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 (http://gov.ca.gov/executive-order/5172/), 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 (http://www.energy.ca.gov/low_carbon_fuel_standard/UC-1000-2007-002-PT1.PDF) 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.

Biographies
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 E