Green Google’s Sea Change In Data Centre Design

Google is preparing to open its latest sustainable data centre in Hamina, Finland, this autumn. The centre will use sea water as its cooling source.

Much of the work of ducting the seawater into the building had already been done when the building was a paper mill. Google will use these 60-year old earthworks to supply ice-cold water to reduce the temperature of its servers.

Heat Exchange Reduces Corrosive Effects

In 2009, Google bought the Stora Enso paper mill for $52 million (£32m) and has spent a further $200 million (£120m) to repurpose the building. Using the mill’s original pumping station built 20 years ago, cold water is drawn from the two-metre diameter pipe leading from the granite tunnels.

The seawater is filtered four times to remove particles and then enters a heat exchanger. This reduces the temperature of a separate, closed, non-saline water system that actually cools the servers. This is necessary to avoid problems being caused by the corrosive nature of salt water.

Google had to conduct extensive thermal testing before deciding whether to use the cooling system which was closed in 2008. The thermal testing tracked differences in ocean temperature in different tidal and weather conditions, which helped the company determine the best depth for the input to provide an optimal temperature. For part of the year, the Baltic Sea freezes and this also had to be taken into consideration.

Minimising Environmental Effects

Once the seawater has done its work, it is also cooled before being returned to the local environment to avoid damaging the marine-life ecosystem. There is no legal imperative for Google to do this but the company feels that, morally, environmental impacts should be minimised.

The process could be criticised because all of the pumping and filtration consumes a fair amount of electricity but the PUE of the site will be kept low by the use of electricity from a nearby wind farm.

Google plans to bring the data centre on-stream gradually in the lead up to the official opening in autumn. A video (see below) has been produced outlining the project.

Google claims that the colder climate location is everything in its decision to use sea water but the Indian Ocean island of Mauritius is already pioneering seawater cooling even though its location, off the African coast, would make it seem inefficient.

There is a secret that makes the co-operative project with Makai Ocean Engineering work. The ocean has a cold water undercurrent and pipelines have been laid two miles off the coast to tap into this natural cold water source. Mauritius plans to use the seawater to enable several more data centres to be housed on the island in coming years.