Energy is critical to data centers; rising prices, potential new regulations and taxes, and limited supply make it a topic that is foremost on the minds of both data center managers and industry observers. But another resource used heavily by data centers bears remembering: water. What should companies do about water when it comes to their data center facilities?
Water Consumption a Concern
All data centers consume energy, making energy the biggest concern for a variety of parties (companies, environmental groups and others) when it comes to resource usage. But water—although it is not used by all data centers—is another concern that is often overlooked. Water is a critical component of some data center cooling systems; large data centers using evaporative cooling, for instance, can consume hundreds of thousands of gallons of water a day. DatacenterDynamics (“Microsoft: we too use recycled water to cool data centers”) notes that Microsoft’s San Antonio data center consumes some eight million gallons of water per month: that’s about 250,000 gallons a day.
A look at the U.S. Drought Monitor shows that the majority of the contiguous 48 states are under drought conditions, particularly those in the western and midwestern states, with a heavy patch of drought in Georgia and Alabama. Water supply is a perennial concern in the west, even when the region is not exceptionally dry. Large data centers with hefty water appetites can outstrip utilities’ ability to supply water, putting pressure on infrastructure and threatening availability of water to residents and companies that consume relatively small amounts. And these situations can quickly be exacerbated by drought conditions.
Some data centers can and do operate without consuming much (if any) water. For these facilities, air-based cooling methods may be sufficient to prevent equipment from overheating. But for data centers with high-density deployments—such as those pursuing high-performance computing or that use blade servers and similar equipment—air cooling is often insufficient. In these cases, liquid-cooling methods are often more appropriate, as water (for instance) is better able to hold and move heat compared with air. Depending on the details of the cooling implementation, such facilities can consume large amounts of water.
What Can Data Centers Do to Conserve Water?
Companies that operate or plan to build data centers should keep water in mind as much as they do energy. Here are a few considerations that can aid in conservation and minimize the impact of data centers on the areas surrounding them.
- Increase IT energy efficiency. Every watt of power consumed in your data center is converted into heat that must be removed to the outside environment. The less heat your facility produces, the less cooling you’ll need to do. Typically, savings in this area focus on reduced costs and energy consumption, but reduced water consumption is another area of savings for those data centers that employ liquid cooling. Greater energy efficiency is beneficial in a variety of ways, and saving water is one of them.
- Consider alternative water sources. Water is (almost) everywhere, but potable water (the stuff that comes out of your tap) is a relatively precious resource. Some companies, such as Google, are instead turning to so-called grey water as a means of meeting their data centers’ need for water while reducing their impact on potable water supplies. Grey water is wastewater from sinks, tubs and similar uses that doesn’t contain human waste. Because it doesn’t require the same treatment as “brown water”—and because data centers do not need potable water—grey water that is cleaned up slightly can be used for cooling. This approach reduces the effort (and energy) needed to treat the water, aiding the utility and reducing pressure on potable supplies. Of course, it’s not quite as simple as running water from bathroom sinks directly into the data center (“Google cools data center with bathtubs, dishwashers”), and it may not be a good alternative for small companies running a data center, but it is a possibility for companies operating large facilities. Even seawater is a possibility for cooling (“Google to double seawater-cooled Hamina data center’s capacity”), although the salt content creates some technical challenges—such novel methods might best be left to companies like Google.
- Improve cooling efficiency in the data center. Increasing IT efficiency is one way to decrease water consumption if you facility uses water-based cooling, but there are other steps you can take. Implement standard industry practices for better cooling efficiency: for instance, use hot-aisle/cold-aisle containment, ensure minimum mixing of hot air and cold air (e.g., plug open cable holes in cabinets) and ensure minimum obstruction of airflow.
- Use free cooling. ASHRAE’s recently updated temperature and humidity guidelines enable many data centers to operate at higher temperatures, meaning less cooling is needed overall. Furthermore, these guidelines make free cooling a possibility for a larger portion of the year—all year long, in most locations (depending on the particulars of the IT equipment). Free cooling provides a host of benefits, including less cooling infrastructure (and hence lower capital costs), lower energy consumption and lower water consumption (thus reducing operating expenses). Although free cooling isn’t really free, it’s much less expensive than traditional cooling methods, and it can ease the pressure large data centers place on both electrical and water utilities.
- Choose your location wisely. If you’re building a data center that relies heavily on water, you will naturally want to select a location where water is readily available. In addition to minding the risks to your business (e.g., the potential for drought and its possible effects on the water supply), consider the impact your facility will have on utilities and, thus, residents and other businesses. Check with utilities to determine if an alternative water source (like grey water) is a possibility. Stay on the good side of everybody as much as possible—you don’t want to earn a reputation as a water hog, particularly if a drought strikes.
- Monitor your water efficiency. The less water you use, the more money you save; so keep track of how much water you’re using. Metrics like The Green Grid’s water usage effectiveness (WUE—similar to PUE, or power usage effectiveness) can help you monitor your data center’s water efficiency. Set goals for improved efficiency and work toward them.
Water isn’t as flashy as energy, but it’s a critical component of many data centers, and it is just as important a resource. If your data center consumes water, you can take steps to improve your efficiency and cut costs as well; the key is to make water a priority, just like energy. Of course, efficiency improvements generally incur some costs, and weighing the costs relative to the benefits is a necessary part of the business. The current drought situation—particularly in the west and midwest—shows that water cannot be ignored. Whether you’re operating a data center or planning to build one, make water conservation a top concern, both for the sake of saving costs and for the sake of protecting a precious resource.
Photo courtesy of dr_relling