More Circularity, Less Drain
University of Arizona and Salt River Project Collaborate to Improve Sustainability of Data Centers
Hickenbottom seeks to close the loop on water-energy circularity through onsite advanced membrane processes coupled with renewable energy generation technologies. First and second images from the left: a pilot project recycling water with solar power. Center image: Co-author Lindsay Ridpath with Hickenbottom at her research facilities at the U of A Water & Energy Sustainable Technology (WEST) Center, also pictured in images to the right.
Leslie Hawthorne Klingler
Tucson, AZ —
How often do we scroll our phones, binge-watch entertainment, shop online or use Chat GPT? Rarely do we consider our digital footprint—the websites we visit, emails we send, and data we share, all of which pass through data centers. These centers, says Kerri Hickenbottom, Associate Professor of Chemical and Environmental Engineering, "require tremendous amounts of water and energy."
Despite Arizona’s water challenges, Phoenix is the second-largest data center hub in the U.S., after northern Virginia, due to its proximity to fiber optic networks, low energy costs and low disaster risk. More than 100 data centers in the area draw nearly 1.4 gigawatts—enough to power over a million homes—with more centers coming. These also require vast amounts of water, with around 2.4 gallons used per kilowatt-hour of energy produced.
Hickenbottom partnered with the Salt River Project (SRP), central Arizona's main water provider and electricity supplier to two million customers, to explore water conservation in data centers. SRP continuously innovates power generation and water resource management. "They balance resource availability with demands," says Hickenbottom. "With so many large industries moving to Phoenix, SRP needs ingenuity to maximize water and energy efficiency to meet the growing demand."
Hickenbottom, who has years of experience working with desert water systems, adds that Tucson’s location forces creativity in sourcing and treating water. "We’re downstream from everyone else. We have to find alternative water supplies and treat them safely and economically—whether for cooling data centers, agriculture, mining, or drinking."
Her team measured the energy and water footprints of various data center cooling systems, finding that there’s always a trade-off: cooling systems using less water generally consume more energy, and vice versa. Currently, potable water is used for cooling, but data centers may not need such high-quality water, prompting the exploration of alternative sources.
Ultimately, Hickenbottom’s team developed a decision-support tool that helps stakeholders evaluate the water and energy impacts of different cooling systems based on inputs like load, reliability, maintenance, water use, and cost. They also created graphical white pages for SRP to share with data center customers, illustrating these trade-offs.
Hickenbottom values SRP’s engaged collaboration and feedback, which ensures the research has broad relevance. "SRP is client-based, and they always want to show how their investments benefit their customers," she says, appreciating SRP’s role in advancing circular water-energy systems.
"This project exemplifies SRP's commitment to research that benefits the community," says Brian Adair, Executive Director for Industry Engagement. SRP has partnered with U of A on nearly 40 projects, from reducing plastic waste in concrete to improving solar forecasting, benefiting master’s and doctoral students in the process. "We couldn't ask for a better partner."