As sea levels rise, more and more coastal areas are getting flooded worldwide. 800 million people from across 570 cities may have to relocate by 2050.1 But instead of relocating the people, what if we moved our cities instead? Someone is…floating…the idea of building an island city over the ocean. But is this Waterworld just a fantasy or will we see some of these technologies emerge back on dry land?

So, why are architects looking for an escape from our dryland ship? In his TED talk, Bjarke Ingels covered the effects of sea level rise on coastal cities around the world.2 By 2050, 90% of major cities across the globe will be facing a wave of climate change. Some have already taken action against this, like Shanghai, which is going to experience sea level rises of up to 2 feet by 2050. To keep itself dry, the Chinese metropolis has already surrounded 520 kilometers of its shoreline with protective sea walls.3 And there’s also the Hafencity flood-proof neighborhood in Hamburg,4 which has waterfront buildings placed on mounds and a gate system that closes off their ground floors in case of a flood. Or the Hammarby Lake City, in Stockholm, where wet gardens handle stormwater.5 When Hurricane Sandy’s surge hit Manhattan in 2012, it left 500,000 homes in the dark.6 Ingels’ group (BIG) has now designed the Dryline project to protect the financial core of New York City from future hurricane-driven floods. With a cocktail of climate security and leisure facilities, this 7-mile long water-repellent ribbon features green parks, seating areas, bicycle shelters, and more.

But are sea walls a viable…dry run…in the long term? According to the Center for Climate Integrity, by 2040 the US will have to spent $400B to protect coastal cities from the rising ocean.7 Clearly, that sounds like an unsustainable cost. But Ingels’ visionary mind seems to have a solution for that too. Besides functional sea walls, the Danish architect is also the creative brain behind Oceanix City, a UN-supported floating city project. And this isn’t the only plan getting floated. While there is some really interesting progress to make the floating dream come true, which I’ll get to in a bit, floating cities have some significant challenges…as you can probably imagine.

New Orleans: Sinking or floating city?

While I don’t think we’ll be living in Kevin Costner’s Waterworld future, New Orleans might be a suitable location for a sequel. It ticks all the boxes. Some areas of the city are sinking at a rate of 2 inches per year and could be underwater by 2100.8 Also, the Crescent City is located on the Mississippi river delta and some areas are up to nearly 10 feet below sea level.9 Not to mention storm surges.10 You can probably see why some engineers suggested seasteading to save New Orleans … but what is seasteading? Basically, it’s about developing a permanent settlement offshore. In other words, instead of a homestead a seastead. If you think about it, there are already examples of seasteads floating around in the ocean. Like anti-aircraft platforms or cargo ships.11,12

So, can we just place an entire city like New Orleans on a shipyard? There are obviously a few challenges, like the weight of the city, which would push the shipyard hull 300 feet underwater. Also, a New New Orleans-size shipyard would be bigger than the three biggest shipyards in the world combined. But the most tricky obstacle is waves. In fact, their impact on the massive shipyard could cause its structural failure. So, what do we do? A solution to that would be to create a flexible system that…surfs the waves, which means interlinking many small pieces into a bigger structure rather than having a single massive rigid platform. The floating New Orleans’ housing could take inspiration from the Netherlands.

In Amsterdam, Waterstudio and other architects13 have already developed a floating village hosting 100 people spread across 46 homes staying afloat.14 Besides providing shelter, the city should be able to sustain itself to let people live independently from the mainland. A bit like a long-term cruise ship. As for energy, besides wind turbines and solar panels, the ocean is the obvious source … with a really interesting technology. Ocean thermal energy conversion (OTEC) is one of the most promising technologies.15 This relies on the natural ocean water temperature gradient between the surface and lower depths, which can be converted into electrical energy. But how does that work? In a closed-loop OTEC system, the warmer surface water vaporizes a low-boiling point fluid, like ammonia.16 The produced steam travels through pipelines until reaching a turbine that is coupled with a generator. To close the loop, colder ocean water is pumped from lower depths to liquify the hot ammonia vapor and use it again. The interesting thing is that the waste cooling water can be fed to aquaculture facilities to grow food, like fish and algae17. Also, an open-loop OTEC plant would have fresh water as a by-product.18 In fact, instead of ammonia, this configuration vaporizes surface seawater by reducing its pressure. So, when you condense it back into a liquid form, you’re left with desalinated water. Overall, an OTEC facility could possibly source clean energy, food and drinking water to the offshore urban infrastructure.

Projects still keeping afloat

But are there any ready-to-float projects coming to the surface?

With the help of the Danish architect Bjarke Ingels19, that I mentioned earlier, and French Polynesia ex-minister of tourism, Marc Collins Chen, they’re creating a UN-supported floating city project called Oceanix City. It will be formed by hexagonal islands each covering the size of three and a half football pitches. Every floating neighborhood will host 300 people.20 Following a stepwise modular design, Oceanix will first develop a six-island village as a core unit of their offshore infrastructure. The village will have its own services, such as healthcare, education, etc.. As part of the seascape, all structures, including bamboo and wood-made houses, will be below 7 stories to better resist wind.21 If that works, they’ll upscale their project by developing six connected villages until reaching a total capacity of 10,800 people. The mobile islands would be assembled on dryland and then towed into place. Each unit will sport customized functional edges, ranging from plantations to public spaces or marinas. Designers will also include small desert islands to ring the archipelago. Besides cushioning the waves and wind blows, these units will have specific functions, like solar energy generation and food production. The first prototype will be tested around the equator area, where most of the city would be outdoors. This would also reduce the energy needed for growing food.

