed ratios, annual crop residue collection technology and equipment, crop tillage practices, land use change to accommodate perennial crops (i.e., grasses and woody crops), biofuels (i.e., ethanol and biodiesel), and secondary processing and other residues. Crop yields are of particular importance because they affect the amount of residue generated and the amount of land needed to meet food, feed, and fiber demands. 37 20 The following three scenarios are summarized in this report: Scenario 1: current availability of biomass feedstocks from agricultural land; Scenario 2: biomass availability through a combination of technology changes focused on conventional crops only; and Scenario 3: biomass availability through technology changes in both conventional crops and new perennial crops together with significant land use change. The types of crop technology changes assumed include yield increases, more efficient harvest technology, changes in tillage practice, and, for scenario three only, changes in residue to grain ratios. The agricultural biomass resources considered for each of these scenarios include residues from major crops, grains and oilseeds used for ethanol and biodiesel production, and residues and waste resources. Switchgrass and hybrid poplars are assumed for perennial crops, but any fast growing grasses or trees could be used. For the three major crops (corn, wheat, and soybeans), a comparison among the USDA baseline and Scenarios 2 and 3 is summarized in Table B.1, Appendix B. 4.3.1 Scenario 1: Current Sustainable Availability of Biomass from Agricultural Lands Current availability is the baseline that summarizes sustainable biomass resources under current crop yields, tillage practices (20-40 percent no-till for major crops), residue collection technology (~40 percent recovery potential), grain to ethanol and biodiesel production, and use of secondary and tertiary residues. In sum, the amount of biomass currently available for bioenergy and bioproducts is about 194 million dry tons annually (Table B.2, Appendix B). This is about 16 percent of the 1.2 billion dry tons of plant material produced on agricultural land. It includes 113 million dry tons of crop residues, 15 million dry tons of grain (starch) used for ethanol production, 6 million dry tons of corn fiber, and 60 million dry tons of animal manures and residues (e.g., MSW and animal fats). The single largest source of this current potential is corn residues or corn stover (Figure 17; Table B.2, Appendix B), totaling close to 75 million dry tons. Other residues 31 Manures 35 Grains to biofuels 15 Other crop residues 6 11 21 Small grain residues Wheat straw 75 Corn stover 0 10 20 30 40 50 60 70 80 Million dry tons per year The total current availability of biomass from cropland is approximately 194 million dry tons/year. Slightly more than one-fifth of this biomass is currently used. Corn stover is a major untapped source of agriculture-derived biomass. Small grain residues include sorghum, barley, oats, and rice. Other crop residues include cotton, other oil seeds (e.g., sunflower, peanuts, canola), tobacco, sugar crops, potatoes, beans, miscellaneous root crops, and double crops. Other residues include secondary agricultural processing residues, MSW, and fats and greases. Figure 17: Current availability of biomass from agricultural lands 38 21 4.3.2 Scenario 2: Technology Change with Conventional Crops Only (No Land Use Change) Scenario 2 assumes an increase in crop yields for corn by 25-50 percent. Yields of wheat and other small grains, sorghum, soybeans, rice, and cotton are assumed to increase at rates lower than for corn. The rates of increase of all crops are the same as those used by USDA-OCE (2004, 2005) in their Baseline Projections (The USDA baseline for three major crops is summarized in Table B.1, Appendix B.). Acres for each crop are fixed at levels predicted for 2014 by USDA-OCE (2005). Soybeans contribute no crop residue under a moderate yield increase (~ 13 percent) but make a small contribution with a high yield increase (~23 percent). Collection equipment is assumed to be capable of recovering as much as 60 percent of residue under the moderate yield increases and 75 percent under the high yield increases but the actual removal amounts depend on the sustainability requirements. No-till cultivation is assumed to be practiced on approximately 200 million acres under moderate yield increases and all of active cropland under high yields. The amount of corn and soybeans available for ethanol, biodiesel or other bioproducts was calculated by first subtracting amounts needed to meet food requirements plus feed and export requirements. All remaining grain was assumed to be available for biofuels. This worked out to a more than three-fold increase over 2001 levels under the moderate yield increase and more than a five-fold increase under the high yield increase. Soy oil used for biodiesel increases dramatically from the 2001 level under both moderate and high yield increases. Further, about 75 million dry tons of manure and other secondary and tertiary residues and wastes, and 50 percent of the biomass produced on CRP lands (17 to 28 million dry tons) are assumed to be available for bioenergy production. Attaining these levels of crop yield increase and collection will require a continuation of research, deployment of new technologies, and incentives. Past trends indicate that such increases are certainly doable. This intensive scenario for use of crop residue results in the annual production of 423 million dry tons per year under moderate yields and 597 million dry tons under high yields (Figure 18; Tables B.3 and B.4, Appendix B). In this scenario, about two-thirds to three-fourths of total biomass are from crop residues. Other residues Manures Grains to biofuels CRP biomass Other crop residues Soybean residues Small grain residues Wheat straw Corn stover 0 High yield increase Moderate yield Increase 50 0 0 25 15 28 28 44 40 44 44 97 56 48 37 57 35 256 170 100 150 200 250 300 Million dry tons per year Total availability of biomass from cropland ranges from 423 to 597 million dry tons per year at crop yield increases of 25% (moderate) and 50% (high) for corn and various rates of increase for other crops. Moderate and high changes in tillage practices and residue collection technology and equipment are also assumed. (Quantities shown do not add to 423 and 597 million dry tons due to rounding.) No changes in the current allocation of cropland are required to attain these levels of biomass. Small grain residues include sorghum, barley, oats, and rice. Other crop residues include cotton, other oil seeds (e.g., sunflower, peanuts, canola), tobacco, sugar crops, potatoes, beans, miscellaneous root crops, and double crops. Other residues include secondary agricultural processing residues, MSW, and fats and greases. Figure 18: Availability of biomass under increased crop yields and technology changes 39 22 4.3.3 Scenario 3: Technology Change with Perennial Crops And Land Use Change Scenario 3 assumes the addition of perennial crops to the landscape, land use changes and changes in soybean varieties, as well as the technology changes assumed under the previous scenario. Soybean varieties are assumed to transition from an average residue-to-grain ratio of 1.5 to a ratio of 2.0 as current varieties are partially replaced with varieties that produce 50 to 100 percent more residue but maintain similar grain yields. The land use changes include the conversion of either 40 or 60 million acres to perennial crop production associated with moderate and high yield increases, respectively. Woody crops produced for fiber are expanded from 0.1 million acres to 5 million acres, where they can produce an average annual yield of 8 dry tons per acre. Twenty-five percent of the wood fiber crops are assumed to be used for bioenergy and the remainder for other, higher-value conventional forest products. Perennial crops (trees or grasses) grown primarily for bioenergy expand to either 35 million acres at 5 dry tons per acre per year or to 55 million acres with average yields of 8 dry tons per acre per year. Ninety-three percent of the perennial crops are assumed available for bioenergy and the remainder for other products. A small fraction of the available biomass (10 percent) is assumed lost during the harvesting operations. This scenario results in the production of 581 to 998 million dry tons (Figure 19; Tables B.5 and B.6, Appendix B). Crop residues increase even though conventional cropland is less because of the addition of more soybean residue together with increased yields. The single largest source of biomass is the crop residue, accounting for nearly 50 percent of the total produced. Perennial crops account for about 30 to 40 percent depending on the crop yield increase (i.e., moderate or high). Other residues Manures Grains to biofuels CRP biomass Other crop residues Soybeans Small grain residues Wheat straw Corn stover Perennial crops 0 High yield increase Moderate yield increase 50 13 25 15 18 18 44 40 44 44 87 56 47 36 48 52 35 256 170 377 156 100 150 200 250 300 350 400 Million dry tons per year Total availability of biomass from cropland, idle cropland, and cropland pasture ranges from 581 to 998 million dry tons per year at crop yield increases of 25% (moderate) and 50% (high) for corn and various rates for other crops. Changes in tillage practices, residue to grain and seed ratios, and residue collection technology and equipment are also assumed. (Quantities shown do not add to 581 million dry tons due to rounding.) The allocation of some active cropland, idle cropland, and cropland pasture to perennial crops is required to attain this level of annual biomass production. Small grain residues include sorghum, barley, oats, and rice. Other crop residues include cotton, other oil seeds (e.g., sunflower, peanuts, canola), tobacco, sugar crops, potatoes, beans, miscellaneous root crops, and double crops. Other residues include secondary agricultural processing residues, MSW, and fats and greases. Figure 19: Availability of biomass under increased crop yields, technology changes, and inclusion of perennial crops 40 23 4.4 Factors Increasing Biomass Resources from Agriculture 4.4.1 Crop Yields Corn grain yields have risen dramatically and steadily over the past 35 years (1965-2000) at an average annual change of 1.7 bushels per acre even while fertilizer inputs have declined (Figure 20) (Dobermann et al., 2002). Continuing increases at the level currently used by USDA for projections (1.8 bushels per acre) will result in a 25 percent yield increase (173 bushels per acre) by 2020 and a 50 percent yield increase (207 bushels per acre) by 2043. This translates to an actual crop yield rate of increase that is less than the current rate of nearly 1.2 percent per year to about 0.9 percent per year by 2030 — a prediction made by FAO (2003). Crop yields and acreage for 2001 were obtained from published agricultural statistics (USDA-NASSa; USDA-NRCS, 2003a). Acreage for conventional crops in the future scenarios are based on the acres projected to be in production in 2014 by USDA-OCE (2005). The high yield expectation of 207 bushels per acre is very reasonable (even conservative) given that this yield level remains well below the projected average corn yield potential of about 300 bushels per acre in both irrigated and rainfed corn belt