Perpetua is a company that has made a breakthrough in thermoelectric energy. Tons of applications to pull small amounts of energy from heat sources to run sensors and provide charges to battery packs etc.
This taken from their technology section on the website
Essentially the product could be used in any place there is a great temperature difference between the hotter surface you are going to attach the device to and the ambient air temperature. The technology seems quite adaptable to difference applications and would appear to be customizable given its flexible nature. All I can think of is all of the heat sinks and radiators that just spew that energy out into the environment. The idea of capturing that energy and using it is very alluring.