Can Oceanix Busan’s Floating City defend against sea level rise?

At the South Korean port city of Busan, a prototype 15-acre floating community is being designed as a possible defense against sea level rise, according to Marc Collins Chen, co-founder of New York-based Oceanix, the project developer. OCEANIX, a blue tech company based in New York, led a team of designers, engineers, and sustainability experts in designing the flood-proof prototype. The BIG-Bjarke Ingels Group and SAMOO (Samsung Group) were the lead architects of OCEANIX Busan, unveiled at the Second UN Roundtable on Sustainable Floating Cities.

The physics of floating concrete cities was described by Koen Olthuis, the founder of the Dutch architectural firm Waterstudio, who designed a floating development in the Maldives. Olthuis told the New York Times: “The physics is very easy…A block of concrete will sink … But if you shape it into a box, then it floats. It’s Archimedes. The amount of volume you push away is equal to the weight of the displaced water.”

In an interview with AJOT, Chen said that the partnership with the City of Busan developed back in 2019 when the South Korean port city had elected a new Mayor and was a candidate for the Expo 2030.

In April 2022, the United Nations-Habitat, the City of Busan, and Oceanix unveiled the design of the world’s first prototype sustainable floating city.

UN-Habitat announced that OCEANIX Busan aims to provide breakthrough technology for coastal cities facing severe land shortages that are compounded by climatic threats: “The challenge is massive: two out of every five people in the world live within 100 kilometers of the coast, and 90 percent of megacities worldwide are vulnerable to rising sea levels. Flooding is destroying billions of dollars worth of infrastructure and forcing millions of climate refugees to leave their homes. With nowhere to expand, rapid urban population growth is pushing people closer to the water, driving housing costs to prohibitive levels, and squeezing the poorest families out.”

City of Busan Partnership

Busan Mayor Park Heong-joon has set an ambitious agenda, including turning Busan into a green smart city: “As Mayor of the Metropolitan City of Busan, I take seriously our commitment to the credo ‘The First to the Future’. We joined forces with UN-Habitat and OCEANIX to be the first to prototype and scale this audacious idea because our common future is at stake in the face of sea level rise and its devastating impact on coastal cities.”

The UN announcement said OCEANIX Busan will compose interconnected neighborhoods totaling 6.3 hectares (15.5 acres) to accommodate a community of 12,000 people: “Each neighborhood is designed to serve a specific purpose - living, research, and lodging. There are between 30,000 to 40,000 square meters of mixed-use programs per neighborhood. The floating platforms connect to the land with link-span bridges … OCEANIX Busan will organically transform and adapt over time. Starting from a community of 3 platforms with 12,000 residents and visitors, it has the potential to expand to more than 20 platforms. The floating platforms are accompanied by dozens of productive outposts with photovoltaic panels and greenhouses that can expand and contract over time based on the needs of Busan.

OCEANIX Busan has six integrated systems: zero waste and circular systems, closed-loop water systems, food, net zero energy, innovative mobility, and coastal habitat regeneration. These interconnected systems will generate 100% of the required operational energy on-site through floating and rooftop photovoltaic panels.”

Chen explained to the AJOT that Busan was an ideal starting point for a floating city because of its port and shipbuilding resources: “Busan was ideal …You have all of the major construction companies and shipyards there … So, you have the big builders, Hyundai Heavy Industries, … Samsung Heavy industries … all those big guys interested in floating infrastructure.”

Aiding the effort, the Korean government “funded 15 million dollars to study floating cities.”

However, Chen said that Oceanix is committed to raising the $220 million funding to build the floating community: “So, we signed … an MOU with the City of Busan where we clarified that all of the studies would be at Oceanix’s expense and that we would be raising the funding on the international markets, local markets, but that it would not be a hit to the city coffers … It's a prototype and it's a little bit difficult to ask a city to fund a prototype … That's something venture capital does … Once the prototype is proven, once we've lowered the costs of construction for future platforms then we can go to cities, and they can raise a bond … but we will have something that's built … it's been demonstrated, it's insurable.”