areas, where soil moisture is generally not a limiting factor. This is based on corn yield simulation models developed at the University of Nebraska (Arkebauer et al., 2004). In recent years, record corn yields have been virtually the same between irrigated and rainfed acreage (Doberman et al. 2003). The adoption of new varieties with many genetic improvements, including the Bt genetic modification and increases in corn planting density, have been crucial in achieving these results. Recent corn selection techniques have optimized genotype/environment interactions leading to increased yield stability and stress tolerance (e.g., tolerance to higher planting densities) (Tollenaar and Lee, 2002). Research results 180 160 140 Bushels per acre 120 100 80 60 40 20 0 1900 1920 1940 1960 1980 2000 Corn grain yields have increased steadily throughout the latter half of the 20th century. Source: USDA-NASS, 2003a Figure 20: Average corn yields, 1900-1999 41 24 and recommendations by Pioneer Hi-Bred Ltd. suggest that increasing the density of corn plantings is a trend that will continue since it can increase profit in many situations (Paszkiewicz and Butzen, 2003). Increasing wheat grain yields by 25 to 50 percent is considered doable but probably not in the same time frame as corn. The most recent estimates from the Wheat Improvement Center in Mexico City (CIMMYT, 2002) show annual yield increasing by 1.7 percent per year in the United States for 1988-2000, higher than the average yield increase rate of 1.3 percent observed in the 1977-988 period. However, a concern is that most genetic research on wheat in the United States currently focuses on developing dwarf varieties (which would reduce residue-to-grain ratios), and increasing disease resistance rather than yields. Only a small amount of research is focused on improving tall wheat varieties. The rate of yield increase assumed by USDA for the next 10 years is about 1.3 percent per year, resulting in a 20 percent increase in wheat grain yields by 2020. The big unknown factor for wheat and other small grains is the effect of biotechnology. A technology being aggressively pursued that could affect wheat is asexual reproduction (Pollack, 2000). Asexual reproduction would allow seeds to be exact genetic copies, or clones, of the parent. If commercially successful, this technique would accelerate breeding, allow genetic adaptation of plants to specific micro-climates, and allow the ability to create and stabilize new genetic combinations. Major biotechnology and seed companies as well as the USDA, universities, and small private groups were all actively pursuing research in the late 1990s (GRAIN, 2001). However, according to Doanes Agricultural Report (February 25, 2005), many research groups are hesitating to pursue biotechnology advancements in wheat due to declining profit margins, for example, Monsanto Company has shelved its plans to offer herbicide resistant wheat. The same Doanes report indicated that the National Association of Wheat Growers is supportive of the use of biotechnology advancements to stay competitive. Wheat Associates is initiating a plan to begin promoting the safety and benefits of biotech wheat. Among the plant growth factors that pose barriers to yield increase, soil moisture is the most limiting factor. Thus, continued selection for stress tolerance, including tolerance to moisture deficits, will be critically important to achieving a crop’s potential yield. While climate change could modify yield potential, a review of climate change impacts on agriculture suggests that the net effects of a doubling of carbon dioxide levels on agriculture may be small if the agricultural community is adaptive (Adams et al. 1999). 4.4.2 Residue-to-Grain or -Seed Ratios The ratio of crop residues to grain is a key variable that has a significant effect on estimates of the availability of biomass. Since grain yields are reported annually, but “biomass” yields are not, an estimate of the relationship between the two is necessary for estimating biomass yields. A wide variation in residue-to-grain ratios exists in the literature. For this analysis, the baseline ratio of crop residues to grain is derived from the Soil Conditioning Index (SCI) of the USDA National Resource Conservation Service Soil (USDA-NRCS, 2003b). If different ratios are given for the same crop, the one associated with conditions that represented the largest crop acreage was used. Clearly, the ratio of residue to grain (or its inverse, the harvest index) does vary within crops from year to year and according to the time of harvest, variety, and density of planting. Prihar and Stewart (1990) indicate that harvest index increases with increasing total yields and decreasing crop stresses. This tendency was also shown in experiments in Minnesota reported by Linden et al. (2000). However, these results contrast with those published by Doberman et al. (2003), where harvest index was found to decrease slightly under the highest yield conditions in Nebraska experiment trials. The salient difference is that the highest yield conditions in Nebraska were associated with higher-density plantings. Tollenar and Lee (2002) report that the corn harvest index has not shown a clear trend in the past seven decades except where plants are grown at higher densities, in which case it decreases. The lowest harvest index measured in the Nebraska experiments, even at the highest density, was 0.49 (Yang et al., 2004). In this analysis, it is assumed that corn stover-to-grain ratios remain at 1:1 on a dry weight basis under all scenarios. It was necessary to adjust the weights published for crops in agricultural statistics (USDA-NASS, 2003b) to a dry weight based on assumed moisture content at harvest (Gupta, 1979). Information on moisture contents were found in Hellevang (1995). A change in the residue-to-grain ratio is a possible technology change that could occur for any crop. In this assessment, however, a ratio change was assumed only for soybeans which presently do not contribute to the removable residue estimates. Most, if not all, soybean residue needs to be left on the ground to meet conservation 42 25 practice requirements. USDA genetic improvement research in soybeans at Beltsville, Maryland has focused on developing varieties that have a higher ratio of straw to beans, grow taller, have improved lodging resistance, have a better over-winter residue persistence, and are able to attain these traits without genetic transformation (Figures 21 and 22). Originally the soybean program was geared to develop larger biomass soybeans for forage production and resulted in three varieties (Devine and Hatley, 1998a, 1998b, 1998c). A recently released variety for the southeast, Tara (Devine and McMurtrey, 2004), has the characteristics of a 1.75 residue-to-grain ratio without sacrificing expected levels of grain yield. It is evident from data on the forage soybean varieties that the potential exists to produce 100 percent more crop residue and thus provide more soil conservation benefits than the conventional varieties (Wu et al., 2004). It cannot be predicted whether farmers will adopt these new varieties, but clearly the technology will be available. Potentially, with such varieties soybean acreage could contribute to the availability of residues for bioenergy and biobased products. Figure 21: Breeding of new giant soybean cultivars for forage production. (Photo by Scott Bauer, USDA, Agricultural Research Service, Beltsville, Maryland) 4.4.3 Residue Collection Technology for Annual Crops Most residue recovery operations today pick up residue left on the ground after primary crops have been harvested. Collection of residues from these crops involves multiple passes of equipment over fields and results in no more than 40 percent removal of stover or straw on average. This low recovery amount is due to a combination of collection equipment limitations, contour ridge farming, economics, and conservation requirements. It is possible under some conditions to remove as much as 60-70 percent of corn stover with currently available equipment. However, this level of residue collection is economically or environmentally viable only where land is under no-till cultivation and crop yields are very high. This analysis assumes that the harvest technology and the percentage of cropland under no-till management are increased simultaneously. Future residue collection technology with the potential of collecting up to 75 percent of the residue is envisioned (DOE, 2003). These systems are likely to be single-pass systems that would reduce costs by collecting the grain and residue together. Single-pass systems will also address concerns about soil compaction from multiple pieces of residue collection equipment, unless the single pass system is heavier than the current grain harvesters (Wilhelm et al. 2004). Further, one-pass systems for corn and grain will need to have selective harvesting capability so that some portions of the residue stream can be reapplied to the field to meet conservation requirements. Figure 22: Soybean residues from large biomass (top) and conventional soybeans (bottom) (Source: Wu et al., 2004) 43 26 4.4.4 Cropland Tillage No-till planting systems are now used on more than 60 million acres in the United States, surpassing mulch till as the favored form of conservation tillage (Figure 23) (CTIC, 2004). With the concerted effort by USDA to educate farmers and conservation advisors, it is anticipated that acres designated for no-till cultivation and other types of conservation tillage will increase in the future. One example of the USDA effort is the CORE4 Conservation Training Practices Guide (USDA-NRCS, 1999). Developing a single national estimate of the amount of residue that must remain on the ground to maintain soil sustainability for any given set of conditions is a challenge. Residue maintenance requirements (RMRs) are most properly estimated at the individual field level with models such as RUSLE (Revised Universal Soil Loss Equation), used together with the SCI (soil conditioning index) tool as described in the National Agronomy Manual (USDA-NRCS, 2002). However, using this approach to provide a national estimate would require actual data from hundreds of thousands of specific locations. Nelson (2002) developed a methodology for making a national estimate that reflected the RUSLE/SCI modeling approach in that it considered soils, rainfall, crop and rotation choices, and tillage choices in determining the amount of residue required to minimize erosion to T (tolerance) levels recommended by USDA. Nelson is a co-author on the Graham et al., (2004) analysis that produced estimates of residue maintenance requirements on land with corn as a rotation crop (using 1995 to 2000 data). Walsh (2004) also relied on Nelson’s approach in developing updated estimates of corn and wheat residue. Both the unpublished Graham et al. and Walsh analysis studies were used to derive national estimates of average RMRs for corn and wheat land. Estimating national-level RMRs under various scenarios for corn land was done by creating factors using the Graham et al., (2004) analysis. Thus, the calculation – (Sustainably Available Residue Estimate/Total Residue) / Acres Harvested – gave an average national RMR factor (in lbs or tons/acre) for minimizing erosion on corn land for current till and all notill cases. The current-till RMR factor