Multi-objective optimization of large-scale grid-connected photovoltaic-hydrogen-natural gas integrated energy power station based on carbon emission priority

Establishing integrated energy systems is conducive for improving renewable energy utilization and promoting decarbonization. In this study, a grid-connected photovoltaic-hydrogen-natural gas integrated energy system is established to explore the effects of the configuration of the integrated energy system on its environment and economy. A multi-objective hierarchical optimization allocation model is developed, and an optimization strategy with carbon emission superior to total cost is established for the first time. Additionally, the economy, environment, and energy efficiency of the system are analyzed. A comparative study is performed using a strategy considering that the total cost is superior to carbon emission. A case study reveals that the levelized cost of electricity increases by 62.24%, levelized carbon emission of power decreases by 74.19%, and energy efficiency increases by 8.51%, as compared with those of the comparison strategy. Thus, the carbon emission of the system is reduced considerably, and the energy efficiency is improved. Although the cost of the system optimized by the proposed strategy is higher, it is economically feasible. Further analyses indicate that extending the grid-connected period would be infeasible, as it might increase the total cost and carbon emission of the system. Moreover, sensitivity analyses show that increasing the natural gas price or carbon tax base price will not reduce the carbon emission of the system.