Circulating liquid is an interesting thought. I hadn’t considered that, but it could be an interesting idea.
It would have to be something that wouldn’t freeze too easily.
Its generically called ‘glycol’...and I assume it is a lot like the water/antifreeze in a car.
I’ve been involved with a few installations at ramps into parking garages and one at a steep drive up to a hospital emergency room...and one very wealthy homeowner.
In general its reserved for steep or critical areas. The system actually takes up indoor space, because their are pumps and controls. And the energy use is very high, as you can imagine....not to mention the cost of the initial installation.
And the tubes are relatively small, so there are a lot of friction losses...meaning there is a finite limit to how far any given pump can push liquid through the tubes. So even a small driveway may have multiple zones (same goes for underfloor heating indoors). But this need for zoning makes it impractical to do really long installations...unless there are booster pumps along the way.
right. done with coolant/glycol mixtures, typically