Biofuels Déjà Vu

In January, a team at the Massachusetts Institute of Technology (MIT) released one of the most ambitious efforts yet to make sense of it all. Led by climate specialist Jerry Mellilo of MIT and the Marine Biological Laboratory in Woods Hole, the team used a complex computer model to produce a vision of the global landscape in 2050.

After assuming that cellulosic fuels provide at least 10 percent of the world’s energy supply, the study concludes that “large tracts of natural forests, woodlands, and grasslands will be converted to either food or cellulosic biofuels production.” By 2050, the land devoted to cellulosic crops mushrooms to about 11 percent of the earth’s total (between 13.9 and 14.8 million square kilometers). Many areas would lose from 20 to 70 percent of their natural habitats, with tropical and semitropical ecosystems able to produce high levels of biomass the hardest hit. On the lengthy danger list: biodiversity “hotspots” in Mesoamerica, the cerrado of Brazil, Guinea/West Africa, Madagascar, Indo-Burma, and the cluster of Philippines, Malaysia, and Indonesia.

In part, that list reflects the expectation that “forests in the tropics could get hit particularly hard by cellulosic ethanol,” says James Bowyer, a forestry industry expert with Dovetail Partners, a nonprofit environmental consulting group in Minneapolis, Minnesota. That’s because natural forests would provide a relatively cheap, easy-to-exploit supply of cellulose. And unlike grasses that must be harvested and carefully stored, “trees are easy biomass to store when they aren’t needed,” says Bowyer. “You just leave them standing in the forest when the market dips, and wait for ethanol prices to rebound.”

Ironically, the MIT team concludes it’s not clear that the profound transformation in land use spurred by cellulosic ethanol would actually reduce greenhouse-gas emissions. In part, that’s because clearing new land can release carbon stored in soil and plants, negating the benefits of using the biofuels to replace fossil fuels. In fact, the land-use changes wreaked by use of cellulosic biofuels would add carbon to the atmosphere in the first half of the twenty-first century. Even under the most optimistic scenario, it would take some 50 years for the use of cellulosic biofuels to offset that added carbon.

Cellulosic fuels advocates say such problems can at least be reduced by planting biofuel crops on so-called marginal lands that have already been plowed, grazed, or logged. But here, too, scale is an issue. A February 2009 study by the Department of Energy’s Sandia National Laboratory and General Motors’ R&D Center, for instance, suggests it could take at least 20 million hectares of currently “idle” or “marginal” U.S. farmlands and forests to grow the biomass needed to produce 170 billion liters of cellulosic fuel a year by 2030. That means putting an area the size of Kansas into cultivation, a feat that could exact a stiff toll on biodiversity.

“You hear a lot about using ‘marginal lands’ and ‘waste wood,’ but that land and debris is still somebody’s habitat,” says Doug Landis, an ecological entomologist at Michigan State University. And in grasslands, “even a degraded prairie or hayfield can be better for biodiversity than planting a switchgrass monoculture,” notes grassland ecologist Mike Palmer of Oklahoma State University.

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