The Department of Defense is among the biggest energy consumers in the U.S., and directives for the military to become more energy efficient are resulting in major changes at its facilities and bases. Going green has been expensive, but military officials say they understand the rationale behind the orders. "Energy reform and the new energy future aren't about politics or slogans. It's about protecting the lives of our troops. ... It's about making our country more secure and more independent," Navy Secretary Ray Mabus said.