16 November 2019 | New Scientist | 39Solutions are nowhere near as obvious for
heavy industry. The world produced more than
1.8 billion tonnes of steel last year, for example.
Concrete production is even higher, and
demand for both is likely to grow for decades.
Both industries seem to fly under the radar
in the climate conversation, but make no
mistake, they produce whopping amounts
of carbon. “They are responsible for half of
all industrial emissions,” says Julian Allwood
at the University of Cambridge, who was lead
author on the problem of industry’s carbon
footprint for the most recent major report
by the Intergovernmental Panel on Climate
Change. Although efficiency drives have
reduced the footprint from steel and
concrete to a degree, they still have a long
way to go to clean up their act.Reuse and recycle
The problem for both materials is that
their production processes seem almost
unavoidably carbon intensive, and tried
and tested, scaleable alternative processes
have been conspicuous by their absence.
Most steel is made using a combination of a
blast furnace to extract iron from its ore and a
basic oxygen furnace to convert this raw iron
to steel. In essence, iron ore is heated byburning carbon-rich coking coal, creating CO (^2)
as a by-product. Hence, “the major thing would
be to shift away from blast furnace operations”,
says Paul Fennell of Imperial College London.
One alternative is to recycle more. It is a
simple enough process: put scrap steel into an
electric arc furnace, where electrodes produce
current that melts the steel so it can be
reworked. This can reduce carbon emissions
by about two-thirds for each tonne of steel
produced compared with that made from iron
ore. The electricity can, in principle, come from
renewable resources.
That sounds like a win-win. Liberty Steel,
the owner of the steel rolling mill I visited in
Newport, certainly seems to think so, because
it has plans to recycle a lot more steel. The mill
isn’t far from Uskmouth B power station, a
1950s coal-fired power plant that has been
dormant since 2017. Now, Liberty’s parent
company GFG Alliance is spending £200 million
on converting the power plant to a lower-
carbon fuel: pellets made from non-recyclable
plastic and other waste. It will send much of its
electricity straight to the steelworks, where the
firm hopes to build an electric arc furnace.
The wrinkle at this stage is that some sectors,
such as car manufacturers, still prefer to use
virgin steel. One concern is that impurities >
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With temperatures
reaching 1300°C,
making steel is a hot
and dirty business
of steel and that other construction staple,
concrete, accounts for as much as 16 per cent
of humanity’s annual carbon dioxide
emissions. That is equivalent to the carbon
footprint of the US.
In the fight against climate change, heavy
industries are the final frontier. Decarbonising
transport and energy is the easy part. Steel and
concrete are different beasts. It is much harder
to produce them without releasing enormous
amounts of CO2 into the atmosphere. And yet
if we want to reach net-zero carbon targets,
we can no longer ignore them.
Cleaning up concrete and steel is such an
immense challenge that it can seem hopeless.
But researchers and forward-thinking
companies are pioneering clever ways to
crack the problem – perhaps pointing the way
to a crucial climate win.
The need to act couldn’t be clearer. If we
don’t keep global temperature rises below
1.5°C, droughts, floods and extreme heat are
predicted to be much worse. Natural treasures
such as corals, not to mention all manner
of other life forms, may be annihilated.
To avert disaster, we need to reduce carbon
emissions to zero as soon as possible, and
certainly no later than the middle of the
century. In the parts of our economies that
emit the most CO 2 , such as transport and
energy, we have most of the technology
we need to make that happen. Electricity
generation can flip to low carbon sources
such as wind and solar, cars can switch from
combustion engines to battery power, and
buildings can be insulated so that they use
less energy. We just need to generate the will
to implement these changes.
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