concrete blocks

As wind and solar energy play a growing part in our energy system, the need for grid-scale energy storage is growing as well. An historic form of energy storage and still the largest in installed capacity is pumped hydro storage, which makes use of the potential energy contained in having water sitting at a higher elevation where it can be released downward to operate turbine generators. This is an effective system but is limited to places where geography cooperates.

For the past five years, a company called Energy Vault has been developing a system that uses the same principle to generate electricity but instead of pumping water to a higher elevation, it uses mechanical devices to lift heavy objects such as concrete blocks to an appropriate height. Lowering the blocks back to the ground drives generators.

To date, Energy Vault has only built demonstration systems with a fraction of the storage capacity needed for grid-scale operation. Their EV1 Tower in Switzerland was successfully grid interconnected in 2020 and demonstrated round-trip efficiency (the fraction of the energy stored that was produced by the generators) above 75%. Their improved EVx system is expected to do better than 80%.

This year the company, along with partners Atlas Renewable and China TIanying, is now in the first phases of commissioning a grid-scale system located outside of Shanghai, China. The 25-MW system is built adjacent to a wind farm and a national grid interconnection site

This is the first grid-scale gravity energy storage system and is expected to be fully online in the fourth quarter of this year. A second, similar system is now under contract to be built elsewhere in China.

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First grid-scale gravity energy storage system undergoes commencement in China

Photo courtesy of Energy Vault.

Earth Wise is a production of WAMC Northeast Public Radio

A potentially transformative utility-scale energy storage technology has won a 2019 “World Changing Idea” award from Fast Company magazine. Known as the Energy Vault, the technology seeks to be the successor to the granddaddy of grid energy storage: pumped hydro.

Shifting water between higher and lower reservoirs is still basis of the vast majority of global grid storage capacity. But it is limited both by its unique location needs and by environmental regulations.

A start-up company also called Energy Vault and based in both Switzerland and Southern California has come up with an extremely creative grid storage concept. The technology consists of a six-armed crane that stacks huge concrete blocks using a currently available source of cheap and abundant grid electricity, and then drops them down to generate electricity when needed.

The system is said to operate at about 90% efficiency and can deliver long-duration storage at half the prevailing price on the market today.

A full-scale Energy Vault plant, called an Evie, would look like a 35-story crane with six arms, surrounded by thousands of manmade concrete blocks, weighing nearly 40 tons each. When charging, the plant will stack the blocks around itself higher and higher in a Babel-like tower. To discharge, the cranes drop the blocks down, generating power from the speedy descent. This configuration can deliver 4 megawatts of power and store about 35 megawatt-hours of energy.

There isn’t even a factory needed. The company would deliver a crane from a manufacturer. The crane will then assemble the blocks onsite using recycled concrete. Operation is then fully automated. The system is expected to run for 30 or 40 years.

So far there is only a one-seventh scale demo unit in Switzerland. But this is a very intriguing idea.

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Energy Vault Wins World Changing Idea Award 2019 from Fast Company for Transformative Utility-Scale Energy Storage Technology

Photo courtesy of Energy Vault.

Earth Wise is a production of WAMC Northeast Public Radio.

Grid-Scale Gravity Energy Storage | Earth Wise

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The Energy Vault

A potentially transformative utility-scale energy storage technology has won a 2019 “World Changing Idea” award from Fast Company magazine. Known as the Energy Vault, the technology seeks to be the successor to the granddaddy of grid energy storage: pumped hydro.

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