Optimization of a solar hydrogen storage system: Exergetic considerations

From production to end-users, the choice of suitable hydrogen delivery and storage systems will be essential to assure the adequate introduction and development of these facilities. This article describes the main options for hydrogen storage when produced from renewable energy, and explains different criteria to be considered in the design and building-up of stationary hydrogen storage systems, with special attention to exergy issues. An example of exergy analysis is done using data from the solar hydrogen storage facility of the Spanish Instituto Nacional de Técnica Aeroespacial (INTA).As expected, the main conclusions of this analysis show the advantage of low pressure hydrogen in comparison with other available methods to store hydrogen. Another interesting option, from the exergy efficiency point of view, is the storage of hydrogen in metal hydride systems. The last option, and the most inefficient, is the high pressure hydrogen storage.