An agreement between Hydro-Quebec and Energir could end up costing Quebecers a lot of money -- at least $7.2 billion by 2050, according to environmental groups who analyzed documents filed with the Régie de l'énergie.

The agreement aims to reduce greenhouse gas (GHG) emissions by converting gas-fired heating systems to dual fuel, but Hydro-Quebec will first have to compensate Energir for lost revenue and plans to pass the bill on to its customers.

This will amount to a bill of $2.4 billion, but consumers will have an even larger amount to pay, according to calculations by analyst Jean-Pierre Finet with the Regroupement des organismes environnementaux en énergie.

Starting in 2026, once Hydro-Quebec's surplus energy has been used up, the Crown corporation plans to build new production facilities to generate more expensive energy.

Over 30 years -- the total time required to install and depreciate dual-energy equipment -- Hydro-Quebec could lose $4.8 billion in revenue, according to Finet's projections.

Hydro-Quebec may then have to raise its rates to make up for a total shortfall of $7.2 billion, according to the group.

The public utility company has already estimated that the deal could result in a 1.4 per cent increase by 2030.

The organizations opposing this agreement are the Regroupement vigilance hydrocarbures Québec, Greenpeace Canada, Nature Québec, Fondation Coule pas chez nous, Équiterre and Sortons la Caisse du carbone.

The Quebec government has repeatedly stated that this agreement is advantageous as it would reduce Quebec's GHG emissions by 540,000 tonnes by 2030.

-- This report by The Canadian Press was first published in French on May 12, 2022.