Today thermal energy storage (TES) has reached different levels of maturity concerning their commercialization and application. Previous projects of the participating universities focused on the improvement of materials, their characterization, the development of new materials and the design and the evaluation of different applications for TES systems and barriers to their implementation. A new challenge is presented by the Circular Economy strategies at European and national level. Circular economy is based on the principle of closing the life cycle of goods, services, waste, materials, water, and energy. Therefore, TES is included in this new circular economy approach of considering our actions, as energy is part of the concept, but one step further is to consider circular economy principles when developing TES systems or materials.

Therefore, the main objective of this project is to develop and validate a methodology to evaluate and improve the sustainability of energy technologies integrating TES in order to come closer to a circular economy and to apply this methodology with different case studies for industry and building applications. The work centres on six main objectives:

• Identification of key indicators for the sustainability assessment and circular economy in energy systems and their relevance in decision making.
• Development and validation of a specific methodology for the sustainability assessment and circular economy.
• Development of models that integrate the developed methodology for multi-objective optimization of the developed case studies.
• Identification and development of most suitable materials for TES applications.
• Evaluation of case studies for materials, buildings and industry applications.
• Training of the participants of the project and students at PhD, master and bachelor level.