Data centers are cropping up around the country, providing centralized computer server and storage capacity for both internet superstars like Google and Facebook as well as a much longer list of brick-and-mortar businesses. Data centers can consume significant amounts of electricity, so data center owners work hard to manage their energy costs and improve their energy efficiency.
Much of a data center's energy budget goes to keeping the servers and the building's airspace cool. Traditionally, this might include mechanical chillers -- effectively, powerful air conditioning units. To manage energy costs and environmental footprints, some data centers are turning to more passive cooling resources. Google recently announced that it is using recycled gray water from a local public water treatment facility to cool its data center in Douglas County, Georgia.
The Douglasville-Douglas County Water and Sewer Authority collects wastewater from local communities, treats it, and releases it into the Chattahoochee River. Google worked with the water and sewer authority to divert up to 30% of the water that would otherwise flow into the river to a special side-stream treatment plant. Once cleaned, this water is piped about 5 miles to Google's data center, where it is used for cooling.
Google's data center relies primarily on evaporative cooling. It takes energy to evaporate liquid water; as a consequence, you can use evaporating water to remove heat from air or other materials. (Think of the cooling effect of a dry breeze on wet skin.) Much of the water evaporates through this cooling process; Google sends any remaining cooling water to an on-site effluent treatment plant, from which the water is returned to the Chattahoochee River.
Using recycled water to cool data centers can save energy compared to mechanical chillers. Where clean water is scarce or expensive, the ability to use recycled water for cooling could also open up new capacity for data centers. Will more data centers turn to recycled gray water for evaporative cooling and energy cost management?