Is this the world’s best battery? It’s not what you’d expect
Solution has proven itself safe and sustainable for nearly 120 years
When we think about the future of energy storage, most of us probably picture sleek lithium batteries powering everything from electric vehicles (EVs) to our smartphones.
While these engineering marvels have gained significant attention in the push toward renewables, another – far older technology – may hold the key to revolutionising our energy systems: pumped hydro-electric power.
It’s a big battery, flexible enough to respond instantly.
Modern challenge, old solution
The UAE is set to join the growing list of countries with this highly-efficient technology generating clean power at a relatively low generating cost, for many decades to come.
Most pumped-storage hydroelectric plants have a typical design life of 40 years.
Switzerland’s Engeweiher pumped storage facility already lasted nearly 120 years – and still works to this day. It was built in 1907, years prior to when reversible turbines were introduced in the 1930s.
Renewed in the early 1990s, it is scheduled to continue operating until at least 2052 – more than 145 years after it first generated electrons.
Today, the European nation gets up 60 per cent of its electricity from more than 1,650 hydroelectric power plants – around 650 facilities with a capacity of 300 kilowatts or more; and around 1,000 micro-or mini hydro power plants. Up to 40 per cent of its power comes from pumped-storage hydro power.
Together, they generate 16,533 MW (16.5 Gigawatts) and an annual production potential of 37,171 gigawatt hours, according to Bundesamt für Energie, the Swiss agency responsible for issues relating to energy supply and energy consumption.
179GW
Quiet power
There are dozens of countries where pumped-storage hydroelectric power plants are in use, including, China, US, Japan, Germany, France, Canada, India, Indonesia, the Philippines, Russia, Italy, Ireland and Norway.
In many of these countries, this old technology is vital to grid reliability, by acting as batteries – instantly generating power during peak-use hours, displacing coal-fired “peaker plants” and storing water during non-peak hours.
As of 2023, the global generating capacity of pumped hydro-electric power is estimated to be around 179 gigawatts (GW): a huge jump from the early 20th century, when the technology was in its infancy.
Overlooked
Often overlooked in favour of newer, flashier alternatives, pumped hydro has proven to be one of the most efficient, scalable, and sustainable forms of energy storage available today.
Could this ancient engineering technique actually be the world's best battery?
Storing energy with water
This rather simple system effectively stores energy by converting it into gravitational potential energy, which can be harnessed on demand.
During times of low electricity demand or when surplus energy is generated (such as when solar panels or wind turbines produce more than needed), excess electricity is used to pump water from the lower reservoir to the upper one.
When demand spikes, the water is released back down to the lower reservoir through turbines, generating electricity as it flows.
This cycle of “charging” (pumping water uphill) and “discharging” (letting water flow downhill to generate power) allows pumped hydro systems to act as giant, renewable batteries.
Given that water is abundant and gravity is a constant force, the system is both sustainable and reliable, with minimal environmental impact compared to many other forms of energy storage.
Grid-scale energy storage
There are several reasons why pumped hydro-electric works in most parts of the world.
For one, it offers unmatched energy storage capacity.
Unlike chemical batteries, which are limited by the physical properties of the materials they use, pumped hydro systems can store vast amounts of energy, enough to power the grid.
In many cases, these plants can store energy for days, weeks, or even months. It is both a short- and long-duration storage solution crucial for stabilising the power grid. In regions heavily reliant on intermittent renewable energy sources like wind and solar, pumped-storage hydroelectric has proven to be a good match.
Efficiency and longevity
Pumped hydro has a round-trip energy efficiency of around 70-85 per cent, meaning that most of the energy used to pump the water uphill can be recovered when it flows back down.
This level of efficiency is comparable to the best chemical batteries on the market, but with one key difference: longevity.
While lithium-ion batteries degrade over time and lose capacity with every charge cycle, pumped hydro plants can last for several decades with minimal degradation. Many pumped hydro facilities built in the mid-20th century are still in operation today, providing reliable energy storage for over 50 years.
Low operating costs
Once the infrastructure for a pumped hydro-electric plant is in place, the operational costs are extremely low.
