New Scientist - USA (2019-11-16)

12 | New Scientist | 16 November 2019

Analysis Recycling

MORE than a million electric cars

were bought globally in the first

half of this year, the same number

sold across the whole of 2017.

This rapid growth is good news for

air quality and climate change, but

there is a potential sting in the tail.

There is no such thing as an

electric vehicle (EV) battery waste

mountain... yet. However, the

number of EVs set to be sold

globally this year could one day

lead to more than 500,

tonnes of battery waste, five times

the weight of all portable batteries

recycled in the European Union

annually (Nature, doi.org/ddwm).

Those lithium-ion car batteries

must be recycled or they will pose

an environmental and safety risk,

says the research by Laura Driscoll

at the University of Birmingham,

UK, and her colleagues. “It’s a

challenge because most current

generation batteries aren’t

designed for recycling,” she says.

For example, Tesla’s high-end

cars use packs of cylindrical

battery cells. In some cases these

are bonded into a battery module,

making them hard to remove and

recycle – though the company

says it is working to improve this.

Nissan’s Leaf model, by contrast,

uses a pouch of rectangular cells

which are easier to open and

separate for recycling. There is no

standardisation among carmakers

on battery packs, and little sign of

any coming soon.

“If the battery packs were more

of a standard design, it would

make the process at end-of-life

much easier,” says Driscoll.

Most EV batteries should last

around 15 to 20 years. While their

first decade will probably be in a

car, some have already gone on

to a second life as solar power

storage batteries in homes, and

more will follow. Still, eventually

they will need to be recycled.

Although dumping electric car

batteries in landfill, where they

can leach toxic materials, is illegal

in the UK, it is unclear whether

recycling facilities can scale up fast

enough. Gloria Esposito of the Low

Carbon Vehicle Partnership says

recycling capacity is “definitely an

issue”, because in Europe there are

just 18 firms looking at lithium-

ion battery recycling, some of

which recycle only certain metals.

Driscoll says it will be

“environmentally disastrous”

if there isn’t a strategy for dealing

with the batteries. What’s more,

stockpiling old batteries poses fire

risks. Another concern is batteries

being exported to a country like

India for a legitimate second use,

such as powering a microgrid,

but where no recycling facilities

exist when they are spent. “That

could be a growing time bomb,

especially if things take off quickly,”

says Jonathan Radcliffe at the

University of Birmingham, who

wasn’t involved in the research.

As well as the environmental

benefits of mining fewer raw

materials, recycling would bring

an economic opportunity through

reclaiming metals from batteries,

says Driscoll. Cobalt, nickel and

manganese are three of the most

valuable to recover from them.

The success of recycling will

depend partly on automation,

as robots can do the job cheaper,

faster and safer than humans, say

Driscoll and her colleagues. Which

brings us back to carmakers: if

they standardised battery packs

or made them machine-readable,

that would aid automation.

“[Carmakers] are a bit conflicted

because they want a competitive

advantage, to make the batteries

as cheap and high-performance

as they can. That might not always

align with making them in a

certain set of standards,” says

Radcliffe. That is why regulation

will be key to manufacturers’

decisions and, in turn, how easily

we can tackle that future battery

waste mountain. ❚

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News

Are we storing up big

problems with a green

transport revolution?

15 to 20

Average lifetime, in years,

of an electric vehicle battery

The looming electric car battery waste mountain

Old batteries are hard to reprocess and could become a

ticking time bomb for the environment, says Adam Vaughan

Voice assistants

Layal Liverpool

ALEXA, can you hear me? A new

way to stop Amazon’s voice

assistant Alexa from doing what

you say has been found. “It was

easier to exploit than we expected,”

says Juncheng Li at Carnegie Mellon

University in Pennsylvania.

He and his colleagues have

created an audio clip that prevents

Amazon’s system from responding

to the “Alexa” command word if it

is played as you speak. Li says he

expects that similar attacks would

work against other voice assistants

too. “These systems are all made

in a very similar way,” he says.

Li and his team first created

their own voice assistant, based

on Alexa. They developed an audio

attack using an AI that attempted

to generate guitar sounds that

the voice assistant didn’t respond

to. Their goal was to find a sound

that the assistant would ignore.

The team then tried the attack

on Alexa. When the clip was playing,

Alexa responded to the audio cue

“Alexa” only 11 per cent of the time,

compared with 80 per cent of the

time when other music was playing

and 93 per cent of the time when

no audio clip was playing at all

(arxiv.org/abs/1911.00126).

Li says attacks like this

could be used to prank,

confuse or distract people.

When asked about the attack,

Amazon responded: “We are

reviewing the findings of

this research paper. What is

demonstrated poses very little

impact on customers. It would

require specific audio samples

to be played at the same time as

a user saying the wake word and

would only increase times where

the wake word is not detected.” ❚

Audio attack blocks

Amazon Alexa

from hearing you

“ When the clip was playing,
Alexa responded to the
audio cue ‘Alexa’ only
11 per cent of the time”