Groundhog day for a keystone cop-out?

Sections of the pipeline prepared but not yet used for Keystone XL

According to Donald Trump, the Keystone XL will be an "incredible pipeline", but could it be that the official signing of the permit in the Oval Office will be the high point for this long-winded process?

Let's look at some of the issues that might see TransCanada, the company behind the project, eventually walk away.

First, making oil from the bitumen-rich Canadian tar sands is a messy and expensive business.

Separating the liquid from the sand requires huge amounts of water and heat, and environmentalists say the process causes about 17% more greenhouse gas emissions than standard oil extraction.

However, both Democrats and Republicans have over recent years supported, however reluctantly, this massive project, which would send more than 800,000 barrels of the tarry oil from Alberta, Canada, to the US Gulf Coast every day.

Back in 2010, then Secretary of State Hillary Clinton said that the Obama administration was "inclined" towards approval, based on an assessment of environmental and economic impacts.

The State department, which carried out the review, believed that there would be at least some jobs created in the short term, and the environmental and safety impacts of diverting that much oil from railroad cars were beneficial.

Environmentalists, though, were aghast at the thought of the overall effect on climate change from endorsing the tar sands source.

But for several years, much to the despair of the green movement, Obama remained conflicted over the project, torn between opting for dirty but secure Canadian oil over cleaner but vulnerable middle-eastern sources.

Problem solved

In November 2015, global warming gave him a way out of the dilemma.

Just a month before the key Paris climate meeting, John Kerry wrote that "moving forward with this project would significantly undermine our ability to continue leading the world in combating climate change". Obama scrapped XL, and it helped persuade the world to sign the Paris Climate Agreement.

President Trump signing the permit to allow the Keystone XL pipeline to go ahead

But the new administration has made clear that jobs and infrastructure top climate change as priorities.

In January, President Trump asked the State department to re-assess the project. It has now found that the economic case makes sense and the pipeline "serves the national interest".

Mr Trump, struggling with healthcare reform, is very keen for a "win" on infrastructure and jobs, and the pipeline fits the bill.

But his rush to approve may actually end up delaying it significantly.

"Trump required the State department to make a decision within 60 days. That didn't allow them to do another environmental review of the project and meet that deadline, as US environmental law requires," said Anthony Swift from the National Resources Defense Council, who are looking to challenge the decision in the courts

"Allowing a decision to be made that flaunts the minimum requirements of our country's environmental laws would set an alarming precedent," he told BBC News.

There are many other complications, most of them centred around the state of Nebraska.

TransCanada has not had a route through the state approved, and that application process will take at least 8-12 months. Many landowners are reluctant to sell to the company and there are ongoing worries about polluting water sources.

"We're living in what feels to be the worst version of Groundhog Day imaginable, as every morning we're waking up to yet another decision made by Trump that would be disastrous for our climate, our communities, and our health," said Michael Brune, from the Sierra Club.

"But Trump will not succeed. The pipeline will pollute our air and water, destroy farmers' and ranchers' property, and enrich the foreign oil barons and corporate polluters that have been stocking Trump's cabinet and pulling his strings from the get-go."

Previous attempts to move forward with Keystone have drawn protests on the streets

The low price of oil makes XL (which stands for export limited and not extra large!) extremely expensive right now and the prospects of getting a good return on that investment is very distant.

As oil companies like Shell look to get rid of their tar sands holdings, a more pressing problem for the pipeline may be getting any oil to put in it.

"The chances of it opening in the next couple of years would appear to be pretty low," said Anthony Swift.

"TransCanada also has to find enough tar sands companies to back the pipeline, to make it economically feasible and in the current market it is hard to see which companies will be willing to commit to that kind of new production for 20-30 years."

And even if Keystone XL is built, it may not fulfil a key Trump requirement - to be constructed with "American steel". It seems that the TransCanada Corp has already ordered sufficient Canadian and Mexican supplies. Oops!

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