The Ammonia Looping System for Mid-Temperature Thermochemical Energy Storage

Abstract

Thermochemical reactions have a great potential for energy storage and transport. Their application to solar energy is of utmost interest because the possibility of reaching high energy densities and seasonal storage capacity. In this work, thermochemical energy storage of Concentrated Solar Power (CSP) based on an ammonia looping (AL) system is analysed. The AL process for energy storage is based on the reversible reaction of ammonia to produce hydrogen and nitrogen. Concentrating solar energy is used to carry out the decomposition endothermic reaction at temperatures around 650 ºC, which fits in the range of currently commercial CSP plants with tower technology. The stored energy is released through the reverse exothermic reaction. Our work is focused on energy integration in the system modelled by pinch analysis to optimize the process performance and competitiveness. As result a novel configuration is derived which is able to recover high-temperature heat for electricity production with a thermal-to-electric efficiency up to 27 %. The current study shows a clear interest of the system from an energy integration perspective. Further research should be conducted to access the potential for commercial applications.