Scotland’s largest petrochemical plant is unlikely to have a long-term future unless a local shale gas industry can be developed, according to the firm that owns the facility at Grangemouth.

Ineos proposes using shale gas as a raw material for its chemicals plants, and has revealed plans to put millions into exploration.

But developing the industry could be stalled or even prevented after the Scottish government announced a moratorium on granting planning consents for fracking – the means by which the gas is extracted.

Growing public concern about the environmental and health impact of the process has led to the moratorium.

Ineos has invested in an ethane supply project at Grangemouth that will allow the firm to import, store and use cheap shale gas from the US.

But the chief executive of the company’s upstream business, Gary Haywood, said the move was not a long-term solution.

Ineos has already acquired fracking exploration licences covering more than 700 sq miles of central Scotland.

Speaking at a conference in Edinburgh, Haywood said it was feasible to get a shale industry up and running in the UK within three to five years.

“If you look forward five years, it is possible we could be producing gas from that point onwards,” he said. “That would mean that we have some time to develop the resource and replace what we get from the US.

“Can we do that efficiently enough to make Grangemouth make sense in the future? That is a real challenge.”

Commenting on the future of the plant without a local shale gas supply, Haywood said: “I think it is going to be very difficult because when you are shipping in material of that nature you are always at a disadvantage … with ethane being available in the US at very low prices, because of the rapid increase in production and the lack of demand in the US.

In the end, if the public decides that it wants to be cold and green, fine

Gary Haywood, Ineos upstream chief

“That has meant we have been able to get that ethane at very, very cheap prices, relatively speaking. We can’t see that going on. Unless we can develop an indigenous source, it is unlikely that the cracker [at Grangemouth] has a long-term future.”

By comparison, Haywood said another Ineos plant in Houston, Texas, has benefited “substantially from the shale gas revolution” in the US.

“It is a big employer of people ... the economics and the local community has benefited greatly,” he said. Grangemouth is somewhat lacking in the sense that it has found a stop-gap solution to the problems that are facing it.”

Haywood said investment in the ethane supply project at the Scottish plant – which will start importing US ethane from next year – means it will have “competitive stock” for the next 10-15 years. “But at that point I have no doubt that US capacity will have caught up and it will not make economic sense to bring this stuff over,” he said.

Gordon Hughes, professor of energy economics at the University of Edinburgh, told the conference: “From the point of view of the Scottish government, we have done enormously well from offshore oil and gas, but that’s going away … The question is what replaces it.

“What we need to focus on is the choices that we have to make. In the end, if the public decides that it wants to be cold and green, fine. That’s the choice, having had a proper discussion, that it can reasonably make. On the other hand, let’s not wander into that simply by ill-formulated and ill-thought-through political posturing.”

Hughes said there was a fear of governments getting into a position where there was an “unwillingness to take any decision”. He also said it was doubtful that any new scientific information would be gathered from further reviews of fracking being undertaken now. “There is no obvious reason why things will be any different in two years’ time,” he told the conference organised by the Scotsman newspaper.