MIT22_081JF10_lec13b

MIT22_081JF10_lec13b - Why Discuss Fossil Fuels in...

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Unformatted text preview: Why Discuss Fossil Fuels in Sustainable Energy? rgy Is improving efficiency to reduce fossil fuel ffic fos fue use by 1 TW the same as adding 1 TW of f renewable energy generation? In what ways is it the same? How is it different? If cost of efficiency and cost of renewable were the same, which would you prefer? Why? Which approach do you think is cheaper? The importance of SCALE: $6,000B/yr f S Small percent changes are HUGE Small percent investment in R&D is HUGE Wedge View of CO2 problem Need 7 approaches, each providing a wedge. Many of the inexpensive options involve improving efficiency of fossil fuel utilization. Graph by Carbon Mitigations Initiative, Princeton University. The McKinsey Curve Estimating $/ton of CO2 emissions avoided Courtesy of McKinsey & Company. Used with permission. One Proposal to stabilize CO2: Efficiency+Biofuel+CO2 CCS Courtesy of Ronald Prinn. Used with permission. Fossil Fossil Fuels III: Liquid Fuels for Transportation ransportation ~30% of fossil fuel use >50% of energy economics Diesel, Gasoline, Jet Fuel and the vehicles that burn them Liquid Fuels Basics Almost 100% of transportation runs on liquid fuels (mostly petroleum) And most petroleum is used for transportation And transportation Wellestablished technology: reliable, convenient Wellestablished enient No No technology in sight to replace liquid fuels for air air transportation. Cars, Cars, trucks, trains: several future options options More efficient internal combustion engines More engines Fuel cells are another type of `engine' Fuel `engine' Alternative liquid fuels Alternative fuels Gaseous fuels (natural gas, H2) Gaseous H2) Need to generate the H2 (from natural gas?) Need gas?) Electric (overhead wires or batteries) Electric batteries) Need to generate the electricity (from coal?) Need coal?) Liquid Liquid Fuel may run short: Since 1990, Discovering Less Oil than we are Burning ng This image from: http://www.usnews.com/usnews/news/graphics/ace060315.pdf Graph from Fournier, Donald F., and Eileen T. Westervelt. "Energy Trends and their Implications for U.S. Army Installations." U.S. Army Corps of Engineers (September 2005): ERDC/CERL TR-05-21. Liquid Fuel Market Changing Dramatically rke ramat Extrapolated Demand IEA 2002 (big increase in Middle East Oil Production) "...these are considered pessimistic projections. Others predict far higher production for the future... The optimists premise their estimates for the future entirely on production from the Middle East and Central Asia." - U.S. Army Corps of Engineers Graph from Fournier, Donald F., and Eileen T. Westervelt. "Energy Trends and their Implications for U.S. Army Installations." U.S. Army Corps of Engineers (September 2005): ERDC/CERL TR-05-21. Experience Experience with Oil Projections Historically, Nothing is Smooth! i.e. the smooth projections are Nonsense onsense Wars, economic cycles, natural disasters Political changes (positive & negative) Political Technology changes Technology changes Fuel demand is not very elastic prices can climb and fall very quickly High prices will inspire production Big increase in Middle East production Increases in all sorts of alternatives as well Lag times of ~5 years in production increases High price can drive world economy into recession. Price Price is almost impossible to predict. Fuel taxes, subsidies & regulations even worse. sidies Graph of crude oil prices from 1947-2009 removed due to copyright restrictions. Big Transportation Fuels Supply Gap Tr rta Extrapolated Demand The Gap: ~10 Gb/yr =27 mbd "...these are considered pessimistic projections. Others predict far higher production for the future... The optimists premise their estimates for the future entirely on production from the Middle East and Central Asia." - U.S. Army Corps of Engineers Graph from Fournier, Donald F., and Eileen T. Westervelt. "Energy Trends and their Implications for U.S. Army Installations." U.S. Army Corps of Engineers (September 2005): ERDC/CERL TR-05-21. What could fill gap between transport oul etw ransport liquid fuel demand & oil production? eman oil rodu on? Venezuelan tar ("extra heavy oil") Unexpected oil discoveries or production rates Improved petroleum recovery rates Gas-to-Liquids Gas-toFaster than expected development of tar sands Improved transport system efficiency Coal-to-Liquids (methanol?) Coal-toShale oil Gaseous fuels for transportation (CNG, H2) Conventional biofuels (from sugars, oils) Fuels from other biomass (e.g. cellulosic) Electricity One way out: don't use liquid fuels at all! Photo by IFCAR on Wikimedia Commons. Chevrolet Volt "Electric "Electric cars are nearly ready..." Boston Globe July 22, 2007 Note electricity probably will come from burngin coal; might solve oil shortage but not greenhouse gas problem. Slide from S. Koonin talk at MIT Sept. 2005 Courtesy of Steven E. Koonin. Used with permission. Or will Or will the