Among the challenges facing technicians struggling to contain the meltdown at the Daiichi Japanese nuclear power units is getting enough water to cool them down. In Japan’s case, the overheating was caused by explosions triggered by the earthquake. Nuclear—as well as fossil-fuel and biomass-fired and some renewable energy systems are impacted by changes in ambient temperature and climate. As has been made clear in Japan, nuclear facilities can be particularly demanding in the need for water.

Brazil relies heavily on its abundant hydropower resources to meet electricity demand, which is rising by about 5% a year. These resources have helped Brazil hook up more than 2.4 million rural homes since 2003, in addition to delivering electricity to its big cities. But