Abandoned farmland key to sustainable bioenergy development

As the U.S. searches for answers to ease its dependency on foreign oil, the answer could lie with a renewed commitment to biofuel development.

But while biofuels are taking blame for high food costs, scientists from the Carnegie Institution and Stanford University say that biofuels can be a sustainable part of the world's energy future, especially if bioenergy agriculture is developed on currently abandoned or degraded agricultural land.

According to a report released by the scientists, using these lands for energy crops, instead of converting existing croplands or clearing new land, avoids competition with food production and preserves carbon-storing forests needed to mitigate climate change.

The report found that sustainable bioenergy is likely to satisfy no more than 10 percent of the demand in the energy-intensive economies of North America, Europe and Asia.

"But for some developing countries, notably in sub-Saharan Africa, the potential exists to supply many times their current energy needs without compromising food supply or destroying forests," the report said.

The researchers estimate that globally up to approximately 1.8 million square miles of abandoned land could be available for growing energy crops -- the equivalent of nearly half the land area of the United States (including Alaska).

But the researchers estimate that the worldwide harvestable dry biomass could amount to as much as 2.1 billion tons, with a total energy content of about 41 exajoules (one exajoule is a billion joules, equivalent to about 170 million barrels of oil). But, at best, it would satisfy only about 8 percent of worldwide energy demand.

The bioenergy potential is largest in the United States, Brazil, and Australia, according to the report, with the Midwest containing the biggest expanse of abandoned pastureland.

But even if 100 percent of these lands were used for bioenergy, that would still only yield enough for about 6 percent of the U.S. national energy needs.

"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," said Christopher 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."