Abandoned farmlands are key to sustainable...(exajoules. While this is a significant a...)

"At the national scale, the bioenergy potential is largest in the United States, Brazil, and Australia," says lead author Campbell. "These countries have the most extensive areas of abandoned crop and pasture lands. Eastern North America has the largest area of abandoned croplands, and the Midwest has the biggest expanse of abandoned pastureland. Even so, if 100% of these lands were used for bioenergy, they would still only yield enough for about 6% of our national energy needs."

The study revealed larger opportunities in other parts of the world. In some African countries, where grassland ecosystems are very productive and current fossil fuel demand is low, biomass could provide up to 37 times the energy currently used.

"Our study shows that there is clearly a potential for developing sustainable bioenergy, and we've been able to identify areas where biomass can be grown for energy, without endangering food security or making climate change worse," says Field, director of the Department of Global Ecology. "But we can't count on bioenergy to be a dominant contributor to the global energy system over the next few decades. Expanding beyond its sustainable limits would threaten food security and have serious environmental impacts."

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