At Redwood, nothing goes to landfill, and no water leaves the facility except the sanitary waste from sinks and toilets. There are no gas lines; everything is electric. It’s also built for scale, allowing the company to quickly break down a truckload of assorted batteries without manual sorting or tedious disassembly.

Recyclers will eventually need to match the pace of car factories. For example, a Tesla factory just 250 miles away in Fremont, California, produced 560,000 EVs last year — more than one every minute. When it’s time for those cars to be recycled, they will generate almost 10 times as much EV battery material as the entire U.S. market processed last year. If recyclers can handle all of that, they would begin to rival traditional mining operations.

“Once we've changed over the entire vehicle fleet to electric, and all those minerals are in consumption, we’ll only have to replace a couple percent each year that’s lost in the process,” said Colin Campbell, Redwood’s chief technology officer and the former head of powertrain engineering at Tesla. “It will become obvious to everyone that it doesn't make sense to dig it out of the ground anymore.”

Straubel left Tesla in 2019 after he grew concerned about a widening gap between EV demand and the materials needed to make batteries. Redwood quickly became the biggest lithium-ion battery recycler in North America before branching into the more lucrative market for complex materials that make up the two sides of the battery — anode and cathode — in the last few years. The company now sells about two dozen products, including lower-value materials like unprocessed aluminum scrap, which is already widely recycled, and calcium sulfate sold off as gypsum to make drywall.

There are three basic approaches to recycling batteries, each with its own drawbacks. You can burn them, which is wasteful and can result in toxic emissions; dissolve them in strong chemicals, which is expensive and uses the most energy; or separate them mechanically, which can be labor-intensive and dangerous. Until the last few years, most U.S. recyclers simply ground up batteries and sent them overseas for someone else to deal with.

Redwood borrows what it sees as the most useful bits from each category. The company’s process starts in an indoor staging area where everything from discarded earbuds and laptop batteries to EV modules from recalled Chevy Bolts are dumped onto a conveyor belt. The jumbled mess is carried roughly 30 feet up to a hole in the wall where it exits the building into a giant churning metal tunnel, dubbed “RC1,” suspended high above the ground.

RC1 is essentially an enormous slow cooker, baking the junk at several hundred degrees for about an hour, and is perhaps Redwood’s biggest innovation thus far. Traditional recycling through burning uses heat well over 1,000C (1,800F) to separate out precious metals, but Redwood’s goal at this stage is to preserve and prepare the materials for the next steps in the most efficient way.

Importantly, RC1 doesn’t use any oxygen — there’s no combustion and, thus, no emissions. It simply reduces the glues, plastics and unwanted fluids into charcoal. The high-grade black carbon left over can be sold for use in black paints and industrial lubrication.

The RC1 also uses surprisingly little electricity, which is key to lowering Redwood’s climate impact. Once the kiln heats up, the energy released from the batteries is self-sustaining. Think of it as a controlled, slow-motion version of a battery fire, running nonstop day and night, week after week. It safely releases the charge in any batteries that could pose a danger to workers, while breaking down the stuff that binds key minerals together.

After leaving RC1, the charbroiled batteries pass through machines that sift the material through screens. Powerful magnets are used to isolate certain materials. The remaining mineral-rich dust, known as black mass, is mixed into a slurry of solvents and fed into another building that resembles a large beer brewery, with towering stainless steel tanks that use chemicals, pressure, filters and evaporation to separate products into their core elements.

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