Key components for Carnot Battery: Technology review, technical barriers and selection criteria

The term Carnot Battery refers to thermo-mechanical energy storage technologies that store electricity in the form of thermal exergy with electricity as the main output. The potential role of such technologies in future energy systems with a high renewable penetration has been increasingly acknowledged in recent years. This article provides a comprehensive and detailed review of the key components relevant to Carnot Batteries, which is highly relevant as the system performance hinges on the component characteristics. Focus is placed on compressors, expanders, thermal energy storage, heat exchangers and working fluids that have been and potentially will be applied to Carnot Batteries, covering their development status, technical performance, characteristic operating parameters, and cost functions. Based on the review and analyses, the most critical research barriers and development needs are highlighted for further development of the Carnot battery systems. This review represents the first of its kind, incorporating an extensive collection of key data for system modelling and optimization, technical performance evaluation, component selection and economic assessment for Carnot Batteries. These aspects are needed to bridge the gap between research and industrial applications, and can guide future research and development of key Carnot Battery components.