‘Boris island’ points to watery future for building

Although ‘Boris Island’, London mayor Boris Johnson’s proposed airport in the Thames Estuary, was scoffed at by critics, it reflects a growing trend of aiming to build on seas and oceans.

When Boris Johnson first aired his suggestion that the UK’s busiest airport should be relocated from Heathrow to an artificial island in the Thames Estuary the prevailing reaction was one of amusement. ‘Boris Island’ as it soon became known was seized on by the media as a potent symbol of the London mayor’s eccentricity.

But forget the concept’s arguably damaging association with Johnson, put to one side concerns over its environmental impact and cost (estimated at £40bn), and there is some logic to the idea. With aircraft descending from the North Sea rather than over residential areas, it would, claim its advocates, provide a neat solution to the problems that have bedevilled plans to expand Heathrow, and with High Speed One now up and running, fast rail connections to London and Europe would be an improvement on Heathrow’s piecemeal transport links.

Plus the idea is not without precedent: both Hong Kong and Japan, faced with similar concerns over airport expansion, built brand-new major airports from scratch in the ocean. Meanwhile the Dutch government is reported to be considering plans to move Amsterdam’s Schiphol airport to an artificial island built 20km out into the North Sea.

The idea of an airport in the Thames is also arguably part of a much bigger picture. With sea levels rising, climate models predicting heavier rainfall and land use under growing pressure, mankind is going to have to adopt new strategies in the way it defends itself from, and makes use of, the water that covers 70 per cent of the planet’s surface. And from the development of floating homes to the installation of new types of offshore energy generators, engineers from a range of sectors are taking the first tentative steps into this new age of offshore construction.

But first, back to ‘Boris Island’, which is actually a revived version of a proposal known as Marinair originally put forward in the mid 1990s. Earlier this year Johnson commissioned Douglas Oakervee, the brains behind Hong Kong’s offshore airport, and former executive chair of Crossrail, to re-examine in detail the feasibility of the scheme as an alternative to plans to build a third runway at Heathrow.

Initial plans detail a four-runway airport built on two separate artificial islands constructed from landfill in the shallow (10-15ft [3.048-4.572m]) waters two miles north of the Isle of Sheppey in Kent. Passengers would shuttle between the islands in a tunnel beneath the river bed, running from Essex on the north bank, to Kent on the south. Underwater turbines, built into ducts running through the body of the islands, would generate nearly all of the airport’s electricity needs by harnessing the tide. The largest of the two terminals, in Kent, would be connected to the high-speed Channel Tunnel rail link and possibly Crossrail.

Although Oakervee declined to talk to The Engineer ahead of the publication of his report — which is now several months overdue — preliminary findings are thought to be positive. On a boat trip to inspect the site earlier this year he reportedly claimed that the scheme would be simpler to build than Hong Kong’s Chep Lap Kok airport, which was built on a large artificial structure formed by levelling two smaller existing islands: Chep Lap Kok and Lam Chau.

While the mayor’s office is waiting to peruse Oakervee’s findings in more detail, plans to build a similar structure in the waters off the coast of Holland — which like the UK is engaged in a debate over airport expansion — are at a more advanced stage.

The proposals have been drawn up by Dutch civil engineering giant Royal Haskoning, a world leader in land reclamation and one of the contractors behind the development of the Palm Jebel Ali artificial island off the coast of Dubai. The company has also recently begun work on Africa’s biggest land-reclamation project — EKO Atlantic, an effort to build a new city off the coast of Lagos, Nigeria on 9km2 of land snatched back from the sea.

North Sea

Talking to The Engineer, Tom Smit, director of spatial development at Royal Haskoning, claimed that the so-called North Sea International airport, which would reduce noise pollution on the mainland and enable freight to fly in and out 24 hours a day, is now part of the Dutch government’s long-term plan for the next 40 years. Under the proposal, while much of the current site of Schiphol would be sold off to finance the development, a terminal building would remain. This would be connected to the sea airport via an underground tunnel.

Built on an artificial island, and elevated 20m above the sea to eliminate any risk of water splashing onto its runways, the airport would occupy an exposed position in an almost perpetually windy location. To cope with the extreme wind conditions out at sea, Smit’s team have developed an intriguing solution: rotating runways that would be adjusted using giant motors to suit the wind direction.

Like the UK proposal, Smit said that the Dutch airport will also make use of the ample energy-generating opportunities afforded by the sea. ‘The aim is to develop a climate-neutral airport,’ he said. ‘From windmills to tidal generators, all of the energy requirements of the airport would be met by the renewable power generated out at sea.’

Commenting on the UK plans, Smit said he believes there are compelling reasons to build a London airport in the water, but that it would face less opposition if it were placed further out to sea. ‘You could quite easily build an airport in the estuary. As far as the technical side is concerned it’s not that big a problem. The problem is more that you are dealing with an estuary that has a lot of birds and is a sensitive environmental area — it’s something you have to be very careful with. Perhaps it would be better to bring the airport more towards the sea than in the estuary.’

