Energize Weekly, June 26, 2019
There is adequate generating reverse to meet summer electricity demands in most of the U.S., while Texas, California and the West may face challenges, according to the North American Reliability Corp. (NERC) 2019 summer assessment.
NERC, a nonprofit corporation overseeing regional electricity reliability in the Lower 48 United States, Canada and parts of Mexico, assess summer demand, generating capacity and reserve margins – the extra capacity a system has.
The anticipated reserve margins, the cushion each system has to meet peak demand, range from 19.3 percent for the Midcontinent Independent System Operator (MISO), which serves utilities in 15 Midwestern states and one Canadian province, to 32 percent for the Southwest Power Pool (SPP), with members in 14 states from Louisiana to Wyoming.
All the country’s major population areas, including New England, the Mid-Atlantic States and the Southeast are covered by grid operators with reserve margins above 20 percent.
The Electric Reliability Council of Texas (ERCOT), however, has one of the lowest reserve margins in the county at 8.4 percent, giving it a thin margin during periods of peak demand.
ERCOT anticipates hitting a new peak hourly electricity demand level of 74,853 megawatts (MW) this summer, or about 1,300 MW higher than the hourly demand record set last July.
“If resource shortfalls occur, ERCOT anticipates implementing operating mitigations,” the NERC assessment said. “These measures include importing additional power if available and energy emergency alerts that allow ERCOT to trigger emergency procedures such as voluntary load reduction.”
The California Independent System Operator (CAISO) is part of the Western Electric Coordinating Council (WECC), which covers 14 Western states, 2 Canadian provinces and Baja, Mexico.
While the WECC has a reserve margin of 28.7 percent, NERC said the CAISO could face ramping problems as its photovoltaic solar generation falls off at the end of the day. Solar provides more than 12 percent of the state’s electricity.
“There is the potential for operational risks at certain times of day as a result of shortages in resources with upward ramping capability,” NERC said. “These shortage conditions are more prevalent during late afternoon as solar generation output decreases while system demand is still high. Transfers from neighboring areas may be needed during normal conditions when short on load-following resources capable of ramping up within the CAISO area.”
The Western U.S. and parts of Canada may also face reliability risks due to summer wildfires NERC said. “Government agencies predict above-normal wildfire risk for summer throughout parts of North America,” the assessment said. “In some areas, pre-season planning includes expanded public safety power shut-off programs in addition to maintenance and operational preparations.”
