A power plant in Montreal's Saint-Michel neighbourhood is back in action turning gas from garbage into clean energy.

The Biomont Energy consortium has revamped the former Gazmont biogas facility on des Regrattiers Street, which closed in 2014.

It's hoping to convert methane emissions from the adjacent former Saint-Michel landfill into power and profit.

This biogas plant in Montreal turns methane into electricity and helps heat buildings across the street. 0:42 "Mother Nature is basically decomposing [that] garbage," said Marc-Antoine Renaud, vice-president of Eolectric, one of the companies in the consortium.

The smelly gas is captured and transformed, allowing the facility to run on the fumes again, as it did years ago.

Built in 1994, the plant closed three years ago as the amount of methane dropped off.

The consortium says a better business plan is now in place, which partly relies on selling the heat from the burning process to its neighbour: the TOHU circus complex.

Marc-Antoine Renaud, director of Biomont Energy, says clean energy will be used to heat water and send it to the nearby TOHU circus complex. (CBC) "The district heating here basically will heat water and will send it to the TOHU…so they don't need to use any natural gas anymore."

Hydro-Québec has also agreed to buy the electricity at an above-market rate as part of its clean energy strategy.

But the wild card in the business model remains the rate of the rotting garbage.

"There's only one thing we're 100 per cent sure of: there will be biogas. How much? That fluctuates," Renaud said, adding that as the methane keeps flowing, Biomont keep can keep converting garbage into green energy.