[anonymousDan]

No idea about the previous poster but I'm pretty sure I know how blockchain(s) work thanks. I don't claim to have a concrete proposal but the idea of proof of useful work has been around for a while as a research area (https://eprint.iacr.org/2017/203.pdf). Having a system that supports arbitrary computations might be hard, but perhaps any task for which solutions are easy-to-verify but difficult to compute might be a good fit. Alternatively, if creating an open/decentralized compute system is a goal then a proof of stake blockchain could allow users to post tasks with associated rewards (again in cases where solutions are easy-to-verify but hard to compute).