Compressed Heat Energy STorage for Energy from Renewable sources

Brief description

A current challenge is the more and more flexible power generation by the increase in wind energy converters and photovoltaic systems. Their discontinuous power generation requires, to an increasing degree, a flexible power supply system which can completely absorb available electricity at any time by intelligent solutions such as smart grids, storage or sector coupling.

The CHESTER project addresses this issue by developing a novel energy management system as well as an innovative power-to-heat-to-power energy storage system. Due to synergies between electrical and thermal grids and thermal stores, excess power from renewable energies is used in order to avoid throttling the generating plants as well as to substantially increase the electric grid’s flexibility. One of the key innovations is to connect energy management systems with energy storage solutions as well as a to comprehensively view the energy supply systems compared to the existing, exclusively electrical or thermal point of view.

The main objective of the project is to develop and validate an innovative system for energy management, energy storage and for flexible supply with various renewable energies into electricity networks and/or heating networks via connecting electrical and thermal sector. In the following drawing, the basic principle of this CHEST system is shown.

Chest principle (c) DLR
Operation principle of a CHEST system: charging (left) and discharging (right)

The CHEST system is so special because of its connection to a district heating system. The main components of the system are a high-temperature heat pump, a high-temperature thermal energy store, a seasonal thermal energy store and an ORC engine for electricity reconversion of stored thermal energy.  Thermal energy from various sources (solar heat, biomass, waste heat) is fed into the seasonal thermal energy store. The high-temperature thermal energy store is charged by heat pump and electricity, e.g. from wind energy converters or photovoltaics. While discharging, electricity is produced via the ORC process. Furthermore, thermal energy from the seasonal energy store can be used for district heat supply.

CHEST charging (c) DLR
Charging of high-temperature and seasonal thermal energy storage through different (renewable) energy sources

At the discharging process, the electricity is generated through an ORC cycle. Furthermore, heat can be taken from the seasonal thermal energy store for district heating purposes.

CHEST discharging (c) DLR
Discharching process with electricity generation and heat generation, e.g. for a district heating system

The CHEST system enables to adjust the ratio of electricity and thermal energy generation to the current demand in a very flexible way. Due to the fact that, during charging, not only electrical but also thermal energy is fed into the system, the efficiency of electrical energy storage (i.e. the ratio of produced electrical energy during discharging versus the charged electrical energy during charging) can also be > 100 %.


Project duration

04/2018 - 03/2022


Project partners

Together with IGTE, the following eleven project partners are involved:

  • Fundacion Tecnalia Research and Innovation (Coordinator)
  • German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt)
  • IREN Spa
  • Planenergi
  • Aiguasol
  • Encontech BV
  • Universiteit Gent
  • Universitat Politecnica de Valencia
  • University of Ulster
  • PNO Innovation
  • Goiener



The CHESTER project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 764042. The authors would like to sincerely thank for their support and assume responsibility for publication.


Dipl.-Ing. Dominik Bestenlehner

Dipl.-Ing. Dominik Bestenlehner

Academic employee

Dipl.-Ing. Sven Stark

Dipl.-Ing. Sven Stark

Academic employee

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