This is what we are doing at Qarnot Computing for 5years.
We created a heater using CPU as a heat source.
People send a docker image (3d rendering, financial analysis...) and we run it on heaters deployed in buildings in Paris where people are heated for free (we refund the electricity cost)
https://computing.qarnot.com https://www.qarnot.com/faq/
Disclosure: I work there :)