Less pollution, less free earth

More forests, deserts and grasslands in the United States will be used to produce energy under a proposal to cap greenhouse gases, an unintended consequence of efforts to fight global warming, according to a Nature Conservancy report released this week.

A bill that boosts energy from wind turbines and biofuels will increase the amount of land needed for energy development as much as 48 percent, or almost 100,000 square kilometers (38,600 square miles) during the next 20 years, said Robert McDonald, a scientist with the environmental group based in Arlington, Va. An area larger than Minnesota will be affected even without any climate-change bill, he said.

Less land will be needed to grow corn for cleaner-burning ethanol and to support electric-generating wind turbines if legislation gives carbon-dioxide emitters more options to reach targets, said the report, published this week in the online journal PloS One. Greater energy conservation can also reduce the amount of land needed for development.

"Climate-change legislation could have a significant impact on land use in the U.S. but it might not if it's properly designed," McDonald, lead author of the report, said in an interview. "We're tying to make sure that energy sprawl is one of the things policy makers are thinking about."

Biofuel made from corn, along with biomass burned to make electricity, affects the most land for every unit of energy produced. Nuclear power uses the least amount of land, the report said.

Corn for ethanol

Growing corn for ethanol on land already used for agriculture is one way to reduce the area needed to meet future energy needs, McDonald said. Allowing utilities and manufacturers with carbon-dioxide caps to use offsets -- credits from projects that lower emissions -- to meet pollution targets also reduces land use for energy.

"Depending on the details of the bill, there may be millions of acres of new development," McDonald said. "While we're changing the rules of the system, we want to think about the land-use impacts."

By the numbers

Without climate-change legislation, new coal-fired power plants will be built on more than 26,000 square kilometers of conifer and deciduous forests, grasslands and desert, according to the report.

Under a climate bill, costs for power from burning fossil fuels will rise, and the area needed for coal-burning power plants will be reduced by 7,500 square kilometers (2,896 square miles).

More land, meanwhile, will be needed for lower-emissions energy from biomass, biofuels and wind turbines. More than 49,000 square kilometers (18,919 square miles) will be needed just to grown biomass that can be burned for electricity under a climate-change bill.