IEA-DHC Annex XII Project 03

Integrated Cost-effective Large-scale Thermal Energy Storage for Smart District Heating and Cooling


  • Storage
  • District heating
  • Energy concepts


  • Research
  • Development
  • Technology transfer
  • Knowledge transfer


  • Private financing


10/2017 – 03/2020




Modern district heating and cooling (DHC) systems are a key technology for the energy transition, because they enable at a large scale to couple the heat and electricity sector and hence to increase the flexibility of the overall energy system. Large thermal energy storages (TES) in DHC systems further render possible the integration of high shares of renewable energy sources, to integrate excess electricity from RES and to optimize CHP.

The project contributes towards the development of data, information and analysis tools to encourage the use of cost-effective large scale underground thermal energy seasonal storage (UTES) in smart district heating and cooling systems. Large scale thermal energy storage technologies of interest for this international collaboration are aquifer and pit thermal energy storage (ATES and PTES).


INTERNATIONAL ENERGY AGENCY TECHNOLOGY COLLABORATION PROGRAMME on District Heating and Cooling including Combined Heat and Power


  • Steinbeis Research Institute Solites (DE)
  • Natural Resources Canada (NRCan) – CanmetENERGY (CA) (Koordinator)
  • PlanEnergi (DK)
  • Thermal Energy System Specialists (TESS) (USA)
  • IF-Tech International (IFTech) (NL)
  • Leidos (CA)


The main objective of the project is the completion of two base case studies:

  1. York University base case study assesses the economic viability of smart district cooling with integrated ambient air-cold aquifer seasonal storage in delivering near 100 % emission-free cooling of buildings and communities with efficiencies significantly higher than those of ground source heat pumps.
  2. Case study for a district heating system with integrated solar pit seasonal storage assesses the economic feasibility of the heat supply of a rural municipality in Germany with 100 % renewables including solar and biomass.


The project is divided into four tasks and concerns following points:

  • State of the Art Reviews for ATES and PTES
  • Two base case studies: York University for an ATES Cold storage and DHC system with integrated solar seasonal PTES for a municipality in a rural area in Germany
  • Technical economic analysis of the two case studies based on TRNSYS simulation models for ATES and PTES, which have been reviewed and validated with performance data from realised projects
  • Dissemination of the results


A status report on „Design Aspects for Large-Scale Aquifer and Pit Thermal Energy Storage for DHC“ including cost information, typical applications, project examples and a list of technology suppliers is available for download here.

A technical report summarizing the review, validation and documentation of the ATES and PTES TRNSYS models as well as results of the two base case studies is under preparation and will be available for download after finalisation

Downloads and links
IEA-DHC Annex XII Project 03

Thomas Schmidt

This project has received funding from

The sole responsibility for the content of this webpage lies with the authors. It does not necessarily reflect the opinion of the funding organization. Neither the funding organization nor the author are responsible for any use that may be made of the information contained therein.