5 March 2022 | New Scientist | 41

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solvents in a reversible chemical reaction,
and that CO2 can then be imprisoned deep
underground. But those same solvents
can’t absorb methane as easily. One reason for
this is that methane molecules are a different
shape, meaning those solvent molecules don’t
pack around them so easily.
One solution is to forget about capturing
methane and instead chemically convert it
to CO2. Releasing extra CO2 into the air might
sound foolish, but given how bad methane
is, it may be a positive move. “Every molecule
of methane released into the air eventually
ends up as carbon dioxide anyway,” says
Jackson. “All we’re trying to do is speed up the
transition.” Most US states are already using
this idea to tackle methane leaking from
landfill sites, using a cover impregnated
with microbes that convert methane to CO2.
Alternatively, we might employ zeolites,
materials that are riddled with atomic-scale
tunnels that molecules can fit inside.
Certain zeolites can absorb methane and
then catalyse a reaction that turns it into
methanol, which can be used in the chemical
industry. Chemists have already found
hundreds of zeolites that do this job to
some extent. This technology isn’t mature,
but Jackson thinks it has great promise.

is crammed into a small space, meaning

lithium batteries fit lots of power into

a small, light package. But there are

other contenders for this charge-carrying

role. One is sodium, which has the

same +1 charge as lithium and is only

a little larger. It is also extremely easy

to source, given that it is part of the salt

in seawater. Sodium-ion batteries have

to be larger to pack as much punch

as their lithium cousins, but for some

non-portable applications, like storing

solar-generated electricity, that is fine.

UK-based firm Faradion has supplied

sodium-based batteries for heavy goods

vehicles in India.

Fully charged

There are many more options for battery

chemistry out there, however, including

using other ions, such as magnesium.

The trouble is, changing the charge

carrier often means redesigning other

parts of the battery too, so that

everything works in synchrony.

Crucial components of all batteries

are the electrodes, which in the case

of lithium-ion batteries are made

If we are going to stop burning

fossil fuels, it is critical that

we have access to electricity

from renewable sources

like wind turbines and solar

panels. But we can’t rely

on the wind blowing or the sun shining

exactly when we need power. We need

a way to store electricity – and in many

cases that is going to mean batteries.

Yet batteries themselves aren’t

without their environmental problems.

The rechargeable lithium-ion batteries in

electric cars rely on lithium, among many

other metals. Sizeable lithium reserves

are found in only a few places: the

element has to either be extracted

from huge salt flats in the Atacama

desert in South America, which involves

using up vast amounts of water, or be

obtained by environmentally destructive

conventional mining of the mineral

spodumene in China and Australia. This

is one major reason why chemists want

to design a more sustainable battery.

Lithium’s job inside a battery is to

carry charge from one side to another.

It does this so well because its ions

are so small. Their +1 electric charge