Comparative analysis of thermal energy storage technologies through the definition of suitable key performance indicators

The importance of Thermal Energy Storage (TES) inside efficient and renewables-driven systems is growing. While different technologies from traditional sensible TES are entering the market or moving towards commercialisation, a common basis for fair comparison and evaluation of these systems is lacking. Aim of the present paper is the definition of a set of KPIs that can be used for the comparative analysis of different TES. A review of methodologies used for the definition of KPIs in different sectors was realised and a novel methodology, based on the comparative assessment of literature analysis and evaluation of technology roadmaps was proposed. According to this methodology, the technical, socio-economic and environmental constraints defined by researchers and policy makers were identified and translated into KPIs. The set of parameters suggested was then applied to different cases studies within the same application, namely covering heating demand in residential buildings. The different technologies were compared and the results evaluated: a significant non-uniformity in the data available and the way they are presented was found, mainly linked to the different level of maturity of the technologies investigated. This strongly confirmed the need for a shared framework of data definition and reduction. Nonetheless, it was possible to calculate the majority of parameters and derive some general trends, thus proving the effective usefulness of the KPIs defined. (C) 2019 Elsevier B.V. All rights reserved.