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 medium 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.