Case study: Recycling data center seawater amplifies energy savings

Case study: Recycling data center seawater amplifies energy savings

When it's time to chill, seawater cooling systems have environmental and cost-effective advantages over other methods used by data centers. Implementation costs may be higher, but such systems pay themselves back in terms of energy savings that translate into a significant reduction of operating costs – as well as an increased IT load capacity.

It’s possible to take the benefits and cost savings of seawater cooling one step further -- as my company Interxion found -- by using the same seawater to cool two data centers and help heat neighboring homes and businesses. This case study details the energy savings and additional benefits that resulted from taking such a nontraditional approach.


Interxion runs a network of data centers in 11 countries across Europe. Like Google, another company using seawater cooling, Interxion has seen success in lowering PUE measurements and increasing data center energy efficiency. Interxion wanted to explore ways to increase energy efficiency and cost savings to an even greater degree.


Seawater cooling systems pump deep, cold seawater through a data center’s HVAC system. As a result, the air circulating within a facility is cooled, which has the effect of lowering the inside temperature. Although the mechanics of this process are similar to chiller systems, seawater cooling completely eliminates the need to cool water down, which is a process that requires very high levels of energy. The traditional seawater cooling system runs an allocation of seawater through a data center once.

Interxion decided to stray from the traditional approach and run the same seawater through two data centers two times each. The reasoning? After running through one data center, the seawater temperature is still cold enough to cool a second. This practice effectively quadruples the use of the seawater and also minimizes the amount that needs to be pumped out of the ocean.

Photo of cooling technology at Interxion's data center (heat exchange units with lightning protection rods on top of them) in Amsterdam courtesy of Interxion.


Reduced energy costs: By running seawater through a pair of data centers two times each, Interxion reduced its energy costs an additional 13 percent.

Increased energy efficiency: Using the seawater four times to cool a pair of data centers, Interxion has boosted energy efficiency across multiple data centers. And by using the seawater a fifth time to offset heating costs in other nearby buildings, Interxion has contributed to the overall energy efficiency of the surrounding community as well.

Interxion’s seawater cooling system has also improved the PUE of each data center from approximately 1.95 (the result of running chillers during an unusually hot summer) to 1.09 -- a measurement only 0.09 away from being completely energy neutral.

Eased heavy IT loads: Before implementing seawater cooling, Interxion’s data centers’ IT loads were so heavy that there was minimal capacity for customers to increase power use. Now the amount of energy needed to cool the data center has been reduced enough to increase the IT load. This enables the company to house additional customers within the same square footage and at a lower cost.


The short, medium and long-term energy savings of a seawater cooling system make it an attractive cost-effective option for data center managers. In addition to the significant operating cost reductions that seawater cooling offers, most data center managers also see a significant drop in PUE within their data centers.

For data centers that allow a single point of failure, including Interxion, there are additional benefits to increase the IT load as energy-consuming chillers are not required anymore.

Compounding these energy savings, seawater cooling systems are highly consistent and reliable, as opposed to chillers that often fluctuate in energy usage.

For example, chiller costs tend to spike in the summer, especially in data centers that aren’t completely sealed, resulting in higher than normal operating costs during the hottest months. For data center operators located in warmer climates, this is an ongoing battle. With seawater cooling, the temperature of deep seawater does not fluctuate. As a result, no extra energy is needed to cool it further. This means that the system can operate consistently on the same amount of power regardless of the outside temperature or a data center’s geographic location.

When one takes these benefits into account, seawater cooling offers immense benefits that other cooling systems simply cannot match.