The Roman physician Galen (circa 130–200 AD) wrote that Archimedes had repelled a Roman fleet in 212 BC by focusing sunlight from soldiers’ shields to set the ships on fire. Although most likely myth, this story illustrates the long history of our interest in harnessing renewable energy. The industrial revolution itself was launched with water wheels, windmills, and biomass fuels.
Modern efforts to harness renewable energy sources increased sharply after the 1973–74 oil embargo, setting in motion significant technical and market advances. These efforts have, for example, reduced the cost of wind-generated electricity by an order of magnitude—down to 4 or 5 cents per kilowatt-hour in areas with good wind resources and favorable financing. In 2000, the global generating capacity from wind turbines increased by 4500 MW, most of which was installed in Europe, to a global total of 18 500 MW. In the US, about 1700 MW of wind-turbine...
