More than 12 million US households could be powered by underground heat by 2025

The US Department of the Interior announced this week that it plans to make more than 190 million acres of federal land, spanning 12 western states, available for the development of geothermal energy. If the initiative translates into actual electricity generation on the same scale, it could increase US geothermal resources by 10 times.

"Because geothermal energy is replenished by heat sources deep in the earth, it is a renewable resource that generates electricity with minimal carbon emissions," said secretary of the Interior Dirk Kempthorne. "Geothermal offers possibilities for reducing the need for conventional energy sources."

The US continues to be the world leader in generating geothermal energy, with about 16,000gWh of energy generated in 2005, according to Kempthorne. "We are talking about a very substantial source of renewable energy," he said.

Under the plan – known as the Final Geothermal Programmatic Environmental Impact Statement – about 5,540MW of new electric generation capacity could be obtained from geothermal sources by 2015, or enough to power 5.5 million homes. There are also longer-term plans to develop an extra 6,600MW by 2025 – which would be enough to power more than 12 million homes, the government has claimed.

The plan is not only being positioned as a way to reduce dependance on carbon-intensive fuels, the federal government is also keen to point out that states and counties will benefit from the scheme with revenue from the leasing of land split between the different stakeholders both local and national. A recent sale of geothermal leases in Nevada brought in $28.2m in August 2008, the agency claims.

Interest in geothermal energy has increased rapidly over recent months – spurred in part by rising oil prices, focus on climate change and the desire for increased energy security – given momentum by both US presidential hopefuls.

In August, Google's philanthropic arm, Google.org, announced plans to invest $10.25m (£5.5m) in research into a new form of geothermal energy technology that advocates claim could provide more than 2,500 times the US annual energy use.