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Unformatted text preview: International Council of Science Biofuels: Are they Environmentally Sustainable?
BioEE2610 – Ecology & Environment Bob Howarth
(Cornell University, USA) Chair, International SCOPE Biofuels Project November 18, 2009 International Council of Science Governments and industry focused on liquid biofuels (ethanol and biodiesel for transportation)
• Global climate change • Energy security • Rural development 1 International Council of Science Governments and industry focused on liquid biofuels
• Global climate change • Energy security • Rural development Global energy use from all sources: • 0.4% liquid biofuels • 10-13 % solid biofuels (wood, charcoal) International Council of Science Governments and industry focused on liquid biofuels
• Global climate change • Energy security • Rural development Global energy use from all sources: • 0.4% liquid biofuels • 10-13 % solid biofuels (wood, charcoal) 2 Comparison of price of solid fossil fuels (coal) and liquid fossil fuels (crude oil) over time. Howarth et al. 2009 Model T Fords were powered by ethanol; diesel engine designed for peanut oil 3 15 billion liters Howarth et al. 2009 Howarth et al. 2009 4 Almost all corn Almost all sugar cane Howarth et al. 2009 2007: International Council of Science United States -- 26% of corn to produce ethanol for 1.3% of total liquid fuel use. Brazil -- 60% of sugar cane harvest to produce ethanol for 15% of liquid fuel use. 5 All liquid biofuels (ethanol, biodiesel) Biodiesel dominated by rapeseed in both EU and elsewhere. Many countries have ambitious liquid biofuel goals -- 10% or more of transportation fuels by 2020 to 2025. It will be difficult at best to meet these biofuel targets using traditional crops. International Council of Science 6 Many countries have ambitious liquid biofuel goals -- 10% or more of transportation fuels by 2020 to 2025. It will be difficult at best to meet these biofuel targets using traditional crops. In 2007 only 1.8% of global liquid transportation fuels. Required 6% of all grains harvest globally (rice, maize, wheat), 8% of vegetable oil, and 28% of sugar cane. International Council of Science What about novel crops (ie, cold pressed oil from jatropha)? “Second-generation” biofuels, using cellulose as feedstock (from switchgrass, corn stover, wood, etc.)? -- cellulosic ethanol -- hydrocarbon fuels such as “biomass to liquid fuels,” or BtL Included in our analysis, but unproven and developing technologies, so much greater uncertainty. International Council of Science 7 International Council of Science Environmental effects (including greenhouse gas emissions) vary, depending upon issues such as: • • • • • • • Which feedstocks Which biofuel Where the feedstocks are grown Where the fuels produced Conversion methods What energy powers these conversions and transportation Interactions with other drivers for land use and land cover changes Net effects on greenhouse gas emissions (compared to gas or diesel) good Break-even point bad Gallagher 2008 8 Net effects on greenhouse gas emissions (compared to gas or diesel) Based on steady-state life-cycle analysis good Break-even point bad Gallagher 2008 Gallagher 2008 9 Gallagher 2008 Gallagher 2008 10 Gallagher 2008 Current life-cycle analyses have two major failings: • Underestimate N2O fluxes • Assume steady state – what happens as production rapidly grows? 11 Forster et al. (2007) -- IPCC ~ 4% of all nitrogen added to the environment by humans ends up in atmosphere as N2O (Galloway et al. 2004). IPCC methodology (used in life-cycle analyses) assumes ~ 1% to 1.5 % 12 Rapid growth, not steady state!
International Council of Science Searchinger et al. 2008. Use of U.S. croplands for biofuels increases greenhouse gases through emissions from land use change. Science (10.1126/science.1151861) • Previous “analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels.” • “… corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse gas emissions ….” Ignores expansion into new lands! Gallagher 2008 13 Indonesia plans to expand palm oil plantations 4X by 2030 (to 26 million hectares). Virgin rain forest will be cut for most of this (67%). A loss of 30% of all Indonesian rain forests. Half of the rain forest land lost would be peat bogs… Estimated increase of 1.4 gigatons CO2 per year (4% of current global CO2 flux) (Bringezu et al. 2008) Conclusions on greenhouse gases: • Biofuels grown on cleared forests or grasslands -- release of greenhouse gases from clearing usually exceeds decades worth of fossil fuel offsets. • If global warming is the primary concern, leaving natural ecosystems (particularly forests) alone is usually a better strategy than clearing them to grow crops.
