26 April 2023
How important is it to find a solution to coastal erosion?
Over half of global coastlines are being eroded, as climate change drives larger waves and more frequent storms. Miami University put out a fantastic paper that showed that the global wave energy is increasing by 0.41% year on year. And when we’ve looked at that same data for Mexico, you’re seeing changes of sort of 1 to 2% in places per year. That doesn’t really sound like a great deal, but when you accumulate this over a decade you get 20% more energy in the sea. Our goal is really to try and take the edge off the waves, to wind the clock back.
And why coral reefs?
Soon after Hurricane Matthew [in 2016] I went to see my sister, who lives in Grand Bahama. It was striking, walking along her coastline. Where there were reefs, the houses had wind damage and trees were disheveled, but they hadn’t lost any land. When you went further up the beach to where the reef stopped, people were losing their entire gardens. It was quite dramatic.
The core issue we’re trying to solve is: Can we replicate natural coral reefs? Can we bring in that protection that natural coral reefs provide to vulnerable coastlines?
People have tried to protect coastlines by doing everything from sinking concrete to sinking ships. Why is your solution better?
If you look at the conventional approaches, I’d argue they haven’t changed since the time of the Romans. You get a pile of rocks or concrete and you pile these up until something happens. That’s the basis of most breakwaters.
If you look at natural coral reefs, on the other hand, which protect the Maldives and many other places, they’re actually working a little bit more subtly below the surface to affect change at the surface. They themselves don’t take the brunt of those waves. It’s estimated around 25% of all the marine life that we know of is either born on or lives in coral reefs, and we have lost 50% of our coral reefs—in the Caribbean they’ve lost 80%. We’ve got to start to really seriously think about how to restore our balance.
We looked at that and said: Can we engineer a lightweight structure like a reef? Currently we make them from steel, which can be manufactured in bulk in a factory—150 meters of reef fits into a single container for transport. A lot of design work went into making units that stack together a bit like supermarket trolleys.
How do you turn that metal structure into a reef?
We use a technology called mineral accretion. This passes a small electric current through the water around the structure which causes sea-water minerals to form rock crystals. This is similar to limescale that forms in kettles, except instead of boiling the water, we increase the pH of water around the reef. The structure goes from being lightweight to a reinforced heavy mass that can then provide resistance against the waves. Our goal is for a reef with 20% porosity, having started at close to 90%. We monitor the reef remotely and use renewable energy wherever possible. Corals or bivalves are able to rapidly thrive upon our reefs; they offer a haven for diverse marine life, just like natural reefs.
Where have you installed these so far?
Most of our work has been in Mexico. Our biggest installation is 120 meters long in a place called Telchac. We’ve got a number of smaller pilots in Cancun. We finished a project out in the Isle of Man where we had three pilot units. And we’ve been running pilot units in Israel, testing out and optimizing the actual rock growth itself.
Additional reporting by Jack Stewart, an Associate with Brunswick’s Business & Society team.