Four emergency gas generators now online in California to serve summer peak capacity: state officials

Four aeroderivative natural gas turbine generators are now in operation in California following a July emergency proclamation to increase summer capacity, regulatory order for emergency generators and a tariff waiver to increase interconnection capacity.

The four units, totaling 120 MW and located next to existing power plants, were installed at two sites in Northern California following an emergency proclamation by Governor Gavin Newsom that directed the Department of Water Resources to work with the California Energy Commission to develop additional energy capacity to safeguard the state's grid from the impacts of climate-induced drought, wildfires and extreme heat waves. California faces an energy supply shortfall of up to 3,500 MW in 2021 and roughly 5,000 MW in 2022.

"DWR's expertise as the fourth largest power producer in California allowed us to work quickly with the CEC, the California Independent System Operator and our regional partners in Yuba City and Roseville to bring these units online," DWR Deputy Director for the State Water Project Ted Craddock said in a Sept. 29 statement. "DWR is proud to play a role in safeguarding the state's energy grid and doing everything possible to avoid power shortages and outages as a result of climate-induced conditions."

The periods of stress have been in early evening hours after solar generation ramps down yet power demand remains high, CAISO said in its 2021 Summer Loads and Resources Assessment released May 12. Low hydro conditions increase grid vulnerability, particularly in late summer.

Generator details

Two units each were installed at Greenleaf 1 in Yuba City, operated by Calpine Greenleaf Holdings, and Roseville Energy Park, operated by Roseville Electric. Each unit has 30 MW capacity. The units run on natural gas, but can run on a blend of up to 75% hydrogen.

"These temporary generators are an important last resort resource that can be relied on to support electricity reliability across California during grid emergencies," CEC Commissioner Siva Gunda said in the DWR statement. "The state's energy agencies are committed to ongoing monitoring of these facilities in coordination with DWR and local partners to ensure any impacts are accounted for."

The generators can be online within five minutes at the direction of the California Independent System Operator or the Western Area Power Authority, according to DWR.

The generators would be deployed under emergency conditions determined by CAISO under a contingency plan developed in coordination with the CEC and the California Public Utilities Commission, according to DWR. The plan includes a range of measures to address potential energy supply shortfalls, including Flex Alerts, coordination with adjacent balancing authorities, demand reduction strategies, and bringing online new resources such as the temporary generators.

The project cost for the four temporary emergency generator units is $196 million, which will be paid for through emergency funds, according to DWR. The units will be available until Dec. 31, 2023.

Regulatory action

The CEC approved two orders in mid-August focused on new emergency and temporary generators, and on changes in design, operations or performance of existing facilities. Both were in response to Newsom's July 20 emergency proclamation declaring a state of emergency due to extreme drought, wildfires and record-breaking heat events.

The proclamation directs DWR and the CEC to enter into contracts to arrange for the procurement of materials, goods and services necessary for projects likely to be online by Oct. 31, that would expand energy supply and storage to respond to energy-supply shortages caused by climate change.

CAISO asked the Federal Energy Regulatory Commission for a waiver to its tariff in order to interconnect two of the generators, which FERC approved in mid-September. The waiver was needed, because under the tariff the ISO can accommodate 50 MW of the 60 MW at Yuba City but needed a waiver for the additional 10 MW. The Roseville units will interconnect under the Balancing Authority of Northern California.

2020 outages

Extreme heat waves in 2020 strained electric operations in California, led to the first rotating outages since 2001 and drove wholesale power prices to all-time record highs.

A final root cause analysis of the 2020 outages was released in January 2021.

The commission, along with CAISO and the CPUC, took actions to provide greater grid reliability for summer 2021, including emergency procurements and increased coordination among balancing authorities in the state.