North America's power grid reliability organization expects power supplies will meet peak demand for electricity in most regions this summer but warned that resource inadequacy in Texas, constrained natural gas supplies in Southern California, and heightened wildfire risk in Northern California and elsewhere might lead to the limited use of grid emergency procedures.
In its newly released "2019 Summer Reliability Assessment" of the continent's bulk power system, the North American Electric Reliability Corp. said projected generation resources going into summer 2019 are at or above the levels needed to satisfy seasonal peak demand under anticipated weather conditions in most of its regions. NERC oversees grid reliability in the continental U.S. and parts of Alaska, most of Canada, and the northern part of Baja California, Mexico.
"The landscape for summer 2019 looks similar to 2018 with more than enough anticipated resources and reserves to assure the reliable operation of the bulk power system in most assessment areas," said John Moura, NERC's reliability assessment and technical committee director, in a press release.
"As the transformation of the resource mix continues," continued Moura, "the real-time operation of the system in all seasons presents opportunities and challenges in managing assets with a diverse set of operating characteristics."
NERC said most of the areas assessed meet or exceed reliability reserve margin requirements and have sufficient supply under anticipated conditions and even more-extreme scenarios. Risks to seasonal reliability include higher-than-expected generation or transmission outages and higher-than-expected electricity demand, NERC explained.
According to NERC, extreme summer peak loads and low-probability generator outage scenarios could result in insufficient resources to meet expected operating reserve requirements, in which case grid system operators may need to rely on demand response, increased energy transfers, and other operational measures to manage resources and loads.
NERC said anticipated reserve margins in all assessment areas except the Electric Reliability Council Of Texas, or ERCOT, meet or surpass the reference margin level, meaning that planned resources in those areas are adequate to manage the risk of loss of load under normal conditions.
Texas is plagued by a resource adequacy problem, NERC explained, and anticipated emergency alerts may be needed to prevent resource shortfalls during periods of peak demand. The report noted that ERCOT's anticipated reserve margin has fallen from 10.9% in summer 2018 to 8.5% for this summer as a result of higher load growth, a generator retirement, and delays in new generation. As a result, the anticipated reserve margin for ERCOT is well below the reference margin of 13.75%.
"If resource shortfalls occur, ERCOT anticipates implementing operating mitigations," NERC 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 Federal Energy Regulatory Commission staff's recently released summer reliability assessment, which partially relied on NERC's report, came to a similar conclusion: despite forecasts of higher than average temperatures for the western, southwestern, and northeastern U.S., grid operators, with the possible exception of ERCOT, should have little trouble maintaining reliability during periods of peak demand this summer.
FERC staff noted that net demand in the U.S. for power is expected to be approximately 0.3% lower compared to last summer due to reductions associated with greater energy efficiency and behind-the-meter systems.
NERC warned that parts of California are also facing certain reliability challenges, including a lack of ramping capability. Even under normal conditions, power supplies from outside the California ISO's market may need to be imported to maintain reliability during late afternoon, when solar generation decreases but the bulk power system's demand for electricity remains high, said the report.
Further, NERC said Sempra Energy subsidiary Southern California Gas Co. has determined that gas supplies from interstate pipelines alone are insufficient to meet the needs of gas-fired generators in Southern California on summer peak load days, leaving local generators at risk of curtailment. Natural gas from SoCalGas' Aliso Canyon natural gas storage facility may, therefore, need to be used to ensure adequate fuel for generators in Southern California.
Elevated risk for wildfires in the western U.S. — including Northern California, which suffered the deadliest and most devastating wildfire in state history in November 2018 — and parts of Canada poses a localized risk to the bulk power system reliability, NERC said. Government agencies have predicted above-normal wildfire risk for the summer throughout parts of North America. In some areas, NERC said preseason planning includes expanded public safety power shut-off programs in addition to maintenance and operational preparations.