GigaOm had a piece earlier this week about biogas powering data centers. It's giving me flashbacks to HP's hype piece about data centers down on the farm. 

First, let's get this out of the way:  Methane, the key component of biogas fuel, comes from rotting, stinking things, typically waste products.  You get methane out of waste dumps, landfills, sewer treatment plants, and from the droppings of animals -- barnyard and human.

By no means is burning methane carbon-free, but the gas remains in the atmosphere for 9 to 15 years and is over 20 times more effective in trapping heat in the atmosphere than stock CO2.  Burning methane gas, be it from a waste dump or leaking from a natural gas or oil well, is ironically a lot better for the environment because the primary waste product is CO2.  Putting "free range" biogas or natural gas in a fuel cell, like a Bloom Energy Server, rather than having it simply leak into the atmosphere helps to slow global warming by a factor of 20 for every unit of gas consumed. 

In a lot of cases, excess methane and natural gas is simply flared off (burned) at a waste dump or well site because it's not economical to capture and pipe it for sale.  You might see a few data centers appear near more urban waste dumps, but the key thing to realize is there aren't many waste dumps next to people.

Which brings me back to farm manure -- an environmental mess at large hog and chicken farms.  Everyone wants to take the ugly, smelly refuse and do something with it, since the runoff poisons waterways and just is foul. 

Do you turn farms into power plants?  Do you put a data center besides a farm? Again, you get into the urban/rural issue of cheaper costs, but less fiber connectivity and trying to hire skilled labor away from the big city.  Some IT people will move out to the countryside to get away from it all, but it's difficult to envision a hundred Bob's Data Barn franchises springing up in the U.S. agricultural heartland.

City and municipal sewage treatment plants may have the right combination of a steady, er, supply of raw materials for biogas for power generation, as well as lower cost (i.e. less desirable) real estate next door.  A green -- but not necessarily odor-free -- data center could find a home next to a large sewage facility, but if you're already in an urban area, it makes more sense just to simply pump bio-gas generated electricity back into the grid.   All the power, none of the odor.