AS THE world grows richer and more populous ever more energy is needed. Rising fossil-fuel prices and supply concerns have prompted many countries to invest in other ways of meeting their energy needs, ranging from new nuclear power stations to wave and solar installations. In 2006 18.3% of the world’s electricity was produced using renewable sources. But by 2030 this will rise to 23.3%, as technology gets cheaper and fossil fuels remain pricey, according to the annual report from the International Energy Agency. Energy produced by hydro and wind power will double by 2030 accounting for most of the growth. But the share of electricity generated by renewables is still far behind that of dirty-but-cheap coal, which will rise to almost 44%. Nuclear fuel, however, will drop to just over 10%.