An innovative material called Biorock or…Seament22..I’m not even joking…will safely anchor each island to the bottom of the ocean a mile off the coast.23 You can create this material underwater through an electrochemical process powered by renewable energy. Basically, you apply a current between a steel bar, acting as a cathode, and a much smaller anode. This makes seawater minerals precipitate, forming a limestone layer around the bar. With similar properties to those of concrete, this material is durable and binds itself to the ocean bedrock, which makes for a very stable mooring point for the floating platform. On top of that, it works as an artificial reef, providing food and shelter for marine life. The island is designed to withstand a category 5 hurricane and tsunamis.24 Marc Chen, the Oceanix founder, envisions his project as a closed-loop system, where the island can rely on its own water, food, and energy stock. Engineers proposed a triple water supply scheme. First, they’ll…tap into the sky reservoir…by collecting and storing rainfall. In addition, they’ll leverage the immense ocean tank by building a solar-powered desalination plant.25

Finally, what if I told you Oceanix could use special solar panels to harvest water out of the air humidity?26 Launched by the Zero Mass Water startup in 2015, this hydropanel, called Source, can provide up to 5 liters of water per day. Ben Sullins has published a couple of really good videos about his experience with Source panels on his home. Definitely go check those out. The module has got an internal fan that pulls in humid air and pushes it through a spongy material. The trapped water vapor is then condensed, mixed with minerals and stored in a tank that connects to your water tap.27 And you can also check how clean the water is. In fact, the company developed a sensor for quality monitoring that transfers data to an app. Although it costs $2,500 including installation, the startup CEO said investing in Source would be cheaper than buying water bottles in the long run.

Based on Oceanix forecasts, each person living in their floating city will consume less than half the water used by the average Congo citizen.28 To achieve that, they will collect both wastewater and greywater, treat it on site and reuse it. As for food, Oceanix citizens will have a pescetarian diet. They’re dedicating up to 32,000 square feet of space for crop cultivation on each island.29 These will include 5 core systems: outdoor communal gardens, indoor farming (greenhouses), aquaponics, vertical farming, and 3D ocean farming.30 In that last system you’d have horizontal ropes lying over the water’s surface and underwater lines running along the entire ocean water column. The ropes are anchored by hurricane-proof floats, while the lines support seaweed crops and hanging cages to grow seafood. What about food waste? They’re hoping to solve the problem through reusable containers and anaerobic digesters to convert food scraps into natural fertilizers and energy. Based on the city design, 60% of the transport could rely on sustainable solutions like walking, cycling, hydrofoil taxis and other types of sharing mobility.

But will the city have enough energy to power all this? Besides harnessing waste-to-energy, waves, solar and wind infrastructures, the project’s creators will give an energy budget to each…floating citizen…to keep power consumption under control. Also, by fanning out the building facades, architects will leverage self-shading to save on cooling and gain on solar coverage. The first Oceanix marine metropolis will be tested near the Pearl River Delta, in the Guangdong Chinese province.31 Apparently, the company aims to deliver the project by 2030.

But is Oceanix City really …unsinkable…? It’s hard to tell as some of the technologies they’re meant to use are still at an early stage. Plus, they haven’t provided enough details on how the city will be run, how much it will cost and where they’re going to get the funds to build it. For instance, what if private investors were to build one of the islands without being subjected to any specific rules? In this case, the floating paradise could easily turn into a climate haven for whoever can afford to escape rising sea levels. You know … the rich. Also, lying one mile off the coast, the isolated urban system may have troubles in case of sudden energy disruptions. It would take a while to get engineers to come and fix any issues.32 Yet, whether or not Oceanix will make it work, some of their ideas such as water and waste recycling could loop back to mainland cities.

Although these projects sound futuristic and will take some years to complete, smaller scale floating structures will soon be commonplace. Like floating villages in the Netherlands, for instance. And it’s not just about cities. You might have the chance of experiencing a solo floating adventure. The Seasteading Institute, which is a nonprofit organization based in California, is supporting Ocean Builders for their Seapods development. The company is currently building their prototypes in Panama using 3D printers.33 Rather than cities, they’re focusing on individual seasteads for tourists and businesses. Back in May 2020, Ocean Builder’s CEO said the first floating pod would have been ready by last November. However, no pods have popped up on the horizon yet. Maybe COVID delayed their plans. If you have some spare money for a special cruise, you could rent an eco-friendly floating home in Brittany.34 You can get on board for just $336 a night. Not exactly a bargain. Running on solar power, this luxury 540-square-foot pod has built-in water treatment systems to avoid polluting the seawater. But there are also more affordable options available. In 2016, BIG stacked 9 shipping containers onto a platform docked in the port of Copenhagen.35 These have now become low-cost accommodation for 12 students. Each unit is warmed up using the seawater thermal energy and is powered by solar panels.

Testing the water

With rising populations and sea levels, we’re desperate for more living space. While economic and technical viability are still to be proven, floating cities could turn a threat into an…ocean…of resources. Seasteading may be the new frontier for urbanization. But even if it doesn’t, it could serve as a springboard for new technologies like 3D printing, waste management and ocean energy that would come handy back on the mainland.

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Matt Ferrell
Matt Ferrell lives in the Boston area and is a UI/UX designer by trade, but has always been obsessed by technology and how it works. In 2018 he started his YouTube channel, Undecided with Matt Ferrell, where he explores sustainable and smart technologies like EVs, solar panels, and smart homes.

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