In August 2019, the Japanese multinational holding firm SoftBank invested $110 million in Swiss company Energy Vault. It was a major boon for the company, which has a somewhat unique take on renewables: It stores potential energy through the use of stacked concrete blocks. Energy Vault will use the investment to build its first two full-scale models in Italy and India.
Energy Vault is only two years old, but has earned its investment through growing interest in energy storage. As renewables rise in use and their prices drop, energy storage is becoming increasingly crucial. Left to their own devices, energy sources like solar panels or wind turbines don’t run forever; solar panels can only produce electricity when the sun’s out, for example, while wind turbines only turn when there’s wind.
Enter storage methods like Energy Vault.
When solar panels in a field in Rome, for example, begin producing energy, they would siphon part of that energy off to a storage facility like Energy Vault. With that energy stored, the company could then run the energy when there was no wind or a cloudy day.
There are many ideas for renewable energy batteries. Energy Vault’s consists of an almost 400-foot tall, six-armed crane with custom-built concrete blocks weighing almost 35 metric tons each. As solar or wind energy is siphoned into an Energy Vault tower, an A.I. directs the concrete blocks to rise up. Then, according to the company’s website, the blocks are “returned to the ground and the kinetic energy generated from the falling brick is turned back into electricity.”
That kinetic energy then turns a motor, which passes through an inverter, sending the energy back into the grid. Energy Vault claims the process had a “round-trip efficiency between 80 to 90 [percent].”
Energy Vault says its tower design means it can scale up or down easily, based on a location’s needs. The company’s website discusses options of 20, 35, and 80 MWh storage capacity as well as anywhere between 4 to 8 MW of continuous power discharge for 8 to 16 hours. What drew investors to the idea in August was its simplicity.
“We at the Vision Fund want to come in when a technology is proven and it’s ready to scale. That’s what’s so exciting about this technology. It’s not a science problem. It’s fifth-grade physics,” said Akshay Naheta, a managing partner of SoftBank’s Vision Fund, at the time of the investment. “There will be teething problems with any new technology. But this is more of a scaling problem.”
The aspect of Energy Vault’s plan that’s most intriguing to potential investors is what’s known as long duration storage. The longer a storage facility can hold energy, the better. There’s no way to know what crises will hit any particular energy grid next, so if Energy Vault could store the energy for months, years, or even indefinitely (there are no time claims on the company’s website), then it would be exponentially valuable to utilities.
Of course, the company doesn’t even have its full-scale prototype built yet. But with SoftBank’s investment, that might change soon.