Periodic Reporting for period 1 - 4TunaTES (For Tunable Thermochemical Energy Storage)
Reporting period: 2024-02-01 to 2025-01-31
To accelerate the energy transition there is an urgent need for energy storage both for electricity and heat due to the intermittency of renewable resources. As a large part of our energy consumption is in form of thermal energy (78% in the built environment), and as there is a large amount of unused low temperature waste heat (8900 PJ in Europe), thermal energy storage offers route towards bridging availability and demand. Long term loss-free compact heat storage is the missing link, and Thermo-Chemical Energy Storage (TCES) has the potential to play this role. 4TunaTES proposes to develop a TCES-prototype that can be used for domestic use cases, which addresses three challenges: 1) radically new TCES materials with tunable phase diagrams by using a second gas or dopants, 2) heat exchanging components with a high degree of manufacturing flexibility, and 3) revolutionary systems with electricity adapted thermodynamic cycles.
On the materials side, TUE, VUB and CIIAE will identify, develop, and analyze through a combination of computational and experimental investigations new TCES materials. Screening for applications at component and system levels will continue with DLR and CNR. The goal is to increase flexibility and efficiency of the thermal energy storage to the point that a proof of concept TCES can be proposed and tested.
On the materials side, TUE, VUB and CIIAE will identify, develop, and analyze through a combination of computational and experimental investigations new TCES materials. Screening for applications at component and system levels will continue with DLR and CNR. The goal is to increase flexibility and efficiency of the thermal energy storage to the point that a proof of concept TCES can be proposed and tested.
Three use scenarios have been identified for benchmarking 4TunaTES technology: A) peak shaving, B) thermal energy communities and C) heat pump/heat battery configurations. Based on these scenarios a set of requirements that can be used for defining the layout of the proof-of-concept, which will be realized at the end of the project. On materials levels detailed screening has been performed on so-called two-gas materials, which has led to a long list of potential candidates. Further, a promising pair of salts has been identified, which demonstrated already the ability to shift the discharging/temperatures by making solid solutions. On component level TPMS (triply minimal surfaces (TPMS) structures have been identified as potential heat exchangers. A modelling activity regarding the detailed CFD modelling of the TPMS under various configurations and operating conditions was carried out. Moreover, a preliminary screening of the manufacturing routes possible was carried out, by defining a “printability” score, which considers the specific printing technology, geometry, wall thickness and printer parameters. For the most promising configurations, compression tests and thermal degradation tests were carried out. On system level options for hybrid electrical and thermal charging have been investigated. Several options have been identified, where electricity could be fed into the thermodynamic cycle and ranked based on their performances.
Since the project is only 1 year underway, it is rather premature to talk about solid results. Nevertheless, a potentially interesting thermodynamic cycle has been identified by DLR. It will be evaluated if and how this idea should be protected. On materials level a promising salt pair has been identified that forms a solid solution, which demonstrates the validity of the approach. To meet the 4TunaTES requirements a broader screening has to be performed.