WarmteStad and KWR demonstrate a sustainable heat system for Groningen using a digital twin

From 2021 to 2026, WarmteStad built the Zernike heat plant in Groningen and developed a multi-source strategy for the system. The district heating network of WarmteStad supplies heat to several neighbourhoods in Groningen and to the university campus. The aim is to supply heat using residual heat from data centres and solar thermal energy, store surplus renewable heat underground, and reduce CO₂ emissions. KWR used the project as a ‘living lab’, developing a digital twin in parallel with construction of the heat plant. 

The heat plant was commissioned at the end of 2022 and has since then been progressively expanded and optimised. During the first few years, the main priority was security of heat supply. Building on this foundation, additional assets were subsequently added to increase the share of waste heat and solar thermal energy as heat demand grows. WarmteStad’s multi-source strategy offers a high degree of flexibility and freedom of choice. The trade-off is that system operation can quickly become complex, placing considerable demands on operators and system developers. 

Figure 1. Energy flows at the heat plant in 2025, based on analysis of WarmteStad monitoring data. 

Digital twin supports optimisation

The digital twin was developed through an iterative process involving model development, processing monitoring data, validation, scenario analysis and evaluation. This made it possible to check the completeness of the monitoring data during the development , assess the performance of individual assets, and repeatedly review the control approach and operational strategy. 

The scenarios explored using the digital twin provide insight into how the heat plant could operate up to 2030. The results indicate a declining contribution from gas boilers and an increasing use of renewable heat. The role of seasonal thermal storage was also evaluated as part of the scenario study. In the situation with an increasing heat demand and a growing availability of renewable heat sources, seasonal storage helps maximise the use of renewable sources over the course of a year, while also performing an important longer-term system function. As supply and demand grow, seasonal storage can act as a buffer within the multi-source strategy, helping the system absorb fluctuations and uncertainties associated with future growth. 

Figure 2. Exploration of WarmteStad’s multi-source strategy up to 2030 using the digital twin. 

CO₂ target expected to be achieved in 2028 or 2029

WarmteStad’s multi-source strategy has a target of achieving a cumulative reduction of 15.7 kilotonnes of CO₂ emissions during the heat plant’s first five years of operation. According to WarmteStad’s sustainability reports, a total CO₂ emissions reduction of 3.1 kilotonnes was achieved between 2023 and 2025. Based on the digital twin results, the target cumulative reduction of 15.7 kilotonnes of CO₂ is expected to be reached in 2028 or 2029. This would be within five to six years of the heat plant becoming operational, depending on actual heat demand and growth in the availability of renewable heat sources. 

The demonstration project has shown that a multi-source strategy can be used in a district heating network with a growing customer base to progressively increase the use of renewable heat sources, resulting in steadily reducing emissions. 

Meer informatie

Further information is available in the KWR report and the interactive web-report. The web-report includes a dashboard with interactive charts showing WarmteStad’s monitoring data and the scenarios calculated using the digital twin.