Port Benefits

The Busan demonstration project is also aimed at looking for areas at ports, the Port of Busan is nearby, where port-related warehousing and new car staging land for roll-on/roll-off vessels can be moved from land to floating structures: “Think about all those cities that still have the old style … warehouses, right?

Not the maximum best use of that property, right? But if you move the warehouses and some of the … container port facilities and the … car delivery facilities and you put those onto floating platforms, suddenly you free up acres and acres of prime real estate. And that's something that cities are very interested in because of the tax base.”

The role of the floating city is to add value to the locality “especially as they're looking at this very dangerous future where they won't be able to insure their waterfront.”

Extreme weather is another feature that is being built into the design: “So when we started designing and conceptualizing what the future floating cities looks like, we had to take into account that sea level rise is one thing, but these structures float, but …[what]…does a future look like with more extreme climate and in particular typhoons and cyclones. So, we work closely with the Massachusetts Institute of Technology Center for Ocean Engineering, and we signed an agreement with them to collaborate on what would be best practices. So, from the ground up, the floating structures are being designed for Category Five storms and now people are talking about five plus storms.”

For that reason, exposed island communities such as those in the Caribbean are not good candidates for the floating cities but “Busan is very well protected.”

Working With Korean Shipbuilders

Chen says that at Busan working with Korean shipbuilders is a bonus because they have built floating offshore oil and gas platforms that operate in challenging sea states which will provide resilient designs for storm conditions. Oceanix is also working with the American Bureau of Shipping which certifies safety and operational standards for ocean-going vessels.

Chen says the long-term goal is to establish a Universal Building Code for floating cities established by the United Nations similar to the standard-making for ocean shipping provided by the International Maritime Organization (IMO). IMO is the United Nations agency with responsibility for the safety and security of shipping and the prevention of marine and atmospheric pollution by ships.

The use of concrete is a critical ingredient in the construction of the floating structures because it is longer lasting than steel and less prone to rust but still faces deterioration from salt:

“Salinity is an issue for concrete. No matter what you do, the salt ions migrate into the concrete. It takes time, but they'll get to your rebar … And that's where you lose your structural integrity if the rebar starts expanding as it rusts and then it cracks. We've all seen what a cracked pier dock looks like. We are very lucky to be working with some of the world's top construction companies. They’ve been looking at… reinforcement … And there are several fancy ways of doing this, but right now they are costly. One of them is stainless steel or a very highly rust-resistant steel. Now it's all encased in concrete, so it still will take a long time (to deteriorate), but that's one route. The other is to replace rebar with fibers, some sort of very strong synthetic fibers … that still give you the resiliency. There will be research in that area to make sure that the floating platform isn't like an oil rig. Oil rigs (made of steel) get decommissioned after 30 to 40 years because the steel just loses its strength.”

Threat to Islands

Chen’s commitment to floating cities began when he was Minister of Tourism for French Polynesia. He read news reports warning of climate change and rising sea levels placing Pacific Islands underwater: “So, I remember seeing a report back in 2007 in the New York Times talking about sea level rise … submerging islands in the Pacific and people saw this and said: ‘wait a minute, what is this? You know, Antarctic ice shelf melting stuff about, and what do we do with all of our islands?’ So, our country has 118 islands. About a third of them are at sea level. We're not like the Maldives … or Vanuatu with one hundred percent at sea level, so they can't … retreat. Where do you retreat to? So, … they're going to other countries … My hope …is in two, three decades when all of this has been proven out is that populations in the Pacific will be able to keep their sovereignty by not leaving their land.”

Right now, Chen said: “There's been some working groups around this and what happens if you extend your islands vertically on pilings … and now you're on a platform above the waves, does that count as a country? Right now, it does not.”