Could seaweed bricks provide the key to more sustainable construction at sea?

Interview with Seabrick CEO John Richardson as he experiments with alternatives to concrete, aluminum, and plastic for offshore construction.
Ameya Paleja
Artistic representation of Seabrick cities made using DALL-E
Artistic representation of Seabrick cities made using DALL-E

John Richardson/ Seabrick 

  • Sea Bricks are buoyant building platforms made from kelp and sargassum
  • Made using simple ingredients like starch, the final product is stronger than concrete
  • Sea Bricks could help billions of people live at sea in case of a climate catastrophe

With rising sea levels, cities and countries need a contingency plan to safeguard their future. Interesting Engineering has previously reported on how the Maldives has spent the good part of the last decade planning its ambitious but also critical Maldives Floating City (MFC).

The rise in the construction of offshore wind farms in recent years has also seen the discussion about construction at sea pick up pace.

Traditionally, construction at sea has involved the use of carbon-intensive concrete, but California-based Sea Brick has been seeking a more sustainable alternative.

According to its website, Sea Brick is an interlocking, buoyant brick system, much like Lego, composed primarily of kelp biomass and "designed to support the marine sector in the journey to decarbonization."

The company has been experimenting with a few prototype bricks made using kelp, pelagic clay, and sargassum – a brown macro alga found in coastal waters.

Both kelp and sargassum are great resources for trapping atmospheric carbon and are estimated to be 20 times more efficient at doing this than trees on land.

So far, Sea Brick has not moved beyond the prototype stage and is currently looking for more funding to move ahead, but it hopes that its technology will provide a more sustainable and cost-effective alternative solution for construction at sea in the near future.

Interesting Engineering caught up with John Richardson, the CEO of Sea Brick, to understand the origin of the Sea Brick and how soon we might see it in action.

Could seaweed bricks provide the key to more sustainable construction at sea?
John Richardson, the CEO of Sea Brick

IE: How did you come across the idea of making bricks from seaweed?

John Richardson: I have always been fascinated by the idea of the ocean - especially the deep ocean - as a future habitat for humanity. Climate change will displace hundreds of millions in the next 60 years - if not faster.

Where will those people go? Land-based ecosystems have already been pushed too far. Many have dreamed about this, from Seasteaders to science fiction writers.

In my opinion, the missing piece has always been affordable, scalable infrastructure. Current floating structures all rely on either floating concrete, steel, aluminum, or plastic. They are emissions-intensive and not scalable in the way we need. We need regenerative approaches. 

Add in the fact that kelp has this incredible potential for sequestering carbon with biomass, to the point that people are sinking it to the bottom of the ocean just to get the carbon credits. It seemed like there could be better things to do with it. And I wondered if we could use that kelp to solve the infrastructure problem and make bricks that float. And what kind of bricks would work best in that environment? We'd need a new form factor.

I poked around and was actually surprised no one had come up with the idea already.

Could seaweed bricks provide the key to more sustainable construction at sea?
3D printed prototype of the Sea Brick at 1/10th scale

How are these bricks made? What is the process? How long does it take?

It is a multi-step process; heat compression of the seaweed biomass with other ingredients, including citric acid, starch, and glucose. We are still optimizing the mix but have created samples stronger than concrete. The biomass is shaped using molds into two halves of the brick, which contains honeycomb cavities inside. Put together, they form a semi-hollow brick, which is then coated with a polymer shell to make it impermeable.

Could seaweed bricks provide the key to more sustainable construction at sea?
3D printed prototype of the Sea Brick

How big are these bricks, and what is their weight-bearing capacity?

A square brick is 50cmX50cmX20cm. It weighs 25kg and can support 12.5kg = that is, they are about half the density of water.

Could seaweed bricks provide the key to more sustainable construction at sea?
Representation of vertical structures that can be built using Seabricks as a base

Where have these bricks been tested so far? What constructions have been made using them?

We are still optimizing the materials and process. This is the subject of a research project at the University of British Columbia. We are planning our first prototypes later this year.

How do you plan to scale up processing?

We have a partnership with the Heiltsuk First Nation and the Construction Foundation to explore creating a manufacturing facility in Bella Bella [British Columbia], which has ideal conditions for kelp farms - and some of the world's largest kelp forests.

The pelagic clay used as an ingredient is found in the deep sea. Wouldn't these bricks promote extraction activities and disturb ecosystems in areas untouched by humans before?

We have largely shelved the idea of pelagic clay; not only for that reason but also because it was too heat-intensive and complex. The better alternative is a bioplastic or biopolymer, which can last 75 years or longer. Best of all - kelp can be used to produce this kind of coating material.

How soon would these bricks be available?

Our hope is to produce the first batch later this year, but it is funding-dependent.

Could seaweed bricks provide the key to more sustainable construction at sea?
Artistic representation of structures that can be built using SeaBricks

What is the Kelp Island project?

Kelp Island is the company we have created to commercialize SeaBrick, at least for the first years. Ultimately the IP is owned by SeaBrick Society, which will open-source the process under a public licensing scheme.

How is Seabrick helping Seasteading Institute in its plans?

At this point, I think merely having a scalable solution to the problem of marine infrastructure is the most significant impact on planning. Visions that haven't been practical or economical can now be contemplated, including self-sustaining cities in the deep ocean.

Ultimately the deep ocean makes the most sense for me when considering where humanity can ride out the coming climate catastrophe. The deep ocean, unlike continental shelves, is almost a desert in terms of the density of life. And it's a vast desert - look at the south pacific in the globe, it's all blue. 

Space isn't a solution, not for the billions of people who can't afford a spaceship. The ocean, however – has all we need. Air, food, water – all right there, and no need for flight control. And we can bring abundance to that desert and create self-sustaining oases of biodiversity. We could have the opposite effect we had on land-based ecosystems. And relieve those land ecosystems of the burden of supporting us.

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