by Peter Maloney
Posted June 6, 2019

Electric power resources should be sufficient to meet expected summer demand, according to the North American Electric Reliability Corp.’ 2019 Summer Reliability Assessment, but the oversight organization does see some potential trouble spots.

In particular, the NERC summer assessment highlighted potential limits on natural gas supplies in Southern California and wildfire risk in Northern California, either of which could “increase the likelihood of grid emergency procedures this summer.”

In most areas of North America, the planning reserve margin, NERC’s key reliability metric, is well above minimum levels, indicating that the owners and operators of the bulk power system will be able to manage reliability risk effectively, the report found.

“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,” John Moura, director of reliability assessment and technical committees, said in a statement.

The West

At the same time, NERC noted that restrictions on withdrawals from Aliso Canyon, the largest natural gas storage complex in California, could threaten electric reliability in the Western Interconnection.

High levels of withdrawals this past winter resulted in below average storage injections coming into the 2019 summer season. Southern California Gas forecasts it will be able to meet forecasted demand under a best-case scenario, but under a worst-case scenario gas from Aliso Canyon would be necessary to meet peak demand. In that scenario, limits on withdrawals could result in gas supply curtailments that could affect electric generation in Southern California, NERC said.

Aliso Canyon has yet to return to full operation because of testing in the wake of the massive October 2015 gas leak.

NERC also warned that government agencies predict above normal wildfire risks this summer for California, the Pacific Northwest, Western Alberta, British Columbia, and Northern Mexico.

Wildfires could present a “localized” risk to system reliability, NERC said, but outages due to wildfires are generally not widespread because of the Western transmission system is widely dispersed.

In addition, utilities are enhancing wildfire prevention planning in California and other areas to address increased risks, NERC said. Those measures include preemptively deenergized transmission lines in areas at high risk of wildfires, as well as enhanced vegetation management, equipment inspections, and system hardening.

In California, the state’s Independent System Operator (ISO) said a snowy winter has replenished hydroelectric resources, reducing the potential of operating reserve shortfalls, but there are concerns about shortages of load-following resources that can quickly ramp up to fill in the gap when midday solar resources taper off in the evening.

That situation could have operators call on neighboring jurisdictions for imports. But widespread extreme temperatures could leave those neighbors with a lack of surplus energy and put California at risk of a shortage in ramping capability.


In Texas, the anticipated reserve margin for the Electric Reliability Council of Texas (ERCOT), which supplies most of the state’s power, is below the reference margin level of 13.75% and has been dropping, NERC says. Last summer, ERCOT’s anticipated reserve margin was 10.9%.

Last summer, ERCOT did not have to resort to issuing emergency alerts in large part because of high levels of generator availability, response to market signals, and unit performance.

This summer, with anticipated reserve margins even lower, ERCOT, in its summer Seasonal Assessment of Resource Adequacy (SARA) report, said it expects that several operational tools may be needed to help maintain sufficient operating reserves.

ERCOT in March said it expects to hit record peak demand this summer.

At the same time, ERCOT estimates that operational mitigations can contribute 1,160 MW of additional resources to support its operating reserve requirements. Those resources include 489 MW of switchable generation resources currently serving the Southwest Power Pool (SPP) market that could be redirected to ERCOT in an emergency, 221 MW of potential imports from SPP and the Mexican grid, and 450 MW of distribution voltage reduction that can be instituted.

Russ Keene, executive director of Texas Public Power Association noted that “The state’s leadership, starting with the governor, is extremely mindful of the decreased reserve margin due to some coal plant retirements.”

Keene said that the Texas PUC and ERCOT “have closely collaborated with industry stakeholders throughout the spring to ensure close coordination and communication throughout the hot Texas summer months.”

Ten Texas public power systems own generation, comprising about 15 percent of the state’s baseload, and sell into ERCOT’s competitive wholesale market. “Our municipally-owned utilities with generation provide a solid, foundational load to stabilize the market,” Keene said.