When people use the internet, they rely on a data center to store, manage and disseminate information. To keep these centers running efficiently, a tremendous amount of energy and water are required, providing yet another example of the important nexus between water and energy resources. Digital cryptocurrencies cause similar concerns.
How Do Data Centers Use Water?
Data centers, which house computer data systems, are energy hogs that use increasingly more energy thanks to the shift towards cloud computing. The large energy appetite of data centers has been well-documented: Facilities are often run at full power 24 hours a day, seven days a week, regardless of demand, gobbling up two percent of the nation’s electricity, and their backup generators are often powered by diesel.
The way data centers use water and how much they use is less well-known.
There are nearly 3 million data centers in the United States, ranging in size from several servers in an office closet to the 3.5 million square foot Switch SuperNAP data center in Las Vegas, Nevada. California has the largest concentration, at 800 centers.
All large data servers use water, both directly and indirectly: They withdraw water directly to cool the servers that get hot from operational use, and they use water indirectly because they power their servers and cooling systems with electricity generated at power plants which rely on water for their own cooling needs.
How Much Water Do Data Centers Use?
Back in 2009 Amazon estimated that a 15 megawatt data center can require up to 360,000 gallons of water a day, leading one of the company’s data center designers to admit that “water consumption (in data centers) is super embarrassing. It just doesn’t feel responsible.”
A report from the US Department of Energy’s Lawrence Berkeley National Laboratory found that the nation’s data centers collectively consumed 165 billion gallons of water in 2014 a number they expect to creep upwards to 174 billion gallons in 2020. The estimate accounts for both direct consumption for cooling at data center sites and indirect consumption via water used to generate electricity. The researchers found that most water use at data centers is indirect since it takes an average 2 gallons of water to generate 1 kWh of energy in the United States, while an average data center uses 0.48 gallons of water for cooling for every kWh it consumes.
The good news is that, over the past decade, the growth of both water and energy use at data centers appears to be slowing down. This can be measured using a handy metric called Water Use Efficiency, or WUE, which has been embraced by data center managers.
In short, WUE is calculated by dividing annual water usage (in liters) by IT equipment energy (kilowatt hours). The resulting number indicates how many liters of water per kilowatt hour are used onsite to operate the data center. For a more accurate WUE, it’s possible to add the amount of water required to generate the electricity used at the data center (The Green Grid Association provides all the figures and formulas needed).
Where Are Data Centers Using Water?
While they can be found throughout the United States, as of 2015, California was home to an estimated 800 data centers (not including smaller business-sized computer rooms), the most of any state. Given California’s recent history with extreme drought, this can create conflict with other water users in the state, not to mention make data centers vulnerable to variable water supplies.
Across the United States
Of course, California is not the only state where data centers face water issues. The NSA’s data center in Utah, its largest, reportedly uses 1.7 million gallons of water per day even during recent drought conditions. Facebook’s and Apple’s data centers in Prineville, Oregon compete for freshwater with farmers and a growing local population thanks to an influx of data center jobs. Back east, Google is looking to draw 1.5 million gallons per day from a South Carolina aquifer in addition to the 4 million gallons of surface water it already uses per day. The request is part of what the Post and Courier called “water wars” between new industries, corporate farms and an influx of new residents.
Some companies are becoming more transparent about their water demands. Facebook, for example, has made its results public, posting real-time water and energy use updates for their data centers in North Carolina and Oregon.
High energy consumption by cryptocurrencies, like bitcoin, are another digital-era concern. One estimate places the total energy for cryptocurrencies above that of Hungary and New Zealand. Because digital currency “mining” requires huge amounts of electricity, the type of fuel powering the process can be incredibly water-intensive.
According to a recent analysis in IWA’s The Source magazine:
“Last November, global bitcoin activity alone used the equivalent amount of 0.7 percent of US energy. By this logic, that single cryptocurrency used 1.13 billion gallons of freshwater per day, or 411 billion gallons (1.6 billion cubic metres) per year.”
If energy consumption continues to climb, in aggregate, even if energy efficiency improves, there could be water scarcity problems on the horizon for digital currencies.
How Can Data Centers Use Less Water?
Many large digital companies have been promoting their growing interest in water efficiency work. Google is reducing water use at its data centers by using reclaimed wastewater. Both Microsoft and Yahoo are reducing their water use by installing air-cooling systems, which can cut water use by 95 percent compared to a traditional data center, although such cooling systems require more electricity to operate.
There are many ways for data centers, big and small, to reduce their water use, from raising the temperature and reducing humidity inside the centers to siting them in areas with optimum climate for using air or recycled water for cooling. Google has set a goal to switch to 100 percent wind and solar power for its data centers and offices by 2020, meaning no greenhouse gas emissions and nearly water-free operation, at least for electricity generation. Microsoft is even looking into placing data centers underwater to take advantage of surrounding cold ocean temperatures, although the implications for sea life are not yet understood.
All choices to reduce water use will impact energy use and carbon emissions, and vice-versa, in sometimes positive or negative ways. As more and more Americans rely on the internet to communicate, watch movies and pay bills, they will place even more strain on energy and water resources. It’s just one more example of how the nexus of water and energy systems plays a direct role in everybody’s life.
Image: Interior of Office Building. Credit: ToolsTotal.com (Creative Commons).