The greenhouse gas emissions from oil flowing through TransCanada Pipelines’ proposed Energy East project would be equivalent to putting seven million new cars a year on Canadian roads, according to a report from an environmental think-tank released today.

The Pembina Institute’s study looked at the potential upstream carbon pollution — that is, from the well to the refinery gate — from oil flowing through the pipeline and found that it could add anywhere from 30 to 32 million tonnes of CO2 a year to the atmosphere.

“For a single piece of infrastructure, that’s huge. It’s more than the emissions of five provinces,” explained Clare Demerse, Pembina’s federal policy director and co-author of the report.

“The single most effective climate policy today [in Canada] is Ontario’s decision to phase out coal [for generating electricity]. The emissions associated with building Energy East could effectively wipe out the gains of our single most effective climate policy by far,” she told CBC News.

Energy East is planned to take both conventional and oilsands oil from Alberta to the deep-water port in Saint John. The project would convert an existing natural gas pipeline that runs to the Ontario-Quebec border to carry oil, then build a new pipeline the rest of the way. When running at full capacity, Energy East would eventually carry 1.1-million barrels of crude a day.

TransCanada has yet to file an application with the National Energy Board, but it is expected to do so in the middle of this year.

Demerse admits that this is a preliminary report and that it is hard to comment accurately on Energy East because so little detail is known about the project. Still, she said, Pembina wanted to start the conversation about it as soon as possible.

TransCanada said it wants to take a closer look at the numbers before it comments on the report. The pipeline company has already held information sessions about the project in communities along the route.