Much of central China along the Yangtze River is in the grip of its worst energy crisis in years. The electricity cuts for industry and households have been exacerbated by a five-month drought that has dried up rivers, reducing hydroelectric generating capacity and leaving many people and large swaths of farmland short of water.

It is a symptom of a key challenge for China in the 21st century. The world's most populous nation and second-biggest economy must make difficult choices between two vital resources, energy and fresh water. Both help drive economic expansion, grow food and raise living standards.

Coal-fired power plants produced 84 percent of China's electricity last month, followed by 11 percent from hydropower (down from 16 percent in 2009). Nuclear and wind generated only about 2 percent each of the country's electricity.