Global: Batteries get hyped, but pumped hydro provides the vast majority of long-term energy storage essential for renewable power – here’s how it works
- Jan 19, 2022 3:00 pm GMT
Source: The Conversation –
Wind and solar power vary over the course of a day, so energy storage is essential to provide a continuous flow of electricity. But today’s batteries are typically quite small and store enough energy for only a few hours of electricity. To rely more on wind and solar power, the
While battery innovations get a lot of attention, there’s a simple, proven long-term storage technique that’s been used in the
It’s called pumped hydro energy storage. It involves pumping water uphill from one reservoir to another at a higher elevation for storage, then, when power is needed, releasing the water to flow downhill through turbines, generating electricity on its way to the lower reservoir.
Pumped hydro storage is often overlooked in the
We created a world atlas of potential sites for closed-looped pumped hydro – systems that don’t include a river – and found 35,000 paired sites in the
Why wind and solar need long-term storage
To function properly, power grids must be able to match the incoming electricity supply to electricity demand in real time or they risk shortages or overloads.
There are several techniques that grid managers can use to keep that balance with variable sources like wind and solar. These include sharing power across large regions via interstate high-voltage transmission lines, managing demand – and using energy storage.
Batteries deployed in homes, power stations and electric vehicles are preferred for energy storage times up to a few hours. They’re adept at managing the rise of solar power midday when the sun is overhead and releasing it when power demand peaks in the evenings.
Pumped hydro, on the other hand, allows for larger and longer storage than batteries, and that is essential in a wind- and solar-dominated electricity system. It is also cheaper for overnight and longer-term storage.
Off-river pumped hydro energy storage
In 2021, the
Creating closed-loop systems that use pairs of existing lakes or reservoirs instead of rivers would avoid the need for new dams. A project planned in
An off-river pumped hydro system comprises a pair of reservoirs spaced several miles apart with an altitude difference of 200-800 meters (about 650-2,600 feet) and connected with pipes or tunnels. The reservoirs can be new or use old mining sites or existing lakes or reservoirs.
On sunny or windy days, water is pumped to the upper reservoir. At night, the water flows back down through the turbines to recover the stored energy.
A pair of 250-acre reservoirs with an altitude difference of 600 meters (1,969 feet) and 20-meter depth (65 feet) can store 24 gigawatt-hours of energy, meaning the system could supply 1 gigawatt of power for 24 hours, enough for a city of a million people.
The water can cycle between upper and lower reservoirs for a hundred years or more. Evaporation suppressors – small objects floating on the water to trap humid air – can help reduce water evaporation. In all, the amount of water needed to support a 100% renewable electricity system is about 3 liters per person per day, equivalent to 20 seconds of a morning shower. This is one-tenth of the water evaporated per person per day in the cooling systems of
Storage to support 100% renewables
Little pumped storage has been built in the
In 2020, about three-quarters of all new power capacity built was either solar photovoltaics or wind power. Their costs have been falling, making them cheaper to build in many areas than fossil fuels.
Shifting electricity to renewable energy and then electrifying vehicles and heating can eliminate most human-caused greenhouse gas emissions. The
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– ref. Batteries get hyped, but pumped hydro provides the vast majority of long-term energy storage essential for renewable power – here’s how it works – https://theconversation.com/batteries-get-hyped-but-pumped-hydro-provides-the-vast-majority-of-long-term-energy-storage-essential-for-renewable-power-heres-how-it-works-174446
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