The initial device was relatively tiny, and only produced 1.3 milliwatts of power. That's enough for basic sensors or communication sensors, however, and it's hard to complain too loudly when it's virtually effortless. It could also be changed to produce energy from other temperature cycles, like those in a fridge or a factory.

There are more than a few potential uses, especially if researchers can increase the power output. MIT envisioned planetary rovers that can keep running for years without needing special conditions. Thermal resonators could also serve as backups for existing renewable energy: if a solar panel goes down, the grid could still have enough power to broadcast a request for help. It wouldn't be an infinite source of power by any means, but it would be trustworthy enough that you could leave a device alone knowing that it always has at least some kind of electricity on tap.