I'm having a bit of difficulty with the "they don't generate heat" aspect of things. They might not generate as much heat as a fridge with a compressor, but they still generate heat.
It's all a matter of (if you'll forgive the pun) degree.
It's also likely that with the lack of mechanical components (like a compressor), these fridge's are slightly more energy efficient (which also means not as much heat is gerated as a by-product).
Don't mind me, just picking nits...