For $1 billion over the next 40 years, the U.S. could develop 100 gigawatts (a gigawatt equals one billion watts) of electricity generation that emits no air pollution and pumps out power to the grid even more reliably than coal-fired power plants, according to scientists at the Massachusetts Institute of Technology. Now Google.org—the charitable wing of the search engine giant—has chipped in nearly $11 million for this renewable resource: so-called geothermal power, or tapping the Earth's heat to make electricity.