[serf]

>It will keep things refrigerator cold for as long as you want, and it's almost completely silent in operation.

that's more a function of the insulation , rather than the cooling ability. The wattage needed for 'thermal maintenance' is far lower than needed for actually removing heat from the system.

Peltiers' are kind of on the same scale of efficiency as using your car (on purpose) to cook food in the engine bay.

[Baeocystin]

...and yet that is still useful enough to be the right answer for some products. For the camp cooler example, it means I don't have to waste precious space on ice packs, nor worry about water as ice melts. If I put in room temperature sodas, they will be cold within 24 hours, which is good enough to be useful. On cold days I can run it in reverse and have a hot drink at break time. And the cooler/heater itself barely adds any weight to the cooler itself.

As a side note, look up the book 'manifold destiny'. It's all about cooking with one's engine bay. An amusing read!