It'll be ludicrously expensive to built, and then you'll also have a ridiculous amount of heat to get rid of. The main challenge will be keeping that from melting the ice again (this, in general, is the underlying issue with TECs: they don't have any means of stopping heat from flowing back through them, so it's a bit like trying to bail out a leaking boat, and it gets worse the larger the temperature difference you're trying to achieve. TECs max out their efficiency at a mediocre COP at very low temperature differences, in comparison to compressor based systems which can achieve better COP with more than 10x the temperature difference)