Rapid Beach Rock
There are many countries in the world where sea level rise is an immediate and urgent problem and that are surounded by healthy coral reefs. Coral sands can relatively easily be turned into rock sufficiently robust to rake out of the sand and use as barriers to block super high tides and build up the land generally. If carbonates are lacking in the sand they can still be cemented by carbonate but this may take a little longer.
A project that can help turn around the CO2 problem is to accelerate beach rock formation and an electrical field with or without appropriate bacteria & nutrients will do that.
A mini sandbed/mudflat apparatus with periodical flood and draining using aerated seawater run by cheap electronic timers will simulate the tides coming and going with seawater containing CO2, Ca & Mg to the materials we experiment with. We suggest using zinc anodes and copper cathode and applying 6v at the first attempt.. Copper should be able to be replaced by iron on a large scale such as a beach
I have tested this in the lab and it works. A full scale implementation would be better to demonstrate how well and profitability.
Our new ideas of making rock from sands including coral sands is is based on the work of Wolf Hilbertz., who proposed depositing calcium minerals from the seawater in situ by electrolysis.
 Wolf Hibbertz (Inventor) "Mineral Accretion of Large Surface Structures, Building Components and Elements," U.S. Patent No. 4,246,075,
(Jan. 20, 1981).