Memo to Pentagon brass from the top United States commander in western Iraq: Renewable energy – solar and wind-power generators – urgently needed to help win the fight. Send soon.

Calling for more energy in the middle of oil-rich Iraq might sound odd to some. But not to Marine Corps Maj. Gen. Richard Zilmer, whose deputies on July 25 sent the Pentagon a "Priority 1" request for "a self-sustainable energy solution" including "solar panels and wind turbines."

The memo may be the first time a frontline commander has called for renewable-energy backup in battle. Indeed, it underscores the urgency: Without renewable power, US forces "will remain unnecessarily exposed" and will "continue to accrue preventable ... serious and grave casualties," the memo says.

Apparently, the brass is heeding that call. The US Army's Rapid Equipping Force (REF), which speeds frontline requests, is "expected soon" to begin welcoming proposals from companies to build and ship to Iraq 183 frontline renewable-energy power stations, an REF spokesman confirms. The stations would use a mix of solar and wind power to augment diesel generators at US outposts, the spokesman says.

Despite desert temperatures, the hot "thermal signature" of a diesel generator can call enemy attention to US outposts, experts say. With convoys still vulnerable to ambush, the fewer missions needed to resupply outposts with JP-8 fuel to run power generators – among the Army's biggest fuel guzzlers – the better, the memo says.

"By reducing the need for [petroleum] at our outlying bases, we can decrease the frequency of logistics convoys on the road, thereby reducing the danger to our marines, soldiers, and sailors," reads the unclassified memo posted on the website InsideDefense.com, a defense industry publication that first reported its existence last month.

Use of renewable energy, such as solar power, is not new to the US military, one of the largest consumers of renewable energy, especially at off-grid outposts in North America. Four 275-foot-tall wind turbines were unveiled last year at the Naval Station at Guantánamo Bay in Cuba, meeting about a quarter of the base's electrical needs and saving hundreds of thousands of gallons of fuel.

Still, Major General Zilmer's request highlights what appears to be a small but growing focus on adding renewable sources of energy to the fuel mix for combat operations as part of Department of Defense planning.

Special operations forces concluded that using foldout solar panels to recharge batteries was better than carrying more disposable batteries into combat, a 2004 study for the Army found. Last year, Konarka Technologies Inc. in Lowell, Mass., received a $1.6 million Army contract to supply flexible printed solar panels to reduce the number of batteries soldiers carry.

A bigger picture of the need for renewables was sketched out in a key 2004 Pentagon study titled "Winning the Oil Endgame," by the Rocky Mountain Institute, an energy think tank in Snowmass, Colo. It found a number of areas where efficiency would boost combat effectiveness, including:

•More than 50 percent of fuel used by the Army on the battlefield is consumed by combat support units, not frontline troops.

•Until recently, the Army spent about $200 million a year annually on fuel, but paid $3.2 billion each year on 20,000 active and 40,000 reserve personnel to transport it.

That was before $70-per-barrel oil. This spring, the Defense Energy Support Center reported the US military used about 128 million barrels of fuel last year, costing about $8 billion, compared with about 145 million barrels in 2004 that cost $7 billion.

"At the tip of the spear is where the need to avoid the cost of fuel logistics is most acute," says Amory Lovins, cofounder of the Rocky Mountain Institute, who led the 2004 study. "If you don't need divisions of people hauling fuel, you can realign your force structure to be more effective as well as less vulnerable."

Zilmer's call for renewable power is also buttressed by Pentagon studies from June 2005 dating back to the 1990s that show the costs and advantages of solar-panel systems in place of or as supplements to diesel generators burning JP-8, the standard battlefield fuel.

Still, such lessons are learned slowly, says Hugh Jones, a former analyst with the Center for Army Analysis, now a consultant on energy issues to the US Army. Analyzing feedback from the frontlines after Operation Desert Storm in Kuwait 1990, he produced a raft of studies on uses for solar power in combat.

But during the 1990s when fuel was cheap, he found little interest in the idea.

"There aren't a lot of people who have expertise in this area of renewable power in combat operations," Mr. Jones says. "There are a lot of people in the service who smell like diesel fuel, but not many who have been in the field using solar power and hybrid-optimized solutions."

Even so, he's noticed "there's much more interest today." The high cost of fuel, and troop casualties in the Iraq war, may be changing that traditional outlook.

One guy who thinks he can solve the general's problem is Dave Muchow, president of SkyBuilt Power Inc. in Arlington, Va. Aided by funding from In-Q-Tel, a venture-capital firm for the Central Intelligence Agency – SkyBuilt makes a hybrid solar-panel and wind-generator power system that fits in a standard shipping container. It can be dropped onto a mountaintop or into the desert. Its solar panels and wind turbine deploy in minutes. And where there's water, a "micro-hydro" unit can be dropped into a stream for an added boost.

Such 007-style systems are not cheap. Today, SkyBuilt's "mobile power system" can cost up to $100,000, compared with just $10,000 for a 10-kilowatt diesel generator.

But costs of such hybrid packages begin to look more reasonable when the cost is considered of delivering a gallon of fuel to a generator gulping it 24/7. The true cost of fuel delivered to the battlefield – well prior to the recent oil price hike – was $13 to $300 a gallon, depending on its delivery location, a Defense Science Board report in May 2001 estimated.

An analysis in Zilmer's memo puts the "true cost" for fuel for a 10-kilowatt diesel generator at $36,000 a year – about four times the amount needed to purchase the fuel itself initially. The rest of the cost is due mainly to transportation. On that basis, a SkyBuilt system could cut costs by 75 percent and pay for itself for three to five years, the memo estimates.

But another cost is time. Even though the Army's REF is moving on it, there is still no firm date for a request for proposal to be made public, the REF spokesman acknowledges. Zilmer's memo, however, warns that without renewable power to replace fuel, victory could be forfeited.

"Without this solution, personnel loss rates are likely to continue at their current rate," the memo says. "Continued casualty accumulation exhibits potential to jeopardize mission success."