Almost all the electricity a data center pulls off the grid comes back out as heat. A data center is, in effect, a very expensive radiator, but most of that warmth gets blown into the sky. The interesting question is what a facility could do with that heat if it decided not to throw it away. Meta’s site in Odense, Denmark, is one of the few places that's channeling its cooling heat straight into nearby homes. Water from the municipal district heating network runs through the facility's cooling units, absorbing that low-level warmth from the servers, and then moves to a nearby plant packed with ammonia heat pumps that raise the temperature further before distribution. Engineering firm Ramboll designed this recovery system for district heating operator Fjernvarme Fyn, lifting water temperatures to around 158º F. That range makes the water hot enough for household radiators once it re-enters the wider distribution network. This situation stands out against a backdrop of growing resistance to data centers elsewhere, particularly in the United States. Communities there have pushed back over land use, water consumption and strain on local electricity grids, but Denmark has proven that data center heat can actually benefit the surrounding community.
