University of
California - Irvine
The United States
could reliably meet about 80 percent of its electricity demand with solar and
wind power generation, according to scientists at the University of California,
Irvine; the California Institute of Technology; and the Carnegie Institution
for Science.However, meeting 100 percent of electricity demand with only solar and wind energy would require storing several weeks' worth of electricity to compensate for the natural variability of these two resources, the researchers said.
"The sun sets,
and the wind doesn't always blow," noted Steven Davis, UCI associate
professor of Earth system science and co-author of a renewable energy study
published today in the journal Energy & Environmental Science.
"If we want a reliable power system based on these resources, how do we
deal with their daily and seasonal changes?"
The team analyzed 36 years of hourly U.S. weather data (1980 to 2015) to understand the fundamental geophysical barriers to supplying electricity with only solar and wind energy.
"We looked at the
variability of solar and wind energy over both time and space and compared that
to U.S. electricity demand," Davis said. "What we found is that we
could reliably get around 80 percent of our electricity from these sources by
building either a continental-scale transmission network or facilities that
could store 12 hours' worth of the nation's electricity demand."
The researchers said
that such expansion of transmission or storage capabilities would mean very
substantial -- but not inconceivable -- investments. They estimated that the
cost of the new transmission lines required, for example, could be hundreds of
billions of dollars.
In comparison, storing that much electricity with today's cheapest batteries would likely cost more than a trillion dollars, although prices are falling.
In comparison, storing that much electricity with today's cheapest batteries would likely cost more than a trillion dollars, although prices are falling.
Other forms of energy
stockpiling, such as pumping water uphill to later flow back down through
hydropower generators, are attractive but limited in scope. The U.S. has a lot
of water in the East but not much elevation, with the opposite arrangement in
the West.
Fossil fuel-based
electricity production is responsible for about 38 percent of U.S. carbon
dioxide emissions -- CO2 pollution being the major cause of
global climate change. Davis said he is heartened by the progress that has been
made and the prospects for the future.
"The fact that we
could get 80 percent of our power from wind and solar alone is really
encouraging," he said. "Five years ago, many people doubted that
these resources could account for more than 20 or 30 percent."
But beyond the 80
percent mark, the amount of energy storage required to overcome seasonal and
weather variabilities increases rapidly.
"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," said co-author Ken Caldeira of the Carnegie Institution for Science. "Options could include nuclear and hydroelectric power generation, as well as managing demand."
"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," said co-author Ken Caldeira of the Carnegie Institution for Science. "Options could include nuclear and hydroelectric power generation, as well as managing demand."