With the popularity of photovoltaic systems and increasingly grid -connected amount of photovoltaic grid, the promotion of energy storage has become imminent. When the amount of grid is relatively small, relying on lithium iron phosphate, which provides continuous power for 1 to 4 hours, can meet most of the demand. But if the grid-connected volume continues to grow, we urgently need new technologies that can supply power for more than 4 hours.
Image source: Overseas website - ESPlaza
Long-Duration Energy Storage is this new technology, which is an energy storage system that is greater than 4 hours and can be cyclically charged and discharged for several days and months. For example, a limit calculation: If a place gets 100% of its electricity from solar power, but there are typically only 8 hours of light in a day, that means that the other 16 hours of power needs will all depend on storage batteries. If the battery power lasts only 4 hours, then the other 12 hours will only be blacked out. But based on the broader goal of carbon neutrality and improving the energy structure, the rate of clean energy such as solar and wind power is rapidly increasing, Long-Duration Energy Storage becomes more and more important.
Flow Battery, from its special construction and working principle, are one of the most suitable battery technologies for Long-Duration Energy Storage. Flow Battery, also known as redox battery, is completely different from ion battery such as lithium battery. Flow Battery store energy in the electrolyte, rather than in the solid positive and negative electrodes of lithium battery and lead battery. Moreover, the positive and negative electrodes of flow battery are liquid, completely independent and placed separately. Flow battery has high safety, flexible capacity expansion, long cycle life, and the electrolyte inside can be recycled. But it has a low energy density and relatively high initial installation cost. For long-term storage, though, these disadvantages are not too difficult to overcome, but the advantages are invaluable.
Image source: Overseas website - ESPlaza
As we all know, we commonly use the photovoltaic is lithium battery. So can lithium battery be used for long-term storage? The answer is: No. The biggest problems with lithium battery are safety and cycle life. To increase their storage capacity, lithium-ion battery has to contain more lithium. But lithium is a relatively "cranky" metal, the higher the lithium content, the greater the safety risk. According to incomplete statistics, in the first half of 2022, there were more than 10 new accidents in the world of lithium battery energy storage power stations, about 80% of which used ternary lithium ion battery, followed by lithium iron phosphate battery. Flow battery can well neutralize these shortcomings of lithium battery. Firstly, flow battery is very safe. Its positive and negative electrolytes are used to store energy, and because the electrolytes are filled with water, there is no organic solvent, so they will not burst into flames. Lithium battery is often unsafe because the heat generated by lithium battery cannot escape, but the heat of a flow battery can easily be transferred from the inside of the battery to the outside with the electrolyte. So flow battery, both BMS and some additional fire protection measures, can be a notch below lithium battery without too much hassle. Secondly, flow battery have a very long cycle life. Because the electrode in the flow battery does not participate in the reaction, it belongs to the inert electrode. The electrode and the bipolar plate and other materials have good stability and do not involve the replacement problem. At the same time, the reaction process does not involve phase transition, so the cycle life can reach 15,000 to 20,000 times. Thirdly, flexibility. Since the power and energy units of a flow battery are independent of each other, this means that the system power and storage duration can be flexibly designed according to different application scenarios.
Image source: Overseas website - ESPlaza
Today, flow battery can last more than four hours and sometimes more than 10 hours at a time. Such duration is very suitable for the future use of large amounts of new energy grid. Due to the high cost of initial investment, the flow battery has not been widely applied. But there is a policy drive to reduce costs that is promising. The expansion of the flow battery industry chain is just around the corner.
