The number of data centres (DCs) in the world are growing to satisfy the increasing demand for internet services. Denmark alone is expected to host several hyper-scale DCs (HSDCs), whose demand for electricity in 2040 may reach 80% of the total Danish electricity consumption in 2017. The waste heat from cooling of DCs can be used in the Danish district heating networks and could cover up to 25% of the district heating supply by 2040 – if utilized.
[Ref. 1: The role of data centres in the future Danish energy system] The figure below from COWIs 2018 “Temaanalyse om store datacentre”, made for the Danish energy agency shows four different scenarios for development in electricity demand for DCs in Denmark. The main scenario in this note is ‘linear growth’ (‘Linær vækst’).
[Ref. 2: Temaanalyse om store datacentre]
To satisfy the rising demand for internet services an increasing number of DCs are needed. It is expected that a large number of these HSDC will be placed in Denmark. These DCs have a high demand for electricity. Satisfying their demand for electricity in 2040 is expected to amount to one third of Denmark’s electricity consumption in 2017.
The electricity consumption of DCs can be split into electricity demand for IT equipment(IT) and an electricity demand for cooling. While the electricity demand for IT is relatively constant throughout the year, the electricity demand for cooling, and therefore the excess heat is greater during summer. This is unfortunate for the utilisation of the excess heat for district heating. The use of thermal storages can solve this problem.
Because of the relatively low temperatures of the excess heat, heat pumps are required to increase the temperature to a level that can be utilised for district heating. The needed temperature lift is relatively low therefore it is expected that the efficiency of the heat pump will be around 500%.
Understanding the operation and interactions of DCs with energy systems is key to understanding their impacts on the need for other DH capacities and on the costs and emissions. We have set up a thermodynamic model of a DC and scaled it up to cover all the DCs in Denmark. Later, we have implemented the DCs in TIMES-DK model to get an understanding of the effects of (future) DCs on the Danish energy system until 2050. The thermodynamic model links the electricity consumption of DCs and excess heat from DCs. The total electricity demand of data centres in Denmark is acquired from “Temaanalyse om store datacentre”[2]. We have used linear growth as our main scenario.We have also tested exponential, opt-out(“Danmarks fravægles”) and disruption scenarios.
The results show that DCs can have a significant impact on Denmark’s power and district heating (DH) sectors if they are realised. Firstly, the electricity consumption for future DCs is equivalent to the production from additional 3-6 GW of offshore wind capacity (i.e. 300-600 offshore windmills) which is 2-4 times the installed offshore windmill capacity in 2018 (1.7GW). Secondly, utilisation of excess heat from DCs is economically beneficial, providing up to 25% of Denmark’s district heat after 2040. Thirdly, DCs are not expected to affect electricity and DH prices significantly.
One of the main underlying assumptions for utilisation of excess heat from data centres for district heating is that data centres will be located within existing central district heating areas, so they don’t have to pay for transmission pipes.
The “linear growth” scenario is assuming no technological development, this could be a critical assumption. Technological development could lead to significant increase in energy efficiency of the DCs IT, resulting in reduction in need for cooling, and thereby reducing the amount of excess heat. This can be critical if the district heating systems are depending on the excess heat from DCs, It is important that that use of excess heat does not prevent development in energy efficiency of the DCs and vice versa.
Building DCs at the rate expected, DCs will increase the Danish electricity consumption in 2040 significantly. Excess heat from DCs in 2040 can potentially provide up to 25% of Danish district heating. Therefore, the importance of technological improvement and utilization of excess heat from DCs will play a major role CO2 neutrality.