SAN DIEGO - The U.S. Navy is launching a carrier strike group to be powered partly by biofuel, calling it a milestone toward easing the military's reliance on foreign oil. But critics, including environmentalists, say biofuel production is too costly and on a large scale may do more harm than good.
Most of the group's ships will run on a mix of 90 percent petroleum and only 10 percent biofuels, though that could change. The Navy originally aimed for the ratio to be 50/50.
Navy Secretary Ray Mabus and Agriculture Secretary Tom Vilsack on Wednesday were inspecting the ships before they set sail off San Diego.
"In 2010, we were losing too many Marines in convoys carrying fossil fuels to outposts in Afghanistan, and the prohibitive cost of oil was requiring us to stop training at home in order to keep steaming abroad, a dangerous and unsustainable scenario," Mabus said in a statement.
The Defense Department uses 90 percent of the energy consumed by the federal government, spending billions of dollars annually on petroleum fuels to support military operations.
All military branches are looking to cut their ties to foreign oil as part of a national security strategy. Since 2008, the Navy has cut oil consumption by 15 percent since 2008 and the Marine Corps has reduced it by 60 percent.
The Navy is aiming to draw half its power from alternative energy sources by 2020 so ships can refuel less, stay out at sea longer and no longer be at the mercy of fluctuating oil prices and oil-producing nations, Mabus said.
The federal government has invested more than $500 million into drop-in biofuels, which can be used without reconfiguring engines. The fleet also includes nuclear vessels, hybrid electric ships and aircraft powered partly by biofuels.
The Navy in 2009 called for ships to run on 50 percent biofuel and 50 percent petroleum. After that, the price for a barrel of oil topped $100 and has since dropped to as low as $29 a barrel.
Some of the biofuel comes from beef fat from the Midwest. Similar contracts are in the works to fuel ships elsewhere.
Retired Navy Capt. Todd "Ike" Keifer, who has published a study on the Navy's plan, said he does not believe the Navy will ever get "any meaningful quantities of cost-competitive biofuels."
"Biofuels sound good, but it turns out that making carbohydrates (biomass) into hydrocarbons (ideal fuels) is a very laborious and wasteful process that is far more costly and much harder on the environment than producing fossil fuels," he said.
Environmental scientist Jesse Ausubel at The Rockefeller University in New York City said biofuels are renewable but not green since they require so much land, fertilizer, pesticide and fuel to produce them.
"There are many ways that the fleet could become truly greener -- through more efficient propulsion, for example," Ausubel wrote in an email to The Associated Press.