It's a genius idea.
Ups and Downs
Switzerland-based startup Energy Vault has broken ground on two huge facilities in Texas and just north of Shanghai, CNET reports, to test whether we can store energy by raising and lowering hundreds of 24 metric-ton (53,000 pound) bricks made of compressed dirt.
The idea is astonishingly simple. By lifting the massive bricks to the facility's upper levels during periods of excess renewable energy production, the facility's cranes can store large amounts of power — and release it by subsequently lowering them back down when demand is high and the energy supply is low.
It's an elegant concept — and one that, if it works in practice, could bolster the resilience and sustainability of the electric grid while lowering the cost of energy storage. Needless to say, we'll be watching.
The Life Kinetic
While it's not the first time Energy Vault has constructed a gravity storage system, the company is hoping to prove its concept works on a much larger scale.
The startup already built a scaled-down pilot system near its headquarters in Switzerland, generating a considerable five megawatts of power. The new facility in China, however, is far bigger at 400 feet in height, with a storage capacity of 100 megawatt-hours. According to CNET, that's enough to power 3,400 homes for an entire day. The facility in Texas, meanwhile, is designed to provide a nearby power company with 36 megawatt hours of capacity.
The Chinese facility makes use bricks made of 99 percent compressed dirt, with water and polymer mixed in. By jamming them inside a giant rectangular building, Energy Vault hopes to use a trolley system to transport the bricks to and from an elevator.
Each brick being lowered at six feet a second can generate an entire megawatt, the company says, for an overall efficiency of at least 80 percent.
Storing energy by lifting and lowering giant blocks of compressed dirt could store solar and wind energy far more cheaply than complex lithium ion-based solutions.
Having this energy capacity on tap could also allow utilities to adjust to a quickly changing energy production environment and lower their reliance on natural gas, coal, and oil.
"If we're ever going to wean ourselves more and more off of fossil fuels and replace that with renewable generation that's intermittent, the only way to solve that is storage," Energy Vault CEO Robert Piconi told CNET.
More on gravity batteries: Scientists Propose Turning Skyscrapers Into Massive Batteries