was used in the 2001 base case; the all-no-till RMR factor was used in the land 35 29.3 30 25 Million acres 20 15.8 15 No-till farming for corn (USDA Photo by: Gene Alexander) 10 6.7 4.4 2.4 1.7 5 0 Soybeans Corn Winter wheat Spring small grains Cotton Sorghum Source: Conservation Technology Information Center ( www.ctic.purdue.edu ) Figure 23: Crops under no-till cultivation 44 27 change–high yield scenario; and an RMR factor halfway between was used in the land change–moderate yield scenario. This resulted in estimation of removal rates of 33 percent, 54 percent, and 68 percent respectively under current tillage mix, increased no-till and all no-till scenarios. For wheat, a similar development of RMR factors was done using results from the updated 2004 analysis by Walsh. Estimated sustainable removal rates were 14 percent, 34 percent, and 48 percent respectively. Development of the soybean RMR factors relied on first calculating an average of the residue maintenance requirements found in the SCIVER25 worksheet from the top five soybean-producing states, adjusting that value based on the soybean residue equivalency value (to corn), and finally, further adjusting the value for no-till conditions for conventional and large biomass soybean (LBS) varieties based on discussions in 2004 with Jim McMurtrey, a member of the soybean research team in Beltsville, Maryland. McMurtrey et al. (in press) found that LBS varieties provided 40-100 percent more residue cover than conventional soybeans, not only because of higher biomass but also because the decomposition of the LBS varieties is slower. Estimated sustainable removal rates were 0 percent for conventional soybeans in all scenarios and 0 percent, 7.4 percent, and 30 percent respectively for LBS varieties under current tillage mix, increased no-till, and all no-till scenarios. The current goal of soil conservation is not just to manage for minimizing erosion but also to increase soil carbon (Puckett, 2003). Practices that enhance soil carbon include high biomass yields, cover crops, reduced or no tillage, rotational grazing, and establishment of perennial crops. All practices except grazing also have the potential of increasing sustainably removable biomass, although the requirements for maintaining or increasing soil carbon may be higher in some locations than the requirements for meeting the soil loss tolerance (T) levels. With annual crop production, the largest increases in soil organic matter will result from continuous no-till cultivation. Leaving the root structure of plants undisturbed is vital to the success of no-till cultivation in increasing soil carbon, in most cases, more so than leaving crop residues on the surface (USDA-NRCS, 1999). Research results on factors affecting soil organic matter or soil carbon are varied depending on soil types, rainfall conditions, crop types and varieties, and tillage methods; thus, work is needed by agronomists and soil scientists to develop recommendations on removal rates that consider specific site conditions (Wilhelm et al. 2004). Nevertheless, it is safe to say that some residue will nearly always need to be left to maintain soil moisture and quality (i.e., nutrients and organic matter), limit rainfall and wind erosion, and maintain or increase soil carbon levels, but the amount that can be taken off sustainably is expected to increase as crop yields and total residue produced increase. 4.4.5 Allocation of Cropland Acres to Perennial Crops It is assumed that significant amounts of land could shift to the production of perennial crops if a large market for bioenergy and biobased products emerges. Studies by de la Torre Ugarte et al. (2003) and McLaughlin et al. (2002) indicate that this could happen today if the price for energy crops were high enough to attract the interest of farmers. These authors report that if a farmgate price of about $40 per dry ton were offered to the farmers, perennial grass crops producing an average of 4.2 dry tons per acre (a level attainable today) would be competitive with the current crops on about 42 million acres of cropland and CRP land. The high-yield scenario for perennial crops in this assessment assumes an average crop yield of 8 dry tons per acre, an amount considered feasible by grass researchers provided there is a concomitant increase in R&D. Current average annual yields from switchgrass clones tested in small plots over multiple years at twenty-three locations in the United States range from a low of 4.2 dry tons per acre to a high of 10.2 dry tons per acre, with most locations having an average between 5.5 and 8 dry tons per acre (McLaughlin and Kszos, 2005). Yields from the best clones were generally 8 dry tons per acre or higher. The highest observed yield at any location or in any year was 15.4 dry tons per acre. The best-performing clones were often the same at a majority of the twenty-three sites spread over the Great Plains, the Midwest, and the South. None of the test plots were irrigated. Assuming an intensive genetic selection and research program on grasses, the feasibility of attaining average yield of 8 dry tons per acre over millions of acres is supported by modeling (McLaughlin and Kszos, 2005). For woody crops, annual yields have been 45 28 generally 5 dry tons per acre in most locations and are currently achieving more than 8 dry tons per acre in commercial plantings in the Pacific Northwest. These test data alone suggest that future yields estimated for perennial crops are well within reason, if not conservative. Yields from small plots are not likely to be representative of average yields across the millions of acres assumed in the perennial crop scenarios. However, with the genetic variability existing in switchgrass and woody crops, the potential for continued yield increases and attainment of 8 dry tons per acre averaged over millions of acres is very high. The technology change with land use change scenario (Scenario 3, Section 4.3.3) assumes that as many as 60 million acres of cropland, cropland pasture, and CRP are shifted to perennial crop production, including grass and woody crops. Forest Service projections of possible expansion of short-rotation woody crop technology were used as the basis for assuming that 5 million acres are shifted to woody crops (Ince, 2001). It was assumed, however, that 75 percent of the harvested wood goes to fiber and 25 percent is available for energy. On the remaining 55 million acres, it is assumed that 93 percent of the perennial crops are used for energy less losses in harvesting operations. Whether the perennial crops are primarily wood or grass may depend on whether the bioenergy emphasis is on fuels or power. Figure 24 summarizes the change in land use among the three broad categories of agricultural land (i.e., active cropland, idle cropland, and cropland pasture) among scenarios under moderate and high crop yield increases. In all cases, USDA baseline projections for food and feed demands continue to be met. Sce na rio 3 High yie ld incre a se 319 27 43 60 Sce na rio 3 Mode ra te yie ld incre a se Sce na rio 2 Mode ra te & high yie ld cha nge Scena rio 1 Curre nt la nd use a lloca tion 0 100 339 27 43 40 344 37 68 344 37 68 200 300 400 500 Million acres Active cropland Idle land (CRP) Cropland pasture Perennial crops Figure 24: Summary of the allocation of agricultural land under alternative scenarios 46 29 4.4.6 Grain to Ethanol or bioproducts and Soybeans to Biodiesel The USDA Office of the Chief Economist projects that under business-as-usual conditions, acreage planted for the eight major crops grown in the United States will decrease by 1 million acres between 2003 and 2013 but harvested acres will increase by 9 million acres (USDA-OCE, 2004). This would suggest that fewer crop failures are expected. All crop use categories increase, with grain to ethanol showing the largest relative increase and exports also significantly increasing. To create scenarios beyond 2013, world population and crop yield trends published by the United Nations Food and Agricultural Organization were considered (UN, 2003 and FAO, 2003). Projections suggest that the North American population will increase by 37 percent between 2001 and 2050 while the world population increase will be only slightly higher. Thus, in the highest crop yield scenarios, corn required for food in the United States is assumed to increase by 37 percent over the 2001 value. The FAO (2003) predicts that export demands from industrial countries will continue to increase through 2030 but at a slowing rate. The USDAOCE (2005) predicts that export demand for corn through 2014 will rise, primarily because of increasing demand for animal feed. This evaluation assumes that corn exports rise by another 10 percent in the high corn yield scenarios. The USDA-OCE (2005) also predicts that exports of wheat and soybeans will remain level through 2014 because of increasing foreign competition. The scenarios assume level export demand after 2014 in wheat and soybeans. The USDA-OCE (2005) projects that demand for corn grain for ethanol will increase from 714 million bushels in 2001 to 1750 million bushels in 2014 or from 7.5 percent to about 14 percent of total corn grain production (Table B.1, Appendix B). This evaluation assumes that food, feed, and export demands are met first and then ethanol (or other bioproducts) is produced from the remaining grain. The results show that with a 50 percent increase in corn yield and land at the 2014 level, over 3,950 million bushels of grain would be available for ethanol or bioproducts. Urbancheck (2001) projected that ethanol use could increase to 8.8 billion gallons in the future; this amount would require 2,464 million bushels. Thus, significant potential exists for meeting increased corn grain demand for both ethanol and bioproducts. The USDA-OCE (2005) projections to 2014 show domestic use of soybeans increasing due to more demand for pork and poultry, but planted and harvest acres of soybeans are projected to decline slightly because of increasing yields. Although the USDA-OCE reports do not project soybean use for biodiesel, biodiesel production from soybeans has already more than doubled from 12.5 million gallons in 2001 to more than 25 million gallons in 2004. Expectations are that demand will continue to rise. Stroup (2004) noted that a “big looming potential for biodiesel is the use of biodiesel blends for transportation fuel” – a possibility that could result from a proposed EPA mandate to reduce sulfur in diesel fuel. This assessment assumes that all soybeans not needed for food, feed, or export could be used to make biodiesel or other industrial products. The maximum amount available is 297 million bushels under the high-yield, no perennial crop scenario which could result in 415 million gallons of pure biodiesel. Soybeans available for biodiesel are reduced to a negative value when 8 million acres of soybeans are assumed to be converted to perennial crops and food requirement demands are also increased by 37 percent similar to corn. Market conditions would determine whether reductions would actually occur in the food, feed, export, or fuel components or indeed whether the acreage reduction would occur in other land uses. 4.4.7 Secondary Processing and Other Residues The largest potential single source of biomass from food/feed processing and post consumer wastes is animal manure. Manure can be readily collected from confined animal feeding operations (CAFOs), which continue to increase in number and size. In the recent past, CAFOs for cattle and hogs have increased slightly while those for poultry increased considerably. 