Turns out that ethanol adds to greenhouse gas at twice the rate of gasoline, factoring all costs, whoops.
REVIEW & OUTLOOK
Greenhouse Affect
February 13, 2008; Page A26
The ink is still moist on Capitol Hill's latest energy bill and, as if on cue, a scientific avalanche is demolishing its assumptions. To wit, trendy climate-change policies like ethanol and other biofuels are actually worse for the environment than fossil fuels. Then again, Washington's energy neuroses are more political than practical, so it's easy for the Solons and greens to ignore what would usually be called evidence.
The rebukes arrive via two new studies in Science, a peer-reviewed journal not known for right-wing proclivities. The first, by ecologists at Princeton and the Woods Hole Research Center, reviews the environmental consequences of increased biofuel consumption, which had never been examined comprehensively. Of course, that didn't stop Congress and the Bush Administration from jacking up the U.S. mandate to 36 billion gallons by 2022, a fivefold increase from a mere two years ago. Such policies are supposedly justified because corn-based ethanol and other "alternatives" result in (very modest) reductions in greenhouse-gas emissions when mixed with gasoline.
The researchers break new ground by exposing a kind of mega-accounting error: Prior studies had never credited the carbon-dioxide emissions that arise when virgin forests, grasslands and the like are cleared to grow biofuel feedstocks. About 2.7 times more carbon is stored in terrestrial soils and plant material than in the atmosphere, and this carbon is released when these areas are cleared (often by burning) and the soil is tilled. Compounding problems is the loss of "carbon sinks" that absorb atmospheric CO2 in the bargain. Previous projections had also ignored the second-order effects of transferring normal farm land to biofuels, which exerts world-wide pressure on land use.
So, incredibly, when the hidden costs of conversion are included, greenhouse-gas emissions from corn ethanol over the next 30 years will be twice as high as from regular gasoline. In the long term, it will take 167 years before the reduction in carbon emissions from using ethanol "pays back" the carbon released by land-use change. As they say, it's not easy being green.
