Yes, kinda like folding@home, just generalized and easy for everyone to use. Also, big advantage is the bandwidth usage (which would likely be a bigger selling point than CPU time).

As for the electricity cost.. The tokens would have to be worth more than what you spend on extra power. And there's also the thing of "why don't I just use my own PC for 2 days instead of 10 PCs for 5 hours each?", to which the answer is go for it if you can. But you may have a problem where you just got the data and need it folded or whatever as soon as possible.

Again, I feel the bigger use case here is the network, which very low extra electrical bill. For compute, you can just rent EC2 or some other compute station in the cloud, but having hundreds of network nodes for short amounts of time is really hard to buy currently.