Microsoft ramped up its commitments today to conserve water and energy in its data centers, laying out new cooling tech and strategies that could push notoriously thirsty and energy hungry servers past their current limits. The company’s latest environmental pledge comes as it plans to dramatically expand the number of data centers it operates around the world, a move that could put more stress on drought-stricken communities unless the company finds ways to use less water.
Microsoft plans to slash the amount of water its data centers use by 95 percent by 2024, with the goal of “eventually” eliminating water use. That builds on a commitment it made last year to become “water positive” by the end of the decade, meaning it would replenish more water than it uses for its operations. In 2020, Microsoft also committed to becoming carbon negative by the same deadline, meaning it plans to draw down and store more planet-heating CO2 than it releases.
Microsoft also announced other sustainability efforts today that could lower greenhouse gas emissions inside and outside the company. It’s looking for building materials for its data centers that are less carbon-intensive, including research into bricks made with algae and structural tubes made with mushrooms. It also previewed a new tool called Microsoft Cloud for Sustainability, which can help organizations track their carbon dioxide emissions.
But the big commitment involves the data centers. Data centers like Microsoft’s are packed with servers which enable people to store files, send messages, and shop and game online. All of that activity uses up a lot of energy and generates heat. Overheating can affect servers’ performance and reliability, but blasting them with air conditioning drives up electricity use and greenhouse gas emissions. It’s possible to use water to cool down servers, but water has become an increasingly scarce resource in many of the arid places where data centers operate.
A typical data center uses about as much water as a city with a population of about 30,000 to 40,000 people, or about 3 to 5 million gallons of water a day, says Venkatesh Uddameri, professor and director of the Water Resources Center at Texas Tech University. Microsoft tells The Verge that its data centers use less water than that, although it varies across different regions and climates.
Microsoft’s data centers currently use adiabatic cooling, which relies on outside air to cool down temperatures inside. It’s a system that uses less electricity than air conditioning and less water than cooling towers. But when temperatures rise above 85 degrees Fahrenheit, outside air isn’t very helpful. At that point, an evaporative cooling system kicks in, which uses water. It works like a “swamp cooler” — cooling the air by pushing it over or through water-soaked screens.
Microsoft today revealed two main strategies it plans to lean on to meet its water conservation goals. First: it researched how its servers perform under higher temperatures, and found that it can set higher limits for when the centers’ evaporative cooling systems kick in. In cooler parts of the world — including Amsterdam, Dublin, Virginia, and Chicago — those higher set points could, over the next few years, get rid of the need for water completely.
But Microsoft’s data centers in desert regions, where water scarcity is a bigger problem, will likely continue to guzzle water for years longer. Microsoft says the same strategy that might eliminate water use in Amsterdam and Dublin would only reduce water consumption in desert regions by as much as 60 percent by 2024.
That’s where the second part of Microsoft’s plan comes in. To get its water footprint down to zero in those hot and dry climates, Microsoft plans to turn to a new way to cool servers: submerging them in fluorocarbon-based liquid baths. As the servers work away, the heat they generate causes the liquid to boil when it reaches 122 degrees Fahrenheit (50 degrees Celsius). The boiling liquid moves heat away from the servers and then turns into a vapor that rises. The vapor hits a cooled tank lid, condenses, and rains back into the tub. The process, called two-phase liquid immersion, creates a closed-loop cooling system that cuts down on water and electricity use while getting rid of heat. It’s a strategy that the company says was inspired by cryptocurrency miners, who also use huge amounts of energy and have turned to liquid immersion cooling for computing equipment.
While experts The Verge spoke to say the technology is promising, they say getting it to work at scale will be another challenge. Microsoft just announced its first trial run with immersion cooling in April and says this technology is still in the research and development stage. Very few data centers — probably fewer than 2 percent — rely on immersion cooling, according to Lucas Beran, principal analyst at the market research firm Dell’Oro Group.
“You also think about the scale of someone like Microsoft deploying the amount of data centers that they are building and the amount of compute they’re deploying — that’s a massive supply chain switch. That’s a massive operation switch,” Beran says. Microsoft will have to study and plan for how that change will affect data center performance and train staff to work in new environments, he points out. “It’s a very large undertaking, but one that has some extremely positive potential outcomes.”
Microsoft tells The Verge it will take a phased approach to rolling out its new cooling strategies for data centers. Immersion cooling will require new, specially designed servers, and Microsoft will wait for its server configurations to age out before replacing them in existing data centers. Even the plethora of new data centers the company has planned will likely first be built with hybrid cooling systems as it transitions to new immersion technology.
Microsoft plans to build 50 to 100 new data centers a year to keep up with demand for its cloud services. Global internet traffic is expected to double by next year, it says. That’s a huge opportunity for the company, but also a big challenge to the company’s new sustainability goals.
Tensions have risen, for example, around data centers in Arizona, where Microsoft opened up a new one this year. After federal authorities declared the first water shortage on the Colorado River in August, Arizona faces imminent cuts to its water supply. The cuts, so far, will primarily limit water for agriculture, but some residents are worried that new data centers in the region will only intensify competition for already scarce water resources.
The company will need to address issues unique to each location where it builds a data center and pay special attention to places under more water stress. “There is no one-size-fits all type of solution,” says Uddameri. “You can become water positive as a company, but it’s not useful if you save all the water in one location, as an extreme case, and you create bigger deficits elsewhere.”
Correction October 27, 11:22AM ET: This post has been corrected to state that Microsoft uses evaporative cooling in its data centers when temperatures rise above 85 degrees Fahrenheit outside. A previous version said that the threshold was 85 degrees Celsius. We regret the error.