Sustainable Data Centers: Energy/Water Tradeoffs

Sustainable Data Centers: Energy/Water Tradeoffs

New CyrusOne sustainable data centers are generally designed to avoid dependence on water. Traditionally, data centers have utilized cooling systems that evaporate water, removing millions of gallons of water from the watershed and discharging wastewater with highly-concentrated contaminants to the local treatment system.

CyrusOne’s Sustainable Data Center Strategy: Avoid Water Dependence

Our sustainable data center strategy is to design our facilities without reliance on water consumption-based cooling, in order to take advantage of the increased reliability and provide regional environmental benefits. This results in a somewhat higher design PUE (Power Usage Effectiveness, a common metric used to measure data center efficiency) than could be achieved by “burning” water instead of electricity, but it allows us to prepare for the future and mitigate the impacts data centers have on regional water supplies, especially in regions identified by our Water Risk Assessment as high water stress, like Phoenix or Dallas. To make this distinction visible, we always report our PUE separately for wet facilities and dry facilities.

While using non-potable water (such as reclaimed water or rainwater) for evaporative cooling can provide some energy-saving benefits to the local treatment works (compared to cleaning the water to potable standards), it does little to help the total water balance in the watershed. Since our goal is to reduce regional water stress through our sustainability design and operations, we favor approaches that eliminate water consumption, rather than consuming an alternative water source.

CyrusOne’s Innovative Design

Our innovative sustainable data center design instead uses an air-cooled chiller with an integrated compressor and condenser to cool a closed loop of water. This chilled water is used to remove the heat from the data hall, but none is evaporated in the process. The water loop is filled once during construction and remains filled throughout the life of the facility. This closed-loop technology avoids new water usage in operations and the release of concentrated pollutants into the wastewater system. Our water-efficient building design not only minimizes water use and, thus, water risk in our operations, but is also significantly faster to build than water-consuming cooling systems used in other data centers. This reduces the need for costly water and industrial sewage infrastructure in buildings as well.

This strategy is not perfect. Climate change is a serious threat to the world, and at some facilities, we are likely emitting more carbon today than we would if we used evaporative cooling. Some may argue that it is better at this moment to consume water than electricity. This is a worthwhile discussion, but we don’t design facilities only for current conditions; rather, when we build a new data center, we design it to operate for decades to come. Global water stress is predicted to increase dramatically in that timeframe, and we want our facilities to be resilient. We do not ignore our carbon footprint — on the contrary, we are aggressively pursuing low-carbon electricity. Our facilities are designed for a future where they will neither consume large amounts of water nor emit large amounts of carbon.