THE owners of Grangemouth petrochemicals refinery are in talks with the Scottish and Westminster governments over a £150 million plan to pioneer importing US shale gas into the site to safeguard 100 jobs and a £1 billion revenue stream.

Ineos, which owns the chemicals part of Grangemouth, has been lobbying Government ministers to provide guarantees that would underwrite a scheme to build storage facilities for liquified gas and modify the dockside at the site.

If it goes ahead, it is likely to be the first time that shale oil or gas has been used in the UK – heralding what could be the beginning of European gas prices falling in the same way as American prices have dropped in recent years.

However, it will also concern environmentalists, who have repeatedly raised concerns about the effect on drinking water of the fracking techniques that are used to obtain the fuels.

The move would enable three gas tankers that are currently being constructed for Ineos in South Korea to supply ethane gas feedstocks for a vital chemical processing plant at Grangemouth that makes ethylene, one of the key components for plastics.

Traditionally, Grangemouth has obtained the feedstocks from its North Sea pipelines, but the steady decline of gas production in UK waters is reaching the point that it will not provide enough to keep the refinery's so-called KG cracker plant economically viable.

One well-placed source said that closing the plant, which employs around 100 people, would be a "disaster" for Grangemouth, since it produces revenues – thought to be in the region of £1 billion – and also supplies petroleum by-products that are used in other chemical processes on the site and at other Ineos sites, including Hull and Runcorn.

It would also hamper Ineos's plan to close its other ageing Grangemouth ethylene plant, known as G4, in the next two years and ramp up KG to about twice its current capacity. Together, the two plants supply nearly 40% of the ethylene in the UK.

The shale gas move would bolster more advanced plans by the company to import the fuel from West Virginia into its Rafnes plant in Norway by 2015. West Virginia's Marcellus deposits are potentially the second-largest gas field in the world, and importing to Grangemouth at the same time could greatly reduce the cost of the overall operation.

Tom Crotty, chairman of Ineos ChlorVinyls, said that building facilities at Grangemouth would be more expensive than Rafnes, because the latter site already imports ethane and only needed to have its capacity increased.

He said: "At this point we are looking at whether the same potential would exist at Grangemouth. The driver is that over the years, the amount of ethane availability to the site has been declining and the North Sea gas mix has changed.

"We have already spent [£70 million] on the KG cracker to allow it to use heavier gases, but ethane from the US could allow us to run the plant much more efficiently and give it a great future."

Crotty described the discussions with the UK and Scottish governments as "ongoing and good and too early to say how they will conclude".

He added: "We see it as an important piece of infrastructure for Scotland. No facility can survive unless it's competitive. Grangemouth has to have competitive feedstocks. Without that, let's be clear: there isn't a future."

He declined to put a timescale on the discussions, which were understood to have been due to complete by March but are now expected to continue until later this year.

Neither would Crotty comment on speculation that Ineos is also in talks with BP and the other production companies that supply ethane to Grangemouth from the North Sea.

Another source told the Sunday Herald that Ineos is renegotiating its feedstock supply contract with BP for the first time since it bought the plant from the latter company as part of a bigger $9bn deal in 2006.

In view of the high gas price, the North Sea suppliers are likely to be putting pressure on Ineos to accept a feedstock price that is considerably higher than the existing one. Turning to shale gas is understood to have the potential to roughly double the profit margins on ethylene at the site, albeit that some commentators believe that the US boom will be temporary and will be undermined by lower-than-expected field recovery rates.

Ineos, which sold half of its oil refineries business to Petrochina several years ago, has also expressed an interest in investing in UK shale gas businesses with a view to securing new sources of ethane closer to home.

Scottish Gas owner Centrica, which itself has invested in UK shale gas, announced earlier this year that it also plans to begin importing shale gas from the US. It will not do so until 2018, however.