TORONTO - Ontario's pledge to shut down sections of two coal-fired generating stations next year was hailed Thursday by environmental groups who called on the government to go even further and shutter all coal-burning plants by the 2011 election.

Coal has proven a politically risky topic for the Liberal government, which has pushed back a campaign pledge to phase-out coal by 2007 more than once.

The new date is 2014.

Trying to put the best spin possible on the announcement that Ontario Power Generation will close another four coal-burning units inside two plants by October 2010, Energy Minister George Smitherman said the shutdowns would come "four years ahead of schedule."

The province has added more alternate sources of electricity that has allowed OPG to speed up the scheduled closure of two of eight coal units at its Nanticoke station, near Simcoe, and two of four units at its Lambton plant, near Sarnia, said Smitherman.

"The fact is that we have brought new production on-line, including new, modern, gas-fired units, 1,200 megawatts of renewable energy and a refurbishment of nuclear units," he said.

"As we continue to bring more production on-line, we certainly have opportunities to take coal-fired generating units out of play."

Environmental groups welcomed the government's promise to close the four coal units next year, but called on the Liberals to push up the 2014 target date for eliminating all coal generation.

"This is an important next step on the road to a coal-free Ontario," said Jack Gibbons of the Clean Air Alliance.

"Hopefully George Smitherman will phase out all of our dirty, coal-fired power plants before the October 2011 provincial election."

The New Democrats said closing the four units next year is a "small part" of what can and must be done.

"It's way overdue. This government could have been moving much faster," said NDP environment critic Peter Tabuns.

"They could have shut down these coal plants by 2011 if they'd been sufficiently aggressive about energy efficiency and renewables."

The four coal-burning units to close next year represent about 2,000 megawatts of generation capacity, and will reduce Ontario's coal use by about 30 per cent.

OPG will look for ways to convert its 11 remaining coal-fired units to other types of fuel such as biomass.

The Atikokan Generating Station about 200 kilometres west of Thunder Bay will be OPG's initial focus for the change to biomass, with a target year of 2012.

The utility also closed Toronto's Lakeview Generating Station in 2005.

Reducing the use of coal to generate electricity will save lives by reducing air pollution and make more room for green, renewable forms of energy on the grid, Smitherman said.

"Ontario is on the edge of creating one of the greenest and cleanest electricity profiles anywhere in the world," he said.

Coal production was down 51 per cent and wind generation was up 80 per cent in the first six months of 2009 compared with the same period last year, the government said.

However, the NDP complained Ontario could have reduced its use of coal even further this year.

"Ontario has been burning coal and exporting power to the United States, and we get to breathe the smog," said Tabuns.