Much vaunted plans to set fire to coal under the sea around Scotland look set to be dealt a blow by an independent review for the Scottish Government, the Sunday Herald has learned.

The review’s author, Professor Campbell Gemmell, has indicated that he shares concerns about climate pollution and the safety standards associated with underground coal gasification (UCG) abroad. This has raised the hopes of environmentalists that he will come down against the controversial technology.

UCG has been proposed in three areas of the Firth of Forth by the multi-millionaire oil and mining tycoon, Algy Cluff. It would involve drilling boreholes up to a kilometre deep, burning coal seams under the seabed, and extracting the resulting gas to heat homes.

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After pressure from campaigners and local communities, the Scottish Government imposed a moratorium on UCG in October 2015. This was in addition to its moratorium on the related but different technology of fracking for shale gas under the land.

Ministers appointed Gemmell, the former chief executive of the Scottish Environment Protection Agency (Sepa) and an environmental research professor at the University of Glasgow, to examine UCG. He is now writing up his report, and is due to deliver it in September.

He researched UCG projects worldwide and looked at the resource in Scotland, he said. He also talked to companies, geologists, climate specialists, regulators, economists, environmental groups, academics and local communities.

He saw a draft of a major report exposing problems with UCG by Friends of the Earth International, which is due to be published tomorrow. “This is one of a large number of useful inputs I’ve received,” he said.

“Together these sources have highlighted the issues the UCG industry faces and the challenges of exploiting the resource. I am considering these challenges in detail.”

Friends of the Earth has concluded from experience in other countries that “industry has thus far struggled to perform to the standards we might reasonably expect,” Gemmell stated. “They have also assessed that, at a time when we are developing a low carbon economy and seeking to maintain Scotland’s strong commitment to tackling climate change through ambitious climate targets, this would be a demanding additional challenge.”

When pressed, he said: “I’d have to say that, on available evidence, these assessments are hard to disagree with.”

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The evidence on safety standards was specific to problems encountered in Queensland, Australia, Gemmell added. There, the state government has accused a UCG company of contaminating 300 square kilometres of farmland with toxic chemical and explosive gases.

Friends of the Earth Scotland has welcomed Gemmell’s remarks. “We hope this is a clear sign that his independent review will come to the conclusion that underground coal gasification should not be permitted to go ahead”, said the group’s head of campaigns, Mary Church.

“UCG trials around the world have led to serious soil and water contamination, subsidence and industrial accidents putting workers health at risk. In the highly unlikely event that UCG could ever be done safely, the climate change consequences of opening up vast coal reserves are enough of a reason to say no to this unnecessary fossil fuel.”

According to Juliana Muir, from the anti-UCG group, Our Forth, the technology’s benefits were “fictitious” and its risks great. Communities would be “relieved but not surprised” if Gemmell came to similar conclusions, she said.

Cluff Natural Resources has licences from the UK Coal Authority to investigate UCG at three large sites in the Firth of Forth. But it says that progress in Scotland “has been delayed due to local politics” and is currently focussing on sites off the northeast of England.

Another company, Five Quarter, has three UCG licences in Scotland, two in the Firth of Forth and one in the Solway Firth. It announced in March that it has ceased trading, but there are fears it could assign its licences to others.

Andrew Nunn, the chief operating officer of Cluff Natural Resources, accepted that a number of foreign UCG projects had failed to meet acceptable standards. “However the fact remains that a number of modern UCG projects have demonstrated that with appropriate site selection, engineering and operational oversight, the technology is capable of delivering a credible alternative to imported natural gas with an overall environmental footprint not dissimilar to many other commonly accepted industrial processes,” he said.

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“There is still an opportunity for Scotland to draw on its world class engineering experience and become a global leader in UCG technology creating a sustainable basis for Scottish industry and generating wealth and jobs both in Scotland and further afield.”

The Scottish Government confirmed that the review of UCG was expected to report later in 2016. “Professor Campbell Gemmell has been asked to lead an independent and evidenced examination of the issues and evidence surrounding underground coal gasification, drawing on published sources of information, expert input and community views to help the Scottish Government formulate future policies or actions,” said a government spokeswoman.