With cryptocurrencies wasting so much computing power, why is there nothing like a "Folding at Home Coin" for scientific computations?

You mean a more environmentally friendly crypto?

It's called cardano

I think it's because the act of "folding" is the same as "mining" with regards to computing cycles, and the "creation" of the crypto is inherent to its design while the "folding" activity from a system like Folding at Home is working at a potential unknown. When crypto is designed, there's already a set idea of how many coins are going to be mined, so there's a determined hash rate and all that. To assign that to a project like Folding at Home, the "coin" would be more like a folding "reward" unless you inserted a blockchain into the folding tasks, which would then just be mining and folding concurrently.