would require roughly 50 square meters of concentrating solar power station -- the same area as a typical British house. And 20 kilowatt hours per day from nuclear power would require roughly a one-millionth share of a modern nuclear power station. If a country with the size and population of Britain -- 61 million people -- adopted that mix, the land area occupied by wind farms would be nearly 10 percent of the country, or roughly the size of Wales. The area occupied by desert solar power stations -- in the case of Britain, they would have to be connected by long-distance power lines -- would be five times the size of London. The 50 nuclear power stations required would occupy a more modest 50 square kilometers. The effort required for a plan like that is very large, but imaginable. Countries that claim to be serious about creating an alternative energy future need to choose a plan, stop arguing and get building.