On-site generation could be the way forward for data centres, says Peter Judge
Building a data centre in Utah can be a dangerous thing. The NSA’s plans to house its controversial surveillance data there are facing trouble because of electrical faults. But eBay’s centre there is going ahead well, despite a more radical approach to electrical power.
eBay, you see, is using on-site generation, effectively making itself virtually independent of the electricity grid. It has a bunch of Bloom Energy fuel cell boxes which extract energy from natural gas, and power the data centre, so the electricity grid can be used for back-up power, and there is no need for diesel generators or conventional uninterruptible power supplies (UPSs).
Bloom Box confidence
This is the biggest data centre (or at least the biggest that I am aware of) to generate its own electricity and effectively go off-grid.
Of course it’s a lot smaller than the centre the NSA is trying to build. With only about 6MW coming from eBay’s Bloom boxes, it’s about one-tenth as big as the NSA’s Bluffdale site.
And eBay’s operation isn’t even a “data centre” building as most of us know it. It’s a facility to connect up containerised servers. HP and Dell have produced new designs for containers, which they claim are respectively the biggest and the densest yet. In total, the site will be smaller than data centres like Apple’s in North Carolina, which partners with the utility and provides solar power from a large array.
But generating your own electricity is more than just a statement of independence. It is potentially a big thing, allowing a lot of rationalisation of other plant on the site.
eBay’s site is still connected to utility electricity for backup, but it can now choose the greenest option it can get for its primary power. Because the power is generated on-site, there should be less energy lost in transmitting it to where it is used. And also, because the grid is there for backup, it doesn’t have to rely on diesel for continuity.
Recovered energy revolution
Power independence has been suggested in the past, with Microsoft floating the idea of co-locating data centers on landfill sites to harvest the biogas they produce. In the UK, we have had Infinity proposing a data center powered by an on-site biomass digester.
The Bloom boxes are a good element but fuel cells run on hydrocarbon fuel, essentially methane. This can either be “natural gas”, taken from the ground by drilling or fracking, or biogas, reclaiming the gas produced by rotting organic waste.
Biogas would be greener, but eBay has had to opt for natural gas from the ground for supply reasons. The environment still benefits, the firm says, because natural gas is about fifty percent greener than the Utah grid average.
And then there is the recovered energy, which may be the most revolutionary part of the story. Using gas on site still requires that gas to be transported, and the gas transport network uses a lot of energy in pumping, compressing, and sometimes liquefying the product.
A lot of that energy is normally lost as waste heat, but the process of compressing and expanding gases is one where energy can be harvested instead of wasted.
The eBay centre will benefit from a recovered energy plant, which uses heat which would have been lost in transmitting the gas. This kind of energy recovery could be used more widely and, if it makes the gas transmission network more efficient, could allow more sites to use on-site generation.
A version of this article appeared on Green Data Centre News.