Biofuels can be produced in large quantities and have multiple benefits, but only if they come from feedstocks produced with low life-cycle greenhouse gas emissions, as well as minimal competition with food production. This consensus emerges in a new journal article by researchers from the University of Minnesota, Princeton, MIT and the University of California, Berkeley.
"The world needs to replace fossil fuels with renewable energy, but recent findings have thrown the emerging biofuels industry into a quandary. We met to seek solutions," said the U of M's David Tilman, a noted ecologist and lead author of the paper. "We found that the next generation of biofuels can be highly beneficial if produced properly."
The article, "Beneficial Biofuels—The Food, Energy and Environment Trilemma," will appear in the July 17 issue of Science. Tilman, a resident fellow of the U of M's Institute on the Environment, said the paper resulted from a year of conversations and debate among some of the nation's leading biofuel experts.
In addition to Tilman, the article contributors include the U of M's Jonathan Foley and Jason Hill; Princeton's Robert Socolow, Eric Larson, Stephen Pacala, Tim Searchinger and Robert Williams; Dartmouth's Lee Lynd; MIT's John Reilly; and the University of California, Berkeley's Chris Somerville.
The paper coincides with climate change policy debates in Congress, and tackles land use issues that have generated much controversy in recent years: Specifically, the greenhouse gases released when land is cleared to grow biofuel crops (or when other lands are cleared to compensate for food crops displaced by biofuel crops) can—for decades to centuries—exceed those from petroleum use.
"It's essential that legislation take the best science into account, even when that requires acknowledging and undoing earlier mistakes," said Princeton's Socolow, co-director of the Carbon Mitigation Initiative.
"Careful scientific reasoning revealed accounting rules that separate promising from self-defeating strategies," added Socolow. "Future carbon dioxide concentrations in the atmosphere will tell us when we're kidding ourselves about what actually works. For carbon management, the atmosphere is the ultimate accountant."
To balance biofuel production, food security and emissions reduction, the authors conclude that the global biofuels industry must focus on five major sources of renewable biomass:
- Perennial plants grown on degraded lands abandoned from agricultural use
- Crop residues
- Sustainably harvested wood and forest residues
- Double crops and mixed cropping systems
- Municipal and industrial wastes
These sources can provide considerable amounts of biomass, at least 500 million tons per year in the United States alone, without incurring any significant land use carbon dioxide releases.
"We need to transition away from using food for biofuels toward more sustainable feedstocks that can be produced with much less impact on the environment," said the U of M's Hill, a resident fellow of the Institute on the Environment.
The U of M's Foley, director of the Institute on the Environment, said the consensus reached in this article is remarkable. "Technology experts, energy systems analysts, climatologists, ecologists and policy experts all agreed: Biofuels 'done right' have a bright future in solving our energy and environmental challenges. Both new and existing biofuel strategies have the potential for being among the green energy solutions we need today."
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