Fraunhofer Institute for Systems and Innovation Research ISI
Fraunhofer Institute for Systems and Innovation Research ISI

Project

Systemic analysis of the potential for utilising excess heat from electrolysers and data centres for an efficient energy system for the future (SAPHyR)

The decarbonization of district heating networks is an essential component of the energy transition in Germany and plays a crucial role in achieving legally established climate and energy targets. To attain the desired climate neutrality in heating networks, a comprehensive transformation is required, in which the integration of current and future excess heat represents a key technology. Utilizing these potentials not only conserves valuable resources and reduces the costs of transformation but also ensures a high level of diversification for future district heating generation.

The SAPHyR project aims to comprehensively investigate future excess heat sources and their potentials for supplying district heating networks, focusing specifically on excess heat from hydrogen production and data centres. Systemic and site-specific analyses will be conducted to ensure the large-scale utilization of these sources. In addition, the necessary legal and regulatory framework will be examined to remove existing barriers.

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Currently, a major share of heat generation in district heating networks is still based on fossil fuels. Decarbonizing these networks plays a central role in achieving climate targets: integrating excess heat conserves resources, lowers transformation costs, and diversifies generation.

The Challenges: Providing a future climate-neutral heat supply via district heating networks requires unlocking new potentials, particularly from two systemically highly relevant but previously under-researched sources:

  • Hydrogen Production: Utilizing excess heat from electrolysis can lower hydrogen production costs and increase the overall efficiency of the combined system. To date, however, it is neither sufficiently considered in the site selection of electrolyzers nor captured in detail within sector-coupled energy system models, leaving a gap in overall quantification.
  • Data Centres: Due to their continuous operation and high processing power, private and commercial data centres produce enormous amounts of excess heat, which will continue to rise sharply with capacity growth. Despite initial practical examples, an excess heat platform, and energy efficiency registers, funded analyses regarding the systemic impact as well as a quantification of the future total potential in Germany are still lacking.

 

 

The overall objective of the SAPHyR joint project is to conduct a comprehensive, integrated investigation of supplying excess heat from hydrogen production and data centres into district heating networks. This includes analyzing the potential for supplying networks, impacts on the overall energy system, and site-specific contextual factors. Furthermore, the current legal frameworks will be evaluated and recommendations for action will be derived, e.g., for identifying future locations for electricity- and heating-grid-supportive planning.

To bridge these gaps, SAPHyR addresses four central research questions:

  • What is the technical and site-specific potential for supplying district heating networks in Germany?
  • What effects does excess heat utilization have on the overall energy system?
  • Under what conditions is this utilization economically viable?
  • How do the legal frameworks need to be adapted for practical implementation?

Answering these research questions is based on four methodical pillars:

  • Methodological Innovation: Improved representation of excess heat from electrolyzers and data centres for supplying district heating networks within energy system models. The project builds upon the sector-coupled energy system model Enertile and the GIS model for heating network potentials and distribution costs DisCo. Additionally, the SPIDER model is integrated for detailed power grid assessments.
  • Systemic Perspective: Analyzing the utilization of future excess heat sources while considering the entire system enables the mapping of synergy effects with other energy sources and sectors. The systemic effects of excess heat utilization on the overall system (for example, the reduction of total system costs) will be analyzed here.
  • Spatial Detailed Analyses: Analyses utilizing highly spatially resolved potentials as well as district heating network expansion. Utilizing the DisCo model and the DINO model to identify the influence of excess heat utilization from electrolyzers and data centres both on the overall energy system and within individual heating networks.
  • Legal Studies: Analysis and evaluation of the relevant legal frameworks to improve excess heat utilization from electrolyzers and data centres and to legally guide site selection.

As the joint project coordinator, Fraunhofer ISI focuses on the application and further development of two models: DisCo and Enertile. The DisCo model is utilized for the improved mapping of spatially available excess heat potentials for heating networks. Furthermore, the Enertile energy system model will be expanded to include the previously missing representation of excess heat from electrolyzers and data centres for supplying district heating networks. Beyond this, Fraunhofer ISI is responsible for the overall assessment of potentials and effects on the energy system, as well as the derivation of recommendations for action.

 

Duration

May 2026 to April 2029

Funding Body / Client

  • Federal Ministry for Economic Affairs and Energy (BMWE)

Partners

  • Institute of Energy Economics at the University of Cologne (EWI)
  • Foundation for Environmental Energy Law (Stiftung Umweltenergierecht)
  • German Business Initiative for Energy Efficiency (DENEFF)