I was talking recently with the IT director of a water and sewage utility company, and he mentioned their new DC project. They are powering the DC with sewage sludge (yes, that is what you think it might be) similar in principle I guess to landfill gas power. I can't remember the numbers of the top of my head, but he was talking about substantial generation capacity on site from the sludge - 100's of kWs if not MWs. Although I'm not sure I'd want to spend too much time there (!), I was rather impressed with this innovative approach.

I read on another thread that Hostgator are generating wind power at each of their sites equivalent to 120% of their usage (although I can't find anything to back that up on Hostgator's website, though I have no reason to doubt it). Again, impressive if true.

The Thor Data Centre in Iceland (hands up here as we represent them) runs on a totally renewables based power grid, with no fossil fuels used for grid power. So practically zero carbon emissions.

More and more people are going to be looking to options like the above as fuel costs and carbon taxes (eg UK CRC tax) continue to rise.

What other impressive energy/CO2 saving programmes have you seen? (And please, not just buying so-called green electricity from a brown grid or doing carbon offsets)