A solar hydrogen hybrid system with activated carbon storage

A solar hydrogen hybrid system has been developed to convert, store and use energy from renewable energy sources. The theoretical model has been implemented in a dynamic model-based software environment and applied to real data. A photovoltaic sub-system drives a residential load and, if a surplus of energy is available, an electrolyzer to produce hydrogen which is stored in a cluster of nitrogen-cooled tanks filled with activated carbons; when needed, hydrogen is used in a fuel cell to supply power to the load. Hydrogen storage is achieved through physisorption at low temperature and low pressures. Physisorption storage provides safer operations along with good gravimetric and volumetric capacities at costs comparable to or smaller than compression or liquefaction storage. Results show that the system has stand-alone capabilities with a surplus production of hydrogen at end of year. Tanks are reasonable in size and weight for stationary applications, and surplus can contribute to recharge batteries or fill tanks for non-stationary uses. © 2009 Professor T. Nejat Veziroglu.