Peak load provision in district heating networks: a survey on the status quo and decarbonisation options

Many district heating networks already use low-carbon options like geothermal energy, biomass, or waste heat for heat generation. Mostly, these units cover the base load. One main challenge to achieve 100 % low-carbon supply is the provision of peak heat load as peak heat load plants are only used for a few hours a year, and require to have low investment costs. Through conducting an international survey among district heating operators and district heating experts, the aim was to clarify the definition of peak heat loads, to amplify the challenge associated with the transition to low-carbon peak heat loads, and to derive empirical results about the district heating operators’ expectations and strategies towards decarbonisation. It is found that (i) there is no uniform definition of peak heat load, which complicates its analysis and policy measures, (ii) today’s peak heat load units predominantly run on fossil fuels, (iii) half of the district heating operators have a strategy for decarbonisation, (iv) strategies focus on proven technologies, relativizing the role of hydrogen or carbon capture in this sector, (v) thermal energy storage is regarded as a key solution for peak heat load supply. • Empirical evidence substantiates that today’s peak heat load provision is fossil-based • 2 types of peaks: behaviour-driven short-term & weather-driven lasting days/weeks • The empirically substantiated peak heat load duration (mean) is 350 hours/year • Half of the DH operators have a decarbonisation strategy, independent of their size • The peak heat load strategies prefer combinations of proven technologies