Blockchain for useful public compute power?

I stumbled across a post by Christopher Allen[1] and pondered the concept
of building a blockchain like method, that used compute tasks for useful
public purpose in addition to the value orientated outcome.

Ie: useful purpose might be something like SETI[2]; but perhaps also more
flexible, so a marketplace of 'bounties' could be used to create the
economics around the compute.  users/clients could select the projects they
want to do, like a share-trading platform.

The output might also be a tradable 'normalised currency' like output for
the compute provider, like an amount of bitcoin or similar.   Theory was to
figure out how that might bring about a more efficient use of energy?  may
also be a means to extend something to be inclusive of labour in addition
to compute/processing/energy consumption.

Yet, in the initial idea; was that 'smart actors' might use their
computational 'agents' to use the energy they consume to generate more
value than it cost them.  bit like a knowledge/compute economy
framework...  The economic outcome of a particularly hard problem might be
worth alot more overtime, contributors end-up with a proof of stake, et.al.

just an idea,  thoughts?  any references?

tim.h.

[1] https://twitter.com/ChristopherA/status/883874266944491520
[2] https://en.wikipedia.org/wiki/SETI@home