The relevance of thermochemical energy storage in the last two decades: The analysis of research evolution

The research field on thermochemical energy storage (TCS) has shown consistent growth over the last decade. This study analysed over 1196 scientific publications in indexed journals and books from the last decades. What can we learn from analysing the evolution of research? There is no other study that has used bibliometrics to perform a detailed analysis of the TCS field, which has only been assessed from the perspective of the whole thermal energy storage field to date. The trends obtained in this study provide an important perspective of the field, indicating the strengths and weaknesses of the thermochemical materials and systems applied to energy storage. The main publication trend shows an exceptional increase in TCS research and in both defined research sub-areas (sorption and chemical reaction heat storage). The sub-category chemical reaction heat storage has fewer publications compared to sorption heat storage, indicating that it is a less explored field. In general, the evolution of the keywords in publications reflects technology maturity since the most recent terms are associated more with final use applications. Remarkably, there has been a change from a total dependence on funding for scientific output to a scenario in which a significant number of publications mention no specific funding, but this trend has changed in recent years.