But while projects such as the North Sea International airport are a modern continuation of the centuries’ old Dutch tradition of reclaiming land from the waves, it’s not all one-way traffic. And in a shift of emphasis that the 16th century builders of Holland’s dikes, dams and canals would have found scarcely believable, modern engineers are now considering plans to surrender ground to the water in an effort to help the country’s rivers cope with increased rainfall and run-off from glacial melt in the Alps.

Instead of building even higher dikes to contain the rivers, the Dutch government has decided to lower the dikes in about 40 parcels of land, allowing them to flood when the rivers rise and taking the pressure off existing dikes further down river.

‘We’re trying to contain the river and make room for it in a way that has never been done before,’ explained Smit, who is one of the leaders on the so-called Room for the River project. ‘We’re making floating homes just next to the river and creating more room for the river by taking out the dikes in some areas.’

Ironically, while Smit claimed that many of the techniques learned during this project could be adapted for use in other low-lying areas of the world susceptible to flooding, such as Bangladesh, much of the pioneering work has been carried out on a project with a considerably less noble purpose: Dubai’s Palm Jebel Ali, a luxury artificial island that features a number of floating homes.

Resting on concrete/foam platforms that rise and fall with the water along steel masts anchored into steel foundations, the houses are shielded from the impact of severe ocean currents and waves by a huge artificial reef that surrounds the development.

But while it’s one thing building floating houses next to rivers or within carefully controlled and heavily protected coastal areas, it’s quite another building them miles out to sea. This is the goal of California’s Seasteading Institute, which wants to kick start the development of offshore living. The group is driven by a libertarian philosophy. Its founder Pat Friedman views the concept as a political experiment.

However, the institute’s chief engineer Wayne Gramlich is more concerned with developing the technology and know-how that would make ‘aquatic homesteads’ a reality.

‘We envisage them being built everywhere,’ he said. ‘Seventy per cent of the planet is water — there are sheltered waters and unsheltered waters, but my focus is on some of the more hostile parts. You haven’t really solved living in the middle of the ocean until you can say “look, this structure can withstand a category 5 hurricane”, and that’s a very stiff challenge.’

Gramlich parts company with some of his colleagues, who envisage the construction of giant floating cities, and believes that smaller unconnected structures floating together as a community are a more plausible concept. ‘Making very large structures is the tricky thing. If you have long wavelength waves up to half a kilometre long you could end up with a situation where your structure is sitting on the crests of two waves and has got nothing underneath it — that’s a bridge and none of us can build a bridge that will span that length, which means you have to build it deep enough that it will never uncover the bottom — big structures and big waves are a terrible combination.’

Gramlich believes the initial economic driver for the development of this technology will be the fishing industry. ‘I view aquaculture as the bread-and-butter business that will get things going,’ he said. ‘People like fish, the fish stocks out in the ocean are in horrible shape and coast-based fish farms have big problems because you have to really worry about keeping the water clean.’

He added that the high cost of buying and running a fishing vessel and the growing likelihood of returning to shore with a meagre catch could create a compelling economic case for fishermen to turn from hunters to farmers and live aboard small fish farms far out to sea. ‘At some point you’re going to reach a tipping point and say “lets go from hunter-gathering to a farming model”,’ said Gramlich.

The question is: ‘Can it actually it be done?’ Gramlich believes strong materials such as ferro-concrete, a reinforced concrete/iron composite widely used in the offshore industry could be well suited to form the building blocks of these watery homes of the future, and the oil and gas industry — which has for some years made use of floating storage and production platforms — has already solved many of the challenges. Another, newer area of the offshore energy industry may also provide some intriguing options. Proponents of wind energy have long thought that the open sea — with its greater wind resource — has huge advantages over coastal areas for wind generation. The big problem, and one of the main reasons offshore wind farms tend to be so close to the coast, is that building foundations for wind turbines is an expensive business. However, in an effort to address this problem, a number of researchers around the world have been investigating the possibility of developing floating wind farms — and earlier this summer the concept finally bore fruit when a team led by Norwegian oil and gas firm Statoil Hydro installed the world’s first large-scale floating wind turbine 10km off the coast of Norway.

Developed with the help of Siemens, the 2.3MW HyWind turbine, which rises 65m above sea level, is mounted on a spar buoy — a floating steel cylinder-filled ballast — that extends 100m beneath the surface and is attached to three anchor points on the seabed. According to its developer, the mooring systems could be used in water depths of up to 700m. And while the construction of a single floating turbine may be miles away from the idea of a floating city, the project is a neat illustration of the fact that it’s possible to build a floating structure that can survive the weather and harvest its own energy.

Closer to shore, with the government’s decision on a third Heathrow runway fast approaching and Douglas Oakervee’s report now several months late, ‘Boris Island’ looks unlikely to make it off the drawing board in the near term. But as changing climate puts growing pressure on land use and humans look to the sea as a source of both problems and solutions, it could still indicate a watery future to come.