The Use of Unwanted Heat from Data Centres in District Heating

The Cool-Data project reports that it is now possible to use flexibility and waste from data centres in Denmark. In this article, we will highlight some questions answered by DTU’s researchers on the utilisation of energy in district heating. 

A research team from DTU, four companies, and a utility work together on the Cool-Data project to develop and implement a new cooling and storage system modified for small and moderate-sized data centres (about 500 servers). 

The European Union desires that data centres be linked to the surrounding district heating network to utilise the excess heat. The Cool-Data project may provide a means to accomplish the EU’s plan. 

Small and moderate-sized data centres are advantageous for supplying excess heat to district heating. Their highest advantage is their proximity to existing networks, significantly lowering potential network transmission losses and extension investments, resulting in improved heat cost-competitiveness of their waste.

Another advantage is that they can directly use their excess heat in whatever commercial building they are located in, which provides more efficiency compared to using the excess heat in a district heating grid.

With all the numerous benefits it brings, it begs the question, why is it not done today? Up until 2021, small participants were not permitted to supply excess heat: they had the same budgets and cost verification requirements as district heating companies.  

Thankfully, 2022 came with a new regulation that transferred the administrative weight to district heating organisations. It also removed the tax on excess heat manufactured from electricity, thereby eliminating the data centre’s principal barrier to heat production.

Another question to consider is, will heat wasting always be profitable? Air-cooled data centres are more common than others, and they need heat pumps to increase the temperature of their waste heat to the level of the district heating network. The closer the temperature gap between the data centre and the district heating network, the lower the electricity consumption of the heat pumps.  

Industry organisations have demonstrated a lot of interest in using excess heat, but because data centre industries are security conscious and demand the use of technologies that have passed test runs in real life, the production of unwanted heat reuse layouts has been slower than expected.