The SPP Marketing Monitoring Unit (MMU)’s quarterly State of the Market report for the winter 2021 period is dominated by the historic winter weather events of mid-February.

The storms left 73% of the continental U.S. covered in snow and broke 3,000 daily and 79 all-time low-temperature records, according to the National Weather Service. The event was “comparable to the historical cold snaps” of 1899 and 1905, the NWS said.

The MMU said in its report that the market’s average load was up 10%; generation outages increased from 30 GW to 43 GW over the previous winter; and high gas prices led to average day-ahead prices of $504.42/MWh and real-time prices of $186.82/MWh in February.

The generation outages were driven by fuel-supply constraints, icing and other weather-related issues. Gas-fired plants competed with high demand for residential heating as wellheads, pipelines and pumping stations froze over. The MMU said natural gas plant outages peaked at more than 25 GW on Feb. 18, including both simple and combined cycle plants.

Wind resources were hampered by an icing event Feb. 7-8 and were slow to recover because of the low temperatures. More than 11 GW of wind generation were offline on Feb. 8, but about 3 GW were back online during the height of the storm.

SPP’s generation was boosted by imports from MISO and PJM, but those decreased because of transmission congestion and the RTOs’ own emergency needs.

The tight conditions resulted in energy offers above SPP’s $1,000/MWh safety-net offer cap beginning Feb. 11. SPP’s tariff allows such offers under FERC Order 831, but the Monitor must verify the offers before they can be used in the market-clearing process or eligible for make-whole payments. Uncapped real-time prices exceeded $10,000/MWh on Feb. 18, when supply was at 40.3 GW, and peaked at $6,302/MWh on Feb. 15, when supply was 45.9 GW.

The MMU commended SPP and market participants for delivering power despite unprecedented demand and supply conditions that stressed the market. It said it is continuing to evaluate market performance and behavior and will present lessons learned and recommendations as part of SPP’s comprehensive winter review process before the Board of Directors in July. (See SPP Launches Review of Storm Response.)

“We look forward to continuing to educate stakeholders on the market implications on this event and improving the market going forward,” the Monitor said.

The MMU will host a webinar to discuss the winter report at 2 p.m. on April 15.