Integrating Solar Energy and Pumped Hydro Storage for Sustainable Power Supply: A Case Study of the West Bengal Power Sector

Abstract

This paper undertakes a real-world performance evaluation of the Purulia Pumped Storage Plant (PPSP) situated in West Bengal and its integration with solar photovoltaic (PV) power plant to assess the technocommercial feasibility of the hybrid system towards mitigation of intermittency nature of solar energy which is a necessity for India’s energy transition and ambitious renewable energy goals, using high-resolution real operational SCADA data instead of simulation-based approaches. Pumped Hydroelectric Plants (PHPs) are primarily utilised during peak demand periods and in instances of major power plant outages. India’s very first pumped storage plant was commissioned in 1985. Presently, out of the 4.75 GW of pumped storage plants installed across the country, 3.3 GW are operational in pumping mode. However, these plants have fallen short of their projected energy generation figures due to insufficient availability of off-peak power for pumping operations, until the advent of various renewable energy sources, notably solar energy, in India. Against this backdrop, this analysis delves into the economic viability of the Purulia Pumped Storage Plant considering real solar generation profiles distributed across the west Bengal state and PPSP operational data of six representative days viz., 6th Feb, 26th April, 8th June, 24th Aug, 4th Oct and 30th Dec across different seasons of the year 2023 to assess critical performance indicators such as Daily Efficiency (DE), Cumulative Pumped Ratio (CPR) and Levelized Cost of Storage (LCOS) for both actual grid power operational scenario and hypothetical solar power generation driven pumping scenario matching with the actual PPSP operation. The study findings reveal that the  hypothetical solar-PPSP hybrid system doesn’t just slightly improve economics, it fundamentally enhances the value proposition by drastically reducing reliance on the grid electricity, achieving up to a 100% displacement on four days except 6????ℎ Feb and 30????ℎ Dec.  This substitution of high-cost grid power of up to 6.01 INR/kWh with low-cost solar energy with LCOE of 2.55 INR/kWh directly caused a dramatic surge in the CPR by 15% to 136% and halved the LCOS range to 0.31-1.05 INR/kWh, fundamentally transforming the plant’s economic viability. CPR on the six representative days have increased from 159.50, 98.36, 102.20, 40.23, 137.37 and 152.18 in actual operational scenario to 182.92, 178.98, 225.64, 94.82, 294.13 and 230.83 respectively in the hypothetical scenario. On the other hand, LCOS has decreased from the range of 0.38 - 2.32 INR/kWh in case of actual operational scenario to the range of 0.31 - 1.05 INR in the hypothetical scenario. This work may therefore contribute as a data-driven evidence base on the technoeconomic advantages of solar-powered pumping for PHP with varying seasonal demand and solar generation patterns, marking a significant departure from model-driven studies and would be useful for policymakers in reinforcing the role of hybridization of the existing and the upcoming PHPs in achieving India’s ambitious renewable energy goal.