Evaluation & optimization of solar-fossil-fuel-based multi-generation system with energy storage

Abstract

The integrated solar energy hybrid system combines decentralized, energy-efficient approaches to various energy production methods, offering benefits such as improved efficiency, emissions reduction, cost-effectiveness, sustainability and reliability. Thus, in this study, the optimal design of a solar-fossil-fuel-based combined cooling, heating, power and freshwater generation system is presented. The main prime movers for generating power and heat concurrently are considered gas engines, diesel engines, gas turbines, and solid oxide fuel cell. The suggested system configuration contains a prime mover, two chillers, auxiliary boiler, desalination unit, parabolic trough collectors, photovoltaic panels, proton exchange membrane electrolyzer, thermal and cooling storage tanks. The genetic algorithm is considered as the optimization method for determining the lowest total annual cost. Various decision parameters are considered in this assessment, including the prime mover's capacity and operating under 12 partial loads, the number of prime movers, mass flow rate of the solar parabolic trough collectors, the electric cooling ratio, operation of 16 partial loads for chillers (with each chiller accommodating 8 partial loads), capacity of the auxiliary boiler, thermal and cooling energy storage tank capacities, number of photovoltaic panels, and the isentropic efficiency of the high pressure pump. The total annual cost comprises economic, energy, and environmental factors. Notably, the current system permits the purchase or sale of electricity to the grid. The optimal results disclosed a reduction of 27.08 %, 13.83 %, and a 23.80 % in the total annual cost of the system including the gas engine compared to the system with solid oxide fuel cell, diesel engine, and gas turbine, respectively. Furthermore, the system with solid oxide fuel cell showed fuel energy savings ratios of 48.6 %, 38.26 %, and 24.46 %, respectively, compared to the system including gas turbine, gas engine, and diesel engine. Additionally, in comparison to systems with solid oxide fuel cell, diesel engine, and gas turbine, the exergy efficiency of the system with gas engine is higher approximately 40.31 %, 3.04 %, and 92.50 %, respectively. The optimum total annual cost and exergy efficiency were determined to be 1.6708 ×106 $/year and 42.08 %, respectively, for the system utilizing the gas engine. Eventually, the comparison and analysis of optimal results from energy, exergy, economic and environmental perspectives were presented.