Demonstration of pit heat thermal storage in large scale CHP based district heating system as a part of a flexible energy system

    Project Details


    Project description

    In the FLEX_TES project a 70,000 m3 pit heat thermal storage (PTES) will be demonstrated in a new function as accumulation tank in a district heating system with CHP from incineration and biomass. This will increase the flexibility and capacity value of CHP plants in the electricity market. Also expensive peak production in the heat market can be replaced by heat discharge from the PTES.

    The storage will be demonstrated in Høje Taastrup Fjernvarmes distribution system but connected to the large VEKS´ transmission system as part of the integrated District Heating system in Greater Copenhagen. This makes it possible for all the CHP plants in the transmission systems of VEKS, CTR and Vestforbrænding to interact with the storage.

    International collaborations:
    The project will be carried out in close collaboration between Department of Civil Engineering, Technical University of Denmark and Vestegnens Kraftvarmeselsskab I/S, Høje Taastrup Fjernvarme a.m.b.a., PlanEnergi, Ea Energy Analyses.

    Key findings

    Implementation of the demonstration project will open a new huge market for PTES as a viable tool for DH systems to be effective integrators of fluctuating renewables. It will be demonstrated that the temperature in the upper part of the storage can be constantly fixed at 90°C making pit storages able to replace the more expensive steel tanks. The objective is to make this possible by change of liner, insulation materials and design. Also it will be demonstrated how advanced operation creates synergy between heat and electricity markets. The price for the storage is expected to be less than 1/3 of the price for similar steel tanks
    A comprehensive monitoring program is part of the project.
    Effective start/end date01/07/201831/12/2024

    Collaborative partners

    UN Sustainable Development Goals

    In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This project contributes towards the following SDG(s):

    • SDG 7 - Affordable and Clean Energy


    • Pit heat thermal storage (PTES)
    • District heating system
    • CHP with incineration and biomass
    • Demonstration
    • System integration
    • Modeling
    • Monitoring
    • Optimization


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