47 30 Data published by USDA on manure production in CAFOs (USDA-ERS, 2001) and studies estimating the amounts of recoverable nitrogen and phosphorus (Kellog et al., 2000; Gollehon, 2002) were used to determine collectable and recoverable dry weights of manure. All future scenarios assume some increase in manure collected. One could assume that all collectable manure is available for bioenergy, however, it was assumed that only the portion in excess of the amounts that can be applied on-farm without exceeding EPA mandated criteria, is available. Estimates of that excess amount are also derived by Kellog et al. (2000) and Gollehon (2001). Of course, manure will need to be handled differently than most other biomass resources. Its use is dependent on development of appropriate technologies and would be best utilized on farm or very close to the source. Approximately 20 percent of the corn kernel is not utilized in the production of ethanol and other starch based products, such as sweeteners and high-fructose corn syrup. It is an excellent near-term biomass resource for bioproducts. Based on NCGA information, it appears that about 90 percent of all corn grain grouped by USDA in the category of food, seed and industrial uses is being processed in a way that results in corn fiber production. The corn fiber produced as a byproduct of ethanol dry mills, DDG (dry distillers grain) is sold for animal feed. It is estimated that about half of the corn fiber produced is (or will be used) for animal feed while the remainder is (or could be) used for bioproducts. The amount of corn fiber available for bioproducts in 2001 was a little over 6 million dry tons. With corn yield increases of 25 percent, corn fiber not used for cattle feed increases to over 8 million dry tons, and with a 50 percent corn yield increase, it increases to over 12 million dry tons. The utilization of other secondary sources of wastes from food and feed processing and tertiary wastes, such as MSW and gas, may be important at a few locations but were not large enough overall to include in a significant way in this evaluation. 48 31 4.5 Agricultural Resources Summary The amount of biomass sustainably removable from agricultural lands is currently about 194 million dry tons annually. This amount can be increased fivefold to nearly 1 billion dry tons within 35 to 40 years through a combination of technology changes (e.g., higher crop yields and improved residue collection technology), adoption of no-till cultivation, and changes in land use to accommodate large-scale production of perennial crops. These results are graphically summarized in Figure 25. By comparison, the total amount of biomass produced on this acreage is 2.1 billion dry tons. There is a large increase both in total amount of plant matter produced due to higher crop yields and in the available biomass due to changes in tillage practices and harvest technology. Without the addition of perennial crops targeted toward biomass production, the maximum amount of sustainably removable biomass would be about 600 million dry tons under the high technology change assumptions. Approximately the same amount of biomass could be produced on agricultural lands within 15-20 years with moderate changes in future yields (e.g., 25 percent for corn), less residue recovery, and less no-till cultivation, provided perennial biomass crops are substituted for other land uses on at least 40 million acres of land. Most of this land could come from idle land (summer fallow and CRP) and cropland pasture. Use of about 15 million acres of active cropland is assumed. Perennial crops with land use change High crop yield increase 446 87 87 377 Mode ra te yie ld incre a se 286 56 84 156 No perennial crops High crop yield increase 413 97 87 Mode ra te yie ld incre a se 284 53 84 0 200 400 600 800 1000 1200 Million dry tons per year Crop residues Grains to biofuels Process residues Perennial crops Figure 25: Summary of potentially available agricultural resources Some factors not considered could limit the maximum amount of biomass estimated to be available. First, if demand for meat production increases (rather than remaining level), it will be more difficult to convert conventional cropland into perennial crop production. Of course, greater animal production would result in more byproducts from the animals (manures, and oils and grease from animal rendering). Second, higher export demands for wheat and soybeans could limit conversion of cropland to perennials. Third, if the total cropland base becomes less due to encroachment of urban populations, cropland conversion will also be less likely to occur. Fourth, the process used for adjusting residue availability as a function of tillage may not fully account for amounts needed to maintain or increase carbon in soils. This assessment also did not account for the use of residues by cattle for forage, which was estimated to equal about 12 million dry tons based on 1997 cattle populations (Gallagher et al., 2003). With the trend toward increasing the proportion of cattle reared in CAFOs, the demand for forage is likely to be decreasing. 49 32 In contrast, other scenario assumptions could increase the maximum amounts of biomass estimated to be available. For instance, the crop yield increases assumed are essentially business-as-usual expectations. None of the scenarios consider the possibility that technology could overcome yield limitations caused by drought and pests or increase nutrient use efficiency. Also, adoption of new cropping technologies in developing countries could further reduce export demands on the United States. Second, it is just as logical to assume that future meat demands will decline rather than increase. Populations will be aging, thus requiring less protein for sustenance. Further, trends towards healthier eating practices may cause reduced meat demand, at least in the industrialized countries. These results are believed to be a reasonable, if not conservative, estimates of future biomass potential in the United States. 50 33 5. Potential Concerns and Impacts Forestland and cropland resources have the potential to provide for a seven-fold increase in the amount of biomass currently consumed for bioenergy and biobased products. This annual potential exceeds 1.3 billion dry tons — the equivalent of more than one-third of the current demand for transportation fuels. More than 25 percent of this potential would come from extensively managed forestlands and about 75 percent from intensively managed croplands. The major primary resources would be logging residues and fuel treatments from forestland, and crop residues and perennial crops from agricultural land. Some additional quantities of biomass would be available from secondary sources; however, most of this biomass would be expected to be used by the forest products industry and food processing industries. Tertiary or residue sources of biomass are small relative to the primary sources. A sizeable fraction of this potential would be captive to existing uses. Examples are most of the biomass resource generated by the forest products industry, fuelwood extracted from forestlands, some urban wood residues, grains used in the production of biofuels, and some agricultural residues. Excluding these captive uses of biomass from the total resource potential still shows 220 million dry tons of forestland biomass (logging residue, fuel treatments, urban wood residues) and, depending on crop yield improvements, 450 to nearly 850 million dry tons of cropland biomass (agricultural residues, perennial crops, and most process residues) as potentially available for new bioenergy and biobased product uses (Figure 26). Producing one billion tons or more of feedstock annually will require technologies that can increase the utilization of currently available and underutilized feedstocks, such as agricultural residues and forest residues. It will require the development of perennial crops as an energy resource on a relatively large scale. It will require changes in agricultural and silvicultural crop management systems. Production yields from these systems will need to be increased and costs lowered. Changes in the way biomass feedstocks are collected or harvested, stored and transported, and preprocessed will also have to be made. Accomplishing these changes will obviously require investments and policy initiatives as well as the coordinated involvement of numerous stakeholder groups to gain broad public acceptance. Much more program coordination among the Departments of Energy and Agriculture and other federal, state, and local agencies will be necessary to attain the billion-ton feedstock goal. The utilization of a significant amount of these biomass resources would also require a concerted R&D effort to develop technologies to overcome a host of technical, market, and cost barriers. Demonstration projects and incentives (e.g., tax credits, price supports, and subsidies) would be required. Additional analyses would be required to discern the potential impact that large-scale forest and crop residue collection and production of perennial crops could have on traditional markets for agricultural and forest products. These policy considerations are very important but were certainly well beyond the limited technical scope of this resource assessment. The remainder of this assessment focuses on utilization issues and analysis limitations. 5.1 Forest-Derived Biomass Resources The three key forest resources identified for this assessment are residues from logging and other removals, fuel treatments, and urban wood residues. There are particular issues associated with the utilization of each of these resources. Accessibility, terrain (e.g., steep slopes), and environmentally sensitive areas limit fuel treatment operations. Where treatment operations are appropriate, costs associated with the removal of the excess biomass may be prohibitive. Separating and marketing larger-diameter trees for conventional (higher-valued) forest products would be necessary to help defray the costs of dealing with large numbers of small-diameter material (USDAFS, 2003). Removing large trees, however, can create unfavorable public opinion and opposition to fuel treatment operations. Transportation costs, usually in the range of $0.20 to $0.60 per dry ton-mile, could severely limit haul distances, if based solely of bioenergy and biobased product values. The availability of markets within viable transport distances may limit the practicality of removing fuel treatment biomass for bioenergy and biobased products. 34 51 Logging & other residue Fuel treatments Urban wood residues Wood processing residues Pulping liquor Fuelwood 0 20 64 60 47 70 74 52 40 60 80 Million dry tons per year Perennial crops 377 Crop residues 446 Process residues 87 Grain-to-ethanol 87 0 100 200 300 400 500 Million dry tons per year Figure 26: Summary of potential forest and agricultural resources Labor availability may be a key constraint in fuel treatment operations. The strategic fuel treatment assessment for the western states notes that there is a disparity between the distribution of skilled forestry workers and the forestlands requiring fuel treatments (USDA-FS, 2003). Mobilizing forestry workers and equipment across large distances can increase costs and reduce competition for contracted projects. 