Demonstration of pit heat thermal storage

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 Fjernvarme’s 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.

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 also be demonstrated that the temperature in the upper part of the storage can be constantly fixed at 90oC.


A comprehensive monitoring program is part of the project.

Further information:


Contact: Hans Henrik Lindboe





Helge Ørsted Pedersen



Ea Energy Analyses Gammeltorv 8, 6th floor1457 Copenhagen KDenmark Tel work+45 60 39 17 16 Fax +45 33 32 16 61

GEO: 55.675932, 12.575096