Water is effectively free, and there are no costly chemical components that need to be replaced over time, as is the case with lithium-ion or other battery technologies.
Maintenance is minimal and generally involves ensuring that turbines and pumps are operating efficiently.
Flexible
One of the most significant challenges facing modern energy grids is the intermittency of renewable energy sources.
Wind and solar energy, for example, do not produce power when the wind isn’t blowing or the sun isn't shining. Pumped hydro can step in to balance these fluctuations.
They can ramp up or down within minutes, offering a flexible and responsive way to stabilise the grid, integrate more renewables, and prevent blackouts.
Green credentials
While building new reservoirs can have some environmental impact, pumped hydro systems, particularly those that retrofit existing reservoirs or natural bodies of water, have far fewer environmental downsides compared to other energy storage methods.
There is no risk of toxic chemical leaks, as with lithium-ion batteries, and the water used in pumped hydro systems can often be repurposed for agriculture, drinking, or industrial use.
Moreover, pumped hydro is a “closed-loop” system, meaning it doesn’t consume water; it merely moves it between reservoirs.
Growth
The growth in pumped hydro-electric capacity can be attributed to several factors, including:
Increased demand for electricity: As populations have grown and economies have developed, the demand for electricity has surged. Pumped hydro-electric power has emerged as a valuable tool for meeting this increased demand.
Advancements in technology: Improvements in engineering and construction techniques have made it possible to build larger and more efficient pumped hydro-electric plants.
Need for energy storage: The growing integration of renewable energy sources like solar and wind power has highlighted the importance of energy storage.
Pumped hydro-electric power can help to balance supply and demand by storing excess energy during peak production periods and releasing it during periods of low production.
More power
China, in its effort to make the Winter Olympics “green and clean”, has activated the world’s largest pumped hydro storage facility.
The $3-billion (18.96 billion yuan), 3.6 GW Fengning Pumped Storage Power Station in Hebei Province will supply 600 MW of electricity to Beijing and Zhangjiakou, the host cities.
This will eliminate the need to burn 480,000 tonnes of coal annually, reducing CO2 emissions by 1.2 million tonnes.
Last year, the State Grid Corporation of China also launched five additional pumped hydro stations and aims to expand its current storage capacity from 26.3 GW to 100 GW by 2030.
26.3GW
For its part, the US pumped storage hydropower fleet includes about 22 GW of electricity-generating capacity and 550 gigawatt-hours of energy storage with facilities in every region of the country.
“Pumped hydro will be crucial in supporting the integration of variable energy sources, as other storage solutions alone can't provide enough capacity or grid flexibility,” says François Le Scornet, senior consultant at Carbonexit Consulting. “The demand for pumped storage is set to rise significantly in the coming decades.”
Challenges
Pumped hydro is not for every place or every country. Despite its many benefits, there are several challenges associated with it.
One of the most significant is geography. Pumped hydro systems require specific natural features—a high elevation difference and access to large amounts of water.
Another key challenge: policy. Building new infrastructure is costly and time-consuming, although retrofitting existing dams and reservoirs can mitigate some of these concerns.
Additionally, while pumped hydro systems are highly efficient, their overall environmental impact depends on factors: the type of land used and the scale of the reservoirs.
Large-scale installations can disrupt local ecosystems, though modern designs often work to minimise these effects.
Climate goals
As the world races to decarbonise power generation, the demand for reliable, long-duration energy storage will only increase.
Given the global threat of climate change, mega tsunamis and rising tides from glacial melts due to unbriddled CO2 emissions, policy support for the age-old pumped-storage hydropower projects as a new solution will play an important role in the evolving power generation system.
The future of pumped-storage hydroelectric power will hinge on striking a balance between its advantages and limitations. As the energy transition gains momentum, this technology could play a crucial role in maintaining a stable and sustainable power grid. Its successful deployment will require meticulous planning and a thorough assessment of potential environmental impacts.
Economic development can only be possible with a safe and secure energy supply. Pumped hydro is uniquely positioned to meet this need.