Design of a two-rail layout funicular mountain gravity energy storage system hybrid with optimized vertical weight storage and its integration with renewables

Solid gravity energy storage is emerging as a promising solution due to its scalability, long lifespan, and potential for large-capacity energy storage. When deployed in mountainous regions, it offers an environmentally sustainable approach, leveraging natural topography to minimize infrastructure requirements. This study proposes a novel two-rail layout funicular mountain gravity energy storage system integrating an optimized vertical weight storage technique using overhead cranes (OVF2R-MGESS). Unlike existing mountain gravity storage systems that rely on extensive horizontal weight storage yards, this proposed approach can enhance storage efficiency and minimize land footprint, while optimizing the levelized cost of storage (LCOS). The proposed system utilizes local stone extracted from the mountain itself, reducing both the need for heavy transportation of storage materials to remote sites. Moreover, integrating these technologies with renewable energy sources (RESs) enables the creation of an efficient, integrated energy system that helps reduce carbon emissions and increases reliance on clean energy in a more sustainable and stable way over the long term. A case study at Al Hada Mountain, Al Taif, Saudi Arabia, demonstrates the integration of OVF2R-MGESS with a grid-connected solar PV system, taking advantage of the region's high solar irradiance and elevated mountainous terrains. A techno-economic analysis using HOMER Pro software is conducted to assess the feasibility of OVF2R-MGESS as a cost-effective energy storage solution that enhances grid stability and facilitates large-scale renewable energy deployment. The findings confirm its competitiveness as an alternative to existing mountain gravity storage technologies and its potential for widespread application in mountainous regions worldwide.