gap be filled with biofuels? Photos by Kables on Flickr and Nyttend on Wikimedia Commons. Will need to convert cellulose too, to significantly close the gap. Conventional biofuel production uses a lot of natural gas. Hydrogen instead of batteries? Hydrogen ins of bat ries Fuel cells instead of heat engines? ins of engine Photo by Anika Malone on Flickr. Honda FCX Prototype H2 could be made from natural gas (w/ CO2 emissions): Price? Distribution? Range of vehicle? Gaseous Fuels: CNG is simple and abundant mpl Photo by Christian Giersing on Wikimedia Commons. Volvo B10BLE Hard to achieve acceptable range with gaseous fuels. Natural Gas supplies are limited in US, EU, China. Maybe better to use it for heating, chemicals, electricity? LIQUID FUEL WOULD BE MUCH BETTER! Options for making liquid fuels ption for ing liquid fuels Gas-to-Syngas-to-Liquids Gas-to-Syngas-to Commercial: Sumatra, Qatar Requires cheap gas, has to compete with LNG Coal-to-SynGas-to-Liquids Coal-to-SynGas-to Commercial: South Africa, now China. Coal Liquefaction Commercialized by Germany during war. Biofuels (Ethanol, treated vegetable oil) Commercial: Brazil, USA, EU. Oil Shale pyrolysis Has been commercial in many countries. Melt tar out of Tar Sands, then upgrade. Commercial: Canada Need to Look at Whole Picture All synfuels processes are complicated Each step adds expense & reduces efficiency. Each efficiency. Most processes greatly increase CO2 emissions! increase CO missions! Modularize to deal with complexity, but... Modularize but... What What do we really want? really want? Gasoline? Jet fuel? Diesel? Fuels for new engines? Gasoline? engines? Electricity? Electricity? Need Need Integrated View View cooptimize "independent" modules. cooptimize les. Integrated View should drive R&D focus. Integrated focus. Policy: CO2 sequestration? Other externalities? Policy: externalities? Making Liquid Fuels from Nonliquids Converting Tar (or Shale) to ordinary fuels 2 mbd operational or under construction Gasto GastoLiquids (FischerTropsch diesel) (FischerTropsc iesel) 0.4 mbd operational or under construction. 0.4 construction. Coalto CoaltoLiquids (FT diesel, FT gasoline, or methanol) (F F asoline, or methanol) 0.15 mbd in South Africa Sout South Africa frica Planned construction of ~1 mbd in China Planned China Common features: Common features: Huge Huge capital investments in the conversion units units Long Long lead times (~5 years). years). Capex Capex dominated: once you build a unit, never turn it off. off. Conversion losses imply extremely large CO2 emissions emissions Capturing & sequestering CO2 reduces efficiency, adds to capex. reduce fficiency, adds to capex. Research Issues: Chemistry Alternative chemical Alternative chemical routes to liquid fuels? CH4 + air,heat something condensable? ir,heat somethin ondensable? avoid twostep process. Air instead of O2? twostep stea Need separation methods that work at reactor T Need Coal + H2 valuable liquids valuable liquids avoid avoid syngas step and air separation separation Need better quality liquid products than made with existing Need existing coal liquefaction processes. Catalysts Catalysts that more selectively remove N from from shale oil, minimize H2 consumption. consumption. Reactions (and separations) that work at T's that Reactions that allow better heat integration. Properties Properties of a successful new fuel Liquid, high energy density. C/H/O only. /O only. Volatility of gasoline or light diesel. If polar, must be biodegradable to avoid groundwater contamination. If soluble in gasoline/diesel, must be some me special advantage in keeping it separate. Much Better Engine or Emissions Performance Alternative Liquid Fuels: The $64,000 Question Currently most new liquid fuels are diluted into petroleumderived petroleumderived gasoline or diesel ne or diesel Minimizes engine perturbation Minimizes perturbation No need for new distribution infrastructure No infrastructure New fuel valued about same as oil. (Risk: oil price New price can fall below cost to produce the new fuel). fuel). In In the future, will gas stations stock some some new 3rd fuel in addition gasoline and diesel? fuel iesel? Would open up many new engine possibilities. Would possibilities. New fuel might command higher price than oil. New oil. But only if it provides a big advantage! But advantage! Some possible new fuels Oil insoluble biodegradable fuels Polyols, certain other polyoxygenates Polyols, polyoxygenates Most likely from biomass Most biomass Relatively little is know about this option. Relatively option. option Alcohols, Alcohols, other oilsoluble oxygenates oilsoluble oxygenate Methanol, ethanol (GTL, CTL, or bio) Methanol, bio) Unusual vaporization & energy density Unusual density Heavier oilsoluble oxygenates (from biomass) oilsoluble from biomass) Similar to oil, any advantage to keep separate?? Similar separate?? What is needed for a 3rd Fuel to ne ded for bec become established? es blish All stakeholders must consent Vehicle makers Fuel makers/distributors Political leaders