Climate change will force boost in electrical grid capacity, mostly from renewables

The extensive power blackouts in Texas this past week have highlighted the problems of an electrical grid not prepared to handle disruptions due to severe weather events. Rolling blackouts also grab headlines in the summertime as demand for air conditioning spikes and power plants cannot keep up.

A new study reveals how power investments in the southeastern US would change if utilities incorporated climate change impacts into their expansion plans. The analysis predicts that by 2050, energy operators will have to boost generating capacity by more than one-third just to avoid summer shutdowns and that most of that new electricity is best delivered by solar and wind power (Environ. Sci. Technol. 2021, DOI: 10.1021/acs.est.0c06547).

Earlier studies have described the climate vulnerabilities of coal, gas, and nuclear power plants, responsible for 85% of US electricity. These thermoelectric plants depend on river water or outside air to dissipate excess heat. But when hot spells make the air and river water too warm to cool the plant, operators curtail or even shut down power output. Meanwhile, other research has forecast that climate change will increase daily peak electricity demand in the summer (Proc. Natl. Acad. Sci. U.S.A. 2017, DOI: 10.1073/pnas.1613193114).

“But we haven’t seen energy-system planners integrating the combined impacts of increased demand and heat-related curtailments in their capacity expansion models,” says Francisco Ralston Fonseca, an energy analyst at Carnegie Mellon University. These industry models provide information on how to invest in new plants 30 to 40 years into the future to deliver the optimum amount of power at the lowest cost to the consumer. So he and his team decided to insert climate risks into planning models for the southeastern US, which include all or part of eight states (not including Texas), where climate impacts are predicted to be severe and thermoelectric plants currently provide over 70% of electricity.

The team’s models forecast future air temperature in the region, calculated electricity demand as a function of temperature, and simulated the way hot weather induces thermoelectric plants to cut back power. All this information then fed into a model that predicted how much additional electricity-generating capacity would be needed by 2050.

Ralston Fonseca and his colleagues compared two different scenarios: one that assumes the climate stays the same as the present and one that assumes global temperature will rise 2–3 °C by 2100. Under the climate-change scenario, annual peak electricity demand in the summer would be almost 16% greater than it would be without climate-change risks included. And because of the summertime heat, the ability of plants to crank out electricity would drop by as much as 13% in some cases. Considering climbing demand and falling power output, the scientists calculated that plant operators would have to increase generating capacity by 35% to meet customers’ needs in the warmer world of 2050.

With no climate risks included, the model showed that investing mainly in natural gas and wind plants for 2050 would result in the lowest cost to the consumer, with solar and wind power making up 30% of the total grid capacity. But with climate risks added, the model recommended that solar and wind rise to 42% of total grid capacity. Another scenario requiring an 80% cut in CO₂ emissions by 2050 lifted wind and solar investment to 55% of total generation in the Southeast.

“These results are telling us that utilities need to increase generating capacity to adapt to climate change and the extra capacity is made up of renewables, which is a win-win for reducing carbon emissions while adapting to climate impacts,” says Ariel Miara, an energy, water, and environment research analyst at the National Renewable Energy Laboratory.

Although the recent events in Texas are beyond the scope of the study, Miara says that the results show that “we need to plan our infrastructure accordingly so that we have safe drinking water and reliable energy supplies under these extreme weather events, during the winter and summer.” He is collaborating with energy system operators to promote incorporation of climate change impacts in grid planning.