California regulators recently gave the green light to two repowerings at coastal natural gas-fired generation plants that represent a combined 1,884 MW of mostly baseload generating capacity.

The five-member California Energy Commission (CEC) last Wednesday approved AES Southland Development LLC’s plans for a proposed new 844 MW gas-fired project at the existing Huntington Beach site, similar to the favorable recommendation for a 1,044 MW gas-fired replacement it has in the works at its Long Beach plant site.

In Long Beach, AES is now authorized to build the Alamitos Energy Center on part of the existing site and eventually replace the 1950s-era, gas-fired and sea water-cooled existing generation complex. For Huntington Beach, the CEC approved a petition to amend an earlier approval related to the gas-fired coastal site that is also water-cooled.

Huntington Beach originally was approved by the CEC as a 930 MW project in 2014. The amended version of that approval will allow for the 844 MW version on a portion of the existing site. In September 2015, the AES unit petitioned to amend the project, lowering its capacity and modifying its operating equipment and design to meet the requirements of a power purchase agreement with Southern California Edison Co. (SCE).

Both projects are expected to have no environmental impacts with the required mitigation measures.

As recommended, the Huntington Beach project will have two generation blocks — a 644 MW combined cycle combustion turbine, and another with twin 100-MW each simple-cycle combustion turbine generators. The former would be operational in 2020, and the two peaking turbines four years later in 2024.

Since state Water Resource Board requirements call for the phasing out of once-through cooling plants, the new facilities will be air-cooled and built within the footprint of the existing power generation facilities.

Water cooling was the technology applied to the coastal plants built 40 to 60 years ago, and up to 17 gas-fired plants along California’s coast have remained the main focus of the state’s water cooling restrictions adopted seven years ago by the state water board in close collaboration with the state’s major energy agencies.

Originally, the arcane and not-fully-developed rules were approved by the water board after five years of analysis, a full day of testimony from staff and stakeholders, and the clarification of 17 last-minute amendments.

More recently, the climate change initiative and other factors have combined to push California regulatory and elected leaders away from natural gas as the debate surrounding methane emissions has intensified in the state since the late 2015 storage well leak at Aliso Canyon drew national attention.