The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [145]
122 Ethanol is more corrosive than gasoline, so engines running on 100% ethanol require specially resistant plastic and rubber components and hardened valve seats. It also has lower energy content than gasoline, so can yield lower mileage results relative to gasoline. However, owing to its high octane of 115, ethanol can be used as an octane enhancer in gasoline instead of groundwater-polluting MTBE. R. E. Sims et al., “Energy Crops: Current Status and Future Prospects,” Global Change Biology 12 (2006): 2054-2076.
123 Drawn from remarks by José Goldemberg, National Academies Summit on America’s Energy Future, Washington, D.C., March 2008.
124 This forecast is not an extrapolation but is based on the number of ethanol plants licensed and under construction in Brazil, National Academies Summit on America’s Energy Future, Washington, D.C., March 2008.
125 José Goldemberg, Suani Teixeira Coelho, Patricia Guardabassi, Sugarcane’s Energy: Twelve Studies on Brazilian Sugarcane Agribusiness and Its Sustainability, Energy Policy 36, no. 6 (June 2008): 2086-2097. Multiple files available for free download from UNICA (Brazilian Sugarcane Industry Association) at http://english.unica.com.br/multimedia/publicacao/; also personal interview with Dr. Matthew C. Nisbitt, Columbus, Ohio, April 18, 2008.
126 Fig. 7.3, summary from National Academies Summit on America’s Energy Future, Washington, D.C., March 2008.
127 “Brazil Ethanol Sales Pass Petrol,” Sydney Morning Herald, December 31, 2008.
128 M. E. Himmel et al., “Biomass Recalcitrance: Engineering Plants and Enzymes for Biofuels Production,” Science 315 (2007): 804-807.
129 Ethanol studies are all over the map in terms of net greenhouse gas (GHG) benefits or penalties, hinging notably on whether or not “coproducts” are included in the accounting. When these factors are considered, the GHG benefits of corn ethanol over petroleum become negligible, about a 13% reduction when the benefits of coproducts are included. But ethanol produced from cellulosic material (switchgrass) reduces both GHGs and petroleum inputs substantially. A. E. Farrell et al, “Ethanol Can Contribute to Energy and Environmental Goals, Science 311 (2006): 506-508.
130 Drawn from remarks by José Goldemberg, National Academies Summit on America’s Energy Future, Washington, D.C., March 2008.
131 C. Gautier, Oil, Water, and Climate: An Introduction (New York: Cambridge University Press, 2008), 366 pp.
132 “Food Crisis Renews Haiti’s Agony,” Time, April 9, 2008; “Looters Running Wild in Haiti’s Food Riots,” San Francisco Chronicle, April 10, 2008; “Hunger, Strikes, Riots: The Food Crisis Bites,” The Guardian, April 13, 2008; D. Loyn, “World Wakes Up to Food Challenge,” BBC News, October 15, 2008.
133 Provided that areas currently used for grazing are converted to agriculture, especially in South America and the Caribbean, and sub-Saharan Africa. E. M. W. Smeets et al., “A Bottom-Up Assessment and Review of Global Bio-energy Potentials to 2050,” Progress in Energy and Combustion Science 33 (2007): 56-106.
134 A. E. Farrell et al., “Ethanol Can Contribute to Energy and Environmental Goals,” Science 311 (2006): 506-508.
135 For example, advanced conversion technologies like enzymatic hydrolysis, and new yeasts and microorganisms to convert five-carbon sugars. Energy Technology Perspectives—Scenarios and Strategies to 2050, International Energy Agency (2006), 483 pp.
136 The ecological footprint is a measure of environmental impact converted to units of land area. Holden and Høyer calculate ecological footprints of four different energy regimes and found that hydropower reduces ecological footprint by -75%, natural gas by -45% to -75% (highest for fuel cells), and oil by -15% to -30%, but cellulosic (wood) biofuel by 0% to +50%. E. Holden and K. G. Høyer, “The Ecological Footprints of Fuels,” Transportation Research Part D 10 (2005): 395-403.
137 G. Fischer, L. Schrattenholzer, “Global Bioenergy Potentials through 2050,” Biomass and Bioenergy 20 (2001): 151-159; and Energy Technology