Philippines revs up flagging green energy engine The Philippines -- thanks to its spot in the Ring of Fire zone of Pacific volcanoes -- has long been one of the world's top producers of geothermal power, but years of neglect have sent it sliding. Now a surge of new exploration efforts are underway in a nation that has some of the world's largest untapped sources of volcanic heat, but which relies on coal for half its electricity. IMAGES AND SOUNDBITES