Mount Pleasant, Wisconsin, USA (Microsoft zero-water evaporation pilot)

Microsoft announced its closed-loop, zero-water-evaporation datacentre design in December 2024, naming Mount Pleasant, Wisconsin and Phoenix, Arizona as the first sites, with further builds coming online from late 2027. Two findings complicate the headline. First, the energy trade is acknowledged but unquantified: Microsoft's announcement concedes that removing evaporative cooling increases PUE, mitigated by high-efficiency economising chillers at elevated water temperatures, but no PUE figure has been published for these sites. Because US grid electricity carries roughly ten times more embedded water at the generating station than the cooling water saved on site, the net water effect cannot be evaluated externally. Second, the Mount Pleasant site required manual fan adjustments and added sound-reduction components after tonal humming complaints from residents. Removing evaporative cooling shifts thermal duty onto mechanical equipment, which produces the tonal noise at issue. The water fix and the noise fix are coupled and must be designed together.