The share of electricity supplied by wind and solar jumped from 1 percent to 8 percent in the U.S. over a decade without causing reliability issues, according to a recent report to members of Congress.
There have also been occasions when renewables supplied the majority of power, energy policy analyst Ashley J. Lawson tells Congress in a reportfrom the Congressional Research Service, and on those occasions, too, their inherent variability did not affect system reliability.
“The share of wind and solar power in the U.S. electricity mix grew from 1% in 2008 to 8% in 2018,” Lawson writes. “According to official metrics, electric reliability was generally stable or improving over the 2013-2017 period. In other words, generation from wind and solar sources does not appear to be causing electric reliability issues at the national level over this period.”
Lawson draws on data from the North American Electric Reliability Corporation (NERC), writing:
NERC’s 2018 annual report on reliability showed that, of the metrics it uses to assess reliability, 9 were stable or improving over the 2013-2017 period and 4 showed trends that were, at least partly, inconclusive. Of the four metrics with inconclusive trends, three improved over this period for a subset of bulk power system components. Data from NERC also indicate that reliability performance is currently stable in regions such as the Midwest and California where the shares of generation from wind and solar sources are above the national average.
Lawson describes several instances in which “wind and solar sources have provided a majority of the energy for electricity generation,” including:
• Generation from wind sources supplied 56% of electricity demand in ERCOT, the regional transmission organization (RTO) covering most of Texas, at 3:10 am on January 19, 2019.