Regulators have put a big question mark over the province's strategy to tap run-of-river hydroelectric and wind power projects to meet growing electricity demand while cutting greenhouse gas emissions.

A complex 236-page ruling by the B.C. Utilities Commission found B.C. Hydro overestimated future demand and rejected the basis for its call for independent power projects under its Clean Power initiative.

The decision instead directs ongoing use of the gas-fired Burrard generating plant, which Hydro had sought to phase out.

Backers of green power projects are calling the ruling a mistake that will mean more air pollution in the Lower Mainland.

"Burrard Thermal is an old-fashioned colossus that needs to be shut down," said Guy Dauncey, president of the B.C. Sustainable Energy Association.

"Ramping up Burrard Thermal and closing down clean energy is exactly the opposite direction to where the government is moving in terms of reducing greenhouse gas reductions."

The decision puts in question future purchases of higher-priced green energy from firms such as Plutonic Power that are proponents of new wind farms and run-of-river projects.

"It flies in the face of B.C.'s Climate Action Plan and could result in clean energy investment and jobs leaving the province," warned green power advocate Tzeporah Berman.

She urged the province to intervene, calling it "absurd" that B.C. be forced to continue its reliance on fossil fuels when global warming poses "the greatest threat humanity has ever faced" and green alternatives are available.

Berman said the ruling also fails to endorse BC Hydro preparations to accommodate rising demand from electric vehicles.

B.C. has pledged to cut greenhouse gas emissions by a third by 2020.

The green energy policy was controversial during the spring election, with some environmentalists backing the strategy to fight climate change while opponents branded it a giveaway of B.C.'s public rivers to private power firms.

Groups opposed to run-of-river power welcomed the ruling, saying it puts pressure on BC Hydro to work harder on energy conservation.

BC Hydro spokesperson Susan Danard said the ruling will be studied closely, but predicted a revised plan will be submitted.

"We certainly believe renewable power producers remain an important part of our plans," she said.

The commission directed Hydro to set potential use of Burrard Thermal at 5,000 gigawatt-hours per year – up from the 3,000 gigawatt-hours the utility proposed.

That provision is far more than the 300 hours of use at the Port Moody generating complex in 2008, but Danard said it doesn't mean a dramatic increase is coming.

Burrard Thermal is run primarily when the grid is at peak capacity, such as in the winter, she said, adding the plant is needed mainly as an emergency backup to supply power to the Lower Mainland in the event power lines from Interior dams were knocked out.