The U.S. Armed Forces are heavily burdened by the financial and tactical costs of transporting fuel to the battlefield. This July, in an effort to address the problem, the United States Marine Corps will deploy a pair of diesel generators coupled with powerful batteries to frontline troops in Afghanistan. The hybrid power systems should cut by 50 to 70 percent the amount of fuel needed to generate electricity, according to the manufacturer, Earl Energy of Portsmouth, Virginia.
The generators that U.S. military camps currently use operate inefficiently because they need to handle ocassional peaks in demand. “You may have a 10-kilowatt generator that at any time is only producing 1.5 kilowatts of power to satisfy its load,” says Doug Moorehead, president of Earl Energy. “So you are wasting 8.5 kilowatts of power that you aren’t storing for later use,” he says.
The diesel-battery hybrid the company developed instead runs generators for short bursts to maximize energy utilization. Not only does this satisfy the immediate energy requirements of a camp, but the system also charges a bank of lithium-ion batteries. When the batteries are fully charged, the generator shuts off and the system begins drawing power from the batteries instead. “Generators can go from running 24 hours a day to three to four hours a day—it’s that good in some cases,” Moorehead says.
The hybrid systems to be deployed in July will combine an 18-kilowatt diesel generator, similar to those currently used in the battlefield, with a 40-kilowatt-hour bank of lithium-ion batteries. The system will also include a 10-kilowatt photovoltaic solar panel array that will further lower fuel consumption.
The entire system, including photovoltaics, sells for “over $100,000,” as compared with $80,000 to $100,000 for a similarly sized conventional generator, Moorehead says. The cost to Earl Energy for just the batteries—which have built-in safeguards against the high temperatures and dusty field conditions of Afghanistan—is $750 to $1,500 per kilowatt-hour of storage.
Moorehead estimates the system will pay for itself within seven to 12 months, depending on the cost of fuel. Bigger savings would come from using the hybrid system without the photovoltaics, which are expensive, and the company is now developing a stand-alone generator without the added solar power, he says.