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Electric cars are often purchased because of their environmental benefits, but if millions of old batteries from these cars aren't managed well, those benefits could be offset. Here are four interesting techniques that are shaping up to make sure that isn't the case. They sort into four Rs.

Scale is good, and a problem

EVs are heading toward major adoption thanks to improving technology and prices, government mandates, carmaker pledges, climate doom-scrolling and soaring gas prices. Paul Anderson, professor of strategic elements and materials sustainability at the University of Birmingham, told the BBC that "the rate at which we're growing the [EV] industry is absolutely scary" in terms of a "battery bomb" in 10 to 15 years that will present a lot of tired EV batteries that need a responsible place to go. Yes, combustion cars will dominate the roads for decades to come, but EVs will achieve critical mass at the same time.

A high bar

We live with a somewhat dated idea that gas-engine cars are the same filthy, smog-belching machines that made LA synonymous with eye-burning smog and have primary responsibility for environmental degradation. In fact, all transportation, including buses, trains, commercial trucks and jetliners, accounts for just over a quarter of greenhouse gases emitted in the US, according to the US Environmental Protection Agency, which also points out that modern cars have 98% lower emissions of most pollutants than those sold in the 1960s.

The point isn't that electric cars won't make an important difference but that they need to improve on an incumbent that is a more nuanced problem than conventional wisdom might suggest. EVs must be a comprehensively better solution, not just a car without a tailpipe. That demands a strong battery life cycle plan around four points: reuse, repurposing, recycling and reduction

Reuse

The best way to keep an EV battery from becoming a problem is to keep it driving a clean EV. That could mean taking good batteries from wrecked EVs and using them in other cars or focusing on swappable batteries, as advocated by VinFast, Nio and battery swap station company Ample. However reuse is executed, it's the most direct way to fully exploit an electric car battery. 

Reuse will become a more powerful concept as the number of EVs in use grows, creating a larger, more liquid market within the existing used car parts sector, which has been growing faster than the US economy overall, according to IbisWorld research. 

But no amount of smart reuse can get around the fact that eventually every EV battery at some point will lose enough capacity that it no longer supplies satisfactory range in a car. That's where the next R comes in. 

Repurpose

When an aged EV battery is removed and put to use in another application, it is said to be repurposed. Nissan repurposing effort 4R Energy depicts such batteries as Grade B or Grade C. Grade B batteries can be put into regular but less demanding use like powering electric train crossing gates or non-highway EVs like electric forklifts that don't inspire range anxiety. Grade C batteries are degraded to the point that they might be used for tasks like emergency LED building lighting where the draw is intermittent and typically low.

VW and Electrify America are among the firms that advocate repurposing EV batteries at charging stations where they can cache solar power or inexpensive off-peak grid power for transfer to electric cars as needed.

Recycle

Breaking up is hard to do, and in few places is that more true than breaking up and reclaiming the materials in an EV battery. These are big, heavy, complex arrays of materials and packaging that don't recycle like a water bottle. It's an intriguing enough challenge that former Tesla CTO J.B Straubel left that company to focus on the problem through startup Redwood Materials. The company likes to say "the largest lithium and cobalt mines in the western hemisphere can be found in our country's junk drawers," not to mention underneath our electric cars.

The lithium, nickel, cobalt and other elements inside an EV battery present a toxic challenge that recycling attacks by keeping batteries from ever being truly discarded.

Reduce

This isn't a technological solution but a perceptual one. Reduction is the idea that EVs need the right range, not the maximum range. When that is conveyed to EV buyers, they may purchase an affordable car with a 200-mile range rather than reaching for one with a range of 400 to 500 miles that costs a lot more and requires a much bigger battery. That reduces the total tonnage of EV batteries produced, making the previous 3 Rs easier to accomplish. It's also technically more elegant, as shorter-range cars spend less of their charge lugging around their own heavy long-range battery. 

The life cycle of an EV's battery is probably going to interest most buyers about as much as their new car's depreciation curve or TCO calculation, but it's a key concern for maximizing the benefits of the coming electric car migration.