Gravity Energy Storage

Using the whole planet to store energy!

SL Staff C

22 Jul 2025 • 2 min read

Gravity energy storage battery under construction in Rudong, China. (Courtesy of Energy Vault.)

Gravity.

It’s not very strong (you overcome the entire planet’s gravitational force every time you lift something), but there’s a lot of it on Earth, and it never quits. Gravity can be exploited as an energy storage mechanism.

How, you ask?

Hydro power is one traditional method. It’s really a form of stored solar energy, where the sun does the work of evaporating water into the atmosphere, which later condenses, falls as rain at higher altitudes into lakes and rivers, and is put to work through turbines as gravity pulls the water downhill. We can also pump water uphill into reservoirs to generate energy later by letting the water flow through turbines, technology known as pumped hydro. Both forms of hydro power depend on geography. The power isn’t necessarily generated where we need it.

There is another way to use gravity to store energy.

Heavy weights can be lifted up in a tower by electric cranes, and lowered back down again later, much like the weights powering a grandfather clock.

In this case, instead of a clock escapement mechanism, the returned gravitational energy is captured by regenerative electric motors. The concept has been around for some time, but one of the first commercial applications is connected to the grid in China.

Energy Vault corporation of Switzerland has built a 25 MW/100 MWh (25 megaWatt peak/100 megaWatthour total energy storage capacity) gravity energy storage system for the State Grid Corporation of China in Rudong, near Shanghai.¹ The project stores electricity from a nearby wind farm to lift weights to the top of a tower. The weights are lowered when needed, to generate electricity that helps smooth electricity demand peaks. The project claims to have a round-trip efficiency of 80% (output vs input), which is comparable to chemical battery energy storage systems.

There are potential advantages to this technology, including no chemical degradation over time, the ability to site the storage near the point of renewable energy generation, and construction that does not depend on scarce critical minerals, except for what is incorporated in the electric motors.

There will be mechanical wear and tear, of course, but the project anticipates a 35-year life.

This is a technology to watch.

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Reading

1. Energy Vault Project – China, Rudong. https://www.energyvault.com/projects/cn-rudong (accessed 2025-07-15).

Reading

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