52 35 Fuel treatment operations have the potential to create environmental impacts, especially if sites are severely disturbed. The impact of erosion and consequent movement of sediments into surface waters is a particular concern. However, studies suggest that there is often a much higher flow of sediments into surface waters as a consequence of wildfires than as a consequence of fuel treatment thinning operations (USDA-FS, 2003). More cost-effective fuel treatment operations and recovery of logging and other removal residue will require the development of more efficient and specialized equipment that can accommodate small-diameter trees. The availability of more efficient equipment will make the recovery of biomass for bioenergy and biobased products much more cost-effective. Federal funding for forestry programs for such activities as private tree planting, forest stand management, and technical assistance are a small fraction (<0.5 percent) of direct agricultural payments to farmers (Alig et al., 2003). Given the size of private forestland ownership, well-crafted policies aimed at providing incentives for landowners to manage their holdings could attract large quantities of biomass. Of course, any policies must be based on good science and call for meeting all sustainability requirements. The availability of urban wood residues is largely governed by the size of tipping fees. Where such fees are high (due in part to the lack of land for landfills), recycling is often higher. Also, high tipping fees provide economic incentives to utilize these resources. Can the same amount of biomass be produced with more environmentally beneficial approaches? The agricultural scenarios assumed are an improvement over current agricultural practices because they include higher levels of conservation tillage, more efficient use of nutrients, and the introduction of perennial crops on some land currently producing annual crops. These benefits are in addition to the benefits attained by displacing fossil fuels with biofuels. As cellulosic ethanol production and other bioenergy and bioproduct markets increase the value of biomass, making it more profitable to displace annual crops with perennial crops, further environmental benefits are possible. Replacement of some corn production with perennial trees and grasses would significantly reduce fertilizer use and improve soil carbon, for example. However, the amount of biomass produced by perennial crops will have to be more than 10 dry tons per acre in order to exceed the harvestable biomass (residue and grain) from corn producing at yields of 207 bushels per acre. Thus, it will be difficult to increase total biomass by replacing corn acres. Replacement of other annual corps with perennial crops would clearly generate more biomass. Some urban wood residues are highly dispersed, making economical recovery potentially costly. Seasonality of the generated residue can also affect the viability of this source. Contamination and commingling of urban wood residues with non-wood products, especially demolition residues and some construction residues, can limit uses. Contamination with dirt and rocks is also a potential issue with yard and tree trimmings. 5.2 Agriculture-Derived Biomass Resources Annual crop residues, perennial crops, and, to a lesser extent, processing residues (e.g., animal manures) have the potential to sustainably contribute more than 900 million dry tons of biomass annually. This number is in addition to biomass that is currently used and likely to be used in the future, such as biofuel production from grains. Issues associated with these resources are as follows. Utilizing crop residues and growing perennial crops on a large scale would require significant changes in current crop yields, tillage practices, harvest/collection technologies, and transportation. The yield and harvest efficiency increases are plausible within reasonable time frames based on current trends and research directions. While no-till management is also increasing, some question that it would ever be adopted on all cropland due to significant transition costs in the form of initial lower yields, possible increase in disease problems, and simple resistance to change. A strong market for bioenergy, however, could be a key to changing attitudes. 53 36 There are long-term economic and environmental concerns associated with the removal of large quantities of residues from cropland. Removing any residue on some soils could reduce soil quality, promote erosion, and lead to a loss of soil carbon which in turn lowers crop productivity and profitability. On other soils, some level of removal can be sustainable and even beneficial (Wilhelm et al, 2004). Establishment and communication of research-based guidelines is necessary to ensure that removal of residue biomass is done in a sustainable manner. A particular concern has been raised regarding the effect of removing the nutrients embodied in residues. At a minimum, there is a cost associated with supplying the lost nutrients through fertilizer applications. If residue removal results in larger fertilizer applications, then the environmental and economic costs associated with producing and acquiring those fertilizers (nitrogen, phosphorous and potassium as well as micro-nutrients) must be considered. Production of nitrogen from natural gas is becoming more expensive. Higher application of fertilizers could exacerbate the problem of nutrient runoff and development of the “dead zone” in the Gulf (Raloff, 2004b). Unless current levels of nutrient runoff are voluntarily reduced, farmers are likely to face increasing regulation to control the problem (Raloff, 2004a). One of the proposed solutions to the nutrient runoff problem has been to increase the acres of perennial crops relative to annual crops. Perennial crops require fewer applications of pesticides and fertilizers. When strategically placed, they can absorb the runoff from annual crop plantings. Other benefits of perennial crops include less erosion and less soil compaction due to less soil disturbance. Perennial crops also provide better habitat for many birds, such as migratory song birds and for several types of mammals. Annual crops are quite variable in yield, particularly at a local level. A key requirement to attaining targeted crop yields is the availability of sufficient water and nutrients. Genetic selection continues to move toward crops that are more stable in yield and more efficient in their use of water and nutrients. However, for specific bioenergy facilities, it will be necessary to consider excess production, storage, and ability to utilize multiple feedstocks in order to ensure adequate supplies in any given year. Redirecting large quantities of animal manure to bioenergy uses can lessen nutrient runoff and reduce contamination of surface water and groundwater resources. The use of biomass has considerable potential to reduce emissions of greenhouse gases, especially if perennial crops are a large component of the resource mix. Depending how the biomass resources are utilized, there could also be reductions in regional and locally significant air emissions. The expanded use of forest- and agriculture-derived biomass resources could result in improvements in water quality (at least relative to wildfires and annual crops) and reduced soil erosion. With increased production of ethanol from corn and small grains, the amount of dry distillers grains, gluten feed and gluten meal will increase. Also, soybean meal will increase as more soybeans are crushed for biodiesel. The co-products of biofuels production can be used as a protein supplement for livestock in place of corn grain. It is also assumed in this evaluation that perennial grasses are processed to remove proteins prior to their utilization as a low-cost ethanol feedstock. With all of these protein sources, there is sufficient feed material for livestock under all scenarios. Finally, this evaluation of the technical feasibility of changes in agricultural systems cannot determine whether markets would respond in a way that would support the biomass potential outlined. 54 37 6. Summarized Findings The U.S. Department of Energy and the U.S. Department of Agriculture are both strongly committed to expanding the role of biomass as an energy source. In particular, they support biomass fuels and products as a way to reduce the need for oil and gas imports; as a way of supporting the growth of agriculture, forestry, and rural economies; and as a way to foster major new domestic industries in the form of biorefineries that manufacture a variety of fuels, chemicals, and other products. The purpose of this analysis was to determine if the land resources of the United States are sufficient to support a large-scale biorefinery industry capable of displacing a significant fraction of our nation’s petroleum consumption. This study found that the combined forest and agriculture land resources have the potential of sustainably supplying much more than one-third of the nation’s current petroleum consumption. Forest lands, and in particular, timberlands, have the potential to sustainably produce close to 370 million dry tons of biomass annually. This estimate includes the residues generated in the manufacture of various forest products and the residues generated in the use of manufactured forest products. It also includes the harvest of wood for various residential and commercial space-heating applications. With the exception of urban wood residues, most of these sources of forest biomass are currently being utilized and there are significant efforts under way to use these resources much more efficiently. Two potentially large sources of forest biomass not currently being used are logging and other removal residues, and fuel treatment thinnings. These sources can sustainably contribute over 120 million dry tons annually. The logging and other removal residues can easily be recovered following commercial harvest and land clearing operations. Fuel treatment thinnings can also be recovered concomitantly with efforts to reduce forest fire hazards and otherwise improve the health of our nation’s forests. Agricultural lands can provide nearly 1 billion dry tons of sustainably collectable biomass and continue to meet food, feed and export demands. This estimate includes 446 million dry tons of crop residues, 377 million dry tons of perennial crops, 87 million dry tons of grains used for biofuels, and 87 million dry tons of animal manures, process residues, and other residues generated in the consumption food products. The perennial crops are crops dedicated primarily for bioenergy and biobased products and will likely include a combination of grasses and woody crops. Providing this level of biomass will require increasing yields of corn, wheat, and other small grains by 50 percent; doubling residue-to-grain ratios for soybeans; developing much more efficient residue harvesting equipment; managing active cropland with no-till cultivation; growing perennial crops whose output is primarily dedicated for bioenergy purposes on 55 million acres of cropland, idle cropland, and cropland pasture; using animal manure in excess of what can be applied on-farm for soil improvement for bioenergy; and using a larger fraction of other secondary and tertiary residues for bioenergy. In the context of the time required to scale up to a large-scale biorefinery industry, an annual biomass supply of more than 1.3 billion dry tons can be accomplished with relatively modest changes in land use and agricultural and forestry practices. 