Indeed. That’s the only way that thing would work down to -30C. There has to be some kind of heat to pump out that is usable (and recoverable) in the first place. The higher thermal ballast of deep earth is the only way, IMO.
I was out east some 40 years ago near the Virginia coast. A prolong cold snap hit. Most HP piping was only about a foot or so below ground level. Lots of people had news worthy issues..