IEA DHC Annex TS3: Hybrid Energy Networks, District Heating and Cooling Networks in an Integrated Energy System Context Guidebook

Hybrid energy networks, i.e. the integration of electricity, heat and gas networks, can make a decisive contribution to optimizing the energy system. The IEA DHC Annex TS3 analyses the potentials and challenges of hybrid energy networks from the perspective of the district heating / cooling system. This is including the analyses of relevant technologies and synergies, an assessment of the different methodological approaches and tools, the analyses of case studies as well as the development of suitable business models and regulations.

Short Description

The coupling of different energy sectors, in particular electricity and gas with heating and cooling, is considered one of the most important measures for decarbonising the energy system. District heating and cooling networks have traditionally connected the heating and cooling sector to the electricity sector and often also to the gas sector through combined heat and power (CHP) plants.

With the phasing out of natural gas power generation and the increasing share of electricity generation from renewable energy sources, the role of CHP will probably change significantly in the future, alternative heat sources and coupling points are needed to provide flexibility. In addition, hydrogen (H2) plays an increasingly important role in the energy system and the resulting synergies must be considered.

The IEA DHC Annex TS3 is an international cooperation platform with the aim of identifying the most important potentials and making recommendations for overcoming the challenges for district heating networks in an integrated energy system context. The annex ran from autumn 2017 to early 2023 and included several workshops, webinars and "special sessions" at various conferences as well as working meetings and bilateral discussions, including cooperation with the IEA International Smart Grid Action Network (ISGAN). One of the most important results of the IEA DHC Annex TS3 is a guidebook whose key messages can be summarized as follows:

  • low temperature / cold networks (4/5GDHC) offer the highest efficiency and flexibility for supporting the electricity sector
  • Thermal storages are important for seasonal energy shifting and for providing ancillary services
  • (Tans-)national energy systems models should consider DH flexibility and efficiency
  • In DH, the optimal share of CHP and HPs will be 3-7%, and 40% - 75%
  • Gas fired CHP have the lowest system costs (depending on the price of renewable fuels)
  • Waste heat from electrolysers could cover up to 64% of the EU DH demand in 2040, in Austria, this value could be 12%.
  • Integrated energy markets are developing, including the idea of energy cooperations
  • Digitalisation can help manage the increasing complexity with integration
  • New approaches for modelling, simulating and optimizing are required
  • The main threats for hybrid energy networks are a possible disruption of existing business and uncertainties (regarding regulatory framework, market design & evolution, availability of waste heat)




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Ralf-Roman Schmidt
AIT Austrian Institute of Technology GmbH
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1210 Wien

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