Green Data Centres Could Run On Pig Manure

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Peter Judge

Google and Apple both look like using the same source to reduce their carbon emissions, says Peter Judge

People keen to reduce the emissions of their data centres are prepared to look in some unlikely places. In North Carolina, that includes pig manure.

Google’s commitment to renewable energy remains strong, although it has curtailed some of its original commitment to green energy research for its own sake. In North Carolina, this led it into the use of pig manure – and it seems likely that Apple could also be diving in to join it.

Pigs poop makes sense

Google got stuck into piggy poo for solid commercial and environmental reasons, as part of its carbon offset programme, by which it keeps the company carbon neutral.

The company runs as efficiently as possible, and buys carbon offsets to make up for the rest of its emissions, by funding projects that reduce carbon emissions elsewhere.

Among the projects Google funds is a waste management system at Loyd Ray Farms in Yadkin County, North Carolina, jointly run with Duke University’s Carbon Offsets Initiative.  The farm’s 9,000 pigs produce 400,000 gallons of manure every week, which is too high in nitrogen to be used as fertiliser. The manure was originally pumped into a local pond, where farm owner Loyd Bryant says it released methane, ammonia and “an unholy stink”, according to the Los Angeles Times.

Google helped fund a $1.2 million system, which puts the manure into an anaerobic digester to collect the methane, which is burnt in a 65kW turbine to provide for half the farm’s electricity needs. Burning methane produces CO2, but methane is 21 times worse as a greenhouse gas than CO2, so the planet ends up ahead, and the energy is useful.

Apple wants methane?

Enter Apple, on a mission to make its Maiden, North Carolina data centre as low-carbon as possible. The firm has put in a 20MW solar array at the site, which provides some – albeit a very small percentage – of its electricity needs.  The project has been criticised for clearing 171 acres to supply only four percent of the plant’s electricity needs.

Apple has since announced its plans for a 5MW fuel cell array at the data centre, which is expected to use Bloom Energy fuel cells . Again, this is a small percentage of the data centre’s overall needs, but the firm feels the need to invest because North Carolina has very dirty (coal-based) electricity.

Like most other renewable energy projects, it serves mostly to show how limited the scope of renewable energy is – and how huge any serious installation would have to be to make a real difference.

However, fuel cells use gas from decomposed biomass, so one or two sites have put the two stories together, and realised that Apple’s could be supplied by gas from the same source as Google’s carbon credits: Pig manure.

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