I wonder if you could use that hot water to drive a Stirling engine for electricity generation. If it worked, in the winter when the air temperature is lower it would get more powerful, the very time your power consumption was higher.
Steve looked at that idea but the problem was the size engine/generator we'd need was not cost effective compared to a common commercial generator. Even then, the Sterling generators on the market all have a gas or diesel powered engine attached to them to provide steady power.
Like hybrid cars it's less expensive (TCO and ROI) to just have a plain old generator.