Below is a terrific critique from some of the folks at the Argonne National Lab -- the people who created the model that Searchinger used in his study. I've highlighted some of the key parts. Now the question is -- will the media ask these same questions and give the critique the same air time that the hyped up "study" was given? And another burning question to ponder -- WILL THE ENVIRONMENTALISTS TAKE NOTE and agree that a study is only as good as the data used to generate it. Garbage In, Garbage Out!
Nothing angers me more than short-sighted environmentalists who line up ARM IN ARM with the oil industry to tear down biofuels -- the one transportation fuel we have now that COULD be sustainable if done right.
Response to February 7, 2008 Sciencexpress Article
Michael Wang of Argonne's Transportation Technology R&D Center and Zia Haq of the Department of Energy's Office of Biomass respond to the article by Searchinger et al. in the February 7, 2008, Sciencexpress, "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change"
Letter to Science
Center for Transportation Research
Office of Biomass Program
Office of Energy Efficiency and Renewable Energy
The article by Searchinger et al. in Sciencexpress ("Use of U.S. Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change," February 7, 2008) provides a timely discussion of fuel ethanol's effects on greenhouse gas (GHG) emissions when taking into account GHG emissions from potential land use changes induced by ethanol production.
Land use change issues associated with biofuels were explored in life-cycle analyses beginning in early 1990s (Delucchi 1991). In general, the land use changes that occur as a result of biofuel production can be separated into two categories: direct and indirect. Direct land use changes involve direct displacement of land for farming of the feedstocks needed for biofuel production. Indirect land use changes are those made to accommodate farming of food commodities in other places in order to maintain the global food supply and demand balance.
Searchinger et al. used the GREET model developed by one of us at Argonne National Laboratory in their study (see Wang 1999). They correctly stated that the GREET model includes GHG emissions from direct land use changes associated with corn ethanol production; the emissions estimates in GREET are based on land use changes modeled by the U.S. Department of Agriculture (USDA) in 1999 for an annual production of 4 billion gallons of corn ethanol in the United States by 2010. Needless to say, the ethanol production level simulated by USDA in 1999 has been far exceeded by actual ethanol production — about 6 billion gallons in 2007 (Renewable Fuels Association 2008). Thus, the resultant GHG emissions from land use changes provided in the current GREET version need to be updated. Argonne, and several other organizations, recently began to address both direct and indirect land use changes associated with future, much-expanded
Many critical factors determine GHG emission outcomes of land use changes. First, we need to clearly define a baseline for global food supply and demand and cropland availability without the
Searchinger et al. modeled a case in which
Corn yield per acre is a key factor in determining the total amount of land needed for a given level of corn ethanol production. It is worth noting that
Searchinger et al. also assumed that distillers' grains and solubles (DGS) from corn ethanol plants would displace corn on a pound-for-pound basis. The one-to-one displacement ratio between DGS and corn fails to recognize that the protein content of DGS is much higher than that of corn (28% vs. 9%). The actual displacement value of DGS is estimated to be at least 23% higher than that assumed by Searchinger et al. (Klopfenstein et al. 2008).
Searchinger et al. estimated that
Searchinger et al. had to decide what land use changes would be needed in Brazil, the United States, China, and India to meet their simulated requirement for 10.8 million hectares of new crop land. With no data or modeling, Searchinger et al. used the historical land use changes that occurred in the 1990s in individual countries to predict future land use changes in those countries (2015 and beyond). This assumption is seriously flawed by predicting deforestation in the Amazon and conversion of grassland into crop land in
In estimating the GHG emissions payback period for corn ethanol, Searchinger et al. relied on the 20% reduction in GHG emissions that is provided in the GREET model for the current ethanol industry. Future corn ethanol plants could improve their energy efficiency by avoiding DGS drying (in some ethanol plants) or switching to energy sources other than natural gas or coal, either of which would result in greater GHG emissions reductions for corn ethanol (Wang et al. 2007). Searchinger et al. failed to address this potential for increased efficiency in ethanol production. [Note - this is part of what EDF was exploring with the policy of certifying low carbon and ultra low carbon forms of ethanol]
In one of the sensitivity cases, Searchinger et al. examined cellulosic ethanol production from switchgrass grown on land converted from corn farms. Cellulosic biomass feedstocks for ethanol production could come from a variety of sources. Oak Ridge National Laboratory completed an extensive assessment of biomass feedstock availability for biofuel production (Perlack et al. 2005). With no conversion of crop land in the
On the basis of our own analyses, production of corn-based ethanol in the
The Searchinger et al. study demonstrated that indirect land use changes are much more difficult to model than direct land use changes. To do so adequately, researchers must use general equilibrium models that take into account the supply and demand of agricultural commodities, land use patterns, and land availability (all at the global scale), among many other factors. Efforts have only recently begun to address both direct and indirect land use changes (see Birur et al. 2007). At this time, it is not clear what land use changes could occur globally as a result of
Birur, D.K., T.W. Hertel, and W.E. Tyner, 2007, The Biofuel Boom: The Implications for the World Food Markets, presented at the Food Economy Conference,
Delucchi, M.A., 1991, Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity, ANL/ESD/TM-22, Volume 1, Center for Transportation Research, Argonne National Laboratory, Argonne, Ill., Nov.
Fargione, J., J. Hill, D. Tilman, S. Polasky, and P. Hawthorne, 2008, "Land Cleaning and Biofuel Carbon Debt," Sciencexpress, available at www.sciencexpress.org, Feb. 7.
Klopfenstein, T. J., G.E. Erickson, and V.R. Bremer, 2008, "Use of Distillers' By-Products in the Beef Cattle Feeding Industry," forthcoming in Journal of Animal Science.
Korves, R., 2007, The Potential Role of Corn Ethanol in Meeting the Energy Needs of the United States in 2016–2030, prepared for the Illinois Corn Marketing Board, Pro-Exporter Network, Dec.
Perlack, R.D., L.L. Wright, A. Turhollow, R.L. Graham, B. Stokes, and D.C. Urbach, 2005, Biomass as Feedstock for Bioenergy and Bioproducts Industry: the Technical Feasibility of a Billion-Ton Annual Supply, prepared for the U.S. Department of Energy and the U.S. Department of Agriculture, ORNL/TM-2005/66, Oak Ridge National Laboratory,
RFA (Renewable Fuels Association), 2008, Industry Statistics, available at http://www. ethanolrfa.org/industry/statistics/, accessed Feb. 13, 2008.
Searchinger, T., R. Heimlich, R.A. Houghton, F. Dong, A. Elobeid, J. Fabiosa, S. Tokgoz, D. Hayes, and T.H. Yu, 2008, "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change," Sciencexpress, available at www.sciencexpress.org, Feb. 7.
Wang, M., 1999, GREET 1.5 – Transportation Fuel-Cycle Model, Volume 1: Methodology, Development, Use, and Results, ANL/ESD-39, Volume 1, Center for Transportation Research, Argonne National Laboratory,
Wang, M, M. Wu, and H. Hong, 2007, "Life-Cycle Energy and Greenhouse Gas Emission Impacts of Different Corn Ethanol Plant Types," Environmental Research Letter, 2: 024001 (13 pages).
For More Information
Contact Michael Wang at email@example.com.