The freezing temperature of ocean water is approx. -2°C (say, Δ25°C), and ice, being nearly 10% less dense than water, stays up due to buoyancy. So, freeze enough of water, and you could make roads floating in the seas like icebergs.
Technically though, there are a couple of things to consider:
- The water specific heat is high, and phase conversion is expensive.
- However, retaining already frozen water isn't that hard, especially, if insulating bags surround water. Bags are cheap to produce.
- Still, the ice would require some form of refrigeration, which may be provided by antifreeze circulating around the inner layers of these bags, beneath insulation, but maybe other ways.
- Energy could be delivered locally, from wind, solar, or waves energy. Options need to be considered, and calculated for the loss of cold due to sunshine.
- Depth of these icebergs need to be adjusted for the amount of load to carry.
- Modularity, interconnection, and maintenance of the road direction during the rough seas should also be considered.
- Perhaps having deep icebergs can help with that, but then, tsunamis also have to be considered.
How to do it cheaper?
Perhaps you don't even need to freeze water: just fill bags with water. Water, due to large mass, has much inertia, and some air in the bags (at the top) could have some buoyancy. To have a stable structure we need both: buoyancy AND inertia (mass).
So, the ocean road design could be prototyped with:
- Large polyethylene bags of water.
- Half-Fill them with table tennis balls.
- Add some sand at the bottom of bags for stability.
This simulates the benefits of ice, without the need to maintain sub-zero temperature.
