Grid monitor warns of U.S. blackouts in ‘sobering report’

The central and upper Midwest, Texas and Southern California face an increased risk of power outages this summer from extreme heat, wildfires and extended drought, the nation’s grid monitor warned yesterday.

In a dire new assessment, the North American Electric Reliability Corp. (NERC) described regions of the country pushed closer than ever toward energy emergencies by a combination of climate change impacts and a transition from traditional fossil fuel generators to carbon-free renewable power.

“’Extreme’ doesn’t mean ‘rare,’” John Moura, director of reliability assessment and performance analysis at NERC, said during a media briefing. “We know these conditions are not rare,” he said of the growing siege of drought, flooding and severe storms.

“It’s a very sobering report. It’s clear the risks are spreading,” Moura said.

NERC’s analysis examined the potential punch of extreme weather, which may wreak havoc on everything from reduced hydropower to transmission lines brought down by wildfires. Grid operators are dealing with an increasing reliance on intermittent resources like wind and solar as coal units retire and the reliability and emissions of gas resources comes under scrutiny. How the summer unfolds also may have political ramifications, as it could affect public support for President Joe Biden’s push to decarbonize the U.S. grid by 2035.

The NERC report also highlighted what it called an increased, urgent hazard to grid operations from the electronic controls that link wind and solar farms to high-voltage grid networks. The devices, called power inverters, must be programmed to “ride through” short-term disturbances, such as the loss of a large power plant or high-voltage line, but too often they are not, Moura said. Those that shut down compound stress on the grid, he added in a briefing yesterday.

The report cited incidents in May and June of last year when the Texas system was hit with widespread solar farm shutdowns, followed by similar outages in California between June and August. The unexpected events disrupted traditional power plants, interfered with grid recovery operations and caused some outages of customer-owned power units, NERC said.

“That is one of the most dangerous things to happen on the bulk power system,” Moura said about the inverter disruption issue, because grid operators can be caught by surprise by the outages just when the finely balanced systems are already dealing with instability.

The issue is not a reason to back away from moving the grid to carbon-free wind and solar, Moura said.

“We truly support that,” he said of the clean energy shift. But the challenges demand quick action on setting technical equipment standards to deal with the problem, he added. “The pace of our grid transformation is a little out of synch” with the technical requirements for the system’s operation, he said.

‘Elevated risk’

Highlighting the most serious regional threats, the report said:

  • The Midcontinent Independent System Operator (MISO), grid manager and energy market operator in the central Midwest, “faces a capacity shortfall in its North and Central areas, resulting in high risk of energy emergencies during peak summer conditions.”

    “More extreme temperatures, higher generation outages, or low wind conditions expose the MISO North and Central areas to higher risk of temporary operator-initiated load shedding to maintain system reliability,” the report said of the MISO region, which runs from Canada’s Manitoba province to Louisiana.

  • “An elevated risk of energy emergencies persists” across the West this summer “as dry hydrological conditions threaten the availability of hydroelectric energy for transfer.” Assuming that nearly 3,400 megawatts of new resources are available as scheduled this summer, California should be able to meet peak power demands this summer, the report said. But a repeat of the heat dome that scorched the entire West in 2019 could threaten the availability of imported power that the state depends on, causing energy emergencies.
  • In Texas, a “combination of extreme peak demand, low wind, and high outage rates from thermal generators could require system operators to use emergency procedures, up to and including temporary manual load shedding.” Delays in completing new transmission lines now underway “may contribute to localized reliability concerns.”
  • Drought conditions in the Missouri River Basin may affect operations of gas, coal or nuclear plants in the Southwest Power Pool that rely on the river for cooling water supplies, the report said.
  • Some coal-fired power plant owners are having a hard time arranging fuel deliveries because of mine closings, rail shipping interruptions and increased coal exports, it added.

The report warned of multiple threats from Western wildfires, where dry weather raises the risk of ignition and smoke from blazes can diminish output from utility- and customer-owned solar panels and short circuit high-voltage power lines, as happened last year in Oregon.
On top of all of this, NERC reported an increased danger of potential Russian cyberattacks on the nation’s power systems in retaliation for U.S. support for Ukraine in the current conflict.

