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How to make electric cars completely clean?

The type of vehicle that uses zero-emission energy and a variety of green materials is very beneficial to the environment, of course it is not perfect.

Around the world, governments and automakers are promoting electric vehicles as a key technology to curb oil use and combat climate change. General Motors has said it aims to stop selling gasoline-powered cars and light trucks by 2035 and will shift its focus to battery-electric models. Volvo goes even faster and introduces an all-electric lineup by 2030.

But as electric cars and trucks become mainstream, they face a nagging question: are they really as friendly as advertised? The New York Times question.

While experts agree that plug-in vehicles are a more climate-friendly option than traditional vehicles, they can still have their own impacts on the environment, depending on how they are charged and manufactured. export. Fortunately, there are ways to solve these problems.

How is electricity generated?

In general, electric cars tend to produce significantly less Earth-warming emissions than most gas-powered cars. But the problem is that people still depend a lot on burning coal to generate electricity to charge them. So the grid still needs to be created in a cleaner way before EVs can truly become zero-emissions.

One way to compare the climate impacts of different vehicle models is to use an interactive online tool by researchers at the Massachusetts Institute of Technology, who have tried to combine all the relevant factors. : emissions associated with car manufacturing and gasoline and diesel fuel production, how much gasoline a typical car burns, and where the electricity to charge an electric vehicle comes from.

Wind power is one of the clean sources of electricity. Photo: Theconversation

If we assume that pure electric vehicles are drawing power from the average U.S. grid, this power system typically includes fossil fuel burning and renewable power plants, then they are mostly as always much greener than conventional cars. Even though electric vehicles produce emissions from the battery manufacturing process, their electric motors are more efficient than traditional fossil fuel-powered internal combustion engines.

For example, an electric Chevrolet Bolt can generate an average of 117 g/km of CO2 over its lifetime. In contrast, a brand new gasoline-powered Toyota Camry is estimated to generate up to 239 g/km. As for the new Ford F-150, the fuel efficiency is even worse, it produces 395 g/km.

But that’s just the average. On the other hand, if the Bolt is charged on a grid generated by coal, such as those currently in the Midwest, it could actually have a worse indirect climate impact than a modern hybrid vehicles like the Toyota Prius, which run on gasoline but use extra batteries to increase range. (Even so, though, the Bolt still beats the Camry and F-150.)

“Coal tends to be the key factor,” said Jeremy Michalek, a professor of mechanical engineering at Carnegie Mellon University. burning more coal to charge them, the climate benefits won’t be as great and possibly even more polluting.”

The good news for electric vehicles is that most countries are stepping up to clean up their electric grids. In the US, companies have decommissioned hundreds of coal plants over the past decade and switched to a lower-emission mix of natural gas, wind and solar power. As a result, researchers have found that electric vehicles in general also become cleaner. And this can continue to improve in the future.

“The reason why electric vehicles seem like such a compelling climate solution is because if we can make our grid carbon-free, so will the gas,” said Jessika Trancik, an associate professor of energy studies at MIT. vehicle emissions will drop. Meanwhile, even the best gasoline-powered hybrids will always have some baseline emissions that can’t be reduced any further.”

NSRaw materials can be a nuisance

Like many other batteries, the lithium-ion cells that power most electric vehicles rely on raw materials – such as cobalt, lithium and rare earth elements – which are of serious concern. on the environment and human rights, especially cobalt.

Charging Bolts in the US.  Photo: Gannett

Charging Bolts in the US. Photo: Gannett

Cobalt mining produces hazardous wastes and slags that can leach into the environment, and studies have found high levels of exposure in surrounding communities, especially in children, to cobalt and other hazardous substances. other metal. Extracting metals from their ores also requires a process called smelting, which can release sulfur oxides and other harmful air pollution.

Up to 70% of the world’s cobalt supply is mined in the Democratic Republic of the Congo, a significant proportion in unregulated “craft” mines where workers – including many children – dig for metal. from the ground using only hand tools exposes them to major health and safety risks, human rights groups warn.

As for lithium, they are mined in Australia or from salt flats in the Andean regions of Argentina, Bolivia and Chile, operations that use large amounts of groundwater to pump into brine, draining native farmers. land and breeders. The amount of water required to make batteries makes electric vehicles about 50% more water-intensive than traditional internal combustion engines. Rare earth mines, concentrated in China, often contain radioactive materials that can release into water and create fallout.

To address the above issues, carmakers and other manufacturers focused on cobalt first, which have committed to removing “manually” cobalt generation from their supply chains, and developing batteries that reduce or eliminate cobalt completely. But that technology is still under development, and the prevalence of existing cobalt mines means these commitments are “not very realistic,” says Mickaël Daudin of Pact, a nonprofit that works with communities. mining in Africa, said.

Instead, Daudin said, producers need to work with these mines to minimize the impact on the environment and ensure miners are working in safe conditions. If companies act responsibly, the rise of electric vehicles will be a huge opportunity for countries like Congo. But if they don’t, “they will put the environment and a lot of miners’ lives at risk.”

Reuse electric car batteries

As first-generation electric vehicles begin to reach the end of their lifecycles, preventing large quantities of used batteries from being discharged is a challenge.

Electric car batteries at the Volkswagen factory.  Photo: Autoweek

Electric car batteries at the Volkswagen factory. Photo: Autoweek

Most electric vehicles today use lithium-ion batteries, which allow more energy to be stored in the same space than older lead-acid battery technology. But while 99% of lead-acid batteries are recycled in the US, the estimated recycling rate for lithium-ion batteries is only about 5%.

Experts point out that used batteries contain precious metals and other materials that can be recovered and reused. Depending on the process used, battery recycling can also use large amounts of water or release air pollutants.

“The percentage of lithium batteries being recycled is very low, but over time and scientific progress, that number will increase,” said Radenka Maric, professor in the Department of Biomolecular Engineering and Chemistry, University of Connecticut. up.

Another promising approach to disposing of used electric vehicle batteries is to find them a second life in storage and other applications. “For cars, when the battery drops below 80 percent of its capacity, the vehicle’s range decreases,” said Amol Phadke, a senior scientist at the Goldman School of Public Policy at the University of California, Berkeley. down. But that’s not a restriction on storage for on-premises devices.”

Manufacturers, including Nissan and BMW, have experimented with using old electric vehicle batteries to store electricity from the grid. General Motors says its battery packs are designed to have a second life for another purpose. But challenges exist: repurposing lithium-ion batteries requires intensive testing and upgrading to ensure they function reliably.

However, as researchers at the Massachusetts Institute of Technology found in a study last year, if done correctly, used car batteries can continue to be used for a decade or longer as a backup storage for solar energy.

Thai Hoang (follow The New York Times)


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