Via HPCwire.com:
Water scarcity has been surfacing as an extremely critical issue worth addressing in the U.S. as well as around the globe nowadays. A McKinsey-led report shows that, by 2030, the global water demand is expected to exceed the supply by 40%. According to another recent report by The Congressional Research Service (CRS), more than 70% of the land area in the U.S. underwent drought condition during August, 2012.
When it comes to 2014, the condition has become even worse in some of the states: following a three-year dry period, California declared state-wide drought emergency. A report by NBC News on this drought quotes California Gov. Jerry Brown as saying, “perhaps the worst drought California has ever seen since records began being kept about 100 years ago”. Many such evidences of extended droughts and water scarcity have undoubtedly necessitated concerted approaches to tackling the global crisis and ensuring water sustainability.
Supercomputers are notorious for consuming a significant amount of electricity, but a less-known fact is that supercomputers are also extremely “thirsty” and consume a huge amount of water to cool down servers through cooling towers that are typically located on the roof of supercomputer facilities. While high-density servers packed in a supercomputer center can save space and/or costs, they also generate a large amount of heat which, if not properly removed, could damage the equipment and result in huge economic losses.
The high heat capacity makes water an ideal and energy-efficient medium to reject server heat into the environment through evaporation, an old yet effective cooling mechanism. According to Amazon’s James Hamilton, a 15MW data center could guzzle up to 360,000 gallons of water per day. The U.S. National Security Agency’s data center in Utah would require up to 1.7 million gallons of water per day, enough to satiate over 10,000 households’ water needs.
Although water consumption is related to energy consumption, they also differ from each other: due to time-varying water efficiency resulting from volatile outside temperatures, the same amount of server energy but consumed at different times may also result in different amount of water evaporation in cooling towers. In addition to onsite cooling towers, the enormous appetite for electricity also holds supercomputers accountable for offsite water consumption embedded in electricity production. As a matter of fact, electricity production accounts for the largest water withdrawal among all sectors in the U.S. While not all the water withdrawal is consumed or “lost” via evaporation, the national average water consumption for just one kWh electricity still reaches 1.8L/kWh, even excluding hydropower which itself is a huge water consumer.