This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.
Singapore is bursting at the seams. With more than 5.9 million people living on just 719 square kilometers, the country is one of the most densely populated in the world.
For decades, the island state has been expanding on the back of imported sand. Singapore has shipped massive amounts of sand from its Asian neighbors and dumped it in its coastal waters. Land claimed from the sea in this way has boosted Singapore’s size by almost a quarter since 1965, and helped its population to triple. But environmental concerns—much of the sand was dredged from sensitive mangrove forests in Cambodia—have led to stricter controls and outright bans on the trade.
Now Singapore is looking for another way to grow. Instead of building more land, the city wants to build on the sea’s surface, with a system of giant floating rafts tethered to the seabed. But first, engineers have to solve an important problem: how do we stop the rafts from wobbling?
Singapore officials are reluctant to discuss the plan, but details were revealed in an academic study published last month. In it, scientists from the Singapore Department of Civil and Environmental Engineering and others propose a grid of more than 40 individual floats, each of which would be 35 meters square—slightly bigger than a baseball diamond—12 meters high, and weigh more than 7.5 tonnes. The array would be connected to an onshore quay and sit in calm sea that is about 18 meters deep. The research at this stage is theoretical and focused on how to connect the individual rafts to keep them stable, for example by using hinges to dampen the bumps from waves. Next they need to test their designs by building a scale model.
Singapore is not alone in its aim to expand. Faced with growing populations, rising sea levels, and shrinking amounts of available land to build on, other coastal cities and regions, from Hong Kong to the Netherlands, are eyeing the creation of floating marine real estate.
Gil Wang, a naval engineer at the Israel Institute of Technology in Haifa, Israel, is leading a team exploring floating platforms as a way to expand the Israeli city Tel Aviv, at the eastern end of the Mediterranean Sea. He says floating cities are a cheaper and more sustainable alternative to building new land. Using piles of sand to build up the seabed is environmentally damaging, and isn’t always feasible on the large scales often required, Wang says. “Many coastal cities that don’t have hinterland to grow into are going to have this issue.”
Using floating platforms for urban development is different from the concept of seasteading, which usually describes independent floating communities far from land and free from national laws. “It’s more like a new suburb,” says Wang, who envisages floating development stretching up to five kilometers from the shoreline.
His team has modeled the behavior of bigger floats than those planned for Singapore: up to 100 meters long and 30 meters wide, bigger than a hockey rink. Each float could support a trio of 10-story buildings. Dozens of floats would be combined to accommodate 2,280 apartments. Developers face challenges related to policies, environmental issues, and engineering. The Israeli design, described in a separate study, satisfies all of Israel’s relevant building codes and marine safety standards, Wang says.
But one engineering challenge has yet to be resolved, and could wind up sinking the whole effort: stopping occupants from feeling seasick.
“You can make things that work, but if nobody wants to use them then there’s no point,” Wang admits.
One way to improve the persistent swaying could be to install a floating breakwater nearby to reduce the impact of the waves. Another approach, like the one taken by the Singapore team, is to design the connectors between the floats so they absorb energy and dampen movement.
The problem is that seasickness is unpredictable, says Matti Scheu, a chief consultant with the engineering firm Ramboll in Hamburg, Germany. Scheu is trying to solve a related wobble problem: how to reduce nausea in technicians working on floating wind turbines. “It can be a bit counterintuitive,” he says. Anchoring a platform firmly in place can reduce the range of movement, but it can also make those movements faster. “Both are important when it comes to motion sickness,” Scheu says.
The solution could be found in a surprising place. There is growing research on motion sickness in office workers in high buildings that are affected by wind. But Scheu says some people will always be susceptible, however long they spend afloat. “I know technicians who have been getting sick for years.”
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Published at Fri, 03 May 2019 14:50:37 +0000