Pumped-storage hydropower (PSH) is a method of storing energy by pumping water from a lower reservoir to a higher reservoir when excess electricity is available (typically during low-demand periods or when renewable sources like wind and solar are producing surplus electricity). The term "pumped-storage hydropower" is appropriately discussed in the context of Long duration energy storage. Pumping water back into the top reservoir necessitates the use of electricity (recharge) with an overall efficiency of 75-80%. PSH functions similarly to a big battery in that it can store and release energy as needed. This article will explain to you about the Pumped Storage Hydro Power Plant which will be helpful in preparing the Environment syllabus for the UPSC Civil Service exam.

What is a Pumped Storage Hydro (PSH) Power Plant?

• Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage utilized by electric power systems for load balancing.
• Water pumped from a lower elevation reservoir to a higher elevation is used to store energy in the form of gravitational potential energy.
• Pumps are often powered by low-cost surplus off-peak electric power.
• During times of high demand for electricity, the stored water is released through turbines to generate electricity.
• Despite the fact that the plant is a net consumer of energy due to pumping losses, the system boosts revenue by selling more electricity during peak demand periods, when electricity prices are greatest.
• If the upper lake receives sufficient rainfall or is fed by a river, the plant, like a regular hydroelectric plant, might be a net energy producer.

PSH Plants - Working

• One of the most prevalent and well-established types of energy storage technologies is pumped storage hydropower (PSH).
• Water is moved between two reservoirs at various elevations at PSH facilities to store and generate power.
• PSH plants work similarly to conventional hydropower plants, with the exception that PSH can reuse the same water.
• When the plant's power is needed, water flows from the higher reservoir through turbines that rotate generators to produce electricity.
• The water then flows into the lower reservoir, where it will stay until the need for electricity decreases.
• When this happens, the turbines reverse direction to push the water back into the upper reservoir, where it can be utilized to create energy again.

Why is PSH Important for Energy Transition?

• To accomplish their climate targets, governments all across the world are switching from fossil fuels to renewable energy sources.
• However, vital power technologies like wind and solar pose difficulties for power grid management.
• The supply from these sources is intermittent because it is weather-dependent.
• Wind farms, for example, generated about a quarter of the UK's total electricity generation in 2020, but on some days, wind met less than 10% of the country's electrical needs.
• Changing weather patterns and extreme weather occurrences, such as prolonged periods of little wind or limited daylight, pose an additional threat to grid stability.
• When renewable energy output drops, grid operators typically resort to gas-fired power plants to fill the void.
• However, depending on fossil fuels like natural gas to balance the grid in the long run may jeopardise efforts to achieve net zero emissions by 2050.
• Pumped storage hydropower plants serve as massive 'water batteries.' They are a cost-effective and scalable technique of storing excess energy generated by renewables.

PSH Power Plants in India

• There are 5,745 big dams in the country, which provide an ideal opportunity for the development of PSH plants.
• This can be accomplished by sandwiching them between two enormous dams or by constructing a dam and a second reservoir on a hilltop.
• In India, 120 locations with a PSH potential of roughly 120GW have been found.
• So far, only nine plants with a total installed capacity of 4,785MW have been commissioned, with three more under development with a total capacity of 2.7GW.

How to promote PSH Plants in India?

Power storage is an important aspect of India's clean-energy programme, and the country must make it easier to set up PSH plants by taking initiatives like the following:

• The International Hydropower Association's sustainability principles should be adopted, as well as an ex-post examination of a few operational storage facilities, to assist alleviate some of the concerns about energy storage projects.
• States should decide and announce a foundation for PSH-project allotments in a transparent, but distinct, manner from that used for conventional hydro projects.
• For faster development, PSH projects should be decoupled from per-unit energy costs.
• PSH project advantages can be shared across state and national borders.
• India has to create market mechanisms and new economic models that allow energy-storage technologies to be evaluated on their merits.
• Projects are to be prioritized based on their location, storage duration, availability of a pre-feasibility report, extensive surveys, investigations, and project reports, among other factors.

PSH Plants - Significance

• Integration of Renewable Energy: PSH plants are excellent solutions for integrating renewable energy power into the power grid.
• Large Scale: This is the characteristic that best positions pumped hydro storage, which is particularly well adapted to lengthy discharge durations for daily or even weekly energy storage applications.
• Mature Technology: Pumped hydro storage has provided a cost-effective and dependable means to deliver large-scale balancing and grid services for decades. Plant owners now have even more flexibility, production, efficiency, dependability, and availability thanks to new hydro storage technologies like variable speed.
• Minimal Biodiversity Impact: The PSH plants will have a minimal impact on biodiversity and would pose few issues in terms of relocation and rehabilitation (R&R).
• Multi functional: Water management, agricultural irrigation control, water distribution, and water waste control are all possible using PSH plants.
• Promote Atmanirbhar Bharat: Pumped storage schemes use locally produced materials, and even the electrical and mechanical pieces are manufactured in India, allowing PSH facilities to contribute to Atmanirbhar Bharat's goals.
• Non Requirement of License: The Ministry of Power (MoP) has emphasized that, under the Electricity Act, energy storage systems are to be considered an inherent part of our power system, and that putting up a standalone energy storage system does not require a license.

