The Upper Hunter station, known as Bayswater B, would have a maximum generating capacity of 2000 megawatts and would be built near the Bayswater power station off the New England Highway.

Protester Stephen Jordan, of Maitland, said he believed Planning Minister Tony Kelly was close to making a decision.

"The decision could be made tomorrow, we have to show that we care about it," he said. ". . . it's bad for the people who live in the area.

"There will be a higher concentration of particulates in the air and an increase in [carbon dioxide] emissions as well if these stations go ahead."

Independent Lake Macquarie MP Greg Piper spoke to the crowd and called for greater use of gas and renewable energy.

"When we build coal-fired power stations in the Hunter Valley we are setting back the potential to build renewables," he said.

"We should be looking to gas. It creates 60 per cent less [carbon dioxide] when it's burnt."

Greens MLC John Kaye said the power station was being put forward on a "big lie" about the state's energy needs.

"We do not need more baseload power stations, we need better demand management," he said.

Upper Hunter resident Bev Smiles said the increased size of Bayswater power generating capacity would put greater strain on the area's irrigators.

A spokeswoman for Energy Minister John Robertson said the case for greater baseload capacity was well established.