The U.S. could reliably source 80 percent of its electricity demand from wind and solar power alone, according to a joint study by researchers from the University of California–Irvine (UCI), the California Institute of Technology, and the Carnegie Institution for Science.
The ability to produce this much renewable energy is encouraging, as the conversion of fossil fuels into electricity is currently responsible for 38 percent of carbon dioxide emissions, a major source of pollution, in the U.S. alone.
The study is published in Energy & Environmental Science.
Both solar and wind are energy sources that are dependent on weather variations.
“The sun sets, and the wind doesn’t always blow,” Steven Davis, associate professor of earth system science at UCI and co-author of the study, said in a statement. “If we want a reliable power system based on these resources, how do we deal with their daily and seasonal changes?”
After analyzing hourly U.S. weather data over a 36-year span (1980-2015) to determine the reliability of solar and wind power, the researchers found that the U.S. could conceivably rely on solar and wind power for the vast majority of its energy needs, provided that there are major investments in transmission and storage capabilities.
“The analysis assumes we’d build lots of solar panels and wind turbines to harness those resources,” said Davis. “But getting to 80 percent would also require substantial increases in either energy storage or our ability to shift electricity around the country via transmission lines.”
This kind of expansion of energy storage and transmission would consist of constructing a continental-scale transmission network or facilities that could store up to 12 hours worth of energy for the entire nation. Doing so would be costly. At today’s prices, new transition lines could cost hundreds of billions of dollars, while battery storage would likely cost over a trillion dollars.
As a result, meeting the 80 percent mark may be difficult, though not impossible, to accomplish in the short term. Falling prices will play a substantial role in making these developments more feasible.
“Add these challenges to technological inertia of our current fossil-fuel burning fleet of power plants, and you can see that getting 80 percent of our power from these sources is going to take considerable time and investment,” Davis said. “But costs of many of the necessary technologies are falling, and in many parts of the country there is remarkable political will and popular support for renewable energy. I think it will happen.”
However, meeting more than 80 percent of electricity demand with only solar and wind energy is unlikely.
“The 80 percent number boils down to natural variability in sun and wind,” said Davis. “If we want to get more than 80 percent of our power from those two sources, the required amount of energy storage or solar and wind generating capacity rises sharply.”
Sourcing 100 percent of the country’s’ energy demand from solar and wind, he said, would require building twice as many solar panels and wind turbines or having several weeks worth of storage, as opposed to the 12 hours required to meet 80 percent of the demand.
As a result, wind and solar energy would need to be supplemented by other sources of energy in order to meet demand. A combination of other technologies and practices could be used to fill the gap.
“Our work indicates that low-carbon-emission power sources will be needed to complement what we can harvest from the wind and sun until storage and transmission capabilities are up to the job,” Ken Caldeira, co-author and climate scientist at the Carnegie Institution for Science’s Department of Global Ecology, said in a statement. “Options could include nuclear and hydroelectric power generation, as well as managing demand.”
Nevertheless, the results of the study bode well for the future of renewable energy.
“The fact that we could get 80 percent of our power from wind and solar alone is really encouraging,” Davis said in a statement. “Five years ago, many people doubted that these resources could account for more than 20 or 30 percent.”
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