Paper industry waste material is being turned into electrolyte to store electrical energy for the next generation of flow batteries.
By one estimate, the world’s pulp mills generate about 50 million metric tons of lignin annually, yet they choose to recover only about 2% of it. In Malaysia alone, almost 20 million tons of lignin-containing oil palm empty fruit bunch (OPEFB) fiber waste was produced in 2018. The race is on to valorise this waste material.
International research teams and companies have already proven that lignin is potentially suitable as a starting material for the production of electrolytes.
Researchers at TU Graz have found a way to convert the aromatic substance vanillin into a redox-active electrolyte material for liquid batteries. “It is ground-breaking in the field of sustainable energy storage technology,” says Stefan Spirk from the Institute of Bioproducts and Paper Technology at Graz University of Technology.
“We refine lignin into vanillin, then into a redox-active material using mild and green chemistry without the use of toxic and expensive metal catalysts, so that it can be used in flow batteries.”
The separation and refining process has been patented and the successful test results were published in the journal Angewandte Chemie.
Before commercialisation the technology has to be tested in real operation. The company is now looking for energy supply companies that can integrate the start-up’s redox flow technology into its infrastructure and thus relieve the burden on the grid. Spirk is convinced of its future success because: “We can keep the value chain ranging from the procurement of raw materials and components to the generation of electricity on a regional basis, enable storage capacities of hundreds of megawatt hours, relieve the strain on the electricity grid and make an important contribution to the green energy storage revolution.”
Redox flow batteries are seen as an important part of the expansion of renewable energies. They are suitable for long-duration energy storage of more than eight hours and can easily be scaled from domestic to grid-level storage.
Flow batteries are less toxic, more recyclable and more fireproof than lithium-ion batteries. Other major advantages are their high life expectancy and low self-discharge.
With the increasing need for energy from data-centres, which are striving to use 100% green energy, organic flow batteries could soon be the answer. Most flow batteries use mined materials and moving to organic materials is seen as the future for the technology.
Image: Tests at TU Graz with a 3 kilowatt hour prototype and with vanillin-based electrolytes proved the effectiveness of the new process. Credit: © Lunghammer – TU Graz
