In Sumatra, new methods are under development to protect cities from tsunamis: “It uses the concept of cathode accretion–putting a small electrical charge in the water that draws calcium carbonate (the stuff reefs are made of) out of solution and onto an iron-based skeleton. The calcium slowly accumulates, creating an artificial reef and wave barrier.” And down the road, the same method may be used to create community hubs as places of refuge from tsunami waters.
Maybe 25 or 30 years ago, I remember being inspired by researcher Wolf Hilbertz, then of McGill University in Montreal, when he proposed this idea, which he referred to as mineral accretion. Hilbertz, who died in 2007, proposed this not only as a way to produce “pre-cast” building materials inexpensively, but also as a way to permanently sequester carbon dioxide. This mineral accretion (cathode accretion) process pulls carbon dioxide out of the seawater to form calcium carbonate and magnesium carbonate, and Hilbertz presented data showing how many floating PV arrays would be required to sequester all of our anthropogenic CO2 emissions.
I see that you can find information on Hilbertz’s ideas on this website.