55 38 References Adams, R. M., B. H. Hurd, and J. Reilly. 1999. A Review of Impacts to U.S. Agriculture Resources. 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USDA-FS (U.S. Department of Agriculture - Forest Service). 2004b. “Roadless Area Conservation,” http:// www.roadless.fs.fed.us/. USDA-FS (U.S. Department of Agriculture - Forest Service). 2004c. “Fuel Treatment Evaluator,” http://ncrs.fs.fed.us/ 4801/hot-topics/bio-fuel-reduction/FTEbrief.pdf. USDA-NASS (U.S. Department of Agriculture – National Agricultural Statistics Service). 2003a. “Trends in U.S. Agriculture,” National Agricultural Statistics Service. http:// www.usda.gov/nass/pubs/trends/. USDA-NASS (U.S. Department of Agriculture – National Agricultural Statistics Service). 2003b. “Agricultural Statistics, 2003,” http:// www.usda.gov/nass/pubs/agr03/acro03.htm. USDA-NRCS (U.S. Department of Agriculture - National Resource Conservation Service). 1999. “CORE4 Conservation Practices Training Guide: The Common Sense Approach to Natural Resource Conservation,” http:// www.nrcs.usda.gov/technical/reference. USDA-NRCS (U.S. Department of Agriculture - National Resource Conservation Service). 2002. “National Agronomy Manual,” 3rd ed, Subparts 502 (Wind Erosion), 503 (Crop Production), 508 (Soil Management). http:// policy.nrce.usda.gov/scripts/lpsils.dll/m/m_190_NAM.html. USDA-NRCS (U.S. Department of Agriculture - National Resource Conservation Service). 2003a. “National Resources Inventory: 2001 Annual NRI,” http://www.nrcs.usda.gov/technical/land/nri01/nri01lu.html. USDA-NRCS (U.S. Department of Agriculture - National Resource Conservation Service). 2003b. “SCI User Guide and Excel File—Version 25,” Soil Conditioning Index for Cropland Management Systems, National Resource Conservation 59 42 Service, http://soils.usda.gov/sqi/soil_quality/land_management/sci.html. USDA-OCE (U.S. Department of Agriculture – Office of Chief Economist). 2003. USDA Agricultural Baseline Projections to 2012. February. USDA-OCE (U.S. Department of Agriculture – Office of Chief Economist). 2004. USDA Agricultural Baseline Projections to 2013. February. USDA-OCE (U.S. Department of Agriculture – Office of Chief Economist). 2005. USDA Agricultural Baseline Projections to 2014. February. Vesterby, M., and L. Krupa. 2001. Major Uses of Land in the United States, 1997. Statistical Bulletin No. 973. U.S. Department of Agriculture, Economic Research Service, September. Walsh, M., 2004. Personal communication to Robert Perlack — Updated Analysis of State-Level Supply Curves for Corn Stover and Wheat Straw. October. Wilhelm, W. W., J. M. F. Johnson, J. L. Hatfield, W. B. Voorhees, and D. R. Linden. 2004. “Crop and Soil Productivity Response to Corn Residue Removal: A Literature Review.” Agron. J. 96(1):1-17. Wu, S., et al. 2004. “Soil Conservation Benefits of Large Biomass Soybean (LBS) for Increasing Crop Residue Cover.” J. Sustainable Agric. 24(1):107–128. Yang, H. S., et al. 2004. “Hybrid Maize: A Maize Simulation Model That Combines Two Crop Modeling Approaches.” Field Crops Res. 87:131–154. 60 43 Glossary Annual removals – The net volume of growing stock trees removed from the inventory during a specified year by harvesting, cultural operations such as timber stand improvement, or land clearing. Asexual reproduction – The naturally occurring ability of some plant species to reproduce asexually through seeds, meaning the embryos develop without a male gamete. This ensures the seeds will produce plants identical to the mother plant. Biobased product – The term ‘biobased product,’ as defined by Farm Security and Rural Investment Act (FSRIA), means a product determined by the U.S. Secretary of Agriculture to be a commercial or industrial product (other than food or feed) that is composed, in whole or in significant part, of biological products or renewable domestic agricultural materials (including plant, animal, and marine materials) or forestry materials. Bioenergy – Useful, renewable energy produced from organic matter – the conversion of the complex carbohydrates in organic matter to energy. Organic matter may either be used directly as a fuel, processed into liquids and gasses, or be a residual of processing and conversion. Biodiesel – Fuel derived from vegetable oils or animal fats. It is produced when a vegetable oil or animal fat is chemically reacted with an alcohol. Biorefinery – A facility that processes and converts biomass into value-added products. These products can range from biomaterials to fuels such as ethanol or important feedstocks for the production of chemicals and other materials. Biorefineries can be based on a number of processing platforms using mechanical, thermal, chemical, and biochemical processes. Biofuels – Fuels made from biomass resources, or their processing and conversion derivatives. Biofuels include ethanol, biodiesel, and methanol. Biomass – Any organic matter that is available on a renewable or recurring basis, including agricultural crops and trees, wood and wood residues, plants (including aquatic plants), grasses, animal manure, municipal residues, and other residue materials. Biomass is generally produced in a sustainable manner from water and carbon dioxide by photosynthesis. There are three main categories of biomass – primary, secondary, and tertiary. Biopower – The use of biomass feedstock to produce electric power or heat through direct combustion of the feedstock, through gasification and then combustion of the resultant gas, or through other thermal conversion processes. Power is generated with engines, turbines, fuel cells, or other equipment. Black Liquor – Solution of lignin-residue and the pulping chemicals used to extract lignin during the manufacture of paper. Coarse materials – Wood residues suitable for chipping, such as slabs, edgings, and trimmings. Commercial species – Tree species suitable for industrial wood products. Conservation Reserve Program – CRP provides farm owners or operators with an annual per-acre rental payment and half the cost of establishing a permanent land cover in exchange for retiring environmentally sensitive cropland from production for 10 to 15 years. In 1996, Congress reauthorized CRP for an additional round of contracts, limiting enrollment to 36.4 million acres at any time. The 2002 Farm Act increased the enrollment limit to 39 million acres. Producers can offer land for competitive bidding based on an Environmental Benefits Index (EBI) during periodic signups, or can automatically enroll more limited acreages in practices such as riparian buffers, field windbreaks, and grass strips on a continuous basis. CRP is funded through the Commodity Credit Corporation (CCC). Cropland – Total cropland includes five components: cropland harvested, crop failure, cultivated summer fallow, cropland used only for pasture, and idle cropland. 61 44 Cropland used for crops – Cropland used for crops includes cropland harvested, crop failure, and cultivated summer fallow. Cropland harvested includes row crops and closely sown crops; hay and silage crops; tree fruits, small fruits, berries, and tree nuts; vegetables and melons; and miscellaneous other minor crops. In recent years, farmers have double-cropped about 4 percent of this acreage. Crop failure consists mainly of the acreage on which crops failed because of weather, insects, and diseases, but includes some land not harvested due to lack of labor, low market prices, or other factors. The acreage planted to cover and soil improvement crops not intended for harvest is excluded from crop failure and is considered idle. Cultivated summer fallow refers to cropland in sub-humid regions of the West cultivated for one or more seasons to control weeds and accumulate moisture before small grains are planted. This practice is optional in some areas, but it is a requirement for crop production in the drier cropland areas of the West. Other types of fallow, such as cropland planted with soil improvement crops but not harvested and cropland left idle all year, are not included in cultivated summer fallow but are included as idle cropland. Cropland pasture – Land used for long-term crop rotation. However, some cropland pasture is marginal for crop uses and may remain in pasture indefinitely. This category also includes land that was used for pasture before crops reached maturity and some land used for pasture that could have been cropped without additional improvement. Cull tree – A live tree, 5.0 inches in diameter at breast height (d.b.h.) or larger that is non-merchantable for saw logs now or prospectively because of rot, roughness, or species. (See definitions for rotten and rough trees.) d.b.h. – The diameter measured at approximately breast high from the ground. Feedstock – A product used as the basis for manufacture of another product. Fiber products – Products derived from fibers of herbaceous and woody plant materials. Examples include pulp, composition board products, and wood chips for export. Fine materials – Wood residues not suitable for chipping, such as planer shavings and sawdust. Forest land – Land at least 10 percent stocked by forest trees of any size, including land that formerly had such tree cover and that will be naturally or artificially regenerated. Forest land includes transition zones, such as areas between heavily forested and nonforested lands that are at least 10 percent stocked with forest trees and forest areas adjacent to urban and built-up lands. Also included are pinyon-juniper and chaparral areas in the West and afforested areas. The minimum area for classification of forest land is 1 acre. Roadside, streamside, and shelterbelt strips of trees must have a crown width of at least 120 feet to qualify as forest land. Unimproved roads and trails, streams, and clearings in forest areas are classified as forest if less than 120 feet wide. Fuel Treatment Evaluator (FTE) – A strategic assessment tool capable of aiding the identification, evaluation, and prioritization of fuel treatment opportunities. Fuelwood – Wood used for conversion to some form of energy, primarily for residential use. Grassland pasture and range – All open land used primarily for pasture and grazing, including shrub and brush land types of pasture; grazing land with sagebrush and scattered mesquite; and all tame and native grasses, legumes, and other forage used for pasture or grazing. Because of the diversity in vegetative composition, grassland pasture and range are not always clearly distinguishable from other types of pasture and range. At one extreme, permanent grassland may merge with cropland pasture, or grassland may often be found in transitional areas with forested grazing land. Growing stock – A classification of timber inventory that includes live trees of commercial species meeting specified standards of quality or vigor. Cull trees are excluded. When associated with volume, includes only trees 5.0 inches in d.b.h. and larger. Idle cropland – Land in cover and soil improvement crops, and cropland on which no crops were planted. Some cropland is idle each year for various physical and economic reasons. Acreage diverted from crops to soil-conserving uses (if not eligible for and used as cropland pasture) under federal farm programs is included in this component. Cropland enrolled in the Federal Conservation Reserve Program (CRP) is included in idle cropland. Industrial wood – All commercial roundwood products except fuelwood. 