Use this as the low-T side of a heat engine, and you've got a nice little generating technology. Maybe filtering the outgoing radiation to enhance an available

Use this as the low-T side of a heat engine, and you've got a nice little generating technology. Maybe filtering the outgoing radiation to enhance an available low-absorbance band (or bands) and you might be able to help yourself to the T of the background sky. I've actually thought about this a fair bit for things like low-T geothermal resources (increasing the Carnot Delta T by working on the low-T side). Any optical physicists want to prove to me that I'm full of crap?