CAISO noted that its 2018 Summer Loads and Resources Assessment, which forecasts the 2018 peak demand to be about the same as last year, modeled thousands of scenarios based on a range of weather-driven demands and system conditions.
The state’s power grid will not have the benefit of abundant hydroelectric resources as in the past year, with late-summer supplies especially low, CAISO said, noting the California Department of Water Resources reports that snowpack water content was 51 percent of average as of April 2.
In total, this year’s hydroelectric production will be down 1,300 megawatts by late summer compared to 2017’s above-normal production.
In addition, natural gas-powered generation will see a drop of about 800 MW due to plant retirements.
The ISO analysis shows 860 MW of generation retirements since last summer, including 837 MW of natural gas generation. Nearly 692 MW of generation was added to the system since last year. Of that, 60 percent is solar, 24 percent biofuel, 7 percent wind, 7 percent natural gas, and 2 percent hydroelectric.
The ISO projects that 51,947 MW of generation capacity will be available to serve demand this summer. The peak demand for this summer is projected to be 46,625 MW under normal conditions.
“If temperatures are warmer than normal, as they were last year, then the power supply margins will begin to tighten up significantly as air conditioning demand rises,” the grid operator said.
Last year’s peak load was 50,116 MW on Sept. 1, 2017.
To help balance supply and demand, the ISO noted that it may issue “Flex Alerts,” a voluntary call for consumers to reduce their power use, or a “Warning,” which is a more urgent call for conservation, and allows the ISO to tap into demand response capacity in the market.
The CAISO analysis expects electricity supplies to be adequate during the day when solar production is high. “However, conditions will become challenging in the evening hours as California’s large amount of solar energy turns off as the sun goes down while consumers begin using energy to cool their homes,” CAISO warned.
The assessment, which analyzes only system-wide conditions, does not take into account the ongoing limitations placed upon the Aliso Canyon Natural Gas Storage Facility in Southern California.
However, natural gas limitations due to storage facility and pipeline outages could add to the summer reliability concerns in Southern California, CAISO said.
Recent report on Aliso Canyon
A May 7 report prepared by the staff of the California Public Utilities Commission, the California Energy Commission, CAISO and the Los Angeles Department of Water and Power offers an assessment of electricity reliability in Southern California given the operating status of the Aliso Canyon gas storage facility.
The report was developed by the Aliso Canyon Technical Assessment Group, which is composed of technical experts and staff from the CPUC, CEC, CAISO and LADWP.
The Southern California Gas system continues to operate at less than full capacity due to a significant number of pipeline outages and continuing restrictions on use of the Aliso Canyon natural gas storage facility,” the report said.
“This reduction in capacity creates a moderate threat to electric reliability this summer. The more serious threat lies ahead. With so many pipeline outages, it will be difficult for SoCalGas to fill storage to a level sufficient to ensure energy reliability throughout the coming winter,” the report said.
It said that the challenges this summer stem primarily from continuing outages on four key natural gas pipelines.
Current available pipeline capacity of 2,655 million cubic feet per day (MMcfd) is significantly lower than the 3,185 MMcfd available last summer.
As a result, the total system capacity, which is a combination of pipeline capacity and non-Aliso Canyon storage capacity, is some 200 MMcfd lower than last year. “Under the assessment group’s assumptions, the hydraulic model results in total system capacity for this coming summer of 3,555 MMcfd under base case assumptions and 3,425 MMcfd under sensitivity assumptions, compared to 3,638 MMcfd in summer 2017,” the report said.
The base case assumes current operating conditions and the sensitivity case assumes additional pipeline outages and mitigations.
The assessment is the fifth in a series launched because of the 2015 Aliso Canyon gas leak. It addresses the electric reliability impact of the extensive pipeline outages and of operating Aliso Canyon at less than full capacity.
The 2018 CAISO Summer Loads and Resources Assessment is available here.