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How much higher would the energy cost be without evaporative cooling? It doesn’t seem that hard to use water-air heat pumps to get rid of the heat without any w
by adrianN 7mo ago
How much higher would the energy cost be without evaporative cooling? It doesn’t seem that hard to use water-air heat pumps to get rid of the heat without any water use, so the reasons it’s not used are probably economic. I suppose you could just make water more expensive?
- bob1029 7mo agoEvaporative cooling gives you a COP beyond 20 in good conditions. It can be 4-5x more efficient than a heat pump.
- perfmode 7mo agoIndirect evaporative systems average around COP 17.5 and dew-point systems can hit ~30, so your numbers check out for the best cases. Worth noting that direct liquid cooling with dry heat rejection is now achieving PUE 1.03-1.06 with near-zero water, which narrows the effective gap considerably for the high-density AI racks that are driving most new builds.
- perfmode 7mo agoVertiv published a 10-year TCO analysis for a 3 MW facility that found waterless systems actually achieved lower overall cost despite higher energy draw, because water treatment, legionella testing, RO filtration, and cooling tower maintenance add up fast. The PUE penalty is typically +0.1 to +0.4, so roughly 10-25% more energy for a hyperscaler currently at PUE ~1.1. Microsoft announced all new builds from late 2027 onward will use zero water for cooling via closed-loop liquid cooling, which suggests the economics have already tipped for new construction.