PACIFIC OCEAN (JULY 18, 2012) Secretary of the Navy (SECNAV) Ray Mabus observes flight operations of aircraft operating on biofuel blends aboard the aircraft carrier USS Nimitz (CVN 68) during the Great Green Fleet demonstration portion of Rim of the Pacific (RIMPAC) 2012. Mabus, Chief of Naval Operations (CNO) Adm. Jonathan Greenert and other senior Navy leaders were on hand to witness the large-scale demonstration of the Navy's use of alternative energy and energy efficiencies during RIMPAC, the world's largest international maritime exercise. (U.S. Navy photo by Chief Mass Communication Specialist Sam Shavers/Released)