A national trade organization for the data center industry is fighting at the Legislature against the disclosure bill, saying it would expose their trade secrets and make their data centers a potential target for terrorists.
How and why data centers cool
Data centers are warehouse-like facilities filled with rows of servers. Those computers generate enough heat that they need a reliable cooling system.
Microsoft estimates that a data center that uses 40 megawatts of electricity — which is smaller than projects now under development in Minnesota — produces enough heat to supply 46,000 households in the winter.
Minnesota’s cold winters mean data center companies don’t have to use much water for most of the year, said Thom Jackson, a mechanical engineer for Dunham Associates who designs cooling systems for data centers.
On warmer days, the cooling options for data centers come with tradeoffs.
One is a refrigerant-based technology that is similar to a home air conditioner. These systems use no water, but they need a lot of electricity, said Jackson, who is president of the Minnesota chapter of a national organization for professionals in the data center industry.
Other common systems need a steady supply of water, but far less power. They are generally cheaper because of smaller electricity costs, but can lose some of that water through evaporation.
Somewhere in between is what Jackson described as an “air-cooled chiller,” which uses refrigerant and water to cool, but without evaporation. It’s a closed system that doesn’t need to be replenished once it’s filled, Jackson said.
The site of a $800 million data center in Rosemount, shown in January. (Renée Jones Schneider/The Minnesota Star Tribune)
Water projections vary widely
There is a wide range of potential water use estimated by data centers in Minnesota.
Facebook’s parent company, Meta Platforms, plans to use a closed-loop cooling system at its $800 million project in Rosemount, said spokeswoman Stacey Yip.
Rosemount estimated Meta would draw 100,000 gallons of water each day from the city’s groundwater system at peak use. Yip declined to confirm the figure or offer an estimate.
That’s about one-sixth of an Olympic-sized swimming pool.
Farmington has estimated the Colorado-based developer Tract could use nearly 24 times that much every day, at least at its peak, roughly the water use of 11,600 homes.
In a December interview, Graham Williams, then chief investment officer for Tract, said the industry is moving away from the most water-intensive cooling technologies and that times of peak demand are short, so the company would not use that maximum amount every day.
Chaska expects CloudHQ to draw about 1.5 million gallons per day at its peak from the city’s groundwater but less at other times, said Podhradsky, who noted the city has plenty of capacity.
Oppidan says its planned Apple Valley campus would use about 8 million gallons of water per year. The Minnesota Zoo uses eight times more water each year, according to Apple Valley.
Amazon and Microsoft declined to estimate their potential water use but each said their operations will replenish, rather than deplete, supplies. Amazon spokesman Duncan Neasham said the company uses no water to cool data centers in Ireland and Sweden for “95% of the year.”
Faribault officials said that they expect developer Archer Datacenters to build a closed-loop project that wouldn’t be water-intensive, but that it’s too soon to estimate water use.
Inside the filter room at Chaska's water treatment plant. (Leila Navidi/The Minnesota Star Tribune)
Localized groundwater risks
Most companies and cities that responded to the Minnesota Star Tribune said the data centers are expected to draw from groundwater, not lakes or rivers.
Heavy groundwater use has risks, said Carrie Jennings, research and policy director for the nonprofit Freshwater. Many of the potential projects — in Farmington, Hampton and Rosemount — are in Dakota County, which Jennings called “one of the most irrigated counties in the state.”
When groundwater is sucked up more quickly than rain and snow can filter back down to replenish it, that creates a “cone of depression” — a zone where the water table is lower. This can dry out shallower household wells on the fringes of small towns, Jennings said.
Jennings said that for communities that rely solely on groundwater, eventually “it either limits growth, or you have depleted groundwater.”
The Minnesota Department of Natural Resources issues permits for high-capacity water users. An agency spokeswoman wrote in an email that the “DNR cannot issue a water appropriation permit if it will cause higher-priority water users (like domestic wells) to run out of water.”
Still, Jennings predicted, “You’re going to see more conflict with private well owners.”
