Plans by the Commonwealth to build a gas-fired power station in NSW in addition to one to be built by EnergyAustralia could accelerate the demise of coal and may not cut prices immediately as the government hopes, Energy Security Board chief Kerry Schott says.

Dr Schott was one of several experts and industry figures who questioned the need for a second, new government-funded plant in NSW after EnergyAustralia confirmed it would proceed with its proposed 316 megawatt, $300 million Tallawarra B project in the Illawarra region.