The US military has a history of fostering change, from racial integration to development of the internet. Now Pentagon officials say their green energy efforts will help America fight global warming.

By size alone, the US Department of Defense can make waves. It accounts for 1.5% of the nation's energy consumption.

The military has set a goal that 25% of its energy should come from renewable sources by 2025 and aims to create machines and methods to help "Main Street America" reach similar targets, says Alan Shaffer, a retired air force officer who leads the Pentagon's research and engineering arm.

"It's only the Department of Defense that is big enough and has the federal mandate for the necessary scope of development" of new energy technologies and products, he says.

While the military marches on a greener path in which "every soldier is a steward of the environment" – in Shaffer's words – the federal government faces widespread criticism for failing to take significant action to slow climate change.

Change 'inevitable'

On the same day Shaffer arrived in California last week to tour military bases that test energy efficiency and renewable power, California announced plans to sue the Environmental Protection Agency for "wantonly" ignoring its duty to regulate greenhouse gas emissions.

The military did not focus on cutting energy use until the price of oil shot up two years ago. But now that it has, Shaffer said, change is inevitable.

Within six years, a portable solar- and wind-power station at the army's Fort Irwin in California could bring a quick return of electricity to hurricane-damaged coastal cities, said retired army colonel John Spiller.

These energy technologies may one day spread to households, as a byproduct of a more efficient military, said Colonel Dave Belote, commander of Nellis Air Force Base, Las Vegas, Nevada. The biggest solar power array in the US has been operating at Nellis since November in a public-private partnership.

"Every time the price of oil goes up $10 a barrel, it costs the Department of Defense $1.3 billion a year," Shaffer said.

Crude oil hit a record $147 a barrel last month. It is expected to average about $127 in 2008, up from $72 in 2007, and $66 in 2006, according to US government figures.

Saving lives

Shaffer said that in the next few years, the military can reduce energy consumption by 10 to 20%. It spends about $14 billion a year on energy, up from $11 billion in 2005, about half on jet fuel.

But saving energy cannot come at the expense of operational effectiveness, Shaffer said. Air force commanders will not ask pilots to cut fuel use.

Renewable energy is not new to the military. Wind turbines supply much of the power used at the isolated US naval base at Guantanamo Bay in Cuba and the geothermal power plant at the China Lake Naval Air Weapons Station in California has been in operation for two decades.

But the desire to ramp up the programme increased in 2006 after Marine Corps Major General Richard Zilmer said bringing solar and wind power to the battlefront would cut down on casualties.

"Cost matters. Lives matter more," said Shaffer. "Every time we have to send a convoy out to refuel tanks or deploy forward locations, it puts people's lives at risk."

Climate Change – Want to know more about global warming: the science, impacts and political debate? Visit our continually updated special report.

Focus on America - Delve into the science and technology questions facing the USA in our special report.