Energetic, Economic and Practical Evaluation of CO₂-, Water- and Geothermal-Based Heat-Transfer Configurations for the Tilburg–Breda District Heating Network

Abstract

In ambition to reach net zero in 2050 the Dutch government announced the total phasing out of fossil fuels within the country. 11,7% of the country's fossil fuel consumption originates from residential heating, which currently relies heavily on natural gas. The government has announced plans to phase out natural gas in the near future, creating a strong reason to explore and research alternative heating solutions. One sustainable option is the expansion of district heating systems in urban areas, where centralized heat production from sustainable sources can serve multiple households efficiently. The cities of Breda and Tilburg are already connected to such a system, currently supplied by the Amercentrale, an incineration plant. However, the contract of the Amercentrale is set to expire in 2027, leaving the district heating network without a heat source. The construction company Heijmans has shown interest in connecting the current infrastructure to new, more sustainable heat sources. Proposed new alternatives include geothermal wells, industrial heat pumps, and a connection to the Moerdijk incineration plant, which is located 16,5 kilometers from the Amercentrale. In recent years, academic research has explored the use of CO₂ as a working fluid for heat transport, due to its ability to become supercritical at achievable temperatures and potentially enable efficient heat-transfer through both sensible and latent heat mechanisms. Motivated by this, Heijmans expressed interest in investigating whether CO₂ could outperform water in terms of thermal efficiency and cost-effectiveness in urban heat transport configurations. To evaluate this, a comparative analysis was conducted on seven heat-transfer configurations, these configurations varied from heat source, working fluid and re- utilized infrastructure. Each configuration was energetically analyzed to determine energy transfer efficiency, economically analyzed to estimate the levelized cost of heat, and qualitatively reviewed through semi-structured qualitative interviews to determine practical feasibility. The results showed that CO₂-based systems performed slightly less efficiently than water-based systems averaging between 0,7-1,7% lower than water based systems. CO2 displayed higher costs of €0,03-0,5/kWh in Levelized Costs of Heating when compared to water-based systems. While geothermal configurations showed strong economic potential, they were constrained by Dutch policies and drilling regulations, making them the least viable in practical feasibility. The recommended configuration was a water- based heat-transfer system utilizing an industrial-scale heat pump. As it showed similar performance to the current system, achieved low Levelized Costs of Heat (€0,03/kWh) when not considering pre-existing infrastructure an could be realized within a shorter timeframe, and posed few practical and regulatory barriers.