Data center operator atNorth and the Swedish heat recovery developer Calentix have signed a project development agreement for the SWE04 campus that atNorth is building in Långsele, Sollefteå municipality. The aim is to take surplus heat from the data center cooling and feed it into the Långsele district heating network, with a possible second phase reaching the larger network in Sollefteå. Both networks are run by the utility Adven, the two companies wrote on 4 November.
An independent heat producer in the middle
The split of roles is the interesting part. atNorth makes the surplus heat available and provides site integration and the infrastructure interfaces. Calentix leads the technical, commercial and financial development and would finance, build and operate the recovery plant as an independent heat producer standing between the data center and the heating utility.
An early feasibility study, carried out together, found heat recovery technically feasible and found local interest. The work now covers technical design, site planning, commercial principles and the agreements between the parties. Nothing is built yet; Calentix lists the project as being in commercial negotiations.
atNorth already sends data center heat to district heating in Stockholm and, through a partnership with Vestforbrænding, to homes in Denmark. In Finland its recovered heat warms a neighbouring supermarket.
Two systems that do not run alike
The companies put it plainly: a data center and a district heating network operate as two very different systems, and the heat has to be made compatible in temperature and character before the network can take it. In practice that interface is where the hydraulic separation sits - usually a plate heat exchanger, often followed by a heat pump to lift the temperature. The data center circuit keeps its own water quality and pressure; the network keeps its own.
One detail worth raising early in such projects: who owns and maintains the exchanger at the boundary, and who may open it. When the heat producer, the data center and the utility are three different companies, that line should be drawn on paper before the first drawing is issued.
