The National Electric Power Regulatory Authority (Nepra) in its 'Performance Evaluation Report of Operational Power Plants for 2023-24' highlights the challenges of transitioning to solar and wind power. The report acknowledges that effectively integrating renewable energy into the national grid requires significant investments in energy storage technologies and flexible grid management to maintain stability.
The National Electric Power Regulatory Authority (Nepra) in its 'Performance Evaluation Report of Operational Power Plants for 2023-24' highlights the challenges of transitioning to solar and wind power. The report acknowledges that effectively integrating renewable energy into the national grid requires significant investments in energy storage technologies and flexible grid management to maintain stability.
Pumped storage hydropower (PSH) is the most reliable and cost-efficient technology for large-scale energy storage, balancing grid fluctuations and supporting renewable energy integration with minimal risks and costs. The global emphasis on green, clean, renewable, and affordable energy has increased the focus on optimising PSH capacity. PSH is a mature and effective energy storage solution that can function as an independent unit or in combination with conventional hydropower facilities.
By absorbing surplus energy during periods of high production and releasing it when supply is low or demand increases, PSH efficiently manages grid bottlenecks. This is particularly valuable when co-located with wind and photovoltaic solar systems. Currently, PSH accounts for over 179 gigawatts (GW) of installed capacity worldwide, with numerous projects under development. Global PSH capacity is projected to double over the next two decades, driven by a market valued at approximately $348 billion. Countries like China, Japan, the United States, Germany, and India have adopted PSH on a significant scale.
PSH systems operate similarly to conventional hydropower plants but offer the unique capability of recycling water. Surplus electricity is used to pump water from a lower reservoir to an upper reservoir during off-peak hours. When electricity demand peaks, the stored water flows back to the lower reservoir, generating electricity as it passes through turbines. This cyclical process makes PSH an effective tool for balancing power supply and demand while enhancing grid reliability.
In Pakistan, PSH remains largely underutilised despite the country's growing reliance on intermittent renewable energy sources like wind and solar. These sources, while sustainable, are inherently variable and require complementary energy storage systems to ensure a consistent power supply. However, the high capital investment required for PSH development makes it unlikely for private-sector players or Independent Power Producers (IPPs) to take the lead. Thus, government intervention is crucial.
One viable approach for Pakistan is the development of pump-back hydropower plants, which combine traditional hydropower with PSH capabilities. Retrofitting existing hydropower plants for PSH use is technically feasible but involves considerable engineering and operational planning. For example, the 300-MW Balakot hydropower project, planned for construction at the Kunhar River in the Kaghan Valley of Khyber Pakhtunkhwa, could potentially be adapted for PSH. However, as a run-of-river project, constructing an additional upper reservoir would be necessary, increasing costs significantly.
In Pakistan, PSH remains largely underutilised despite the country's growing reliance on intermittent renewable energy sources like wind and solar. These sources, while sustainable, are inherently variable and require complementary energy storage systems to ensure a consistent power supply. However, the high capital investment required for PSH development makes it unlikely for private-sector players or Independent Power Producers (IPPs) to take the lead
A more practical candidate for PSH adaptation is the Tarbela Dam, one of Pakistan's largest hydropower producers. Tarbela’s existing reservoir infrastructure could facilitate the integration of PSH by utilising downstream structures like the Ghazi-Barotha Canal as the lower reservoir. During off-peak periods, surplus electricity from renewable sources like solar or wind could pump water back to the main reservoir, enhancing sustainability and providing critical grid support during peak demand and emergencies.
Adapting Tarbela for PSH would require installing pumps, pipelines, and reversible pump-turbines or dual-function turbines to enable both pumping and generating operations. While technically feasible, careful water management would be essential to avoid disrupting Tarbela’s primary functions, such as irrigation, flood control, and conventional power generation.
The elevation difference at Tarbela is suitable for PSH, and its proximity to the national grid makes it a strategic asset. Retrofitting existing infrastructure for PSH would likely have a lower environmental impact than greenfield projects, though potential effects on aquatic ecosystems and local communities must be carefully managed.
Despite these advantages, challenges remain. PSH projects require substantial upfront investment, and Pakistan’s ongoing water scarcity could limit the feasibility of continuous operations at Tarbela without compromising its irrigation role. Thus, a comprehensive model integrating PSH with conventional hydropower is necessary for optimal energy management. This approach could maximise revenue through efficient electricity generation while ensuring grid stability.
Realising the potential of PSH at Tarbela requires detailed feasibility studies to assess environmental, economic, and technical aspects. Such studies should leverage insights from global PSH experts and explore collaboration with international stakeholders for funding and technical assistance. Notably, Tarbela’s power station units 1-4 and 5-8, each with a capacity of 175 MW and commissioned between 1977 and 1982, have already outlived their useful life. Their planned replacement and refurbishment present an ideal opportunity to integrate PSH capabilities.
The adoption of PSH in Pakistan aligns with the country’s broader energy goals of reducing reliance on imported fuels, enhancing energy security, and promoting renewable energy integration. As the energy landscape evolves, PSH represents a forward-looking strategy to address Pakistan’s energy challenges while contributing to global climate objectives. Integrating PSH functionality into infrastructure like the Tarbela Dam would not only enhance energy resilience but also support the nation’s emissions reduction targets, paving the way for a sustainable energy future.
The writer is a retired chairman of the State Engineering Corporation and former member (PT) of the Pakistan Nuclear Regulatory Authority.
