[Terr_]

> but I don't see how this is "solid state"

I think the idea is that there are actually two jobs going on, and one of them has been solid-state-ified: (1) cycling something between hot and cold and (2) ensuring emit-heat-to-environment happens separately from the absorb-heat-from-contents part.

In a regular refrigerator, refrigerant is pumped around doing both things at once, however we could imagine a system where there's two loops with a heat-exchanger: One small liquid+gas loop for refrigerant, and another silicone-oil loop.