U.S. energy infrastructure is increasingly vulnerable to acute weather events and long-term changes in the climate, the Government Accountability Office (GAO) says in a new report. Options to help reduce those risks include measures to improve its durability and resiliency.

The Mar. 4–released report titled “Energy Infrastructure Risks and Adaption Efforts,” cites data from the National Research Council (NRC) and the U.S. Global Change Research Program (USGCRP) when it claims climate change trends are expected to continue. But, it declares, while the nation’s energy supply can adequately respond to weather variability, most energy infrastructure may not be resilient to the expected increases in the magnitude and frequency of extreme weather events and long-term climate change.

Fossil fuel and nuclear plants risk suffering diminished water supplies, warming temperatures, and severe weather, it says. Though energy production, which includes thermoelectric power, accounted for about 11% of U.S. water consumption in 2005—second only to irrigation—droughts can cause water levels to drop below the level of intake valves that supply cooling water to power plants, as in a 2007 southeastern event. In 2007, 2010, and 2011, the Tennessee Valley Authority had to reduce power output from its Browns Ferry Nuclear Plant in Alabama because the temperature of the river was too high to receive discharge water without raising ecological risks, and the cost to replace that power was estimated at $50 million. And in August 2012, a unit of Dominion’s Millstone Nuclear Plant in Connecticut was forced to shut down because intake cooling water from the Long Island Sound exceeded temperature specifications.

At least 25% of existing generation will be sited in counties with high or moderate water supply risks by 2030, and competition for water with other sectors could affect reliability of future generation, the GAO says.

However, higher temperatures could also diminish the efficiency by which power plants convert fuel to power. USGCRP claims that even small changes in efficiency could have drastic consequences: An average reduction of 1% in power generated by fossil fuel plants nationwide could mean a loss of 25 billion kWh per year.

As with risks borne by power plants located along the U.S. coastline from a rising sea level and hurricanes, even plants inland are vulnerable to flooding and storm surge, as occurred at the Fort Calhoun nuclear power plant in April 2011. Seasonal flooding should be managed to reduce these risks, the GAO recommends.

Renewables, too, aren’t immune to climate change. Hydropower is highly sensitive to rising temperatures, changes in precipitation, and river discharge. The USGCRP provides a telling statistic: Every 1% decrease in precipitation results in a 2% to 3% drop in streamflow, and in the Colorado Basin, for example, could decrease hydropower generation by 3%. Western rivers are already seeing significant changes in the amount of streamflows, the report says.

For solar photovoltaics, the risks come from increased haze, humidity, and dust, and for concentrated solar power, a vulnerability to water shortages for cooling purposes. Geothermal could suffer many of the same calamities as fossil fuel plants, including efficiency losses and water shortages. Even wind, which doesn’t use water, is vulnerable to extreme weather.

The grid is perhaps the most vulnerable. The transmission and distribution infrastructure is aging, the report says. Citing the Department of Energy, it notes while most of the national grid system was designed to last 40 to 50 years, in some parts of the country it is now 100 years old.

The GAO offers two broad solutions: To invest in hardening and resiliency efforts. Hardening will require physical changes to make infrastructure less susceptible to storm damage, such as elevating electrical substation control rooms to reduce potential flooding hazards. Resiliency involves the ability to recover quickly from damage to facilities’ components, and includes measures such as purchasing backup power generators to restore power more quickly.

Because much energy infrastructure is owned by the private sector, state and federal governments should cooperate with energy infrastructure owners to help them get rate increases to cover the costs of hardening their infrastructure, the GAO advocates.

Some indirect impacts will be harder to manage. Increases in temperatures could affect the cost, type, and amount of energy consumed in the U.S. Over the past four years, for example, demand for cooling has risen and the demand for heating declined.

And impacts from climate change also make resource extraction and processing infrastructure especially vulnerable, most of all, facilities that are located on coastlines, the report says. Fuel transportation infrastructure, including the nation’s 2.6 million mile network of gas pipelines, and storage facilities are also at risk. Extreme weather has in the past disrupted barge transportation and washed out rail lines, impeding the delivery of coal to power plants. Flooding of rail lines is already a notable problem in the Appalachian region and along the Mississippi River, and the resulting rerouting of deliveries “can cost millions of dollars,” it says.

The report also provides a case study of how Entergy Corp. is addressing climate-related risks. That company’s New Orleans subsidiary Entergy New Orleans filed for bankruptcy after major damage to its infrastructure and declining demand after mass evacuations following Hurricanes Katrina and Rita in 2005. It also profiles California-based Pacific Gas and Electric Co.’s measures to tackle limited water availability, and Florida Power and Light’s safeguards to its Turkey Point nuclear plant, which the company told the GAO is “potentially vulnerable” to extreme weather events, storm surges caused by hurricanes, and sea level rise.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)