Two reports about Biofuels are available in this week's Science Magazine. The reports were released to the press in early February and mass media outlets released headline after headline indicating that biofuels will release more carbon to the atmosphere than they would offset when compared to fossil fuels. Bio-fuels have been touted as the answer to our climate change energy dilemmas and now they are being slated as potentially a bigger threat than fossil fuel power plants. We need a clean, renewable high yielding source of energy - each time a solution is suggested early hopes are dashed as we realize that there is no single energy solution.
The advantage of bio-fuels over fossil fuels is that in the short term carbon goes into and out of a biofuel, while fossil fuels only release carbon; i.e. some of the carbon cost of energy production using biofuels is offset by recent photosynthesis. However, the a report by Fargione and colleagues (Science, 2008) pointed out that when you change a particular bit of land from one thing into bio-fuel producing facility you use energy and release CO2 from the ecosystem in that location. This increases the carbon cost of the fuel by increasing the CO2 released which makes the bio-fuel less useful as a low carbon fuel. The conclusion is that bio-fuels should not be adopted where the carbon cost of creating the fuel is many times greater than the benefit gained by selecting bio vs fossil fuels. Before any bio-fuel system is adopted, we need a full accounting of the gains and losses.
A second report by Searchinger and others (Science, 2008) points out that when we use cropland for bio-fuel production we need to grow those crops elsewhere. If we think globally lots of changes in land use (e.g. moving natural land into crop production) can be attributed to bio-fuels. This change releases carbon into the atmosphere and makes biofuels less attractive. The authors conclude that farmland should not be used for biofuel production. I doubt that this conclusion can be true for all cropland everywhere. Especially for marginal or excess cropland.
The authors argue that "Truly excess croplands would revert either to forest or grassland and sequester carbon." (Searchinger et al. 2008.). I don't agree. When land is taken out of crop-production, often, it is converted to housing, industrial or commercial property resulting in greater carbon emissions than before. If it were profitable to produce biofuels on marginal cropland they would make a positive contribution to providing low carbon energy.
Neither of these results are surprising - they are however important - there are situations where bio-fuels are not the best option and we should think very carefully about the wider consequences of our actions. Think globally and act locally is a useful but one dimensional slogan but this research indicates that a single local action designed to address a global problem can have unintended consequences in other localities. We need to emphasize the co-ordination of global actions. Blindly adopting bio-fuels or any other low carbon solution is foolhardy, but we shouldn't throw viable solutions away because they do not work everywhere on earth.
Abstracts for the reports in Science
Science 29 February 2008: Vol. 319. no. 5867, pp. 1235 - 1238 DOI: 10.1126/science.1152747
Land Clearing and the Biofuel Carbon Debt
Joseph Fargione,1 Jason Hill,2,3 David Tilman,2* Stephen Polasky,2,3 Peter Hawthorne2
Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to low-carbon fuels a high priority. Biofuels are a potential low-carbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food crop–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 (GHG) reductions that these biofuels would provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on degraded and abandoned agricultural lands planted with perennials incur little or no carbon debt and can offer immediate and sustained GHG advantages.
1 The Nature Conservancy, 1101 West River Parkway, Suite 200, Minneapolis, MN 55415, USA.
2 Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55108, USA.
3 Department of Applied Economics, University of Minnesota, St. Paul, MN 55108, USA.
Science 29 February 2008: Vol. 319. no. 5867, pp. 1238 - 1240 DOI: 10.1126/science.1151861
Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change
Timothy Searchinger,1* Ralph Heimlich,2 R. A. Houghton,3 Fengxia Dong,4 Amani Elobeid,4 Jacinto Fabiosa,4 Simla Tokgoz,4 Dermot Hayes,4 Tun-Hsiang Yu4
Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These 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. By using a worldwide agricultural model to estimate emissions from land-use change, we 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.
1 Woodrow Wilson School, Princeton University, Princeton, NJ 08544, USA. German Marshall Fund of the United States, Washington, DC 20009, USA. Georgetown Environmental Law and Policy Institute, Washington, DC 20001, USA.
2 Agricultural Conservation Economics, Laurel, MD 20723, USA.
3 Woods Hole Research Center, Falmouth, MA 02540–1644, USA.
4 Center for Agricultural and Rural Development, Iowa State University, Ames, IA 50011, USA.