Biofuels and carbon: changing land use makes ethanol increase carbon concentrations

Lynne Kiesling

This new article in Science tackles a question that I’ve had for years, and is creating a stir in the process: once you take into account the emissions of carbon during the corn growing process, what is the net effect of ethanol production and use on carbon concentrations?

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. 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.

See also the discussion in the Seattle Times and in Wired magazine. As the Wired article notes,

Biofuels seemed so promising at first — what could be cleaner than running our cars and factories on plants? But early prognostications were a bit thin on details. They didn’t always account for the energy that would be needed to grow, harvest and refine the fuels. Most importantly, they didn’t consider that greenhouse gas-gobbling vegetation would need to be cleared for fuel crops — or, if these were planted on existing pastures, that new fields would be cleared to make space for displaced food crops.

Put these factors in the equation, and biofuels don’t do much good at all. The first study, led by Princeton University environmental law researcher Timothy Searchinger, found that replacing fossil fuels with corn-based ethanol — the darling of the U.S. biofuel industry — would double greenhouse gas emissions for the next thirty years. Even switchgrass, seen as a far more efficient alternative, would produce a 50% bump in emissions.

Combine this result with the effects that U.S. biofuels policy have had on food markets, particularly increasing the prices of basic foods to poorer populations, and perhaps we have enough impetus to overcome the massively successful agri-business lobby in Washington.

I’ll be very curious to see how the junior Senator from Illinois handles this issue when he’s campaigning at home in his Presidential bid … he’s been singing the agri-business tune for years.

Note also that a a response from the Renewable Fuels Association executive director doesn’t address the actual data:

Bob Dineen, the executive director of the Renewable Fuels Association, said: “It is important that we all take a step back and reflect on why we must aggressively deal with climate change. It’s because for more than 100 years we have burned fossil fuels like coal and oil without concern for the environmental consequences. This laissez faire attitude has [created] a “carbon debt” that can never be repaid. Failing to adopt technologies available today, like biofuels and improved gas mileage… relegates the world to more of the same…You must ask yourself, if not biofuels, what?”

Hat tip: Slashdot.