Wind And Solar's Share Has Grown 700 Percent Without Reliability Issues

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 report from 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.
• Generation from solar sources supplied 59% of electricity demand in CAISO, the RTO covering most of California, at 2:45 pm on March 16, 2019.
• Generation from wind supplied 67.3% of electricity demand in SPP, the RTO covering many central states, at 1:25 am on April 27, 2019.
"These events all set records for maximum share of generation from renewable sources, and the bulk power system maintained reliability during them."
Lawson cautions members of Congress that reliability could still become an issue if renewables grow faster than expected, and solar alone is expected to grow by as much as 6,500 percent by 2050. Congress can prepare for the possibilities, she tells them, by
• guiding FERC and NERC to develop new reliability standards
• assessing whether the current regulatory framework is sufficient, including regulations governing the siting and approval of transmission projects (Transmission can support reliability by transferring renewable power from areas of the country where is it abundant to areas where it may be insufficient).
• supporting reliability at the state and local distribution level (where most outages occur) by studying the causes of outages, supporting local reliability efforts and encouraging new ways of operating distribution systems.
• supporting "the emerging and related issue of electric resilience" through grid modernization and systems integration, as the National Academies have recommended, and
• supporting the energy sources that are used to balance wind and solar with tax credits, grants to states or other entities, and DOE research programs.

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