The USS John C. Stennis Carrier Strike Group (JCS CSG) has become the first group of U.S. Navy warships to operate on a fuel mix containing waste beef fat.

The ships are part of the Great Green Fleet, a year-long Navy initiative to use energy efficiency and alternative fuels to "increase combat capability and operational flexibility."

The USS Stockdale is among first Navy warships to operate on the biofuel mix. Image credit: U.S. Navy."The Navy's use of renewable energy in the Great Green Fleet represents its ability to diversify its energy sources, and also our nation's ability to take what would be a waste product and create homegrown, clean, advanced biofuels to support a variety of transportation needs," says U.S. Secretary of Agriculture Tom Vilsack.

The advanced fuel blend was produced by California-based AltAir Fuels from a feedstock of beef tallow—waste beef fat—provided by Midwest farmers and ranchers, and petroleum provided by Tesoro. It was purchased through a partnership between the Department of the Navy and the Department of Agriculture aimed at making alternative fuel blends a regular part of the military's bulk operational fuel supply.

Pursuant to Navy requirements, the alternative fuel is drop-in, meaning it requires no changes to ship engines, transport or delivery equipment or operational procedures. The Defense Logistics Agency awarded a contract to AltAir Fuels for 77.6 million gallons of the alternative fuel blend at a cost of $2.05 per gallon.

JCS CSG, the centerpiece of the Great Green Fleet, is also using an array of energy conservation measures (ECMs), including stern flaps, LED lights and energy-efficient operational procedures. Other ships, aircraft, amphibious and expeditionary forces and shore installations using ECMs and/or alternative fuels in the course of performing planned mission functions will join in the Great Green Fleet initiative throughout 2016.