Identification of industrial waste heat potential for district heating systems by pinch-based systematic graphical approach

Recent global challenges necessitate shifting towards a more circular and efficient economic model. The European Union actively pursues this direction, emphasising energy security and diversification. Notably, industrial facilities and district heating systems are among the largest consumers of fossil fuels and contributors to pollution despite significant strides in renewable energy adoption. This paper explores the potential for energy collaboration between industrial sites and district heating networks, aiming to reduce heat loss and primary energy consumption. Using a systematic graphical approach based on pinch point analysis, energy efficiency and identifying the thermodynamically available heat from industrial processes for integration into district heating systems were investigated. This study examines the simultaneous optimisation of heat transfer in district heating systems alongside the cooling processes in industrial operations. Specifically, the fertiliser, polymer and cement industries were analysed to assess their compatibility with district heating networks. The findings reveal substantial potential for energy and emission reductions, with maximum recoverable heat from a light hydrocarbon distillation estimated at 28.85 GWh/y for low-temperature district heating, a notable 76.60 GWh/y from a nitric acid plant for high-temperature systems, and 186.48 GWh/y for high-temperature district heating. Corresponding emissions reductions are projected at 6.03 ktCO₂/y, 16.00 ktCO₂/y and 38.95 ktCO₂/y for the respective case studies. The insights from this research offer valuable contributions to both scientific knowledge and practical applications in enhancing energy efficiency and promoting partnerships between industry and district heating systems.