Police rescuers cut the chains from 12 protesters to free them from the conveyor belt. A police spokeswoman said 27 people would face a range of trespass charges.

"Renewable energy is the future and it's bright," protester and retired coal miner Graham Brown said in a Greenpeace statement.

The state-owned Eraring Power Station, which has a generating capacity of 2,640 megawatts, said it reduced output as a safety measure during the protest, but did not shut down, and resumed normal output by late morning.

The protest came a day before the Australian government's key adviser on climate change, prominent economist Ross Garnaut, releases a report on carbon trading, which is due to start in Australia in 2010.

His report is expected to recommend a cap-and-trade scheme, to cover as much of Australia's economy as possible, which experts say will make it one of the world's most comprehensive trading regimes.

But another prominent economist and central bank board member Warwick McKibbin on Thursday warned the government to avoid firm targets and timetables for cutting greenhouse gas emissions.

McKibbin said unforeseen events, such as the rise in oil prices or increased demand from Asia for beef and dairy products, could make it impossible for countries to meet their targets and would then undermine global efforts to cut emissions.

Instead, McKibbin, from the Australian National University, and Peter Wilcoxen from Syracuse University in the United States, propose a hybrid system of a fixed supply of long-term carbon permits, and an flexible supply of annual permits.

"A hybrid policy with a modest annual permit price would generate larger investment incentives than a more draconian, but less credible emissions target imposed by a system of targets and timetables," McKibbin said in a speech on Thursday.

Australia is responsible for about 1.5 percent of global carbon emissions, but is one of the highest per-capita polluters because of the nation's position as the world's biggest coal exporter and its heavy reliance on fossil fuels for energy.

Australia emits 28.1 tonnes of carbon per person, due to reliance on coal for electricity, down from 32.6 tonnes in 1990. (Editing by David Fogarty)