Optimal sizing and deployment of gravity energy storage system in hybrid PV-Wind power plant

Abstract

The world today is continuously tending toward clean energy technologies. Renewable energy sources are receiving more and more attention. Furthermore, there is an increasing interest in the development of energy storage systems which meet some specific design requirements such as structural rigidity, cost effectiveness, life-cycle impact, and increased energy capacity. Gravity energy storage (GES) is one of those innovative storage technologies that is still under development. Hence, this study proposes a new methodology which aims to optimally design and deploy a large-scale GES system in a hybrid PV-Wind plant to make it more competitive technically and economically. The objective of this study is to minimize GES construction cost restricted by handling mechanical load applied on the system's structure. The sizing methodology is based on genetic optimization algorithm which aims to determine the optimum dimensions of GES components. A case study has been used to verify the effectiveness of the proposed model. The findings of this study have shown that the optimal system's height is about 48 m with a diameter of 24 m and a wall thickness of 3m. The construction cost of the system reaches 6.7 M€ with the piston representing the largest cost share. The cost of electricity was found equals to 0.19 €/kWh. In addition, this work investigates the integration of GES with a hybrid wind-solar grid-connected power plant to properly dispatch renewable power by incorporating an efficient storage strategy preventing overcharging/discharging of GES. The findings demonstrate the ability of this new storage system to balance the energy supply and demand. A comparison between the obtained results with that of a battery energy storage has shown that GES performs better due to its high DOD and lifetime, as well as its good efficiency.