Thermal Energy Storage Working Group

Thermal Energy Storage Working Group

General Coordination: Esther Rojas, CIEMAT, Spain


Promoting collaboration on Thermal Energy Storage (TES) to improve its reliability, integration on CSP plants and to develop a common language.

If you are willing to participate in any of the following Activity lines, do not hesitate to get in contact with the corresponding coordinator of the activity or with Esther Rojas (general coordinator).

Current Activity lines

  • Characterization of specific equipment for commercial TES

CoordinatorMargarita Rodriguez, CIEMAT, Spain


    • Components reliability with molten salt is not proved before installing them at plants.
    • In commercial plants if one of these components presents a malfunction, it will just be repaired (often by component replacement)
  • Aligned with task 6.4 of the European project SFERA-III
  • Dissemination activities funded by MOSAICO Project Towards the standardization of molten salt loops, instrumentation and components)

Partners and facilities currently involved



Capability of testing




Valves, flowmeters, HX, vertical pumps, pressure transducers


Valves, flowmeters, parabolic trough receivers, pressure transducers


Molten salt loop – lab-scale

Valves, flowmeters, pressure transducers, strain gauges



Valves, flowmeters, parabolic trough receivers, flexible joints, pressure transducers


Valves, flowmeters, pressure transducers

Current status:

  • Identification of critical equipment and related problems (open to new problems that could appear in commercial plants)
  • Definition of tests.
  • Tests on valves, flanges, flowmeters, heating elements, pressure sensors and flexible joints.
  • MOSAICO project. This project joint the efforts performed in this activity line with those of the SFERA III project to present the testing methodologies to the industrial sector.
  • Survey of R&D Activities on Thermal Storage Systems

CoordinatorRocío Bayón, CIEMAT, Spain

Motivation:  Promoting current research activities and collaborations on TES by creating an open access document that contains information of R&D activities and installations in thermal storage developed by up to 25 institutions from all around the world.

Current status: The document is updated every year and the participation is open to any institution from the IEA country members. Willing to participate? Do not hesitate in contacting the coordinator!

Survey of R&D activities on TES updated 9/2022

  • Next updating on October 2023

Previous Activity lines

  • Storage Materials

Coordinators: J. Nieto (Tecnalia/Spain), J. González (IMDEA Energía/Spain)

Main Achievements:  3 Round Robin Tests performed:

  • Specific heat capacity of sensible materials (Solar salt with nanoparticles) 9 participants, including industry; Achieved agreement in accurately measuring cp with DSC, according to normalized methods ASTM E1269 and MDSCTM in the range of temperatures 200 and 400ºC (SolarPACES 2016).
  • Reaction enthalpy of thermochemical materials.
  • Cobalt oxide: 7 participants, including industry; there was no coherency and agreement in the results obtained by different partners (SolarPACES2016).
  • Perovskites: 7 participants; Some discrepancies in results (SolarPACES2018).
  • Prototype Testing

Coordinator: P. Garcia, CEA, France

Main Achievements:

  • Report  Definition of common procedures for testing thermal storage prototypes for STE plants (2016).