Bioleaching with bacteria can boost EV battery recycling
In terms of energy and carbon emissions, electric vehicles are far more environmentally friendly than gas-powered ones. But EVs are far from perfect. They require metals such as cobalt, lithium, and nickel that come from hard-to-reach places. Mining those can harm unspoiled landscapes and, if not facilitated by renewable energy, still lead to unwanted emissions. Recycling old batteries is a good solution in theory, but the process is costly and therefore not one most for-profit companies would willingly undertake. An invisible ally might help turn things around. It’s the bacterium Acidithiobacillus ferrooxidans, and its bioleaching capabilities could make recycling a more promising option.
As the name indicates — ferrooxidans means “iron-oxidating” — bioleaching bacteria oxidize metal, recovering the materials for reuse. Prof. Sebastien Farnaud and colleagues at Coventry University in the UK have been doing quite a bit of research and confirmed that every metal used in EV batteries can be retrieved via bioleaching.
“Bacteria like Acidithiobacillus ferrooxidans and other non-toxic species target and recover the metals individually without the need for high temperatures or toxic chemicals. These purified metals constitute chemical elements, and so can be recycled indefinitely into multiple supply chains,” Farnaud wrote on The Conversation.
This method could limit the emissions and energy use from the largest lithium-ion battery recycling plants, which tend to melt the batteries to recover the metals inside.
Conversely, “(s)caling up bioleaching involves growing bacteria in incubators at 37°C, often using carbon dioxide. Not a lot of energy is needed, so the process has a much smaller carbon footprint than typical recycling plants, while also contributing less pollution,” Farnaud wrote.
The bacteria produce sulfuric acid as a byproduct, which can spell environmental trouble when they’re deployed on mining sites to recover metals, seeping the acid into the ground. Rather than leave the bacteria to do their work out in the open, recycling plants can pulverize mineral matter containing the bacteria by putting it in a bioreactor tank full of water.
Drop enough batteries in the tank and the bacteria will work their magic, making a solution the recovered metals can be filtered out of. The sulfuric acid byproduct can be contained and disposed of properly. This method of bioleaching already yields a significant amount of the gold (approximately 5%) and copper (20 to 25%) currently extracted. It’s also been used on e-waste and solar panels.
Farnaud wants to take things a step further.
“This is not enough for industry. We combine bioleaching with electro-chemical methods that can fish out these metals and make them useful for supply chains,” he wrote.
Companies such as Houston-based Cemvita Factory apply synthetic biology to mining and mineral pre-processing.
“We believe the adoption rate and market size growth of our target applications will only accelerate due to the urgency for a low-carbon energy transition,” CEO Moji Karimi said in August as Cemvita announced the initial closing of Series A financing. “The future of manufacturing will be low-carbon biomanufacturing and the future of mining will be sustainable biomining.
“Decarbonizing heavy industry is one of the most critical challenges in addressing climate change.”
Could Cemvita and like-minded enterprises scale up EV battery recycling? Maybe so, but Farnaud believes it will take more to make a large-scale difference.
“Industries can’t always afford to innovate, so it’s up to the government to mandate changes and invest in cleaner alternatives,” he wrote. “EV batteries are a technology still in their infancy. The reuse of their components should be considered as part of their design. Rather than remaining an afterthought, recycling can become both the beginning and end of an EV battery’s life cycle with bioleaching, producing high-quality raw materials for new batteries at low environmental cost.”
Bioleaching could make a single-cell organism so small you can’t even see it a big player in green energy, but it will take a major investment to make that happen.