Alex Arthur tells DCM about how it created a green data centre

When we conceived the Elean Data Campus, near Cambridge, our overriding mission was to design a services system that would be the greenest in Europe.

We are all aware of Government and other agencies’ concerns about the relentless growth of energy usage in the data industry. Indeed, it is estimated that the data industry will soon overtake the aviation industry, in carbon production.
Elean's USP is that it uses absorption cooling as part of a combined heat and power system to generate electricity and chilled water 50% cheaper than the Grid.

Each building is stand alone, and fitted out to the client’s required Tier Rating. However, all electricity and chilled water is produced on site, and distributed through a ring main.

The site is supported by two independent Grid supplies, giving an on site load of 25MVA.

Elean enjoys a top specification of 1500 / 2000 watts per square metre within the data halls, and utilises all current technology.

The halls and buildings have been arranged to accommodate Tier Levels of 1 - 4 plus.

So, how does Elean’s absorption cooling system work?

All of the site electricity is generated from gas, derived from two independent supplies, and initial hot water comes from the adjacent biomass power station at 45˚C. The plant will only use 100% carbon-neutral waste as a power source, reducing its environmental impact.

At this point it is introduced to the exhaust jackets on the gas engines, where it is super-heated to high pressure steam.
This steam drives the absorption chillers, which, as they are a chemical rather than mechanical refrigeration process, use virtually no electricity.

In this way, we have reduced the maximum projected load of 65MVA to 34MVA.

Waste heat from the plant will be available not only as an energy source to cool the data centres but could also heat the 400 homes of an accompanying Eco Village.

Absorption cooling is not a new product, it has been around since the 1920’s, and is in everyday use, in the petroleum, pharmaceutical, and marine industries - in fact anywhere there are large quantities of steam.

In Elean’s case, the absorption chillers operate through a simple heat exchange process using super-heated lithium bromide, which would be energised using the off-take heat from the power station, then superheating it through the exhaust flues of the generating gas engines on site, consuming almost no new energy.

It would not be economic to raise steam for absorption if you were paying for the gas as a direct source, but in our case it is a free bi-product.

These energy savings represent a 52% reduction against a conventional data centre solution.
Each tenant at the Elean Data Campus may draw their electricity and chilled water, and pay 27.5% less than current Grid prices.

This translates into a saving across the site of £12.5m per annum.

Projected savings over twenty-five years are estimated at £1.25bn.

Because the electricity and chilled water is being produced by combined heat and power, the entire facility will be carbon tax free.

With initial actual costs of carbon at £15 per carbon ton, and estimates of tax at £50 plus per carbon, when it goes open market in 2012 the above savings could double over a twenty-five year period.

Perhaps not just Europe’s greenest data centre, but also the best vale for money, too?