Consumers Mutual consent must persist for many years What could prompt such remarkably broad and long-lived consensus? long- What could prompt longlived long consensus on a new fuel? All the stakeholders should derive some benefit from the new fuel's introduction. There must be a significant advantage to the 3rd fuel. fuel How to share the benefit amongst all How all shareholders? shareholders? Most Most challenging for fuels which mix into oil. oil. Must be a clear advantage in keep n the van eepi g he in new fuel separ te. para Boring Boring version of Dual Fuel: Fuels are not miscible. Use Fuel B only if Fuel A is not available available (backup for unreliable distribution system) ystem) Photo of a diesel/CNG bus in New York City removed due to copyright restrictions. Dual Fuel Compressed Natural Gas/Diesel (since CNG is not available everywhere) Flexible Flexible Fuel Vehicles: Again, vehicle compensating for unreliable fuel ting distribution system Photo of an E85 Chevrolet Avalanche at the Chicago Auto Show, February 8, 2006 removed due to copyright restrictions. No compelling reason to keep E85 separate from the main gasoline stream Interesting versions of DualFuel: Performance Advantage from using both fuels Adjust fuel mix to optimize performance. Photo of ArvinMeritor test vehicle and Clean Air Power dual-fuel truck removed due to copyright restrictions. ArvindMeritor bus running diesel/H2 mix Clean Air Power truck running CNG/diesel mix Many other promising dual fuel concepts, e.g. for SI, HCCI... Are benefits sufficient to drive wide introduction of a 3rd fuel? Third Third "fuel" could be Electricity: e.g. PlugIn Hybrids Plug Photo of plug-in hybrid cars removed due to copyright restrictions. A pair of plugin hybrid electric vehicles are tested at Argonne's Transportation Technology R&D Center Approaching a fork in the road... Huge change in liquid fuel mix is coming: change There is not enough oil! It is expensive! Ther ot enough oil! It is expensive! Current system is not environmentally responsible. Current responsible. No one has energy security. No security. Difficult Difficult to predict which fuels will fill gap gap depends on policy decisions (climate, security, economics) depends economics) Window of opportunity to add a 3rd fuel at the pump fuel at th ump Electricity (e.g. plugin hybrid)?. Gases?? Polar liquids?? plugin ases?? Pola iquids?? A third oilsoluble fuel could become widely available, if... oilsoluble ailable, if... new vehicle technology can deliver big advantages by new by keeping the third fuel distinct. The benefits of the new fuel are perceived and shared The shared amongst the many stakeholders. A taste of R&D Mechanical Engineering, Nov. 2009: "Blending Diesel Fuel with Gasoline can improve diesel engine fuel efficiency by an average average of 20%...the best tests achieved achieve 53% thermal efficiency" This engine invented by Rolf Reitz was a dual dual fuel variant on HCCI A proposed new engine: HCCI proposed (homogeneous charge compression ignition) ession Gasoline SI Diesel HCCI Fuel/Air Air Fuel/Air Premixed? CI? Ignition Peak T Spark Hot: NOx Injection Hot: NOx Chemistry Cool Temperature Distribution Strongly Affects Ignition Chemistry Temperature field (TDC) 1250 K 1200 1150 1100 1050 Side View Basis: Basis: Basis: 2d calculation (pancake cylinder) no chemistry working fluid is pure air thermal correction applied later 1000 950 900 850 800 750 Mesh: 160 x 190 grid coarser mesh in core fine mesh in BL (60 m spacing) Top View Calcs using KIVA, by A. Amsden, LANL Chemistry Chemistry can be quite complex 4500 4000 3500 Reactions Number of Reactions Popular Kinetic Models for Fuel Chemistry PRF (Curran et al.) iso-octane (Curran et al.) n-heptane (Curran et al.) 1000 3000 2500 600 2000 1500 1000 500 0 0 1 2 3 4 5 6 7 8 9 Carbon Number hydrogen methane (GRIMech3.0) propane (Marinov) n-butane (ENSIC Nancy) 400 200 0 Species Number of Species 800 Each Each chemical reaction has its own (complicated) story CH3 + H2CO CH4 + HCO -11 -12 sec log(k) cc/molec sec -13 -14 -15 -16 -17 Susnow et al., Chem. Phys. Lett. 1999 -18 0 0.5 1 1.5 2 2.5 3 3.5 1000/T Courtesy of Elsevier, Inc., http://www.sciencedirect.com. Used with permission. What Speed What SpeedLoad Range can this HCCI engine deliver? can Fuel = n-heptane C.R.=9.5 Figure removed due to copyright restrictions. See Figure 14 in Yelvington, Paul E., et al. "Prediction of Performance Maps for Homogenenous-Charge Complression-Ignition Engines." Combustion Science and Technology 176 (August 2004): 1243-1282. Boost = 0.7 bar Yelvington et al., Combust. Sci. Tech. (2004). Integrating engine's performance over the driving cycle Morgan Andreae PhD thesis 2006 With this information, can estimate mpg for new engine/fuel combo MIT OpenCourseWare http://ocw.mit.edu 22.081J / 2.650J / 10.291J / 1.818J / 2.65J / 10.391J / 11.371J / 22.811J / ESD.166J Introduction to Sustainable Energy Fall 2010 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms. ...
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