A new study has determined that biomass production for fuel or electricity generation will have the biggest impact on landscape and habitats.
According to a report in Nature News, the broad analysis of potential US energy and climate-mitigation scenarios compared the land and habitat impacts of various energy mixes - from nuclear power to biofuels - resulting from an array of policy options.
In a supplement to the study paper, the authors re-ran their estimates to take account of the likely impact of the American Clean Energy and Security Act of 2009, also known as the Waxman-Markey bill.
The bill, which is awaiting approval by the US Senate, includes a cap-and-trade system to regulate greenhouse gases.
The researchers estimate that regardless of whether the Waxman-Markey bill were enacted, the amount of land affected by energy development by 2030 will be between 21-70 million hectares - an area which is, even at its lower bound, about the size of the state of Wyoming.
"A cap-and-trade bill may have some incremental effect in increasing energy sprawl, but most of the development that's going to happen is because of other laws that are already in place," said study author Robert McDonald, a landscape ecologist with The Nature Conservancy, a non-profit environmental organization based in Arlington, Virginia.
Those other laws include the US renewable fuel standard, which requires that the volume of renewable fuel blended into gasoline is increased from 34 billion litres in 2008 to 136 billion litres by 2022.
That increase will require an area of between 19 and 31 million hectares - the largest component of McDonald's projected energy sprawl, despite the fact that biofuels are expected to comprise less than 5 percent of the country's total energy budget.
The US Energy Information Administration predicts that ethanol derived from corn alone might reach annual production levels of 39 billion litres by 2030.
McDonald and his colleagues calculate that this would require more than 9 million extra hectares of land to be planted with corn (maize), an area about the size of the state of Indiana.
"If we are to prevent serious, damaging climate change, it will require one of the largest land-use changes in the history of the country," said Jimmie Powell, a policy expert at The Nature Conservancy and a co-author of the study.
"Because the change is so big, it's important that we do it carefully to minimize the environmental impacts of these new energy resources," he added.