Review of tools and methods to identify excess heat potentials in district heating

Utilising excess heat for district heating is relevant to the decarbonisation of the energy system, as this integration allows for a more efficient use of energy. Excess heat for district heating can come from a range of different sources, such as industrial processes, data centres and Power-to-X. The potential for excess heat varies depending on local conditions; therefore, a range of methods and tools have been developed and used in various studies to assess excess heat potentials across different geographical scales. To identify tendencies, a review is presented categorising methods and tools. This includes synthesising key limitations and risks of prevailing methods, with implications for future assessments. A total of 253 publications are included in the review, spanning the years from 1988 to 2025. The publications are categorised according to various aspects, allowing the identification of key tendencies and characteristics. The review shows that the number of publications in this field is increasing, suggesting a growing scientific interest. Historically, research has focused almost exclusively on industrial processes. However, new types of excess heat sources, such as data centres and Power-to-X facilities, are receiving increasing attention within research. Most studies have employed energy system analyses to identify potential sources of excess heat, with a smaller share utilising Geographical Information Systems. Furthermore, the review also shows that most studies are authored by researchers from Europe and China, and most of the excess heat studies are conducted for these countries.