INTEGRATED PHOTOVOLTAIC-FUEL CELL GENERATION METHODOLOGIES: DESIGN, DEVELOPMENT AND OPTIMISATION FOR DISTRIBUTED APPLICATIONS

Abstract

Renewable energy technologies based on solar, wind, biomass, tidal, hydro, geothermal sources have shown the potential to significantly substitute fossil fuels in the emerging energy infrastructures. There are ongoing investigations into the applications of integrated photovoltaic-fuel cell (IPVFC) systems for grid and off-grid applications in the upcoming hydrogen economy. Consequently, this study focuses on how the overall effectiveness of IPVFC systems can be improved using a model-based systems engineering approach. Firstly, an energy and exergy efficiencies enhancement analysis (E4A) methodology was proposed to investigate the interrelationships between cost, efficiency and complexity as usage and conversion losses are targeted for recovery in photovoltaic (PV)-led integrated energy systems (IESs). Findings showed that improving the PV, electrolyser and fuel cell components could improve the overall efficiency of IPVFC systems. Thus, a code-based modelling (CBM) approach was developed to facilitate the design, modelling, and simulation of photovoltaics. This approach enabled a creation of a photovoltaic-thermal model. Investigations with the proposed model showed that the overall improvement in exergy of a PV module could be up to 51% if the waste heat generated was utilised for useful thermal work as in photovoltaic-thermal (PV/T) systems. However, the open circuit voltage degraded with an increase in the temperature of the PV module. The CBM approach was also applied to create a thermophotovoltaic (TPV) model. TPV is another application of photovoltaics for power generation. A parametric study with the proposed TPV model indicated that a silicon-based PV module can produce a power density output, thermal losses, and maximum voltage of 115.68 W cm-2, 18.14 W cm-2 and 30.87 V, at a radiator and PV cells temperatures of 1800 K and 300 K, respectively. Alike the solar photovoltaic generation, the open circuit voltage degraded when the temperature of the TPV cells increased. For an 80 W PV module, there was a potential for improving the power generation capacity by 45% if the radiator and PV cells of the TPV system were operated at a temperature of 1800 K and 300 K, respectively. Indeed, the intermittency of meteorological variable affects PV-based technologies such as an IPVFC system. Thus, a thermodynamic-based procedure was developed to determine an optimal location among multiple locations for installing a large-scale photovoltaic power generation to achieve economic, performance and environmental objectives. To achieve an improved efficiency, reduced cost, and lesser complexity of IPVFC systems, a Unitized Regenerative Proton Exchange Membrane Fuel Cell (URPEMFC) system was considered to replace electrolyser and fuel cell components. This is because an IPVFC system with a lower complexity would be beneficial during the manufacturing and operation stages of the system. Although the theoretical thermodynamic efficiency of a URPEMFC system was about 68.86%, the study predicted an efficiency of 44% for a stack of 10 cells at a current density of 0.5 A cm-2. This performance level of a URPEMFC component was better than using a PEME and a PEMFC for electrolytic and galvanic functions, respectively. Still, to advance the performance of the URPEMFC component, the inherent power hysteresis effect needs to be addressed by reducing the overpotentials and irreversibilities in the component. Lastly, a systematic and systemic analysis of possible thermodynamic pathways to realise an IPVFC system with the optimal cost-efficiency-complexity benefits was performed. The finding indicated that a PV/T-Battery-URPEMFC system with unitized converter-inverter appeared to offer an optimal configuration to generate power, heat and hydrogen and it is therefore recommended for further investigation for various distributed applications. Overall, improving the effectiveness of IPVFC systems depended on the thermodynamic characteristics of the compo

Date of Award	31 Dec 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Adel Nasser (Supervisor) & Chamil Abeykoon (Supervisor)