Biofuels, Land Conversion and Climate Change

Fri, 25 Apr 2008 16:00:00 GMT

Are all biofuels equal in terms of their capacity to reduce greenhouse gas emissions relative to the use of gasoline? If not, what factors determine which biofuels have greater capacity to reduce greenhouse gas emissions? What is the most reliable method of measuring a biofuel’s effectiveness for reducing greenhouse gas emissions? What role does land conversion make in determining the effectiveness of biofuels in reducing greenhouse gas emissions? Which biofuels of the future are likely to result in maximal reductions in greenhouse gas emissions? How close are we to that future?

  • Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society
  • Dr. Joseph E. Fargione, Regional Science Director, The Nature Conservancy, Central US Region, Minneapolis, MN
  • Timothy Searchinger, Visiting Scholar and Lecturer in Public and International Affairs, Princeton University, Woodrow Wilson School, Princeton, NJ
  • Dr. Daniel M. Kammen, Class of 1935 Distinguished Professor of Energy, Professor in the Energy and Resources Group Energy and Resources Group (ERG) , Professor of Public Policy in the Goldman School of Public Policy, Professor of Nuclear Engineering in the Department of Nuclear Engineering, and Co-Director, Berkeley Institute of the Environment, and Founding Director of the Renewable and Appropriate Energy Laboratory (RAEL), University of California, Berkeley, CA
  • Dr. G. David Tilman, Regents’ Professor and McKnight Presidential Chair in Ecology, University of Minnesota, St. Paul, MN

Program Summary

Biofuels: Threats and Opportunities

  • It is possible to make biofuels that reduce carbon emissions, but only if we ensure that they do not lead to additional land clearing.
  • When land is cleared for agriculture, carbon that is locked up in the plants and soil is released through burning and decomposition. The carbon is released as carbon dioxide, which is an important greenhouse gas, and causes further global warming.
  • 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 carbon dioxide than the annual greenhouse gas reductions that these biofuels would provide by displacing fossil fuels.
  • Depending on future biofuel production, the effects of this clearing could be significant for climate change: globally, there is almost three times as much carbon locked up in the plants and soils of the Earth as there is in the air and 20% of global carbon dioxide emissions come from land use change.
  • Global demand for food is expected to double in the next 50 years and is unlikely to be met entirely from yield increases, thus requiring significant land clearing. If existing cropland is insufficient to meet imminent food demands, then any dedicated biofuel crop production will necessarily create demand for additional cropland to be cleared.
  • Several forms of biofuels do not cause land clearing, including biofuels made from algae, from waste biomass, or from biomass grown on degraded and abandoned agricultural lands planted with perennials.

Present Generation of Biofuels: Reducing or Enhancing Greenhouse Gas Emissions?

Previous studies have found that substituting biofuels for gasoline will reduce greenhouse gasses because growing the crops for biofuels sequesters takes carbon out of the air that burning only puts back, while gasoline takes carbon out of the ground and puts it into the air. These analyses have typically not taken into consideration carbon emissions that result from farmers worldwide converting forest or grassland to produce biofuels, or that result from farmers worldwide responding to higher prices and converting forest and grassland into new cropland to replace the grain (or cropland) diverted to biofuels. Our revised analysis suggests that greenhouse gas emissions from the land use changes described above, for most biofuels that use productive land, are likely to substantially increase over the next 30 years. Even advanced biofuels from biomass, if produced on good cropland, could have adverse greenhouse gas effects. At the same time, diverting productive land raises crop prices and reduces consumption among the 2.8 billion people who live on less than $2 per day.

Simply avoiding biofuels produced from new land conversion – as proposed by a draft European Union law – does not avoid these global warming emissions because the world’s farmers will replace existing crops or cropland used for biofuels by expanding into other lands. The key to avoiding greenhouse gas emissions and hunger from land use change is to use feedstocks that do not divert the existing productive capacity of land – whether that production stores carbon (as in forest and grassland) or generates food or wood products. Waste products, including municipal and slash forest waste from private lands, agricultural residues and cover crops provide promising opportunities. There may also be opportunities to use highly unproductive grasslands where biomass crops can be grown productively, but those opportunities must be explored carefully.

