SAN FRANCISCO – SoftBank Group Corp.’s massive Vision Fund is making its first-ever energy storage bet — and it’s on a rather unconventional type of battery.
The fund is investing $110 million in Energy Vault, a Swiss startup that’s using cranes and concrete to store energy. An electric crane hoists up blocks of concrete and stacks them into a tower when power is plentiful. When power is needed, it uses gravity to take the structure apart brick by brick. The weight of the descending blocks converts kinetic energy into electricity.
The startup faces stiff competition. Huge lithium-ion batteries have emerged as the storage of choice for utilities looking to deal with short-term fluctuations on their grids. The costs of those have plunged 85 percent since 2010. Entrepreneurs have long pitched alternatives that can hold more energy and supply for longer — including ones that compress and liquefy air and split and store hydrogen, but none have taken off the way lithium-ion has.
SoftBank’s $100 billion Vision Fund is betting on the need for more affordable and bigger storage systems to expand the use of renewable power and wean the world off fossil fuels. Even as the price of wind and solar plummets, they remain intermittent, supplying electricity to the grid at some times and not others. Unlocking a cheap way to bottle up clean power and dispatch it at will could change everything.
Energy Vault uses the same principle that’s long been employed by pumped-hydro storage dams, which use huge reservoirs and gravity to store energy and generate power. SoftBank is convinced the tower concept can scale quickly, with the systems installed next to existing solar power plants or wind farms.
“The minute you have one solar power plant with these towers up and running, we think the scalability goes through the roof,” Akshay Naheta, managing partner for SoftBank Investment Advisers, said in an interview.
He estimates the system can be deployed for 15 percent of the price of a similarly-sized lithium-ion battery installation. SoftBank itself will become one of Energy Vault’s customers and is installing one of the systems at an undisclosed location, Naheta said. Energy Vault also is building a demonstration plant in Italy and a plant for India’s Tata Power Company Ltd.
Robert Piconi, Energy Vault’s co-founder and chief executive officer, said the technology will allow wind and solar facilities to supply electricity to the grid 24 hours per day, undercutting the costs of fossil fuel plants. Grid-scale lithium-ion battery packs, in contrast, typically deliver power for just four hours.
“We’re solving a problem that, today, there’s just not a lot of answers for,” Piconi said.
One advantage is that Energy Vault’s technology can be installed almost anywhere, unlike pumped-hydro systems that need at least two massive reservoirs at different elevations to work. That said, Piconi does not expect Energy Vault’s concrete towers to sprout in urban centers, where the aesthetics may not be appreciated.
“Obviously, this is not something that’s going to fit in the middle of a city,” he said.