Design and thermo-environmental analysis of a novel solar-driven system integrating desalination, photocatalytic water splitting, and fuel cell technologies

Abstract

Photocatalytic water splitting (PWS) is one of the promising hydrogen production technologies. Studying the operation characteristics of multi-energy coupling system based on photocatalytic hydrogen production is beneficial to the popularization and application of this technology. A novel zero-carbon emission system that integrates freshwater, hydrogen, and electricity co-generation driven by solar energy is developed in this paper. The integrated system comprises a multistage flash desalination (MSFD) subsystem, a PWS subsystem, and a fuel cell (FC) subsystem. Considering the inherent variability and intermittency of solar energy availability, an energy storage module is strategically implemented to ensure stable and reliable system operation. The detailed model of the complete integrated system is meticulously developed and refined using Aspen Plus software. Taking the meteorological data of Hainan, China as an example, the operational parameters of the system are designed. Parametric analyses are conducted on the system’s freshwater production, hydrogen generation, and electricity output. A comprehensive evaluation is made on the thermodynamic and environmental aspects of the integrated system. The results demonstrate that the system, designed to operate continuously throughout the year, achieves this with an initial storage capacity of 85 m³ for freshwater and 130 kmol for hydrogen. Over an annual cycle, MSFD subsystem produces approximately 1812.23 m³ of freshwater, while PWS subsystem utilizes 1560.00 m³ of this freshwater to generate 2830.82 kg of hydrogen. Subsequently, FC subsystem consumes approximately 2816.63 kg of hydrogen per year to generate 43,800 kWh of electricity, while the total annual electricity consumption for the integrated system is recorded at 1995.01 kWh. The system demonstrates an average annual energy efficiency of 58.4 % and exergy efficiency of 11.2 %, illustrating both effective energy use and conversion. Furthermore, the system’s operation leads to a significant reduction in carbon dioxide emissions, amounting to a total annual decrease of 31884.98 kg. Collectively, the significant contribution of this study is to emphasize the potential of autonomously operated joint systems through the synergistic utilization of renewable energy and hydrogen energy. The specific innovative zero-carbon emission system, driven by solar energy, provides a theoretical framework for the development of integrated strategies for the utilization of solar and hydrogen energy.