Last week, a Marine company from California arrived in the rugged outback of Helmand Province bearing novel equipment: portable solar panels that fold up into boxes; energy-conserving lights; solar tent shields that provide shade and electricity; solar chargers for computers and communications equipment.

The 150 Marines of Company I, Third Battalion, Fifth Marines, will be the first to take renewable technology into a battle zone, where the new equipment will replace diesel and kerosene-based fuels that would ordinarily generate power to run their encampment.

Even as Congress has struggled unsuccessfully to pass an energy bill and many states have put renewable energy on hold because of the recession, the military this year has pushed rapidly forward. After a decade of waging wars in remote corners of the globe where fuel is not readily available, senior commanders have come to see overdependence on fossil fuel as a big liability, and renewable technologies — which have become more reliable and less expensive over the past few years — as providing a potential answer. These new types of renewable energy now account for only a small percentage of the power used by the armed forces, but military leaders plan to rapidly expand their use over the next decade.

In Iraq and Afghanistan, the huge truck convoys that haul fuel to bases have been sitting ducks for enemy fighters — in the latest attack, oil tankers carrying fuel for NATO troops in Afghanistan were set on fire in Rawalpindi, Pakistan, early Monday. In Iraq and Afghanistan, one Army study found, for every 24 fuel convoys that set out, one soldier or civilian engaged in fuel transport was killed. In the past three months, six Marines have been wounded guarding fuel runs in Afghanistan.

“There are a lot of profound reasons for doing this, but for us at the core it’s practical,” said Ray Mabus, the Navy secretary and a former ambassador to Saudi Arabia, who has said he wants 50 percent of the power for the Navy and Marines to come from renewable energy sources by 2020. That figure includes energy for bases as well as fuel for cars and ships.

“Fossil fuel is the No. 1 thing we import to Afghanistan,” Mr. Mabus said, “and guarding that fuel is keeping the troops from doing what they were sent there to do, to fight or engage local people.”

He and other experts also said that greater reliance on renewable energy improved national security, because fossil fuels often came from unstable regions and scarce supplies were a potential source of international conflict.

Fossil fuel accounts for 30 to 80 percent of the load in convoys into Afghanistan, bringing costs as well as risk. While the military buys gas for just over $1 a gallon, getting that gallon to some forward operating bases costs $400.

“We had a couple of tenuous supply lines across Pakistan that are costing us a heck of a lot, and they’re very dangerous,” said Gen. James T. Conway, the commandant of the Marine Corps.

Col. Robert Charette Jr., director of the Marine Corps Expeditionary Energy Office, said he was “cautiously optimistic” that Company I’s equipment would prove reliable and durable enough for military use, and that other Marine companies would be adopting renewable technology in the coming months, although there would probably always be a need to import fuel for some purposes.

While setting national energy policy requires Congressional debates, military leaders can simply order the adoption of renewable energy. And the military has the buying power to create products and markets. That, in turn, may make renewable energy more practical and affordable for everyday uses, experts say.

Last year, the Navy introduced its first hybrid vessel, a Wasp class amphibious assault ship called the U.S.S. Makin Island, which at speeds under 10 knots runs on electricity rather than on fossil fuel, a shift resulting in greater efficiency that saved 900,000 gallons of fuel on its maiden voyage from Mississippi to San Diego, compared with a conventional ship its size, the Navy said.

The Air Force will have its entire fleet certified to fly on biofuels by 2011 and has already flown test flights using a 50-50 mix of plant-based biofuel and jet fuel; the Navy took its first delivery of fuel made from algae this summer. Biofuels can in theory be produced wherever the raw materials, like plants, are available, and could ultimately be made near battlefields.

Concerns about the military’s dependence on fossil fuels in far-flung battlefields began in 2006 in Iraq, where Richard Zilmer, then a major general and the top American commander in western Iraq, sent an urgent cable to Washington suggesting that renewable technology could prevent loss of life. That request catalyzed new research, but the pressure for immediate results magnified as the military shifted its focus to Afghanistan, a country with little available native fossil fuel and scarce electricity outside cities.