When Interxion opened its latest data center in Copenhagen last month one of the most interesting features of the new facility was under the surface - literally. Taking advantage of the region’s geology, Interxion is supplementing the free air cooling afforded by the Danish location with a custom groundwater cooling system.

– Interxion

Using two large chambers dug 70m below the surface into the chalk substrate Interxion provides naturally cooled water to its chillers for the cost of pumping. The water is circulated through the chillers, providing 1200 MW of cooling relief, before being recycled back down to the subterranean chamber where the waste heat is bled off into the surrounding chalk walls.

The system is unlike other groundwater cooling systems, says the Danish manufacturer Grundfos, in being built from plug-and-play components. Grundfos believes the system can be replicated on other sites blessed with suitable geology.

Environmental safety

Groundwater cooling is energy efficient and has little impact on the environment, but earlier this year Bavarian fish farmer Anton Kurz tried to block e-Shelter from using groundwater cooling, arguing that the small temperature rise would reduce his yields.  

Kurz withdrew his complaint, and Interxion has no environmental worries. Bob Landstrom, director of product management for Interxion, told DatacenterDynamics that the system in Copenhagen is simple and secure, with no risk to the local aquifer.

In fact, Landstrom told us the water used is considered potable and is marked as a reserve supply for city use in the event of an emergency. The green nature of this cooling is also attractive to Interxion for more than just the cost reduction - it is reckoned it could save 1.2 GWh per year if fully operational, or 308 tonnes of CO2. 

Customers moving to Europe from the US have green technologies high on their list of considerations when selecting a data center provider. And the nature of the regulatory environment in Europe is such that efficient use of power is critical for meeting those requirements.

Groundwater cooling is a popular option in Amsterdam where Telecity, the provider which attempted to buy Interxion has a site cooled in this way. By coincidence, Equinix, the eventual buyer of Telecity, also has a groundwater-cooled data center in Amsterdam.

And this isn’t Interxion’s first foray into alternative cooling methodologies; the company has been using seawater cooling in its Stockholm data center since 2013.