The generation of renewable energy from sources like wind and solar is one thing, but there are many other factors to consider when delivering renewable energy to consumers. A big one is the issue of storage.
One Oregon startup, ESS Tech Inc. is fixing this problem with its flow batteries.
Making storage more fluid
A flow battery is distinct because of the two external tanks full of electrolytic solution that gets pumped through the battery as it charges and discharges. These tanks are the defining principle behind this device’s lengthening of battery life, as the size of the tanks determines how long they can hold a charge.
“For the whole machine, what you need to do is add more liquid rather than adding many, many more batteries,” said Jun Liu, a University of Washington professor and a fellow at the Pacific Northwest National Laboratory.
A flow battery can be as small as a minifridge or as large as a shipping container that houses many tanks, like the ones being installed at a clean energy development area in San Diego. These could last as long as 12 hours compared to the typical four hours of their lithium-ion counterparts. What’s more, the ESS flow battery doesn’t require rare metals like lithium or vanadium since its main ingredients are iron, salt, and water.
Flow batteries, however, are not yet thought of as a replacement for lithium-ion batteries. Developers and installers think of them as meeting the part of the market that is looking for longer-lasting energy storage, eight hours or more. Lithium-ion batteries are here for the foreseeable future for shorter-term energy storage.
Flow batteries are also finding their place in terms of cost as a new technology in new markets. A 2020 report estimated an installed cost of $551 per kilowatt-hour for a 4 megawatt-hour system. Developers can still install lithium-ion batteries at a much lower cost.
The continued interest in and installation of flow batteries like the ESS system in San Diego continues to grow and optimize the technology and the market, and flow batteries could grow to become a vital part of our renewable energy storage needs.