Harvard engineers and scientists have created a battery type that is more reliable, cheaper and could transform how electricity is stored. This new, metal-free organic flow’ battery was created and tested at Harvard School of Engineering and Applied Sciences in Cambridge (MA). In a Nature paper, the team describes their work. Michael J. Aziz is senior author and chief of the laboratory. He is also the Gene and Tracy Sykes Professor in Materials and Energy Technologies at SEAS. Sykes says that the problem with solid-electrode battery is that you cannot separate energy storage and power conversion hardware. They are all packed together into one unit. They can’t operate at maximum discharge for longer than an hour before they are drained. It is not an ideal way to backup intermittent renewable energy such as solar or wind. Flow batteries, on the other hand, store energy in electrochemistry fluids in separate tanks that are not connected to the conversion hardware. They can also be sized independently, so the energy they store is limited only by how big the storage tank. This allows for larger storage capacities and lower costs than traditional batteries. You could store 50 hour of electricity from a 1 Megawatt Wind Turbine using traditional batteries. However, they would only have 50 megawatt-hours energy storage. They’d also come with 50 megawatts power capacity. When you need only 1 megawatt, it doesn’t make financial sense to buy 50 megawatts of power capacity. Flux battery technology that is cost-effective and does not contain metals based on Quinones. Until now, the development of flow batteries technology has been hindered by a lack of economically-friendly materials. Currently, flow batteries are made with expensive metals such as platinum and vanadium. Michael J. Aziz presents the prototype of a metal-free battery. Professor Aziz, along with his colleagues, have developed and successfully tested a flow-battery made from a nonmetal material known as quinone. Their flow battery is cheaper than vanadium-based and requires no precious metal electrocatalysts. Quinones, a family of organic and carbon-based molecules commonly found in oil and plants, are similar to the energy-storing molecules in animals and plants. The researchers developed a molecular screening technique that allowed them to find the perfect quinone. This was pioneered at Harvard by Alan Aspuru–Guzik (Professor of Chemistry, Chemical Biology). They were able to determine the electrochemical properties and sort through over 10,000 quinone molecule molecules using this technology. The researchers see both domestic and commercial applications. A large storage tank is necessary to back up commercial wind turbines. You would likely need several large storage tanks if you have many solar panels or turbines. They add that consumers could also benefit from the same technology. A tank of the same dimensions as your basement’s heating oil tank could be used. It could hold a day’s worth solar energy from your roof panels. This would allow you to have enough power to power the following morning without burning any fossil fuels. A prototype flow battery from Aziz’s laboratory (Photo by Harvard). Professor Aziz said that they plan to optimize their lab bench system, as well as bring it to commercial scale. He added, “So far we haven’t seen any sign of degradation after 100 cycles. But commercial applications require thousands of cycle.” They also want to improve the chemical composition of the battery. The Connecticut-based Sustainable Innovations LLC, which is a coworker on this project, plans to demonstrate the organic flow battery using a small unit the same size as a horse trailer within three years. This portable battery could connect to the solar panels of commercial buildings, and allow solar energy to either be stored or used immediately. Professor Aziz believes that there’s no reason to not put such a device on every node of the grid. “If there’s enough market volatility, you could place a storage device there to buy electricity and store it until it’s high again,” Trent M. Molter (CEO of Sustainable Innovations) said.
