We are standing on a balcony outside Iceland's Hellisheidi geothermal power plant, newly built on the side of an active volcanic mountain in Hengill. It's pretty cold, but we are wreathed in warm steam that started out in the center of the Earth. Some of the turbines have been humming since 2006, but the plant is still under construction, on its way to producing 300 megawatts of electricity and (beginning in 2009) 400 megawatts of heat energy to warm factories and households.