Within minutes of Thursday's announcement that the Energy East pipeline was dead, politicians were scrambling to assign and deflect responsibility.

At the federal level, Prime Minister Justin Trudeau was blamed for new emissions criteria that would have been part of the regulatory review of the project.

And in New Brunswick, Premier Brian Gallant was blamed for not fighting those criteria — a decision Opposition leader Blaine Higgs said "started a death spiral" for the pipeline.

But more neutral observers say the project's demise has less to do with politics and policy than with the economic fundamentals of the free market.

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Trevor Tombe, an economist at the University of Calgary who studies energy, environment and trade, says the National Energy Board emissions criteria weren't wise, but they can't be blamed for killing Energy East. (Submitted by Trevor Tombe)

"The new NEB regulations are not advisable, but they're unlikely to be the dominant factor in TransCanada's decision to cancel Energy East," said University of Calgary economist Trevor Tombe.

Energy East would have shipped oil sands bitumen 4,500 kilometres from Alberta to Saint John. Most of it would have been loaded onto ships for export, and a smaller amount would have been refined at the Irving Oil refinery.

When the previous Progressive Conservative government got behind the project in 2013, a barrel of oil sold for almost twice the price it sells for now. The oil sands were booming.

But shipping that growing supply of oil was difficult via either the United States or Canada's Pacific Coast. Pipeline projects in both directions were stalled.

Four years later, there's less oil than forecast, and there are more pipelines on the way.

"We believe it is clear that TransCanada is not proceeding with its application for the Energy East pipeline because recent changes to world market conditions and the price of oil have negatively impacted the viability of the project," Premier Brian Gallant said.

Company blamed new rules

When TransCanada announced last month it was suspending its application for 30 days, it cited "the significant changes to the regulatory process" by the National Energy Board.

The board said in August it would take into account the emissions that would be caused by the pipeline both where oil was extracted in Alberta, and where it was burned by end consumers.

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New Brunswick Premier Brian Gallant complained earlier that the rules kept changing for the pipeline project. (Canadian Press)

That was a first. In the past, the NEB only looked at the emissions from the construction and operation of the pipeline itself.

Gallant said in September it was "unfortunate" that those rules had been added in the middle of the review process.

"This process has had lots of twists and turns, and that makes it tough for anybody to invest," he said.

It was an awkward criticism, given that the NEB first floated the idea of the new criteria back in May, and Gallant's government never exercised its right to file a submission arguing against the change.

"I can confirm that we did not provide any comments on the proposed criteria in May," said Environment Department spokesperson Sheila Lagace.

But there was another possible explanation for TransCanada's decision: Energy East wasn't urgently needed anymore.

Other pipelines approved

Oil production is still growing in Alberta, but since 2014, it's been growing much more slowly because of low prices. The projection for 2030 is for two million fewer barrels a day than what was expected when Energy East was announced.

At the same time, two pipelines once considered long shots — the Trans Mountain line to B.C. and Keystone XL to the United States — have been approved, along with the replacement of aging Enbridge's Line 3.

"These combined will be enough to facilitate that additional production, so Energy East might not have been needed, strictly speaking, until about 2030 or so," Tombe said.

"So part of today's decision likely reflects market conditions and the likelihood that those other pipelines are probably going to go ahead."

That was also Ottawa's argument. Accused by opponents of strangling Energy East with the new NEB rules, Natural Resources Minister Jim Carr said TransCanada based the cancellation on the same market conditions Tombe described.

"This is a business decision," Carr said Thursday. "Conditions have changed since TransCanada made its interest known in the Energy East project."

Carr said the Trudeau cabinet, which has the final say on pipeline approvals, would have treated Energy East like any other proposal. He pointed out the cabinet has already approved Trans Mountain and Line 3.

Gallant less direct

Gallant didn't directly criticize the new NEB rules Thursday as he did last month. Since the suspension, he lobbied Ottawa to pay for any emissions review, something Carr agreed to.

But that wasn't enough to change TransCanada's calculations. In its letter to the NEB on Thursday withdrawing its application, the company cited the new rules again but also mentioned "the increasingly challenging issues and obstacles" for the project — a phrase that could encompass a range of causes.

Tombe said circumstances could change again. TransCanada could revive the project years from now if growth in the oil sands takes off again and requires more pipelines.

Map of Energy East

TransCanada Corp.'s proposed pipeline would have carried 1.1 million barrels of oil a day from Alberta through Quebec to Saint John, where most of it would have been exported. (Canadian Press)

Tombe said he thought the new emissions criteria were a bad idea because Ottawa already plans to tackle emissions through a price on carbon that will reach $50 per tonne by 2022.

But that doesn't mean those criteria killed the project. He said the key factor was still the price of oil and the unexpected surplus of pipeline capacity once Trans Mountain and Keystone XL are built.

"To say that it's due to changes around how the NEB evaluates these projects in terms of their greenhouse gas emissions is somewhat of a stretch," he said.