The lack of adequate energy storage systems is one of the biggest problems associated with the rise of renewables such as wind and solar in recent years. In an effort to provide a solution, a Dutch startup has invented the Ocean Battery — an energy storage system that operates by the same principles as a hydroelectric dam. 

Energy storage solution

Developed by Ocean Grazer, the energy storage solution is designed to be installed at the bottom of the sea, near offshore wind turbines or floating solar farms. It consists of three key components: a flexible bladder, concrete reservoirs, and the machinery units containing pumps and turbines.

The concrete reservoir lies on the seabed, holding up to 20 million liters (5.3 million gallons) of fresh water, stored at low pressure. The pumps and turbines connect this reservoir to a flexible bladder on the seabed.

Using excess electricity from the surrounding solar or wind farm, the water from the reservoir is pumped into the bladder. When demand is high, the bladder releases and, aided by the pressure of the seawater above it, squeezes its water back into the reservoir. On its way back, the water spins a set of turbines, generating electricity that’s fed into the grid.

According to the team behind the design, the system boasts an efficiency of between 70 and 80 percent and could run an unlimited number of cycles over its lifetime of 20 years. The system boasts a capacity of 10 MWh and the team claims that it can be further scaled to increase general capacity.