In an article in the journal Nature Climate Change, scientists measured temperatures now and projected what they would be at midcentury. The temperatures vary according to the time of year, and, even if the extremes remain similar, they will be more frequent — meaning that the water will be too warm to allow full power production, they predict.
All power plants that burn coal or split uranium, and most of the plants that burn natural gas, turn the resulting heat into steam, which spins a turbine that turns a generator to make power. Then the steam has to be converted back to water before being reheated. If the river or lake water used to condense the steam is getting warmer, the amount it can condense is reduced, leading to a decline in power output.
Using computer projections of climate change possible outcomes, the researchers wrote that generating capacity in the United States could fall 4.4 to 16 percent on hot days from 2031 to 2060. And the number of days when river water is at a temperature that is now considered extremely high will be triple the number today, on average, they said.
The idea of varying availability of cooling water is not new; many American steam-electric plants already have a summer power rating and a winter power rating. Read the full report here.
Source: by Matthew L. Wald, New York Times.