NERC raised the issue of solar power interruptions after the 2016 Blue Cut Fire in Southern California, when wildfire triggered short circuits in transmission lines, leading to voltage drops and outages at nearby solar units.

As the penetration of inverter-based wind, solar and battery resources grows, the need for precise modeling studies of these systems “will only grow exponentially,” the new report said. NERC reliability standards must ensure that essential performance standards for inverters are defined and met, it added.

“We cannot integrate [renewable] resources reliably without doing these studies,” Moura said.

Earlier this month, California officials described conditions that could occur this summer — including potential blackouts because of power supply shortages (Energywire, May 9). Among the times with high risks: the early evening when solar power goes away and the month of September.

“There is real potential for potential outages, and we have to be prepared for that,” Mark Rothleder, chief operating officer at the California Independent System Operator, told reporters. “It really depends on how many things and how extreme the events are that we actually experience.”

‘Lights are going to stay on’

Grid officials in Texas painted a more optimistic picture Tuesday, saying they will be able to keep the lights on in an extreme heat scenario this summer — even after a weekend when the state’s main power grid operator asked residents to conserve energy amid a heat wave.

Brad Jones, interim CEO of the Electric Reliability Council of Texas (ERCOT), said in a press conference he was “confident” about electricity reliability, even with projections showing record demand for the summer.

ERCOT, in a seasonal assessment of resource adequacy released this week, forecasts summer peak demand of 77,317 MW, a potential record. The report also anticipates 91,392 MW of resource capacity during peak hours.

“The grid is more reliable than it ever has been before,” Peter Lake, chair of the Public Utility Commission of Texas, said at the Tuesday press conference.

Lake attributed the strong forecast to policies enacted in the aftermath of sustained power outages during the February 2021 winter storm, which saw more than 4 million homes and businesses lose power amid freezing temperatures.

“The reforms are working,” Lake said. “The lights are going to stay on this summer.”

Analysts, however, are less confident than the state officials, especially as temperatures rise across the state.

Daniel Cohan, associate professor in the civil and environmental engineering department at Rice University, said new solar and wind generation has helped bolster the grid but that an extreme heat wave could still lead to blackouts.

“I’m not as sanguine as ERCOT seems to be,” Cohan told E&E News.

The latest report, he said, did not seem to account for the compounding problems that happen during an extreme heat wave: stagnant wind that limits power generation, unexpected power plant outages and spiking demand as homes and businesses crank the air conditioning.

While the grid may operate under any one of those conditions, he said, an extreme heat wave that causes a cascade of problems could result in rolling blackouts.

“To me, it’s sort of a roll of the dice that we might have serious problems this summer, a rough guess of a 1 in 6 chance,” Cohan said. “And as the climate continues to warm, we’ll keep loading the dice with greater possibilities of extreme weather.”

MISO officials have agreed with NERC’s cautions about the strains on the region’s power supplies.

MISO is facing increased retirements of coal, natural gas and nuclear generation, leading to an inadequate response last month as it lined up power reserves to create a required cushion against system disruptions and unexpectedly heavy power demand (Energywire, April 18).

The region enters the summer 1,230 MW short of meeting its planning reserve margin.

“The reality for the zones that do not have sufficient generation to cover their load plus their required reserves is that they will have increased risk of temporary, controlled outages to maintain system reliability,” said MISO President and Chief Operating Officer Clair Moeller in a statement last month.

David Patton, MISO’s independent market monitor, said during a call Friday that the auction results are “the outcome we’ve been worried about for a decade.”

MISO market rules that suppressed capacity prices in previous years, he said, have led to the retirement of otherwise economic power plants. And steps to improve the market have proven “woefully inadequate,” he said.

“If we’re going to say reliability is an imperative, we need to fix this,” Patton said.

Reporters Jeffrey Tomich and Anne C. Mulkern contributed.



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