62 45 Live cull – A classification that includes live cull trees. When associated with volume, it is the net volume in live cull trees that are 5.0 inches in d.b.h. and larger. Logging residues – The unused portions of growing-stock and non-growing-stock trees cut or killed by logging and left in the woods. Nonforest land – Land that has never supported forests and lands formerly forested where use of timber management is precluded by development for other uses. (Note: Includes area used for crops, improved pasture, residential areas, city parks, improved roads of any width and adjoining clearings, powerline clearings of any width, and 1- to 4.5-acre areas of water classified by the Bureau of the Census as land. If intermingled in forest areas, unimproved roads and nonforest strips must be more than 120 feet wide, and clearings, etc., must be more than 1 acre in area to qualify as nonforest land.) Nonindustrial private – An ownership class of private lands where the owner does not operate wood-using processing plants. Other forest land – Forest land other than timberland and reserved forest land. It includes available forest land, which is incapable of annually producing 20 cubic feet per acre of industrial wood under natural conditions because of adverse site conditions such as sterile soils, dry climate, poor drainage, high elevation, steepness, or rockiness. Other removals – Unutilized wood volume from cut or otherwise killed growing stock, from cultural operations such as precommercial thinnings, or from timberland clearing. Does not include volume removed from inventory through reclassification of timberland to productive reserved forest land. Other sources – Sources of roundwood products that are not growing stock. These include salvable dead, rough and rotten trees, trees of noncommercial species, trees less than 5.0 inches d.b.h., tops, and roundwood harvested from non-forest land (for example, fence rows). Poletimber trees – Live trees at least 5.0 inches in d.b.h. but smaller than sawtimber trees. Primary wood-using mill – A mill that converts roundwood products into other wood products. Common examples are sawmills that convert saw logs into lumber and pulp mills that convert pulpwood roundwood into wood pulp. Pulpwood – Roundwood, whole-tree chips, or wood residues that are used for the production of wood pulp. Residues – Bark and woody materials that are generated in primary wood-using mills when roundwood products are converted to other products. Examples are slabs, edgings, trimmings, sawdust, shavings, veneer cores and clippings, and pulp screenings. Includes bark residues and wood residues (both coarse and fine materials) but excludes logging residues. Rotten tree – A live tree of commercial species that does not contain a saw log now or prospectively primarily because of rot (that is, when rot accounts for more than 50 percent of the total cull volume). Rough tree – (a) A live tree of commercial species that does not contain a saw log now or prospectively primarily because of roughness (that is, when sound cull, due to such factors as poor form, splits, or cracks, accounts for more than 50 percent of the total cull volume) or (b) a live tree of noncommercial species. Roundwood products – Logs and other round timber generated from harvesting trees for industrial or consumer use. Salvable dead tree – A downed or standing dead tree that is considered currently or potentially merchantable by regional standards. Saplings – Live trees 1.0 inch through 4.9 inches in d.b.h. Secondary wood processing mills – A mill that uses primary wood products in the manufacture of finished wood products, such as cabinets, moldings, and furniture. 63 46 Sound dead – The net volume in salvable dead trees. Timberland – Forest land that is producing or is capable of producing crops of industrial wood, and that is not withdrawn from timber utilization by statute or administrative regulation. Areas qualifying as timberland are capable of producing more than 20 cubic feet per acre per year of industrial wood in natural stands. Currently inaccessible and inoperable areas are included. Timber Product Output Database Retrieval System (TPO) – Developed in support of the 1997 Resources Planning Act (RPA) Assessment, this system acts as an interface to a standard set of consistently coded TPO data for each state and county in the country. This set of national TPO data consists of 11 data variables that describe for each county the roundwood products harvested, the logging residues left behind, the timber otherwise removed, and the wood and bark residues generated by its primary wood-using mills. 64 47 Appendix A Forest Resource Analysis Table A.1: Current availability of logging residue and other removals National Forest Forest R esource million dry tons Logging residues Other removals Total 1.1 0.5 1 .6 3.2 0.7 3.9 44.4 17.1 61 .5 48.8 18.3 67.1 Other Public Private Lands Total N o t e : Conversion of volumetric data assumes an average density of 30 dry lbs/ft3 (Timber Product Output database) S o u r c e : Timber Product Output database (USDA-FS, 2004a) Table A.2: Availability factors for logging residue and other removals under current recovery conditions Portion of Forest R esource Available Forest R esource Accessible Fraction 1 1 1 1 R ecovery Fraction 0.65 0.65 0.5 0.5 Biomass Fraction 1 1 1 1 Total Availability 0.65 0.65 0.5 0.5 Harvest Frequency Logging residue Pu b l i c Private Other removals Pu b l i c Private Annually Annually Annually Annually Notes: Logging residue and residue from other removals are assumed to be 100% accessible p rovided these materials are removed concurrently with harvest and/or land clearing op erations. Recovery fractions are based on field studies and average site conditions. The lower recovery fraction for other removals is because of generally smaller p arcel size making collection more difficult. The small and scattered p iece-size limits the recovery of this material. All recovered material is assumed to be available as a feedstock for bioenergy and biobased p roducts. 65 48 Table A.3: Availability of logging residue and other removals under current recovery conditions National Forest Forest R esource million dry tons Logging residues 0.7 2.1 28.9 31.7 Other Public Private Lands Total Other removals Total 0.3 1 .0 0.4 2.5 8.5 37.4 9.2 40.9 Notes: Availability of logging and other removal residue is based on the p roduct of the total resource size (Table A.1) and availability factor (Table A.2). Table A.4: Availability of logging residue and other removals under future grow th and recovery conditions National Forest Forest R esource million dry tons Logging residues Other removals Total 1.0 0.5 1 .5 3.1 0.7 3.8 42.3 16.3 58.5 46.4 17.4 63.8 Other Public Private Lands Total N ot es : Under future conditions (mid-century), harvested roundwood products are assumed to increase by 35% and 47% for softwoods and hardwoods, respectively. The amount of logging residue generated is assumed to decline from 6.7% to 6% for softwoods and from 12.4% to 9% for hardwoods. These assumptions are derived from Haynes (2003). The fraction of recoverable logging and other removal residue is assumed to increase by 20%. 66 49 Table A.5: Total fuel treatment thinnings resource National Forest Forest R esource million dry tons Timberland Other forest land Total 1,849 147 1 ,996 770 158 928 5,175 310 5,486 7,794 616 Other Public Private Lands Total 8,410 Note: Conversion of volumetric Forest Inventory Analysis data assumes 30 dry lbs/ft3. Tree volumes were par titioned into two utilization groups - trees greater than 7 inches taken to a 4 inch minimum top diameter and the remaining smaller material (tops, limbs, small diameter trees). The larger-sized material was assumed merchantable for higher-value products and the smaller-sized material suitable for bioenergy and biobased products. Source: Fuel Treatment Evaluator (USDA-FS, 2004c) Table A.6: Assumed availability factors for fuel treatment thinnings Portion Of Forest Resource Available Forest Resource Accessible Timberland Pu b l i c Private Other forest land Pu b l i c Private 0.6 0.8 0.6 0.8 Fraction 0.85 0.85 0.85 0.85 Recovery 0.3 0.3 0.9 0.9 Fraction 0.15 0.20 0.46 0.61 Harvest Frequency 30 years 30 years 30 years 30 years Notes: These assumptions are based in par t on from USDA-FS (2003). 67 50 Table A.7: Availability of fuel treatment thinnings National Forest Forest R esource million dry tons Timberland Other forest land Total 9.4 2.2 11 .7 3.9 2.4 6.3 35.2 6.3 41 .5 48.6 11.0 59.6 Other Public Private Lands Total Notes: Availability of fuel treatment thinnings is based on the p roduct of the total resource size (Table A.5) and the resp ective availability factors (Table A.6) divided by the harvest frequency (Table A.6). Table A.8: Forest products industry processing residues Energy Source Product And Other Uses Unused Total Mill R esidue Byproducts (mllion dry tons) Primary wood processing mills Secondary wood processing mills Pulp and paper mills 39.4 50.3 1.7 93.1 ____ 9.5 6.1 15.6 52.1 52.1 ____ ____ Notes: Primary wood processing mills account for 91.3 million dry tons split among bark, coarse wood, and fine wood in the following propor tions - 26.5%, 42.9%, and 30.7%, respectively. Mill residues are projected to increase by about 30% and somewhat less for black liquor generated at pulp and paper mills. Source: Timber Product Output database (USDA-FS, 2004a) 68 51 Table A.9: Summar y o f availability o f ur ban w o o d r e sidue s Dispo sitio n o f R e sidue Ur ban Wo o d R e sidue So ur ce Ge ne r ate d R e co ve r e d, Co mbuste d Fo r Ene r gy & Unusable millio n dr y to ns Construction residue Demolition debris Woody yard trimmings (MSW) Wood (MSW) To tal 11.6 27.7 9.8 13.2 62.3 3.0 16.1 8.0 7.3 34.4 8.6 11.7 1.7 6.0 28.0 Available No te s: Woody yard trimmings were conver ted to dry tons based on 40% moisture content. The amount of urban wood residue generated is estimated to increase by about 30% . This estimate is based on trends associated with residential and nonresidential construction, demolition, and remodeling, as well as in the disp osal of durables and p ackaging residues. So ur ce : McKeever (2004) 69 52 703 5 Appendix B Agriculture Resource Analysis Table B.1: Comparison of USDA baseline for major crops with change scenarios Major Crop USDA Baseline 2001 Corn Harvested acres (millions) Yield (bushels/acre) Production (thousand bushels) Total grain supply (000s bushels) Use Food, See, Res. (000s bushels) Animal Feed (000s bushels) Export (000s bushels) Industry/fuel (000s bushels) Stocks (000s bushels) Total grain Use (000s bushels) Wh e a t Harvested acres (millions) Yield (bushels/acre) Production (thousand bushels) Total grain supply (000s bushels) Use Food, Seed, Res. (000s bushels) Animal Feed (000s bushels) Export (000s bushels) Industry/fuel (000s bushels) Stocks (000s bushels) Total grain Use (000s bushels) Soybeans Harvested acres (millions) Yield (bushels/acre) Production (thousand bushels) Total grain supply (000s bushels) Use Food, Seed, Res. (000s bushels) Animal Feed (000s