Used similar ones all the time, although not for generating. It's very inefficient.
There is a max delta t and and a max t. Think of it as a solid state heat pump. Delta T is usually around 40 or 60 C, The current trend is to use PWM to modulate the cooler. Usually we had a water cooled tap water block for one side and we were trying for 25 C on the other. Response time is also slow. Usually you don't have to control the temperature (i.e. PID), just the block voltage. It's advisable to have current limit.
I also used a larger "module" for air to air and air to block modes.
I think Derstrom8 was expecting something like "I think this would be better than my USB coffee warmer" What do you guys think? Besides that I can use it to cool beverages too. DerStrom answered your question. For the standard "What's up?" line, I reply back with "A relative direction, usually that way (and point up)". or for "Do you want to eat in or take out?" If I'm in a playful mood, I'll say "Yes".
These are use in some refrigerators and medical coolers.