Industry Perspective is a regular Data Center Journal Q&A series that presents expert views on market trends, technologies and other issues relevant to data centers and IT.
This week, Industry Perspective asks Lex Coors about Interxion's use of seawater to cool its data centers helped greatly reduce energy costs. Lex is VP of the data center technology and engineering group, as well as chief engineering officer, at Interxion, a European provider of cloud- and carrier-neutral colocation data center services.
Industry Perspective: Consumption of fresh water by data centers is a concern, particularly in drier regions. What are the benefits of using seawater instead?
Lex Coors: Seawater resources are not for consumption. Seawater cooling systems filter water up from the bottom of the seafloor, where water is very cold, through the HVAC system of nearby data centers to counteract very hot servers, and then back to the sea. Therefore, there is no impact on the availability of water in a given region as every drop is returned to its origin.
IP: How does your facility address the technical challenges of using seawater, particularly with regard to corrosion?
LC: Interxion builds all of its data centers in large European cities and therefore has been dealing with air corrosion for years. Given that experience, the company has applied its knowledge of corrosion prevention to the seawater cooling system. For instance, Interxion uses materials like Cunifer and titanium, which will last approximately 10 years in seawater. We also engage in significant cleaning to prevent barnacles and other marine life from attaching to our piping.
IP: Broadly, how does your cooling system operate?
LC: Seawater cooling systems pump deep, cold seawater through a data center’s heat-ventilation-AC (HVAC) system, cooling the air that is circulated in the facility and 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, a process that requires very high levels of energy.
Interxion took that technique one step further to cool its Stockholm data center campus, which has multiple facilities that require cooling. Because the seawater temperature after filtering through one data center’s HVAC system is still relatively cold, Interxion’s system runs the same seawater through phases 1 and 2 twice, with a third filtration through phase 3 of the data center. This effectively triples the use of the seawater, minimizing the amount that needs to be pumped out of the ocean and into the system.
IP: Roughly, what is the temperature of the seawater at intake?
LC: The temperature of the water at intake is 6 degrees Celsius (43 degrees Fahrenheit).
IP: What operational benefits do you garner by using seawater for cooling, specifically in the area of energy efficiency?
LC: Interxion’s seawater system has resulted in an 80 percent reduction in energy costs, as compared with a traditional chiller system. Plus, Interxion has dramatically improved the PUE of its Stockholm data center campus from approximately 1.6 to 1.09, or nearly energy neutral.
Interxion’s seawater cooling system has also eased the data centers’ previously heavy IT loads. Before implementing seawater cooling, the IT loads of Interxion’s data centers 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, granting Interxion the ability to house additional customers in the same square footage and at a lower cost.
IP: Although use of water for cooling may not create any damaging chemicals, the heated water can have negative effects when returned to the environment. How do you address these kinds of concerns at your facility?
LC: After processing through the data centers, the seawater in Interxion’s system reaches about 70 degrees Fahrenheit and is, by today’s standards, no longer usable to cool a data center facility. While depositing this water back into the expansive ocean likely wouldn’t impact the water’s temperature, it may have an effect on local wildlife. Therefore, instead of immediately returning the heated water into the ocean, Interxion distributes it among local homes and businesses to help heat buildings. Not only does this cool the water back down, it also helps offset heating costs for the local community. In addition, we rely on the current of the sea to spread water used in our system over a large area, thereby reducing the impact of warmer water on marine life.