EnergyAustralia has further delayed its go-ahead date for a $400 million gas power station in NSW into next year, in a blow to the push to get fast-start generation into the market to smooth out wind and solar power and help replace the Liddell coal plant.

The utility, one of the "big 3" integrated generator-retailers, had been hoping to give the green light for construction of the Tallawarra B plant in the Shoalhaven region late this year after already delaying the go-ahead from late 2018-early 2019.