The world energy economy is poised for a sweeping shift away from imported oil and environmentally damaging coal during the next few decades, despite the belief by most energy planners that the future will probably see a continuation of past trends, Pushed by the need to stabilize the earth's climate, and pulled by the investment opportunities that beckon, the world's economies are beginning to move more rapidly toward more efficient, decentralized and cleaner energy systems, Among the changes expected are a new generation of lightweight, super efficient electric cars that can be re-fuelled at home; the rapid conversion of coal and nuclear plants to efficient gas turbines; a new generation of mass produced wind and solar generators that are cost competitive with the most advanced fossil plants; tiny fuel cells and rooftop solar panels that allow people to generate their own electricity; and the gradual emergence of hydrogen as the world's main energy carrier, supplanting oil and natural gas, The paper envisions an energy scenario in which carbon dioxide concentrations in the atmosphere stabilize during the next half century, as called for in the Rio Climate Treaty.