The Gravity Battery

2 min read

Scientists are working on gravity batteries as an alternative to traditional battery energy storage. A gravity battery works like a giant elevator. It uses electricity (ideally from renewable sources) to lift a heavy load from the bottom of a structure to the top in charging mode. The potential energy accumulates and charges the battery. When electricity is needed, the load is allowed to fall under the force of gravity, while the structure extracts energy from this movement and the electric motors deploy it to the consumer in generator mode.

Since the falling speed of the load can be controlled, the battery system can deliver electricity for 8 hours. The heavier the load, the greater the energy output. Likewise, the higher the structure, the greater the energy output.

In 2021, Gravitricity developed its first test prototype in the port of Edinburgh, Scotland. This 15 m high structure lifts a 25-ton load using electric motors powered by solar. The result is 250 kW of energy, almost enough to power 80 UK homes for 6 hours. It is estimated that one structure could output as much as 1 -20 MW for 8 hours. Gravitricity’s engineers estimate that a 20 MW power grid could fuel 63 000 homes for every discharge hour. The company proposes using abandoned coal mines which can stretch 3 km underground.

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Other companies have their hands in this technology too. Energy Vault built their own test prototype in Switzerland consisting of 6 cranes on a 110 metre tower, each lifting and dropping its own 35 ton load to produce 80 MW of peak power. Ares Energy, in Nevada, USA, uses solar energy to pull concrete carts uphill and collect energy from them as they roll back downhill. One 300 ton cart can generate 50 MW of power.

The first practical gravity battery is set to be released in 2023 or 2024, with an estimated capacity of 4 MW. This would require a height (or depth in a mine) of 1 km. It will, however, be many years before we will see gravity batteries everywhere. That is, assuming the technology gets the funding, innovation and other forms of help it needs.

What do you think of gravity batteries? Do you think this is a technology that will scale into something widely used such as solar? Share your thoughts by replying to this email!

For more information on gravity batteries, or any other energy related articles, view the blog posts on my website and be sure to open my weekly emails every Tuesday at 9am CAT.

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