Flow batteries store their energy in separate electrolytes, that circulate through electrochemical cells where they exchange ions across membranes. This arrangement distinguishes them from conventional batteries, that store their energy in electrodes. There is growing interest in using flow batteries for long energy storage, as we describe below.
More About Long Energy Storage Flow Batteries
Flow batteries working on the redox principle, help maintain grid stability by adjusting supply to demand. They do this by storing surplus electricity, and then releasing it during high use periods. This is an ideal application for renewable energy, which may not be available during early morning and evening peaks.
Using flow batteries for long term energy storage is hence, part of the key to reducing dependence on fossil fuel. However, their chemistry also has an important secondary purpose. They can support small, isolated communities that rely on renewables as their primary electricity source.
Vanadium Flow Storage Batteries
Vanadium flow batteries date back to the 1980s, and are making inroads within increasing power and capacity. They store their energy in electrolytes containing ions, with four different oxidation states.
These electrons move between the electrolytes during charging and discharging, through external circuits. Their sheer physical size lowers their energy density, making them unsuitable for small devices.
Iron Flow Redox Batteries
Iron-based flow batteries work similarly to vanadium ones, except they use iron salt at their active ingredient. This makes them a more affordable and environmentally-friendly option, able to achieve 10,000 charge / discharge cycles. However, they are even bulkier than vanadium flow batteries.
Organic Flow Batteries Coming
Organic flow batteries are an exciting alternative, attracting much research interest. That’s because their chemistry uses carbon-based molecules, as opposed to vanadium or iron metals.
Organic options may turn out to be the cheapest, non-toxic flow batteries for long term energy storage. However, these are still early days in their development, and we shall have to wait patiently and see.
More Information
Zinc-Vanadium Chemistry For Storage
Iron Flow Batteries Touch Down At Schiphol
