Fossil fuels may be keeping the world running, but they're also destroying the planet. What viable alternatives do we have, and what technological breakthroughs are on the horizon? In this brilliantly wide-ranging, one-stop guide WIRED journalist Nicole Kobie outlines the environmental threats we face through our reliance on carbon-based energy, and considers whether and when sustainable energy can take its place. She looks at the major technologies currently available - solar, wind and geothermal among them - explaining how they work and what potential they possess.