Flow batteries offer significant advantages over lithium-ion batteries. They have a much longer lifespan, can be fully discharged and recharged many thousands of times without damage, and have no danger of explosion or fire due to overheating. They also tend to be heavy and bulky, which makes them unsuitable for use in automotive applications.
Known to the scientific community as redox (reduction oxidation) batteries, they involve two tanks of liquid — one positively charged and one negatively charged — separated by a membrane which allows electrons to pass between the two tanks but not molecules. In the right setting, they can store prodigious amounts of electricity safely and inexpensively.
German utility company EWE says it is planning to build the world’s largest battery based on flow technology in a pair of salt caves currently used to store natural gas. Taken together, the caves have a volume of 3.5 million cubic feet — enough to store up to 700 megawatt-hours of electricity with an output capacity of 120 megawatts, according to Digital Trends.
To put that into perspective, a battery with that much capacity could meet the electrical energy needs of the city of Berlin for an hour or 75,000 homes for a day. “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 project, which has been named brine4power.
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