Capacity optimization of pumped storage hydropower and its impact on an integrated conventional hydropower plant operation

Abstract

The energy sector contributes to around 60% of total greenhouse gas emissions. To limit climate change, the world is going through an energy transition to clean and affordable energy, therefore the share of variable renewable energy is increasing day by day. Power systems require significant flexibility to operate reliably. Pumped storage hydropower allows load balancing and stable integration of intermittent renewable energy in the electrical grid. All energy storage technologies, including pumped storage hydropower, are considered a net negative contributor to the grid since they draw more energy than they deliver. This paper uniquely investigates the true potential of pumped storage hydropower and its optimum operation along with existing conventional hydropower. It considers power, energy production, and utilization for both installations to determine an equilibrium condition for a net positive energy balance. The case study of the 300 MW Balakot conventional hydropower plant in Khyber Pakhtunkhwa, Pakistan indicates that the pumped storage hydropower sites, where additional water streams reach the upper storage reservoir, can reduce pumping energy consumption by up to 166 GWh/year. Accordingly, a pumped storage hydropower facility is proposed at Paras, Pakistan, modeled, and optimized in an integrated manner with the Balakot conventional hydropower plant for a net positive annual energy generation and profitability. The integrated power and energy modeling and capacity optimization of the hydropower complex highlight the importance of suitable site selection for pumped storage hydropower near existing conventional hydropower reservoirs. Value-added contribution of this configuration is that it can enhance annual energy generation from integrated conventional hydropower, reduce the upfront capital cost of the project by 10–15%, squeeze the project implementation schedule and result in a smaller carbon footprint to meet the ultimate objective of limiting climate change. Additionally, it unlocks huge untapped pumped storage hydropower potential besides existing conventional hydropower. Furthermore, the study guides the scientific and engineering organizations on optimum capacity utilization without impeding energy generation from conventional hydropower facilities.