Sept. 12 (Bloomberg) — The U.S. would be wise to adopt more aggressive measures to avert water and energy shortages as population and power consumption rise, according to a report.

Climate change is worsening heat and drought, raising demand and lowering cooling supplies for nuclear, coal and natural-gas plants that generate 97 percent of the nation’s electricity, according to the “Water Constraints on Energy Production” report prepared for the Civil Society Institute.

Subsidizing renewable power generators such as wind turbines and solar cells that require little or no water would help, the report said. Clean energy also demands less water in an era of increasing scarcity in the U.S. West and elsewhere than the extraction of coal, gas and uranium, said the report by Synapse Energy Economics Inc. of Cambridge, Massachusetts.

“It is time to be decisive, to choose an energy path that is sustainable and that protects public health,” Pam Solo, president of the Washington-based institute, said in the report. “A hard-headed analysis of our water resources and how to manage them in the context of energy choices should be our road map.”

Nuclear, coal and gas-fueled plants withdraw 41 percent of the nation’s freshwater, the most of any sector including agricultural irrigation, according to the report. Though most plant cooling water is returned to streams, data shows that 4 billion gallons a day is lost to evaporation and use.

A drought in the normally damp Southeast from 2007 to 2009 put at risk the cooling supplies for almost one-fourth of U.S. reactors while last year, Connecticut’s Millstone reactor had to shut because of too warm cooling waters, Solo said.

To contact the reporter on this story: Jim Polson in New York at jpolson@bloomberg.net

To contact the editor responsible for this story: Randall Hackley at rhackley@bloomberg.net