The breadth and coverage of analytical expertise in the IEA Technology Collaboration Programmes (TCPs) are unique assets that underpin IEA efforts to support innovation for energy security, economic growth and environmental protection. The 38 TCPs operating today involve about 6 000 experts from government, industry and research organisations in more than 50 countries1.

Energy Storage (ECES TCP)


Improving efficiency, lowering costs and reducing CO2

The ECES TCP develops and demonstrates advanced thermal and electrical energy storage technologies and encourages their use as standard engineering design options. Innovative energy storage materials were found to increase energy efficiency and reduce CO2 emissions in a wide range of applications. 

Testing the efficiency gains and CO2 reductions from phase-change materials in building walls (Lleida, Spain).*

During conversion (electricity generation, refineries, combustion engines), nearly 50% of the world’s primary energy supply is lost due to low efficiencies of the mechanisms. Therefore, increasing the efficiency of energy conversion processes is crucial to reducing CO2 emissions.

Further emissions reductions are possible by recuperating the surplus heat created from the combustion process to be re-used, either within the plant or by transferring the heat to a nearby industrial complex or heat distribution system.

For these reasons the ECES TCP sought to measure the CO2 mitigation potential of thermal energy storage (TES) technologies in industry, power generation, appliances, and vehicles. The project conducted 20 case studies of new TES materials and applications in eight countries representing Europe, North America and Asia. The project findings show that TES materials can increase energy efficiency and reduce CO2 emissions by reducing heat loss and recuperating surplus heat for other applications.

One case study examined commercial concentrated solar power (CSP) plants. CSP plants use molten salts to store the heat which can then be used at night or overcast days. Yet molten salts are expensive (from USD 630/tonne to USD 945/tonne), sources are scarce and the maximal temperature is limited to approximately 600°C. To resolve these issues, the molten salts were replaced with a low cost (USD 10/tonne) ceramic material recycled from industrial waste, capable of withstanding temperatures close to 1 100°C. This innovative approach presented no health hazards, no environmental impact and has the potential to increase the economic viability of CSP plants.

Another case study sought to reduce the temperature loss from opening freezer doors and electrical power failure. Participants found that the use of phase change materials (such as paraffin, fatty acids, salt hydrates and specialised salt mixtures) maintained the freezer temperature 4°C to 6°C lower than conventional freezers during three hours of power failure. The use of PCM was shown to maintain freezer temperatures relatively constant (from 12°C to 14°C) for more than three hours of power loss which protected the food quality.

A further case study evaluated the cooling effect of walls with PCMs (paraffin and salt hydrates). The PCMs delayed the rise of the temperature inside the building during the day, reducing the need for air conditioning. At night, when temperatures were lower, the PCMs released the stored heat to indoor and outdoor ambient air, keeping the room temperature comfortable. Findings confirmed energy savings of 15% to 17% compared to cubicles without PCMs. Further research on PCMs is needed before the technology is widely commercialised. These and other results were assembled in the final report, Surplus Heat Management using Advanced TES for CO2 Mitigation.

* Photo courtesy of the University of Lleida


  • Distributed energy storage for renewable energy
  • Future electric energy storage demand
  • Materials research and development for improved systems (a joint activity with
    the SHC TCP)
  • Optimisation and automation for net zero energy buildings
  • Thermal energy storage for cost-effective energy management and CO2 mitigation


  IEA member 
Contracting Parties  16  2  1
Sponsors -  -

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