While Tesla is building a battery system capable of storing 100MW of energy in Australia, this system is made up of thousands of smaller individual cells.
Instead EWE GASSPEICHER, a subsidiary of German utility company EWE, plans to build the huge battery in a cavern using salt water and recycled plastics. It is working with the Friedrich Schiller University in Jena to develop the components needed.
“We need to carry out some more tests and clarify several issues before we can use the storage principle indicated by the University of Jena in underground caverns. However, I expect that we will have an operating cavern battery by about the end of 2023,” says Ralf Riekenberg, head of the brine4power project.
“Since salt water in caverns is also known as brine and we intend to store power according to the redox flow principle, we have named the project brine4power, or b4p for short,” he said. “However, we will not initially be using actual caverns, but enormous plastic containers that will be set up at the gas storage facility in Jemgum in East Frisia, probably in the fourth quarter of this year.”
EWE currently operates eight caverns in Jemgum in an underground salt dome for storing natural gas.
“If everything works, this may fundamentally change the storage market,” said Peter Schmidt, managing director of EWE GASSPEICHER. “The amount of electricity this kind of storage facility contains – consisting of two medium-sized caverns – is sufficient to supply a major city such as Berlin with electricity for an hour. It means that we will have built the world’s largest battery. In contrast to other energy storage facilities that convert the electrical current into other energy carriers – for example into compressed air – we are storing the electricity directly with brine4power.”
In a redox flow battery, two different electrolytes are used. These are distributed across two separate containers. Both electrolytes can strongly attract electrons (negatively charged particles). The electrolyte with the stronger bond to electrons is called the catholyte and the electrolyte with the weaker bond is called the anolyte. The power supply from outside (for example from electricity generated by wind turbines or photovoltaic power plants) effectively snatches away the electrons from the catholyte (oxidation) and feeds them to the anolyte, which binds them to itself (reduction), charging the battery. On discharging, the “stronger electron bonder”, the catholyte, snatches back the electrons from the weaker one, the anolyte, creating a useful flow of electricity.