Development and evaluation of a solar based integrated hydrogen energy system for mobile applications

Sustainable and nature-friendly energy systems are critical in playing a key role in meeting the needs for better energy security and reduced environmental impacts which appear among the primary concerns of today's modern society in the 21st century. The present study, in this regard, undertakes the development and thermodynamic investigation of a unique solar energy-based multigenerational energy system for modular and transportable applications. Electricity, heat, hot water, hydrogen and clean water are the useful commodities generated by this uniquely integrated energy system. This system employs a photoelectrochemical reactor stack for wastewater treatment and hydrogen production. The hydrogen generated from the photoelectrochemical water splitting process is employed within a proton exchange membrane fuel cell providing electricity and heat for hot water. The system's energetic and exergetic efficiencies under different operational conditions are investigated and comparatively evaluated. The key effects of varying prime operational conditions and state properties on the system performance and hence the efficiency, as considered in the system analysis, are parametrically investigated, and the obtained results are comprehensively discussed along with explanations about the main drivers. The integrated system provides 1.026 kW electrical power along with, 2.1 kW space heating, 0.6 kW heat for hot water, and hydrogen and clean water production rates of 22.97 mg/s and 9.79 g/s, respectively. An overall energy efficiency of 16.79 % and an overall exergy efficiency of 17.31 % are obtained and discussed. The presently developed system is capable of operating as a self-standing system in an off-grid manner. Furthermore, the number of PEC reactors required to sustain the system needs to be maintained, which can be achieved by potential improvement in PEC water splitting process.