California Hopes to Avoid Repeat of Summer Outages

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California Hopes to Avoid Repeat of Summer Outages

May 17, 2021

Will California again suffer through rotating electrical outages, as it did  on August 14 and 15, 2020? 

The California Independent System Operator May 12 said it was “guardedly optimistic” it would avoid repeating last summer’s “load shed” events, but “potential challenges in meeting demand” remain, according to its 2021 Summer Loads and Resources Assessment.

The 2021 Assessment considers the supply and demand conditions across the entire ISO balancing authority area, and to a more limited extent, the entire Western Electricity Coordinating Council (WECC).

The ISO anticipates supply conditions to be better than 2020, but sees challenges during extreme heat waves affecting a substantial portion of the Western Interconnection, which cause simultaneously high loads across the West and reduce the availability of imports into the ISO balancing authority area.

Improvements to supply conditions include new resources. However, significantly lower than normal hydro conditions, virtually unchanged forecasted load levels, and increased possibility of extreme weather events indicate the ISO may still face challenges in meeting load this summer. Reduced levels of net imports during high-demand conditions significantly affects system reliability.

Conservation during extreme events will again be critical to avoid shedding load. The ISO and State entities have taken significant measures to inform consumers in a timely manner through the Flex Alert campaign to conserve energy when requested to avoid outages.

The ISO 2021 peak demand forecast is 45,837 MW, which is 0.2 percent above the 2020 weather normalized peak demand of 45,742 MW.

The ISO projects system capacity of 49,583 MW in June, 50,734 MW in July, 50,010 MW in August, and 47,385 MW in September for summer 2021. The decline of available capacity from July to September results from the declining effective load carrying capability of solar and hydro generation. The declining effective load capability for grid-connected solar and hydro is primarily due to the shifting of peak loads to later in the day due to behind-the-meter solar generation, and declining hydro energy expectations, respectively.

The net of additions and retirements represents an increase of 3,880 MW, with a net increase of dispatchable capacity of 1,570 MW. Of the new resource capacity working to be operational for this summer, 1,493 MW is from battery energy storage systems (BESS) coming online by September.

In addition to the gas-fired generation, hydro, and renewable generation described above, 1,218 MW of demand response resource capability available to the market reported in 2020 was carried forward into the 2021 analysis.

Analysis reveals the criticality of net imports to the ISO during system peak hours at high load conditions. If the ISO is limited to the more conservative net import levels of the sensitivity case, the probability of having to shed firm load to maintain required operating reserves is significantly increased. This indicates that the ISO will be at the greatest operational risk during a late summer widespread heat wave that results in high ISO loads and low net imports due to high peak demands in its neighboring balancing authority areas, concurrent with the diminishing effective load carrying capability of solar resources and the wane of hydro generation.

The 8 p.m. period during high-load days is emerging as the period of highest risk, as daily solar output drops off.

Conservation during extreme events will continue to be critical to avoid shedding load. The Assessment does not include potential risks associated with transmission facility forced outages, including transmission outages due to wildfires, which could hinder imports during critical supply conditions. Supply disruptions due to public safety power shutoff procedures are also not addressed in this report.

With the significant unknowns in how the COVID-19 pandemic will continue to impact society and how the various electric sectors use energy, no attempt was made to predict potential ongoing impacts to loads due to COVID-19 beyond the impact the forecast model attributes to changes in economic growth associated with the forecast from Moody’s.

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