Biofuels and a Low-Carbon Economy

The low-carbon fuel standard is a concept and legal requirement in California and an expanding number of states that targets the amount of greenhouse gases produced per unit of energy delivered to the vehicle, or carbon intensity. In January 2007, California Gov. Arnold Schwarzenegger signed Executive Order S-1-07, which called for a 10-percent reduction in the carbon intensity of his state’s transportation fuels by 2020. A research team in which Dr. Kammen participated developed a technical analysis of low-carbon fuels that could be used to meet that mandate. That analysis employs a life-cycle, “cradle to grave” analysis of different fuel types, taking into consideration the ecological footprint of all activities included in the production, transport, storage, and use of the fuel.

Under a low-carbon fuel standard, fuel providers would track the “global warming intensity” (GWI) of their products and express it as a standardized unit of measure—the amount of carbon dioxide equivalent per amount of fuel delivered to the vehicle (gCO2e/MJ). This value measures vehicle emissions as well as other trade-offs, such as land-use changes that may result from biofuel production. For example, an analysis of ethanol shows that not all biofuels are created equal. While ethanol derived from corn but distilled in a coal-powered refinery is in fact worse on average than gasoline, some cellulosic-based biofuels – largely those with little or no impact on agricultural or pristine lands have the potential for a dramatically lower GWI.

Equipped with detailed measurements that relate directly to the objectives of a low-carbon fuel standard, policy makers are in a position to set standards for a state or nation, and then regulate the value down over time. The standard applies to the mix of fuels sold in a region, so aggressively pursuing cleaner fuels permits some percentage of more traditional, dirtier fuels to remain, a flexibility that can enhance the ability to introduce and enforce a new standard.

The most important conclusions from this analysis are that biofuels can play a role in sustainable energy future, but the opportunities for truly low-carbon biofuels may be far more limited than initially thought. Second, a low-carbon economy requires a holistic approach to energy sources – both clean supply options and demand management – where consistent metrics for actual carbon emissions and impacts are utilized to evaluate options. Third, land-use impacts of biofuel choices have global, not just local, impact, and a wider range of options, including, plug-in hybrid vehicles, dramatically improved land-use practices including sprawl management and curtailment, and greatly increased and improved public transport all have major roles to play.

Biofuels and Greenhouse Gas Emissions: A Better Path Forward

The recent controversy over biofuels notwithstanding, the US has the potential to meet the legislated 21 billion gallon biofuel goal with biofuels that, on average, exceed the targeted reduction in greenhouse gas release, but only if feedstocks are produced properly and biofuel facilities meet their energy demands with biomass.

A diversity of alternative feedstocks can offer great GHG benefits. The largest GHG benefits will come from dedicated perennial crops grown with low inputs of fertilizer on degraded lands, and especially from those crops that increase carbon storage in soil (e.g., switchgrass, mixed species prairie, and Miscanthus). These may offer 100% or perhaps greater reductions in GHG relative to gasoline. Agricultural and forestry residues, and dedicated woody crops, including hybrid poplar and traditional pulp-like operations, should achieve 50% GHG reductions.

In contrast, if biofuel production leads to direct or indirect land clearing, the resultant carbon debt can negate for decades or longer any greenhouse gas benefits a biofuel could otherwise provide. Current legislation, which is outcome based, has anticipated this problem by mandating GHG standards for current and next generation biofuels.


Dr. Joseph E. Fargione is the Regional Science Director for The Nature Conservancy’s Central US Region. He received his doctorate in Ecology from the University of Minnesota in 2004. Prior to the joining The Nature Conservancy, he held positions as Assistant Research Faculty at the University of New Mexico (Biology Department), Assistant Professor at Purdue University (Departments of Biology and Forestry and Natural Resources), and Research Associate at the University of Minnesota (Departments of Applied Economics and Ecology, Evolution, and Behavior).

His work has focused on the benefits of biodiversity and the causes and consequences of its loss. Most recently, he has studied the effect of increasing demand for biofuels on land use, wildlife, and carbon emissions. He has authored 18 papers published in leading scientific journals, including Science, Proceedings of the National Academy of Sciences, Proceedings of the Royal Society, Ecology, and Ecology Letters, and he was a coordinating lead author for the Millennium Ecosystem Assessment chapter titled “Biodiversity and the regulation of ecosystem services.” His recent paper in Science, “Land clearing and the biofuel carbon debt” was covered in many national media outlets, including the New York Times, Washington Post, Wall Street Journal, National Public Radio, NBC Nightly News, and Time Magazine.

