Biofuels May Create More Greenhouse Gas Than They Offset
By Kevin Miller
Earlier this week, GM announced that half of all cars it sells in the United States will be capable of running on ethanol by 2012. GM will have eleven ethanol-capable vehicles on sale this year, and fifteen models will be available in 2009. Also this week, Coskata Inc, part owned by GM, announced it has teamed up with engineering firm ICM, Inc, to open a plant in 2010 which will mass produce cellulose-based ethanol.
Ethanol is an alcohol fuel which is manufactured by fermenting and distilling starchy crops such as corn, or “cellulosic biomass” such as trees or grasses. E10, a mixture of 10% ethanol and 90% gasoline, is sold in many parts of the United States and is approved by automobile manufacturers for use in standard gasoline engines. E85, a blend of 85% ethanol and 15% gasoline can be used in Flexible Fuel Vehicles (FFVs), which are specifically engineered to run on E85, normal gasoline, or any combination of the two. When FFVs are operated on E85 they typically get 20-30% fewer miles per gallon than when they are operated with gasoline, because ethanol has a lower energy content than gasoline.
The U.S. energy bill signed into law by President Bush in December, 2007, calls for a large increase in biofuel production for America’s automobiles – 36 billion gallons by 2022, with 16 billion gallons from cellulosic ethanol. The European Union has proposed that 10% of all fuel used for transportation should come from biofuels by 2020. Biofuel opponents claim that the recent emphasis on ethanol and biofuels has inflated the price of corn (thereby making food more expensive) and strained water supplies.
A big premise behind the use of ethanol and other biofuels in the United States and around the world is that doing so will reduce the nation’s dependence on foreign petroleum fuels as well as reducing greenhouse gases, which are said to cause global warming. This week, two studies published in Science suggest that the growth of crops for production of biofuels such as ethanol may actually be increasing greenhouse gas emissions rather than lowering them.
The first study published in Science, contradicts prior studies’ findings that substituting biofuels for gasoline reduces greenhouse gases because biofuels absorb carbon from the atmosphere when the “feedstock” crop is grown. Those prior studies, however, did not account for the carbon emissions that occur as farmers convert forest and grassland to new cropland to replace the farmland converted to biofuels. Using a worldwide agricultural model to estimate emissions from land use change,the study found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products for production of biofuels.
The second paper in Science asserts that while biofuels are a potential low-carbon energy source, whether they offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food-based biofuels in Brazil, Southeast Asia, and the United States creates a ‘biofuel carbon debt’ by releasing 17 to 420 times more CO2 than the annual greenhouse gas reductions these biofuels provide by displacing fossil fuels. However, biofuels made from waste biomass or from biomass grown on abandoned agricultural lands planted with perennial vegetation incurs little or no carbon debt and offers immediate and sustained greenhouse gas reduction.
According to Reuters, cellulosic ethanol production currently costs about double that of traditional U.S. corn-based ethanol and Brazilian sugar-based ethanol. Coskata claims their biofuel production process can produce ethanol almost anywhere in the world, using a wide range of materials (including agricultural or municipal waste), for less than US $1.00 per gallon, with the production process using less than one gallon of water for every gallon of cellulosic ethanol produced and reduction of carbon dioxide emissions by 84 percent compared with gasoline. According to Coskata, tests carried out by Argonne National Laboratory have shown their cellulosic ethanol generates 7.7 times the energy used to produce it, compared with 1.3 times for corn-based ethanol.
The fact that the US Engergy Bill mandates biofuel production and FFVs essentially means that the government is inadvertently promoting an increase in production of greenhouse gases. And while ethanol-powered vehicles will be reducing the nation’s dependence on foreign oil, they will do so at the cost of higher fuel consumption and increased carbon emsissions, which increase global warming rather than reducing it.
While Coskata’s process holds promise for lower-carbon (and lower cost) production of ethanol, plenty of traditional (corn-based) ethanol is already being produced to fill ethanol demand and meet US government goals. GM’s forecast of half its fleet being ethanol compatible by 2012 will help them comply with the government’s ethanol consumption goals, whether or not those goals are environmentally sound. Meanwhile, GM’s investment in Coskata could benefit them if that company can, in fact, produce ethanol in a manner which is as environmentally-sound as they claim.
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