Solar-Powered Hydropower storage in abandoned mines

India's research suggests the financial viability of repurposing idle open-cast coal mines for pumped hydropower storage of solar energy. The study, titled Feasibility study of solar photovoltaic/grid-connected hybrid renewable energy system with pumped storage hydropower system using abandoned open cast coal mine: A case study in India, conducted by the Sardar Vallabhbhai National Institute of Technology, explores the potential of this approach for a mine along India's Godavari River.The researchers propose a pumped hydro storage system, using surplus solar energy to pump water from a lower to a higher reservoir, subsequently generating energy during periods of low solar output or at night. The innovative aspect is using an open-cast coal mine, resulting in an expansive crater, as the basis for this concept.The configuration envisions the river as the upper reservoir, leading to significant construction cost savings. The project's cost estimation amounts to $188 million, with $91 million allocated for the solar plant and $85 million for the pumped storage hydro-power plant (PSHP).With a maximum capacity of 50 MW, the solar plant dedicates approximately 25% of its energy output to the pumped hydro station. Calculations indicate a projected levelized cost of energy (LCOE) of around $0.2693/kWh for this project in India. Factors like unexpected changes were considered, revealing that a 10% solar panel outage raises the LCOE by 19% to $0.320/kWh. In the event of a 10% increase or reduction in capital expenditures (CapEx), the LCOE adjusts to $0.3177/kWh and $0.2491/kWh, respectively.The study concludes that the system boasts a positive net present value (NPV) of $16.408 million, affirming its economic viability. The proposed approach is deemed scalable and cost-effective, presenting a potential solution to meet future electrical requirements at the chosen site.