CIC energiGUNE is committed to nanoconfined fluids to recover and store waste heat that is currently wasted due to a lack of viable materials and solutions

The STES project, included in the ‘Knowledge Generation Projects’ programme of the Ministry of Science, Innovation and Universities, aims to develop thermal energy storage materials from water and nanoporous materials that facilitate the recovery of the 468 TWh dissipated each year in the EU from waste heat below 100ºC.

CIC energiGUNE’s goal is to discover fundamental properties of nanoconfined supercritical fluids (cSCF) that open the door to developing a novel approach to thermal energy storage in the medium-low temperature range, offering high energy density, simple implementation and environmental compatibility.

CIC energiGUNE, a Basque reference centre in electrochemical energy storage and conversion and thermal energy storage and conversion, aims to create a viable alternative for the recovery and storage of waste heat at low and medium temperatures, with the objective of capturing the more than 460 Terawatt-hours (TWh) generated by this type of energy that are wasted every year in the European Union. This work is part of the STES project, led by the Basque centre and funded by the ‘Knowledge Generation Projects 2023’ programme of the Ministry of Science, Innovation and Universities.

‘If we take into account that one TWh could power, approximately, the whole of Spain for a week, we can get an idea of how important it is to make progress in the recovery of this type of waste heat,’ said Yaroslav Grosu, Principal Investigator of the STES project at CICenergiGUNE and head of the Interfacial Phenomena and Porous Media group at the Basque centre.

According to data recorded by the EU, 468 TWh of waste heat below 100°C and another 300 TWh of industrial waste heat at 100°C-200°C are dissipated on the continent every year, and the main reason is that there is no satisfactory recovery solution. Through STES, CIC energiGUNE aims to solve this problem by developing viable thermal energy storage materials with high energy density and, at the same time, low cost.

Specifically, STES aims to discover fundamental properties of nanoconfined supercritical fluids (cSCF) to develop a novel approach to thermal energy, simultaneously achieving high energy density, low operating temperatures and pressures, simple implementation and environmental compatibility. This will build on an innovative concept previously developed at the Basque centre, which has enabled the reduction of the critical temperature of water to ~100°C.

‘This reduction of the critical temperature is unprecedented and has been achieved because we used an approach never before considered in the study of confined fluids,’ said Professor Grosu. ‘Instead of condensing the vapour phase inside the cavities of the porous material, which limits the pressure to values below the saturation pressure of the fluid, we introduce the fluid in a liquid state, resulting in water confined in nanoporous materials with high hydrophobicity such as metal-organic frameworks, functionalised silica and zeolites, which can also be of natural origin.

The STES project also includes the construction of a demonstrator in which the applicability of the materials developed will be tested. This opens the door to minimising the carbon footprint of the industry and the efficient use of resources. The project will also facilitate the implementation of decarbonised processes and allow problematic waste to be used as raw material, which will contribute to long-term sustainability and reduce the overall environmental impact.

‘While STES starts from high-quality advanced nanoporous materials for fundamental understanding and knowledge generation, the aim is to extend the project results to economic waste or natural porous materials,’ concludes Prof. Grosu.