This is a really neat idea. I had hoped that they owned the dam and the power generation too which would have upped the awesome factor considerably. They're "only" just doing most things right rather than everything conceivable. Oh well!
I think this is a great hack in the bitcoin world. Bitcoins don't care where they're mined so might as well mine them in places which minimize costs. Arbitrage!
Why would it not be more profitable for them to just mine the bitcoins for themselves?