Improved marketing strategy of a hybrid renewable plant integrated with gravitational energy storage: Techno-economic analysis and multi-objective optimization

Abstract

The intermittent nature of renewable energy sources, which could negatively impact the stability of the electricity grid and the economic viability of the technologies, has intensified concerns about their extensive contributions to the national energy systems' electricity supply. Energy storage systems have become increasingly relevant as a means for securing grids' stability with high shares of renewables. The purpose of this study is to investigate the potential of utility-scale gravitational energy storage as a ‘bidding strategy facilitator in the day-ahead market’ for renewable energy plants. With this ultimate goal, the size of the storage unit is not necessarily very large compared to the peak production capacity of the plant. This is in favor of the cost-effectiveness of the power plant due to today's unsupportive electricity pricing and market regulations for justifying large-scale energy storage systems. The gravitational energy storage system is assumed to accompany a PV farm in Denmark, just as a sample case study. The system is designed, sized, and planned for the optimal marketing strategy of the PV plant using rigorous techno-economic modeling and optimization techniques. According to preliminary findings, a 100 MWP PV plant with 5 MWh storage capacity can be built with a capital expenditure of $126.96 million, at a discounted payback period of 10.6 years, and reduced annual penalties of over 94.5 %.