Bye-bye batteries: storing energy in big blocks

Energy Vault's tower with crane perched on top (blocks)
Image: Energy Vault

Startup Energy Vault is working on a unique energy storage method using big blocks that has seen it raise over $100 million in Series C funding, according to a report by Singularity Hub.

The method was inspired by pumped hydro, which has been around since the 1920s and uses surplus generating capacity to pump water up into a reservoir. When the water is released, it flows down through turbines and generates energy like conventional hydropower.

Energy Vault uses the same method utilising heavy blocks and a tall tower instead of water and a reservoir.

“When there’s excess power—on a sunny or windy day with low electricity demand, for example—a mechanical crane uses it to lift the blocks 35 stories into the air. Then the blocks are held there until demand is outpacing supply. When they’re lowered to the ground (or lowered a few hundred feet through the air), their weight pulls cables that spin turbines, generating electricity,” the report said.

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The blocks are made of a composite material that uses soil and locally-sourced waste, which can include anything from concrete debris and coal ash to decommissioned wind turbine blades. Besides putting material that would otherwise go into a landfill to good use, this also means the blocks can be made locally and don’t require transporting.

The cranes that lift and lower the blocks are controlled by automated custom software. Energy Vault says the towers will have a storage capacity up to 80MWh and can continuously discharge 4-8MW for up to 16 hours. The technology is best suited for long-duration storage with very fast response times.

Energy Vault plans to use the cash from its Series C funding to roll out its EVx platform, which includes performance enhancements like round-trip efficiency up to 85 per cent, a lifespan of over 35 years, and a flexible, modular design that’s shorter than the original—which means it could more easily be built in or near densely-populated areas.

The company will roll out its EVx platform in the US this year before moving on to fulfill contracts in Europe, the Middle East, and Australia in 2022.