120718-N-AC887-004 PEARL HARBOR (JULY 18, 2012) Lt. j.g. K. Smith, right, explains energy-efficient systems aboard the guided-missile destroyer USS Chafee (DDG 90) to Secretary of the Navy (SECNAV) the Honorable Ray Mabus during the U.S. Navy's Great Green Fleet demonstration. Mabus observed the large-scale demonstration of the Navy Surface Ship Energy Efficiency Initiatives during the 2012 Rim of the Pacific (RIMPAC) exercise, the world's largest international maritime exercise. (U.S. Navy photo by Chief Mass Communication Specialist Sam Shavers/Released)