Impact of recent district heating developments and low-temperature excess heat integration on design of industrial energy systems: An integrated assessment method

Abstract

One of today’s biggest challenges is taking effective measures to mitigate negative effects and consequences of human-made climate change such as sector coupling and excess heat valorization. In this work, sector coupling of residential and industrial heat supply are considered in an optimization-based design and operation evaluation for industrial energy supply systems with the aim of minimizing costs and determining the impact of on-going developments and progresses in district heating systems. The developed method is applied to a use case with a superstructure for the industrial energy system including a biomass-fired steam generation unit, two heat pumps and various thermal storages, generic industrial load profiles for steam, hot water and excess heat and simulation-based district heating load profiles. The most relevant results reveal that depending on the district heating setting total annual costs, including fuel costs and annualized investments, increase between 2 and 39% compared to no additional district heating supply by the industrial energy supply system. However, the lowest cost increase does not coincide with the lowest additional energy amount. Thus, synergies such as corresponding temperature levels between energy supply for all domains have been identified as crucial criteria for economic success. Also, unit integration for excess heat recovery occurs always combined with thermal storages adapting the temporal occurrence of excess heat. Results for the evaluated use case highlight the importance and relevance of combined considerations for sector coupling measures. Thus, methods, as presented in this work, can contribute crucial information for future assessments. However, further development of the model, e.g. a larger set of generation technologies, and further use cases with other temperature levels, demand profiles are identified as relevant next steps.