Thanks to our ever increasing reliance on the Internet, the amount of data online is skyrocketing. The global data volume is expected to grow sixfold from 2018 to 2025. It might seem like that information is swirling in the cloudy sky, but it’s stored in physical data centers.
Landon Marston, an assistant professor at Virginia Tech, recently noticed news articles addressing the growing energy requirements of the data center industry. As an expert in water resources engineering, he wondered how those energy requirements translated into water consumption. “We know data centers use a lot of energy, and energy uses a lot of water. So how much water is being used?” said Marston. “We suspected that there could be large impacts at a very local scale, but there hadn’t really been a spatially detailed analysis looking at the environmental impact of data centers.”
In a study recently published in Environmental Research Letters, Marston and colleagues attempted to map how and where data centers consume energy and water in the United States. The results showed that it takes a large amount of water to support the cloud and that the water often comes from water-stressed basins.
Connecting Water Consumption to Data Centers
The researchers identified over 100,000 data centers using previous data from the Lawrence Berkeley National Laboratory and the websites of commercial data centers. While most of the data centers are small operations run by individual companies, the majority of servers in the United States are housed in fewer than 2,500 “colocation” and “hyperscale” data centers, which store data for many companies and the public simultaneously. Hyperscale data centers are the biggest type of data center, typically housing over 5,000 servers, but are designed to be more energy efficient by using cutting-edge cooling methods and servers.
All data centers consume water directly (to cool the electronics at the site) and indirectly (through electricity generation at the power plants that service the sites). Using records from the U.S. Environmental Protection Agency and the U.S. Energy Information Association, and data from previous academic studies, the researchers matched the data centers with their most likely sources of electricity and water. Then they estimated the data centers’ annual energy, direct water, and indirect water consumption based on their energy and cooling requirements. By piecing all this information together, “we can have a spatially explicit representation of the environmental footprints associated with each of the data centers,” said Marston.
They mapped the U.S. data center industry’s carbon footprint, water footprint, and water scarcity footprint. The last calculation accounts for the pressure that water consumption will put on a region based on local water availability and needs.
Hot, Dry, and Hydroelectric
The results revealed that data centers use water from 90% of watersheds in the United States. The water consumption of individual data centers varies dramatically depending on where they are located and their electricity source. For example, data centers in the Southwest rely on water-heavy hydroelectric power, and the hot climate there leads to more evaporation compared with other regions in the country. Data centers in the cooler, wetter climates of the East Coast also tend to use more solar and wind energy, which require less water.
Of the total water footprint attributed to data centers, 75% was from indirect water use at power plants and 25% was from on-site water use. “This is important because most [data center] operators don’t really look at their power consumption as part of the overall water footprint,” said David Mytton, a researcher at Imperial College London and the Data Center Sustainability Research Team at the Uptime Institute. Mytton was not involved in the new study.
A. B. Siddik, a graduate student at Virginia Tech and the study’s lead author, explained that on-site water consumption has a bigger impact on the water scarcity footprint, indicating that many data centers are in water-stressed regions. “Most often they are in the middle of a desert, or in the Southwest, like California, Nevada, and Arizona,” said Siddik. “Those are hubs of data centers.” The overall water scarcity footprint was more than double the water footprint, suggesting that data centers in the United States disproportionately consume water from water-stressed regions.
Planning for the Digital Future
As the demand for data storage grows, so will the need for hyperscale data centers. Although these buildings are more efficient than smaller data centers, concentrating the energy and water demands in fewer locations could tax the local environment.
Further innovations in energy-efficient technology and investments in renewable energy will help curb energy and water usage, but Marston also recommended building new data centers in regions with smaller carbon and water-scarcity footprints. “Simple real estate decisions could potentially be the solution here,” he said.
Technology companies have already tried out extreme locations for data centers. For example, Google converted an old mill in frigid northern Finland into a data center, and Microsoft experimented with putting data centers in the ocean. But according to the study, locations such as New York and southern Florida that have an abundance of water and renewable energy sources would have a lower environmental impact.
Mytton agreed that it’s important to consider the locations of future data centers, adding that climate change complicates these decisions because places that are not water stressed now might become drier and hotter over time. Plus, there are many other factors that contribute to where data centers are built, such as the local taxes, regulations, and workforce. Strategically placing data centers based on water resources is also an important economic consideration for the industry, Marston said, because water-stressed regions are prone to electricity blackouts and brownouts, which are detrimental to the operation of data centers.
“Data [are] so critical to the way our society functions, and data centers underpin all that,” Marston said. “It’s not just about the environmental footprint. It’s also a potential risk for these data centers.”
—Andrew Chapman (@andrew7chapman), Science Writer