. 14 • Using wastes and agricultural and forest residues for biofuels is likely to produce greenhouse gas benefits. • Care must be taken to assure that enough residuals are left behind to protect soil health and carbon levels. • Marginal and degraded lands -- an opportunity to produce biofuel crops while restoring the landscape. • Often requires substantial investment in irrigation and fertilizer. • Some of these regions include areas of high biodiversity. • Great uncertainty over the magnitude of lands that could be farmed in a sustainable, environmentally beneficial way. 15 SCOPE Project conclusions on other environmental effects: International Council of Science Biofuel production and consumption have a variety of effects on the local and regional environment. Growing crops is essentially the same for biofuels as for other agricultural purposes. However, the environmental impacts of agriculture often increase as more land is used, land is farmed more intensively, and marginal lands are placed into agriculture. International Council of Science • Biodiversity is greatly threatened by deforestation and conversion of grasslands and savannas to biofuel crops. Conservation reserve lands are also threatened with conversion to agriculture in support of biofuel production. On the other hand, natural grasslands and forests may be managed for harvest of biofuel material at moderate levels, providing reasonable protection for biodiversity. 16 International Council of Science • Freshwater is increasingly in short supply and may not meet future demands for food production in many regions. Using irrigation to grow biofuel crops will aggravate these shortages, reducing water available for other uses and further impacting freshwater and coastal marine ecosystems. • agriculture already responsible for 70% of global freshwater use. International Council of Science 17 International Council of Science • Air pollution from the burning of sugar cane before harvest contributes smoke, fine particles, and nitrogen gases to the atmosphere, causing acid rain and a variety of human health impacts. • Ethanol and biodiesel can reduce the emissions of some pollutants from vehicle exhaust (such as fine particles and carbon monoxide), but tend to increase other pollutant emissions (such as nitrogen gases). Sept. 19, 2008 -- Piracicaba/SP /Brazil International Council of Science (Luiz Martinelli) 18 Lara et al. (2005) Lara et al. (2002) Krusche et al. (2003) International Council of Science • Severe water pollution can result from runoff from agricultural fields and from wastes produced during the production of biofuels. Nutrient losses from corn fields and organic wastes from sugar cane processing are particular problems. • When perennial crops such as switchgrass are used instead of annual ones such as corn, water pollution is much less. 19 International Council of Science Corn is a particular problem for nitrogen pollution, due to shallow root system and short active period of nutrient uptake (~ 60d) Tile drainage and lack of winter cover crops aggravate nitrogen pollution. Corn-ethanol goals in US predicted to increase nitrogen inputs to Mississippi River by 37%. National goal is to reduce nitrogen by at least 40% to mitigate the “dead zone“ in Gulf of Mexico. “Dead Zones” (low-oxygen waters) from Excess Nitrogen Pollution Diaz & Rosenberg (2008) 20 “Cellulosic ethanol” = ethanol fermented from cellulose (wood, grasses) “Cellulosic ethanol” = ethanol fermented from cellulose (wood, grasses)
• corrosive (difficult and expensive to transport and store) • must be distilled to remove water (energetically costly) • high in oxygen, leading to greater nitrogen emissions 21 “Cellulosic ethanol” = ethanol fermented from cellulose (wood, grasses)
• corrosive (difficult and expensive to transport and store) • must be distilled to remove water (energetically costly) • high in oxygen, leading to greater nitrogen emissions Liquid hydrocarbons or methane gas from cellulose probably far better fuels. Better yet, burn cellulosic biomass instead to co-generate heat and electricity. Greater efficiency, so less land needed, less environmental problems. -----------------------Per area of land: • • • 1 unit of energy for ethanol from corn 3.5 units for ethanol from switchgrass 9 units from burning switchgrass 22 Direct combustion of solid biofuels reduces fossil fuel oil, since 40% of global use of oil is for stationary, nontransportation uses. (photo by Jeff McNeely) 35% of homes and commercial buildings in Sweden are heated by burning biomass 23 The way forward…. International Council of Science • Energy plans must start with conservation, greater efficiency, and reduction in demand. • Biofuels are not able to replace oil.
Ferrari F430 runs on biofuel (photo by Jeff McNeely) International Council of Science Current mandates and targets for liquid biofuels should be reconsidered in light of the potential adverse environmental consequences, potential displacement or competition with food crops, and difficulty of meeting these goals without large-scale land conversion. Given the constraint of not competing with food production or causing deforestation, biofuels can probably never make up for more than a few percent of the current rate of liquid fossil fuels in transportation. 24 International Council of Science Direct use of biomass for electric power and heat generation can be more efficient than conversion to liquid biofuels for transport. These alternatives are probably the best use of biomass for energy. International Council of Science R. Howarth and S. Bringezu (editors). 2009. Biofuels: Environmental Consequences and Interactions with Changing Land Use http://cip.cornell.edu/biofuels 25 ...
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