Princeton, NJ-based independent power supplier NRG Energy Inc. said Monday it will close three natural gas-fired generation plants in Southern California, underscoring the region’s abundant supply of generation and desire to de-emphasize fossil fuel-fired power plants, particularly older ones.

Included are coastal plants in Santa Barbara and Ventura counties and an inland plant 40 miles east of Los Angeles in Rancho Cucamonga, all of which are to be shut down later this year or in early 2019. NRG subsidiary GenOn, which filed for Chapter 11, owns the plants. GenOn expects to emerge from bankruptcy as an independent company.

“The decision to retire these units was made due to economic reasons,” said NRG spokesman David Knox. Collectively, the plants, which were built in the 1960s and 1970s, represent 2,236 MW of generating capacity.

The closures are also the result of policy decisions to ban the use of seawater for plant cooling, as well as an aggressive push to mitigate climate change through reducing the state’s carbon footprint. The latter has made natural gas-fired power generation less attractive to state policymakers.

NRG’s Ormond Beach plant (1,516 MW) already had been scheduled for replacement, along with another Ventura County property at Mandalay Bay (560 MW). That changed last fall when NRG filed a motion with the California Energy Commission (CEC) to suspend its $300 million project application to replace two of three gas-fired generation units at Mandalay Bay. Ormond Beach is now scheduled to close on Oct. 1, with Mandalay Bay to follow by the end of this year.

Under the state water regulatory board’s 2010statewide ban on seawater cooling, both of the coastal plants were slated to end seawater cooling by the end of 2020. The Ellwood Generating Station (54 MW) in Goleta in Santa Barbara County is scheduled to shut down on Jan. 1. The Etiwanda plant (640 MW) east of Los Angeles is scheduled to close on June 1.

Opponents of the replacement plans cited cleaner and technically feasible alternatives to the gas-fired plants, leading to CEC officials to recommend the proposed project for rejection and NRG subsequently to suspend its filing to the commission. Monday’s announcement by NRG prompted the environmental group Food & Water Watch to call for more gas plant closures.

NRG would continue to have a significant footprint of gas-fired generation in California as it still operates nine other plants totaling more than 3,800 MW. The 869 MW Encina facility in Carlsbad north San Diego County is in the midst of replacing the baseload facility with a series of five 100-MW peaking units on part of the 100-acre site.

“The Carlsbad Energy Center is under construction and expected to be online by the end of the year,” Knox said. “It is also important to note that the assets set to close are all GenOn plants and have already been separated from the NRG fleet.”