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District Heating and Cooling

Annex XIV Project 06

The Research / IEA DHC Annexes / 2023-2026 / Annex XIV / Annex XIV Project 06

HY2HEAT Using electrolysis waste heat in district heating networks

Project summary

Hydrogen will play a central role in a future climate-neutral energy system. It will primarily be produced by electrolysis, and significant production capacities are planned on a global scale. Approximately one third of the electricity used to generate the hydrogen will be wasted as heat. This may translate into a future waste heat amount of 4000 TWh (800 GWth at 5000 full-load hours) globally until 2050; compared to 3200 TWh global district heating (DH) demand in 2014. A potential that must be considered as a heat source for DH networks.

Hydrogen can be used directly to cover peak load demands and/or in combined heat and power (CHP) plants, including fuel cells, to generate electricity. However, these are evident applications of hydrogen and are therefore out of scope of this project. HY2HEAT focuses on the waste heat utilisation from electrolysers for DH purpose.

The aim of HY2HEAT is

  1. to analyse the techno-economic synergies of electrolysis waste heat integration in

    DH systems (including the assessment of the role and expected volumes),

  2. to evaluate the best technical solutions for capturing and upgrading the electrolyser

    waste heat for utilisation in DH networks, and

  3. to derive a practical guide for DH operators for the pursuit of the potential and its

    technical integration.

The project has no limitations in terms of waste heat temperature or the DH supply temperature. Thus, established DH networks with higher temperature operation as well as low-temperature DH networks are addressed. Temperature upgrading is achieved by heat pump integration.

HY2HEAT essentially supports the decarbonization of heat supply systems by integrating sustainable energy sources and thus replacing alternative (fossil) production capacities.
In addition, the project aims to improve the overall system efficiency by reducing the need for primary energy carriers in the heat supply of DH networks. Integration of hydrogen production and DH
systems also supports the energy transition at a larger scale by improving the profitability of hydrogen production and thus accelerating the penetration of low-carbon energy technologies.

The project addresses the following questions: How can an integrated infrastructure for hydrogen production and waste heat utilisation for DH be designed? Taking into account the optimal location of the electrolyser, the pipelines to be constructed, the heat pumps for upgrading the heat, and possibly the use of thermal energy storage. What are the necessary framework conditions that must be in place to enable efficient and value-creating coupling of hydrogen production and heat generation? Under what circumstances is the coupling advantageous in terms of overall system efficiency, and what constitutes a win-win-situation? What is the economic impact of sector coupling on the production costs of hydrogen and heat? To what extent can existing or planned heat generation plants be replaced by the utilisation of waste heat, offering new business models? Finally, how can the sector-coupling approach be integrated without breaching contractual obligations with hydrogen and DH operators?

To reach this objective, the research partners build on their extensive experience and networks in the areas of DH and hydrogen. Methods include literature review on hydrogen strategies and electrolysis technologies; analysis of best practices from existing projects and initiatives; technical analysis through calculations supported by simulations; conducting expert interviews/workshops with DH companies, electrolyser suppliers, branch associations, and policy makers.

Target audience

  • DH operators

  • Electrolysis plant operators

  • Authorities responsible for energy planning and regulation

  • Governments


  1. Estimating expected electrolysis capacity in all IEA-DHC member countries, with more detailed analyses of Austria, Norway, Estonia (project partner countries).

  2. Quantification of congruence & mismatch of electrolysis waste heat supply and DH demand, regarding electrolyser technology, time, site, and technical requirements.

  3. Elaborating three concrete use cases (refer to attached LOIs) and their technical design, techno-economic benefits, and business/collaboration model.

  4. Finding best practices for the technical integration: evaluating optimal approaches for capturing heat at highest possible temperature together with electrolyser suppliers, and deriving optimal combinations of heat upgrade technologies and thermal storage systems; .

  5. Performing techno-economic assessment of hydrogen costs alone, and hydrogen and heat costs in a coupled production from the perspective of electrolysis operators (i.e., demonstrate the benefit offered by DH integration) and DH operators.

  6. Conducting a survey of current perception: perspective of DH operators and expected electrolysis operators on perceived relevance of future collaboration, expected barriers, and competitiveness with other heat sources.

Project lead

Energieinstitut an der Johannes Kepler Universität Linz (EI-JKU)
Altenberger Straße 69
4040 Linz

Dr. Simon Moser
Phone: +43 676 4404755
Email: moser@energieinstitut-linz.at

Partner Organizations

  • SINTEF Energy Research, Norway

  • Department of Energy Technology (DET) at Tallinn University of Technology, Estonia

  • AIT Austrian Institute of Technology GmbH, Austria