Highly Efficient Grid-scale Electricity Storage at Fifth of Cost
Rows of huge tanks full of chemical solutions storing energy generated from massive solar and wind farms and powering whole cities: It’s a landscape that millennials might very well equate with the new normal. Batteries will power this new paradigm, and they won’t necessarily all be lithium-ion batteries. The flow battery is staking a claim in the renewable energy world of the future. Flow batteries are definiively the future of energy storage, or at least an important part of it.
What are flow batteries? They are systems of two connected tanks, both containing electrolyte liquids: one with a positively charged cathode and the other with the negatively charged anode, just like a lithium-ion battery. Electricity passes from one electrolyte liquid to the other via a membrane between the tanks.
Rechargeable like lithium-ion batteries, flow batteries have longer lives because the electric current flowing from tank to tank does not degrade the membrane. True flow batteries are also called redox flow batteries, after the two reactions they utilize: reduction, or a gain of electrons, and oxidation, or loss of electrons from electrolyte liquid to electrolyte liquid.
Now researchers in WMG at the University of Warwick, in collaboration with Imperial College London, have found a way to enhance hybrid flow batteries and their commercial use. The new approach can store electricity in these batteries for very long durations for about a fifth the price of current technologies, with minimal location restraints and zero emissions.
The scientists enhanced three hybrid flow cells using nitrogen doped graphene (exposed to nitrogen plasma) in a binder-free electrophoresis technique (EPD). Wind and solar power are increasingly popular sources for renewable energy. Unfortunately, intermittency issues keep them from connecting widely to the National grid. One potential solution to this problem involves in the deployment of long-duration battery technology, such as the redox flow battery. Despite its great promise the current costs of this system are a key determining factor to real-world adoption. An affordable grid battery should cost £75/kWh, according to the US Department of Energy. Lithium-ion batteries, which lead the charge for grid storage, cost about £130/kWh. The hybrid flow battery’s total chemical cost is about 1/30th the cost of competing batteries, such as lithium-ion systems. Scaled-up technologies may be used to store electricity from wind or solar power, for multiple days to entire seasons, for about £15 to £20 per kilowatt hour.