Renewable electricity is vital in our fight to curb climate change. Wind and solar power are the most popular sources, but intermittency issues keep them from connecting widely to the national grid. That’s why energy storage will play a massive role in the renewable energy revolution—it’s the solution to this dilemma.
The three main ways to store electricity are lithium-ion (Li-ion) batteries, pumped hydroelectric storage, and redox flow batteries.
Li-ions are great because they can respond to changes in voltage or frequency very quickly. However, they are still expensive, even though their cost has dropped significantly in recent years. According to the United States Department of Energy, an affordable grid battery should cost about $104/kWh (£75/kWh), but Li-ions still cost about $180/kWh (£130/kWh).
Pumped hydro is very good at storing energy, but it cannot react as fast as batteries, and it takes up a lot of land.
Redox flow batteries are unique in that the amount of power and energy they store can be adjusted to the requirements of any particular use case. The vanadium redox flow battery is one of the most commercially developed chemistries. They can store electricity for extended periods, meaning power generated by solar panels in the summer can be stored for winter use. Their energy density is 500 times higher than pumped hydro. Plus, they have a smaller footprint than batteries and pumped hydro. They can be used almost anywhere and in places with limited space, like within city limits, next to an existing utility substation, or a renewable energy installation.
Despite all their advantages, a redox flow system’s costs have been holding it back from real-world adoption. But now, researchers at Warwick University, in collaboration with Imperial College London, have found a way to reduce the cost and thus improve their prospects for commercial use.
The team brought the price down to about $21 to $28 per kWh (£15 to £20 per kWh) or less using inexpensive materials found in abundance in nature like manganese and sulfur. Using these materials also helps reduce the battery’s environmental impact.
The cost of materials alone is about 1/30th that of the materials needed for a Li-ion, which tends to use expensive elements like cobalt.
The researchers modified the redox flow battery electrodes with nanomaterials to achieve a highly efficient grid-scale electricity storage unit. The new approach is scalable and can store electricity from renewables for long or short periods.
Dr. Barun Chakrabarti, one of the paper’s lead authors and a research fellow in WMG at Warwick University, said, “This EPD technique is not only simple but also improves the efficiencies of three different economical hybrid flow batteries thereby increasing their potential for widespread commercial adoption for grid-scale energy storage.”
If all works out and the team’s redox flow battery holds up in actual-world use, it could push the use of renewables towards unimaginable heights. The breakthrough is a leap in the right direction for energy storage.
