It would cost at least £3 billion to move Medway’s gas terminal if plans for an international airport here went ahead.

That’s according to Rochester and Strood MP Mark Reckless, who has raised the figure with bosses at the plant.

He claims he was told it would cost a huge sum to move the National Grid’s £1bn gas import terminal on the Isle of Grain, pictured above, which is the largest in Britain.

Mr Reckless, left, spoke on Thursday after chiefs unveiled a new pipe to use waste heat from E.ON’s next-door power station at Grain LNG.

He said: “The National Grid was there and the manager of the LNG import terminal said it would cost at least £3 billion to move.

“He would like to know how Boris [Johnson] would pay for that, but we’ve had no answers.

“Then you would have to find another site for it that was suitable and which people didn’t object to.”

The Isle of Grain, the home of huge industry projects since the 1960s, is the target for a four-runway airport hub proposed by the architect Lord Foster (pictured below).

The government is examining the plan, which Medway’s political parties all oppose, as one of many to increase air capacity in the South East.

A final decision is only expected after the 2015 election.

National Grid refused to confirm the £3bn figure, saying it will give full evidence to the government.

A spokesman told the Messenger: “When the final airport plans are known, a full assessment of any impact on Grain LNG can be made.

“If a relocation of the importation terminal was required as part of this, a full assessment would need to be carried out to estimate the cost.”

The spokesman added: “National Grid will respond to the government’s call for evidence on the matter when it is published later this year, and we’ll do all we can to make sure the crucial role that our infrastructure plays in supplying Great Britain’s energy needs is taken into consideration.”

Energy Secretary Ed Davey unveiled the pipeline on Thursday to an audience of experts.

The pipe links the gas terminal Grain LNG, run by the National Grid, to the nearby combined heat and power station run by E.ON.

Chiefs realised the power station was producing huge amounts of waste heat – while the gas terminal needed heat to warm up its liquefied supplies.

So the double pipeline now takes hot water from E.ON to National Grid then back again, saving both firms money and reducing emissions.

Five million litres of water – equal to 26,000 baths – can loop the 2.8-mile system in 12 minutes where it cools from 42 to 15 degrees.

Mr Davey told an audience at the site: “The co-operation between National Grid and E.ON is an excellent example of how one’s waste can benefit another and makes this gas-fired power station one of the most efficient in the world.

“The gas saved is equivalent to the amount used by 100,000 houses per year and the reduction in carbon emissions equates to taking 60,000 cars off the road.

“It shows by constantly looking for efficiencies in everything we do, we can make a big and lasting difference.”

Steve Holliday, chief executive of National Grid, said: “It’s a ‘win win’ for us as companies, and for the environment.”