The True Cost of Biofuels

A major study published by The Nature Conservancy and University of Minnesota concludes that land clearing releases 17 to 420 times as much carbon dioxide as is replaced by using the biofuel produced from that cleared land.

What is “carbon debt”? The lead author of “Land Clearing and the Biofuel Carbon Debt,” Joe Fargione, explains in an interview:

“All the biofuels we use now cause clearing of natural ecosystems for agriculture. Adding energy production to our current and growing demand for food production inevitably requires more land to be converted to agriculture, whether or not the biofuel is grown directly on that land. So biofuels either directly or indirectly cause land clearing, which releases carbon to the atmosphere and contributes to global warming. This is the biofuel carbon debt.

“Now, making and using biofuels adds less carbon to the atmosphere than does making and using fossil fuels — if you ignore the effects of land clearing. But how does this compare to the carbon debt from land clearing? How many years would you have to use biofuels for the amount of carbon saved to exceed the amount of carbon released by land clearing?”

Some of the study’s major findings:

• Converting rainforests, peatlands, savannas, or grasslands to produce 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 fossil fuels they replace.
• Converting lowland tropical rainforests in Indonesia and Malaysia to palm biodiesel would result in a biofuel carbon dept that would take approximately 86 years to repay.
• Converting tropical peatland rainforest with an average depth (3 meters) could incur a biofuel carbon debt that would take more than 840 years to repay. 
• Soybean biodiesel produced on converted Amazonian rainforest would incur a biofuel carbon debt that would require approximately 320 years to repay.
• Sugarcane ethanol produced on Cerrado sensu stricto, which is the wetter and more productive end of this woodland-savanna biome, would incur a biofuel carbon debt that would require approximately 17 years to repay.
• Soybean biodiesel from the drier, less productive grass-dominated end of the Cerrado biome would incur a biofuel carbon debt that would require 27 years to repay.
• For US Central grassland on farmland that has been enrolled in the United States Conservation Reserve Program for 15 years, converting it to corn ethanol production creates a biofuel carbon debt that would take approximately 48 years to repay.
• The analyses suggests that biofuels produced on converted lands could, for long periods of time, be greater net emitters of greenhouse gasses than the fossil fuels they typically displace.
• For current or developing biofuel technologies, any strategy to reduce greenhouse gas emissions that causes land conversion from native ecosystems to cropland is likely to be counterproductive.