A SCOTS-BORN businessman operating from California says his company has the technology to remove redundant oil installations in the North Sea without leaving their legs – higher than the Eiffel Tower – and other remnants on the seabed.

Stewart Lang, who was born in Glasgow and co-founded Seaways Engineering International, said he disagreed with Shell’s plans to leave 300,000-tonne steel and concrete jackets behind when they decommission four platforms in the Brent field.

Lang told The National: “Our vessel, which we call Nessie, is a simple floating dry dock with a modification that allows us to surround and lift structures rather than lift them from over the top, a very dangerous and limiting option.”

He was speaking after we reported how two of Scotland’s leading oil experts – professors Alex Russell, chair of the Oil Industry Finance Association, and Peter Strachan, of Robert Gordon University – attacked Shell’s proposals, saying the structures will take hundreds of years to disintegrate, and would leave a “potentially hazardous” legacy for future generations.

Russell told The National: “Seaway Engineering and Stewart Lang’s ideas sound like manna from heaven and must be taken into account as a benchmark for approval by the UK Government when decommissioning plans are presented for their approval. They provide prima facie evidence that the technology already exists for removing safely and economically all the concrete and steel gravity-based structures that pin many oil platforms to the North Sea floor.

“This resonates perfectly with the claims of Oil and Gas UK and the Oil and Gas Authority of remarkable advances in the use of technology by the industry.

“There is huge potential for gains across the Scottish economy by deploying such technology for decommissioning and that is on top of the prize of having a debris-free North Sea for future generations to enjoy”

Nessie is a Novel Extended Semi-Submersible for Installation and Decommissioning, and Lang said it could be built and operated in Scotland.

“It could provide good jobs, for thousands of people, for decades to come,” he said.

“It does require an investment, but there is $100 billion (£75bn) up for grabs in the UK sector alone, just in decommissioning. There will be new industry spawned around a vessel like this and expertise will radiate from Scotland to the other decommissioning markets.

“There are thousands of rigs waiting to be decommissioned – thousands of rigs, years of well-paid work.”

Lang said Seaways’ approach differed from others, in that they would build a bigger version of their “patented and affordable” multi-purpose semi-submersible (MPSS). It would be similar to a floating dry dock, but with a twist.

“We delete the deck, giving us the ability to surround an object below us and lift from above. Simply the only way to do it.

“Outfitting Nessie with off-the-shelf gear will also reduce costs and shorten the build time. Lifting will be carried out with many small winches that will spread the loads evenly.”

He said that by creating a web of wire rope – similar to a cat’s cradle – they could pull up on areas of the structure at different rates, allowing the jacket to be lifted then rotated into a horizontal position.

“Once the jacket is horizontal and between the pontoons, lines are attached to secure the jacket for transit.”

He added that using a vessel with multiple winches would also make short work of subsea salvage.

“Instead of waiting for a rig decommissioning Nessie could spend down time harvesting valuable subsea equipment,” he said.

“The seabed is littered with valuable equipment that should be cleared. With Nessie it becomes a profitable venture and much of the equipment can be reused or recycled.”

A Scottish Government spokeswoman said: “We recognise that decommissioning – along with recovering the substantial oil and gas resources remaining in the North Sea, and offshore renewables – has the potential to deliver enormous economic benefits for the whole country.

“That is why we are committed to supporting industry and investing in the necessary infrastructure support so that decommissioning work remains in Scotland.”