Product: Construction Equipment
Ice Caisson   (+8)  [vote for, against]
Refrigeration coil makes frozen walls to hold back water

Form the coil into a mesh of the general shape you'd like the structure to be. Add refrigerant and wait, then pump out water. Using several electric compressors (and long cords) you could make modular coil sections to create some really big and interestingly shaped underwater ice buildings. Add fibres for greater strength.
-- the porpoise, Nov 20 2015

This would work as long as the surrounding water is close to freezing. Otherwise, I think you'd need a huge amount of coolth to outweigh the warming effect of the water.
-- MaxwellBuchanan, Nov 20 2015

Habbakuk/Pykrete ?
-- 8th of 7, Nov 21 2015

You would be sunk if your freezer compressors ever wore out.
-- travbm, Nov 21 2015

You might enjoy reading about the ice battleships of World War II. Some navies seriously tried freezing seawater mixed with sawdust, to make giant iceberg aircraft carriers. It worked well but was too weird to actually deploy.
-- sninctown, Nov 22 2015

I imagine the cooling pipes being furry. Or perhaps with knitted covers. The fibres would strengthen the ice/pykrete, but more importantly they'd hamper local currents that would sap so much power during the initial cooling.

In polar regions, you could use passive heat pipes with radiators fins above the water level.
-- mitxela, Nov 22 2015

random, halfbakery