14 | New Scientist | 7 November 2020News
A computer simulation of
the MAST nuclear fusion
reactor in Oxfordshire, UK$1 trillion
The annual cost of pandemics in
treatment and economic lossesRESEARCHERS have successfully
tested a new £55 million nuclear
fusion machine in the UK, which
could provide vital insights for a
future prototype power station.
The Mega Amp Spherical
Tokamak (MAST) Upgrade at the
Culham Centre for Fusion Energy
in Oxfordshire took seven years
to build. Last week, the machine
produced its first plasma, the state
hydrogen reaches when heated
to extremely high temperatures.
Our understanding of how
stars are powered by hydrogen
fusing into helium dates back
around a century, but efforts to
harness clean energy from the
reaction in a commercial power
station still face many barriers –
not least how to extract more
energy than we put in.
One key problem is the heat
from the plasma, which reaches
millions of degrees Celsius. This
means it gradually burns away the
exhaust system that extracts heat
from the tokamak, the machine in
which the fusion reaction occurs
with the plasma held in place by an
electromagnetic field. In a power
station, that could mean replacingthe exhaust every three years or
so, an unacceptable interruption
and cost for a commercial plant.
The MAST Upgrade team hopes
to crack this by using a new type of
exhaust called a “super-X diverter”.
It works by sending the plasma a
long distance around the machine
and across a wider area than usual,
reducing the heat density so it
cools before being extracted.
Ian Chapman at the UK AtomicEnergy Agency, the project’s parent
body, says the design could reduce
the heat by 10 times, akin to taking
temperatures facing a spacecraft
entering Earth’s atmosphere down
to that of a car’s engine.
Juan Matthews at the University
of Manchester, UK, says designing
an exhaust that doesn’t need
regular replacement is a big issue,
but only one of many. “It’s just
one of the huge number of
problems that are going to have
to be solved before a [fusion]
power system is built.”
Most tokamaks are doughnut-shaped, but this one is spherical
with a thin column in the
middle, producing a plasma
shaped like a cored apple.
Around 90 per cent of the
Culham machine is new. The rest –
primarily the building and steel“vaccum vessels” that contain
the plasma – was salvaged from
the original MAST, which ran
from 1997 to 2013. The first plasma
produced is about two years later
than planned and the machine is
over budget, but Chapman says
that is unsurprising given how
hard the technical challenge is.
The new facility will operate
at “near fusion” conditions
of 50 to 100 million °C, which
is hotter than the sun. By contrast,
the world’s biggest fusion project,
ITER in southern France, aims
to produce plasma in 2025 at
150 million °C. In July, ITER
entered the assembly phase
of its construction. ❚“ The new facility
will operate at 50 to
100 million °C, which
is hotter than the sun”UKAE
ABiodiversitySaving forests could
help prevent future
pandemicsWE COULD avoid future pandemics
if unsustainable practices such as
deforestation and the industrial-
scale wildlife trade are halted,
according to a global biodiversity
report. The cost of doing so would
be paid back many times over,
simply because it reduces the
chances of another pandemic.
Millions of people are living or
working in close contact with wild
animals that carry diseases, andthese industries aren’t properly
regulated. The more people cut
down forests for farmland, for
example, the more they are pushing
into animals’ habitats and thus
coming into regular contact with
disease-carrying wildlife.
Controlling the global wildlife
trade and reducing land-use change
would cost $40-58 billion per year,
the report says. That is a lot, but the
covid-19 pandemic is estimated
to have cost the global economy
$8-16 trillion by July. Before the
covid-19 crisis, pandemics such
as the HIV and influenza ones cost a
total of $1 trillion per year, includingtreatment costs and economic and
productivity losses.
“It’s a really incredible, efficient
economic return on investment
we’re going to see if we can do
this right,” says report author Peter
Daszak at EcoHealth Alliance in New
York. The report was published by
the Intergovernmental Science-
Policy Platform on Biodiversity
and Ecosystem Services (IPBES).
Almost every known pandemicdisease came from an animal,
says Daszak. Covid-19 may have
come from bats in China. “HIV
emerged from the hunting of
chimpanzees,” he says, and recent
Ebola outbreaks came from the
hunting of wild primates.
The report will feed into the next
major meeting of the Convention
on Biological Diversity, which is
taking place in China in 2021 after
having been postponed due to the
pandemic, says Anne Larigauderie,
executive secretary of IPBES. The
meeting will set global biodiversity
goals for the next decade. ❚
Michael MarshallEnergyAdam VaughanFusion energy but cooler
A spherical nuclear fusion reactor in the UK is testing a new heat-reducing design