SAN DIEGO — The Navy is launching a carrier strike group to be powered partly by biofuels.

Officials are calling it a milestone toward easing the military’s reliance on foreign oil.

Navy Secretary Ray Mabus and Agriculture Secretary Tom Vilsack are inspecting the ships Wednesday before they set sail off San Diego. At the head of the pack is the nuclear-powered USS John C. Stennis supercarrier.

The maritime branch is touting the warships as the centerpiece of its “Great Green Fleet.” Most of the group’s ships will be run for now on a mix made up of 90 percent petroleum and only 10 percent biofuels, though that could change in the future. The Navy originally aimed for the ratio to be 50/50.

Critics say biofuel production is too costly and on a large scale may do more harm than good.