Ammonia synthesis for producing supercritical steam in the context of solar thermochemical energy storage

Abstract

In ammonia-based solar thermochemical energy storage systems, the stored energy is released when the hydrogen (H2) and nitrogen (N2) react exothermically to synthesize ammonia (NH3), providing thermal energy to a power block for electricity generation. However, ammonia synthesis has not yet been shown to reach temperatures consistent with the highest performance modern power blocks. Two similar ammonia synthesis reactors with different lengths have been used to study the ammonia synthesis reaction at high temperature and pressure and to begin the process of model improvement and validation. With the longer reactor, supercritical steam with flow rate up to 0.09 g/s has been heated from less than 350°C to ∼650°C. This result shows the technical feasibility of using ammonia-based thermochemical energy storage in a CSP plant with a supercritical steam Rankine cycle power block.