An experimental “Green Hornet” fighter jet that uses biofuel. The “Prius” warship running on a hybrid engine. The Navy is increasingly going green thanks largely to a desire to reduce its dependence on fossil fuels that come from hostile places in the world. The Navy, the Pentagon’s second-largest user of oil, also sees it as an expensive bill to pay as budgets get leaner. And in the San Diego region, the results are easy to see: Rooftops full of solar panels at San Diego naval bases. Electric carts. Biodiesel bulldozers. Even windmills off the coast on San Clemente Island. “The Navy is a complex animal, but in some areas of environmental protection, they are moving forward as fast as any agency,” said Michael Jasny of the Natural Resources Defense Council, which has long fought the Navy over the effect of military sonar on whales.