PSH Plants - Challenges

• Requirement of Environmental Permission: Land, forest, and environmental permissions are required for PSH plants.
• Too Expensive: Users, such as discoms, find them excessively expensive and unappealing as a storage solution.
• Private Limited Engagement: Private engagement in PSH projects has been limited due to high investment costs and a protracted gestation period.
• Backing Up of Numerous Policy Makers: Apart from central governments, hydro and PSH projects are a state government legislative matter that require the backing of numerous policymakers and electrical regulators.

Conclusion

According to several recent studies, Pumped Storage Hydro Power Plant projects are a better option for long-term storage (about 8-10 hours), but battery storage systems are better for shorter-term storage (4-6 hours). Existing Pumped Storage Hydro Power Plant units with multiple-cycle operations can be installed for shorter-duration demands. It would also be worthwhile to develop a common nomenclature system for Pumped Storage Hydro Power Plant projects, with energy and capacity (in MWh and MW), as well as their energy-to-power ratio, suitably labeled, so that their utility for peak energy and power ramping is obvious.

FAQs

MCQs

1. What is the primary function of a Pumped Storage Hydro (PSH) power plant?

A) Generate electricity using solar power
B) Store energy and release it during peak demand
C) Generate power from wind energy
D) Desalinate seawater for freshwater

2. What is the environmental impact of building a PSH power plant?

A) Minimal impact due to renewable energy use
B) Destruction of habitats and land use changes
C) No impact on local biodiversity
D) High emissions from power generation

3. What is a major advantage of using PSH power plants in energy grids?

A) They generate electricity from fossil fuels
B) They provide energy storage for intermittent renewable sources
C) They are cheaper to build compared to other power plants
D) They are used exclusively for nuclear energy storage

4. Which of the following is a limitation of PSH power plants?

A) No environmental impact
B) Limited locations due to geographic requirements
C) Low operational cost
D) No dependency on natural resources

5. How does a PSH power plant contribute to reducing the use of fossil fuels?

A) By using fossil fuels to generate electricity
B) By storing renewable energy and reducing reliance on fossil fuel-based plants
C) By eliminating the need for all types of power plants
D) By generating electricity only during non-peak hours

GS Mains Questions and Model Answers

Q1: Discuss the environmental and economic benefits of Pumped Storage Hydro (PSH) plants in the context of renewable energy integration.

Answer: Pumped Storage Hydro (PSH) plants offer significant environmental and economic benefits in the integration of renewable energy into power grids. Environmentally, PSH plants help mitigate the intermittency issues associated with renewable sources like solar and wind by storing surplus energy during low-demand periods and releasing it during high-demand periods. This reduces the need for fossil fuel-based power plants, thereby decreasing carbon emissions. Economically, PSH plants provide cost-effective grid stabilization, reduce the need for additional power generation capacity, and support the widespread use of renewables by making the energy supply more flexible and reliable.

Q2: What challenges do Pumped Storage Hydro plants face in terms of construction and operation? How can these challenges be addressed?

Answer: The main challenges faced by PSH plants include their high capital cost, environmental impact from reservoir construction, and geographical limitations. These plants require significant infrastructure, including reservoirs, tunnels, and turbines, making the initial cost high. The construction of large reservoirs can also have environmental impacts, such as habitat destruction and land use changes. To address these challenges, governments and companies can focus on improving site selection, using advanced construction techniques to minimize environmental disruption, and investing in renewable energy subsidies to offset the high initial costs. Additionally, integrating PSH plants with other forms of renewable energy storage systems can further enhance their efficiency.

Q3: How do Pumped Storage Hydro plants complement other renewable energy sources like wind and solar?

Answer: Pumped Storage Hydro (PSH) plants complement wind and solar power by providing a reliable and flexible means of energy storage. Wind and solar are intermittent sources, meaning they generate power when conditions are favorable (e.g., sunny or windy days), but their output can fluctuate significantly. PSH plants store excess energy generated during periods of high wind or sunlight and release it when the demand is high or when renewable energy production is low. This makes the power grid more stable and ensures that renewable energy can be used efficiently, even when the weather conditions are not optimal for generation.

Previous Year Questions on PSH Plants

1. UPSC CSE Prelims 2020:

Question: Which of the following is a key advantage of Pumped Storage Hydro (PSH) power plants in the context of renewable energy?

A) They generate electricity continuously without interruption
B) They store excess renewable energy for use during high demand
C) They replace the need for all thermal power plants
D) They use fossil fuels for energy generation

Answer: (B)

Explanation: PSH plants store excess renewable energy during low-demand periods and release it during high-demand periods, thereby enhancing grid stability and supporting renewable energy integration.

2. UPSC CSE Mains 2019 (GS Paper 3):

Question: Analyze the challenges and opportunities presented by Pumped Storage Hydro (PSH) plants in the integration of renewable energy sources.

Answer: PSH plants offer significant opportunities by providing a means of storing renewable energy and balancing the grid, especially as wind and solar power become more prevalent. However, challenges include high capital costs, environmental impacts from large reservoirs, and geographical limitations. Despite these challenges, PSH plants are a crucial component of future renewable energy infrastructure, supporting grid stability and reducing reliance on fossil fuels.