By Robert Mullin

New generation and a rebound in hydroelectric capacity mean healthy operating reserve margins for California this summer but impending restrictions on the Southern California gas pipeline system could result in load sheds, CAISO warned in its 2016 Summer Loads and Resources Assessment last week.

As a result of the pipeline restrictions — stemming from the closure of the Aliso Canyon gas storage facility — the situation confronting the state this summer is far from normal. (See CAISO Seeks Rapid Response to SoCal Gas Restrictions.)

“We’re immediately faced with running the system in a way that it’s never been run before,” Rob Oglesby, executive director of the California Energy Commission, said at the California Energy Summit in Santa Monica earlier this month.

The ISO’s annual summer reliability report, which outlines its preparedness for California’s peak consumption season, describes a largely favorable situation.

Load in the CAISO balancing area is forecast to peak at 47,529 MW, up just 0.8% from last summer’s peak, due to modest economic growth. At the same time, the ISO has brought on 1,951 MW of net qualifying capacity — or deliverable generating output — over the past year, outpacing the projected growth in peak load.

Operating reserve margins are forecast to remain “well above” the threshold for firm load shedding under the most extreme scenarios. That analysis applied systemwide, as well as generally in the ISO’s NP26 (North) and SP26 (South) regions, although it does not break out reserves for specific load zones. The ISO also sees no shortage in flexible capacity and meet spikes in demand.

Hydroelectric conditions have improved significantly compared with the dire drought conditions seen last spring throughout California and up into the Northwest. Statewide snow water content was at 87% of the historical average as of March 30. While snowmelt is advancing more rapidly than normal, CAISO says the situation is “not significant enough” to require a revision of its hydro assumption in the summer assessment. In addition, water levels behind The Dalles Dam — a benchmark for the federal Columbia River system of hydroelectric plants — stand at 101% of average.

“There are no concerns with Pacific Northwest hydroelectric generation,” CAISO said, indicating the winter-peaking region should be able to provide California with significant generation during the summer.

CAISO’s summer concerns instead focus on Aliso Canyon’s impact on the gas system serving 9,500 MW of gas-fired generation located in CAISO’s southern region and the balancing area of the Los Angeles Department of Water and Power, the state’s largest municipal utility.

The ISO notes that its assumed summer reserve margins do not account for the risk of gas curtailments, which could translate into the depletion of reserves in SP26, an area largely served by Southern California Edison and San Diego Gas and Electric.

Even more significant: Curtailments could be large enough to interrupt electricity service to millions of Southern California customers on as many as 14 days during the summer. The ISO attributes that risk to potential mismatches between gas schedules and gas burn, outages on pipelines and at other gas storage facilities, and prolonged heat waves that could drive increased power demand.

“The natural gas issues facing Southern California this summer will require deft management, particularly during hot days when power plants fueled by natural gas are needed to meet peak demand,” ISO CEO Steve Berberich said in a statement.

CAISO’s Board of Governors earlier this month approved a plan to mitigate the effect of gas curtailments through improved gas-electric coordination with pipeline operator Southern California Gas, new market measures incorporating a gas usage constraint and a provision for reserving transmission capacity into Southern California ahead of potential gas emergencies. (See CAISO Board Approves Aliso Canyon Market Response.)

Officials from CAISO, the Energy Commission, Southern California Edison, LADWP and Peak Reliability presented their summer outlooks to FERC at last week’s monthly commission meeting. CAISO has asked FERC to approve the gas contingency plan by June 1, the start of summer electricity operations in California.