bushels) Export (000s bushels) Industry/fuel (000s bushels) Stocks (000s bushels) Total grain Use (000s bushels) 438,303 1,084,262 1,353,835 8,929 254,926 3,140,254 467,914 1,307,438 1,272,500 35,714 243,533 3,327,099 3,195,007 3,477,751 3,195,007 3,088,087 517,197 1,307,438 1,272,500 97,872 600,475 1,307,438 1,272,500 297,338 517,197 1,307,438 1,272,500 97,872 600,475 1,307,438 1,272,500 -92,326 73.0 39.6 2,890,682 3,140,749 71.4 43.6 3,115,000 3,328,000 71.4 44.748 3,195,007 71.4 48.708 3,477,751 71.4 44.748 3,195,007 63.4 48.708 3,088,087 1,010,000 193,000 961,000 0 777,000 2,941,000 1,049,000 230,000 1,200,000 0 553,000 3,032,000 2,513,760 2,911,772 2,513,760 2,635,579 1,191,800 230,000 1,200,000 -108,040 1,383,700 230,000 1,200,000 98,072 1,191,800 230,000 1,200,000 -108,040 1,383,700 230,000 1,200,000 -178,121 48.8 40.1 1,957,043 2,941,000 52.3 45.9 2,400,000 3,032,000 52.3 48.1 2,513,760 52.3 55.7 2,911,772 52.3 48.1 2,513,760 47.25 55.8 2,635,579 1,340,000 5,874,000 1,889,000 714,000 1,599,000 11,416,000 1,5000,000 6,200,000 2,975,000 1,750,000 1,179,000 13,604,000 13,232,650 15,879,180 13,232,650 15,879,180 1,581,200 6,200,000 2,975,000 2,476,450 1,835,000 6,820,000 3,272,500 3,950,880 1,581,200 6,200,000 2,975,000 2,476,450 1,835,800 6,820,000 3,272,500 3,950,880 68.8 138.2 9,509,266 11,416,000 76.6 161.8 12,395,000 13,604,000 76.6 172.75 13,232,650 76.6 207.3 15,879,180 76.6 172.75 13,232,650 76.6 207.3 15,879,180 2014 Technology changes without land use change, no perennial crops Mo d e r a t e High Technology changes with land use change to accomodate perennial crops Mo d e r a t e High 71 54 72 55 Table B.2: Current availability of biomass from agricultural lands - baseline summary Product yield Fiber yield million dry tons/year 3.3 1.4 1.8 1.7 1.9 1.2 1.6 4.3 1.0 0.0 0.0 0.0 0.0 1.0 20.1 20.1 1.5 0.0 0.0 18.1 0.0 0.5 0.0 2.0 2.0 2.0 0.0 1.5 0.0 0.0 na 0.0 0.0 na 6.0 2.0 na 0.0 na 0.0 na 0.0 12.7 0.0 101.3 0.8 0.0 na na 0.0 4.4 na 0.0 50.8 na 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 54.9 3.5 na 0.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 40.8 0.0 0.0 67.4 0.0 0.0 70.6 0.0 0.0 17.7 13.3 2.7 2.7 0.0 0.0 0.0 0.0 18.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 23.7 14.2 5.7 5.7 193.0 115.8 46.3 0.0 35.5 20.1 8.0 2.2 0.0 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 35.1 0.9 23.7 37.7 6.0 21 .1 1233.1 550.4 204.3 113.2 14.6 65.9 95.4 60.1 24.0 8.8 0.2 4.8 3.2 1.3 0.1 0.0 12.8 7.7 3.1 0.7 0.2 24.8 12.4 5.0 0.0 0.5 450.0 225.0 90.0 74.8 13.5 6.2 94.6 0.5 0.8 0.1 8.9 2.2 0.2 5.7 2.7 0.0 0.0 0.0 0.0 18.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 35.1 0.9 23.7 193.7 R esidue yield Total cropland plant mass Total residue produced R esidue logistically removable Grains used for bioenergy R esidue sustainably removable Secondary & tertiary residues available Total sustainable biomass Crop Acres harvested or reserved dry tons/acre/year 3.3 1.4 1.2 0.8 1.1 0.9 1.1 2.9 0.3 3.0 1.7 6.6 4.4 1.0 na na na na na na na na na na na na na na million acres Corn grain 68.8 Sorghum 8.6 Barley 4.3 Oats 1.9 Wheat-w inter 31.3 Wheat-spring 17.5 Soybeans 73.0 R ice 3.3 Cotton lint 13.8 Alfalfa 23.8 Other Hay 39.7 Silage corn 6.1 Silage sorghum 0.3 Other Crops 20.1 Double Crops Crop failure 10.0 Summer fallow 21.0 Grasses (CR P) 25.4 Trees (CR P) 2.2 Environment (CR P) 6.4 Unaccounted 3.0 Pastur e 67.5 Wood fiber 0.1 Perennials 0.0 Ma nu r e Fa t s & gr e a s e s MSW Totals 448.1 Table B.3: Summary of biomass from agricultural lands under moderate crop yield increases w ithout land use change Product yield Fiber yield R esidue yield Total cropland plant mass million dry tons/year 4.1 1.7 2.2 1.9 2.3 1.4 1.8 5.1 1.1 0.0 0.0 0.0 0.0 1.2 23.1 23.1 1.7 0.0 46.9 0.0 0.0 0.0 20.8 10.0 0.5 0.0 2.0 2.0 2.0 0.0 1.5 0.0 0.0 na 0.0 6.0 na 0.0 2.0 0.0 na na 0.0 na 0.0 na 0.0 4.4 12.7 0.0 101.3 0.8 0.0 na na 0.0 50.8 na 0.0 0.0 na 0.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 68.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 66.8 0.0 0.0 81.2 0.0 0.0 18.4 13.8 5.5 5.5 0.0 0.0 0.0 0.0 20.8 10.0 0.0 0.0 25.4 2.2 0.0 0.0 0.0 0.2 0.0 28.5 17.1 10.3 10.3 213.3 128.0 76.8 0.0 46.3 26.2 15.7 7.4 0.0 2.6 0.0 0.0 0.0 0.0 0.0 0.0 2.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 43.5 2.0 29.4 42.8 6.0 24.7 1490.3 693.8 386.7 283.8 55.9 83.6 121.8 76.7 46.0 27.4 0.0 4.5 3.0 1.8 0.7 0.0 13.8 8.3 5.0 2.8 0.6 22.8 11.4 6.8 1.3 1.8 626.2 313.1 187.9 169.7 46.9 8.6 225.2 3.1 3.4 0.7 27.4 7.4 2.6 10.3 5.5 0.0 0.0 0.0 0.0 22.8 12.0 0.0 0.0 25.4 2.2 0.0 0.0 0.0 0.2 0.0 43.5 2.0 29.4 423.2 Total residue produced R esidue logistically removable Grains used for bioenergy R esidue sustainably removable Secondary & tertiary residues available Total sustainable biomass Crop Acres harvested or reserved dry/tons/acre/year 4.1 1.7 1.5 0.9 1.4 1.1 1.2 3.4 0.4 3.4 2.0 7.6 5.1 1.2 na na na na na na na na na na na na na na million acres Corn grain 76.6 Sorghum 6.8 Barley 3.7 Oats 1.6 Wheat-w inter 33.3 Wheat-spring 19.0 Soybeans 71.4 R ice 3.4 Cotton lint 12.3 Alfalfa 23.8 Other Hay 34.2 Silage corn 6.1 Silage sorghum 0.3 Other Crops 20.1 Double Crops Crop failure 10.0 Summer fallow 21.0 Grasses (CR P) 25.4 Trees (CR P) 2.2 Environment (CR P) 6.4 Unaccounted 3.0 Pastur e 67.5 Wood fiber 0.1 Perennials 0.0 Ma nu r e Fa t s & gr e a s e s MSW 73 56 Totals 448.2 74 57 Product yield Fiber yield dry tons/acre/year 4.9 1.9 1.7 1.0 1.6 1.2 1.3 3.9 0.4 3.9 2.2 8.6 5.8 1.3 na 1.3 26.1 26.1 na 0.0 1.9 0.0 0.0 23.5 na 0.0 53.1 0.0 0.0 na 0.0 75.5 0.0 0.0 na 0.0 91.8 0.0 0.0 na 1.2 19.9 14.9 8.9 8.9 0.0 0.0 0.0 0.0 23.5 15.0 0.5 0.0 2.0 2.0 2.0 0.0 1.5 0.0 0.0 na 0.0 6.0 2.0 0.0 na na 0.0 na 0.0 na 0.0 12.7 0.0 101.3 0.8 0.0 na na 0.0 4.4 na 0.0 50.8 na 0.0 0.0 na 0.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 68.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.0 0.0 0.0 25.4 2.2 0.0 0.0 0.0 0.2 0.0 na 5.8 32.6 19.6 14.7 14.7 na 2.0 232.1 139.3 104.5 0.0 na 1.6 53.6 30.3 22.7 12.2 0.0 7.9 0.0 0.0 0.0 0.0 0.0 0.0 4.0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 43.5 2.0 29.4 47.7 6.0 28.1 1701.0 793.8 542.3 413.1 97.0 87.2 na 2.7 141.1 88.8 66.6 44.9 2.5 na 2.1 5.0 3.3 2.5 1.2 0.0 na 2.6 16.0 9.6 7.2 4.7 0.9 na 1.9 25.9 12.9 9.7 4.0 2.8 na 4.9 751.4 375.7 281.8 256.1 74.8 12.3 million dry tons/year 343.2 6.8 5.7 1.2 47.5 12.2 7.9 14.7 8.9 0.0 0.0 0.0 0.0 27.5 19.0 0.0 0.0 25.4 2.2 0.0 0.0 0.0 0.2 0.0 43.5 2.0 29.4 597.3 R esidue yield Total cropland plant mass Total residue produced R esidue logistically removable Grains used for bioenergy R esidue sustainably removable Secondary & tertiary residues available Total sustainable biomass Table B.4: Summary of biomass from agricultural lands under high crop yield increase w ithout land use change Crop Acres harvested or reserved million acres Corn grain 76.6 Sorghum 6.8 Barley 3.7 Oats 1.6 Wheat-w inter 33.3 Wheat-spring 19.0 Soybeans 71.4 R ice 3.4 Cotton lint 12.3 Alfalfa 23.8 Other Hay 34.2 Silage corn 6.1 Silage sorghum 0.3 Other Crops 20.1 Double Crops Crop failure 10.0 Summer fallow 21.0 Grasses (CR P) 25.4 Trees (CR P) 2.2 Environment (CR P) 6.4 Unaccounted 3.0 Pastur e 67.5 Wood fiber 0.1 Perennials 0.0 Ma nu r e Fa t s & gr e a s e s MSW Totals 448.2 Table B.5: Summary of biomass from agricultural lands under moderate crop yield increase w ith land use change Product yield Fiber yield R esidue yield million dry tons/year 4.1 1.7 2.2 1.9 2.3 1.4 2.4 5.1 1.1 0.0 0.0 0.0 0.0 1.2 23.1 23.1 1.7 0.0 0.0 20.8 46.9 0.0 0.0 66.8 0.0 0.0 81.2 0.0 0.0 18.4 13.8 5.5 5.5 0.0 0.0 0.0 0.0 20.8 10.0 0.5 0.0 2.0 2.0 2.0 0.0 1.5 0.0 0.4 na 0.0 6.0 2.0 4.7 na na 0.0 na 0.0 na 0.0 12.7 0.0 63.8 40.8 175.0 na na 0.0 4.4 na 0.0 30.8 na 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 10.2 162.8 68.0 5.0 na 0.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9.2 146.5 0.0 0.0 15.4 2.2 0.0 0.0 0.0 9.2 146.5 28.5 17.1 10.3 10.3 255.9 170.6 102.4 12.7 46.3 26.2 15.7 7.4 0.0 2.6 0.0 0.0 0.0 0.0 0.0 0.0 2.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 43.5 2.0 29.4 43.2 6.0 30.0 1690.5 909.2 557.8 441.9 55.8 83.6 121.8 76.7 46.0 27.4 0.0 4.5 3.0 1.8 0.7 0.0 13.8 8.3 5.0 2.8 0.6 22.8 11.4 6.8 1.3 1.8 626.2 313.1 187.9 169.7 46.9 8.6 225.2 3.1 3.4 0.7 27.4 4.5 15.3 10.3 5.5 0.0 0.0 0.0 0.0 22.8 12.0 0.0 0.0 15.4 2.2 0.0 0.0 0.0 9.2 146.5 43.5 2.0 29.4 581.3 Total cropland plant mass Total residue produced R esidue logistically removable R esidue sustainably removable Grains used for bioenergy Secondary & tertiary residues available Total sustainable biomass Crop Acres harvested or reserved dry tons/acre/year 4.1 1.7 1.5 0.9 1.4 1.1 1.2 3.4 0.4 3.4 2.0 7.6 5.1 1.2 na na na na na na na na na na na na na na million acres Corn grain 76.6 Sorghum 6.8 Barley 3.7 Oats 1.6 Wheat-w inter 33.3 Wheat-spring 19.0 Soybeans 71.4 R ice 3.4 Cotton lint 12.3 Alfalfa 23.8 Other Hay 34.2 Silage corn 6.1 Silage sorghum 0.3 Other Crops 20.1 Double Crops Crop failure 10.0 Summer fallow 16.0 Grasses (CR P) 15.4 Trees (CR P) 2.2 Environment (CR P) 6.4 Unaccounted 3.0 Pastur e 42.5 Wood fiber 5.1 Perennials 35.0 Ma nu r e Fa t s & gr e a s e s MSW Totals 448.2 75 58 76 59 Pr o duct yie ld Fibe r yie ld dr y/to ns/acr e /ye ar 4.9 1.9 1.7 1.0 1.6 1.2 1.3 3.9 0.4 3.9 2.2 8.6 5.8 1.3 na 1.3 26.1 26.1 na 0.0 1.9 0.0 0.0 23.5 na 0.0 53.1 0.0 0.0 na 0.0 64.5 0.0 0.0 na 0.0 91.8 0.0 0.0 na 1.2 19.9 14.9 8.9 8.9 0.0 0.0 0.0 0.0 23.5 15.0 0.5 0.0 2.0 2.0 2.0 0.0 1.5 0.0 0.6 na 0.0 7.4 na 6.0 2.0 na 0.0 na 0.0 na 0.0 12.7 0.0 63.8 40.8 440.0 na na 0.0 4.4 na 0.0 30.8 na 0.0 0.0 na 0.0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 10.2 409.2 68.0 5.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9.2 368.3 0.0 0.0 15.4 2.2 0.0 0.0 0.0 9.2 368.3 na 5.8 32.6 19.6 14.7 14.7 na 2.6 247.4 164.9 123.7 47.9 na 1.6 48.0 27.1 20.3 10.9 na 2.7 128.3 80.8 60.6 40.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4.0 4.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 43.5 2.0 29.4 48.3 6.0 36.1 2108.4 1227.4 930.4 823.0 87.4 87.2 na 2.1 5.0 3.3 2.5 1.2 0.0 na 2.6 16.0 9.6 7.2 4.7 1.9 na 1.9 25.9 12.9 9.7 4.0 2.8 na 4.9 751.4 375.7 281.8 256.1 74.8 12.3 millio n dr y to ns/ye ar 343.2 6.8 6.6 1.2 40.9 10.9 47.9 14.7 8.9 0.0 0.0 0.0 0.0 27.5 19.0 0.0 0.0 15.4 2.2 0.0 0.0 0.0 9.2 368.3 43.5 2.0 29.4 997.7 R e sidue yie ld To tal cr o pland plant mass To tal r e sidue pr o duce d R e sidue lo gistically r e mo vable Gr ains use d fo r bio e ne r gy R e sidue sustainably r e mo vable Se co ndar y & te r tiar y r e sidue s available To tal sustainable bio mass Table B.6: Summar y o f bio mass fr o m agr icultur al lands unde r high cr o p yie ld incr e ase w ith land use change Cr o p Acr e s har ve ste d o r r e se r ve d millio n acr e s Co r n gr ain 76.6 So r ghum 6.8 Bar le y 3.7 Oats 1.6 Whe at-w inte r 30.3 Whe at-spr ing 17.0 So ybe ans 63.4 R ice 3.4 Co tto n lint 12.3 Alfalfa 23.8 Othe r Hay 29.2 Silage co r n 6.1 Silage so r ghum 0.3 Othe r Cr o ps 20.1 Do uble Cr o ps Cr o p failur e 8.0 Summe r fallo w 16.0 Gr asse s (CR P) 15.4 Tr e e s (CR P) 2.2 Envir o nme nt (CR P) 6.4 Unacco unte d 3.0 Pastur e 42.5 Wo o d fibe r 5.1 Pe r e nnials 55.0 Ma nu r e Fa t s & gr e a s e s MSW To tals 448.2 77 60 ...
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This note was uploaded on 09/13/2011 for the course SOCIAL SOCIALWORK taught by Professor Staff during the Spring '09 term at University of Nevada, Las Vegas.

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