Timothy Searchinger is a Visiting Scholar and Lecturer in Public and International Affairs at Princeton University’s Woodrow Wilson School. He is also a Transatlantic Fellow of the German Marshall Fund of the United States, and a Senior Fellow at the Georgetown Environmental Law and Policy Institute. Trained as a lawyer, Dr. Searchinger now works primarily on interdisciplinary environmental issues related to agriculture.

Timothy Searchinger previously worked at the Environmental Defense Fund, where he co-founded the Center for Conservation Incentives, and supervised work on agricultural incentive and wetland protection programs. He was also a deputy General Counsel to Governor Robert P. Casey of Pennsylvania and a law clerk to Judge Edward R. Becker of the United States Court of Appeals for the Third Circuit. He is a graduate, summa cum laude, of Amherst College and holds a J.D. from Yale Law School where he was Senior Editor of the Yale Law Journal.

Timothy Searchinger first proposed the Conservation Reserve Enhancement Program to USDA and worked closely with state officials to develop programs that have now restored one million acres of riparian buffers and wetlands to protect important rivers and bays. Searchinger received a National Wetlands Protection Award from the Environmental Protection Agency in 1992 for a book about the functions of seasonal wetlands of which he was principal author. His most recent writings focus on the greenhouse gas emissions from biofuels, and agricultural conservation strategies to clean-up nutrient runoff. He is also presently writing a book on the effects of agriculture on the environment and ways to reduce them.

Dr. Daniel M. Kammen, Class of 1935 Distinguished Professor in the Energy and Resources Group (ERG), in the Goldman School of Public Policy and in the Department of Nuclear Engineering at the University of California, Berkeley. He is also the founding Director of the Renewable and Appropriate Energy Laboratory (RAEL) and Co-Director of the Berkeley Institute of the Environment.

Previously in his career, Dr. Kammen was an Assistant Professor of Public and International Affairs at Princeton University, and also played a key role in developing the interdisciplinary Science, Technology, and Environmental Policy (STEP) Program at Princeton as STEP Chair from 1997 – 1999. In July of 1998 Kammen joined ERG as an Associate Professor of Energy and Society.

Dr. Kammen received his undergraduate degree in physics from Cornell University (1984), and his masters and doctorate in physics from Harvard University (1986 & 1988) for work on theoretical solid state physics and computational biophysics. First at Caltech and then as a Lecturer in Physics and in the Kennedy School of Government at Harvard, Dr. Kammen developed a number of projects focused on renewable energy technologies and environmental resource management.

Dr. Kammen’s research interests include: the science, engineering, and policy of renewable energy systems; health and environmental impacts of energy generation and use; rural resource management, including issues of gender and ethnicity; international R&D policy, climate change; and energy forecasting and risk analysis. He is the author of over 200 peer-reviewed journal publications, a book on environmental, technological, and health risks, and numerous reports on renewable energy and development. He has also been a lead author for the Intergovernmental Panel on Climate Change that shared the 2007 Nobel Peace Prize.

Dr. G. David Tilman is Regents’ Professor and McKnight Presidential Chair in Ecology at the University of Minnesota. He is an elected member of the American Academy of Arts and Sciences and the National Academy of Sciences, and has served on editorial boards of nine scholarly journals, including Science. He serves on the Advisory Board for the Max Plank Institute for Biogeochemistry in Jena, Germany. He has received the Ecological Society of America’s Cooper Award and its MacArthur Award, the Botanical Society of America’s Centennial Award, the Princeton Environmental Prize and was named a J. S. Guggenheim Fellow. He has written two books, edited three books, and published more than 200 papers in the peer-reviewed literature, including more than 30 papers in Science, Nature and the Proceedings of the National Academy of Sciences USA. The Institute for Scientific Information recently designated him as the world’s most highly cited environmental scientist of the decade.

Dr. Tilman’s recent research explores how managed and natural ecosystems can sustainably meet human needs for food, energy and ecosystem services. A long-term focus of his research is on the causes, consequence and conservation of biological diversity, including using biodiversity as a tool for biofuel production and climate stabilization through carbon sequestration. His work on renewable energy examines the full environmental, energetic and economic costs and benefits of alternative biofuels and modes of their production.


This event's trackback address