24 The EconomistDecember 7th 2019
1O
n one sideof a utility road at the edge
of Drax power station in Yorkshire sits
a vast pile of deep black coal. On the other
side, trains loaded to the brim with com-
pressed wood pellets. “The old and the
new,” says a worker.
Opened just under half a century ago,
Drax (pictured) was not only the biggest
coal-fired power station ever built in Brit-
ain: it was the last. Now only two of its six
mighty boilers are still fired by coal, and at
the end of November they had sat idle since
March. In the first half of 2019, coal ac-
counted for just 6% of Drax’s electricity
output. The rest came from those wood
pellets. Biomass burned at Drax provides
11% of Britain’s renewable electricity—
roughly the same amount as all the coun-
try’s solar panels combined.
And soon Drax—the power plant is
owned by a company of the same name—
hopes to be more than an electricity suppli-
er. It hopes to be a carbon remover. By
pumping the CO 2 it produces from its pel-
lets into subterranean geological storage,rather than returning it to the atmosphere,
it hopes to pioneer a process which climate
policymakers see as vital: so-called “nega-
tive emissions”.
The Paris climate agreement of 2015
calls for the Earth’s temperature to increase
by no more than 2°C over pre-industrial
levels, and ideally by as little as 1.5°C. Al-
ready, temperatures are 1°C above the pre-
industrial, and they continue to climb, dri-
ven for the most part by CO 2 emissions of
43bn tonnes a year. To stand a good chance
of scraping under the 2°C target, let alone
the 1.5°C target, just by curtailing green-
house-gas emissions would require cuts
far more stringent than the large emitting
nations are currently offering.
Recognising this, the agreement envis-
ages a future in which, as well as hugely re-
ducing the amount of CO 2 put into the at-
mosphere, nations also take a fair bit out.
Scenarios looked at by the Intergovern-
mental Panel on Climate Change (ipcc) last
year required between 100bn and 1trn
tonnes of CO 2 to be removed from the at-mosphere by the end of the century if the
Paris goals were to be reached; the median
value was 730bn tonnes–that is, more than
ten years of global emissions.
This is where what is going on at Drax
comes in. Plants and algae have been suck-
ing carbon out of the atmosphere and turn-
ing it into biomass for over a billion years.
It is because the carbon in biomass was,
until recently, in the atmosphere that
burning it in a power station like Drax
counts as renewable energy; it just puts
back into the atmosphere what the plants
took out. The emissions from procuring
and transporting the biomass matter too,
but if the supply chain is well managed
they should be quite small in comparison.
The pellets at Drax are mostly made from
sawmill refuse and other by-products in
America; they are then transported by rail,
ship and rail to the site where they will be
pulverised and burned.
If, instead of burning the biomass, you
just let it stand, the carbon stays put. So if
you increase the amount of vegetation on
the planet, you can suck down a certain
amount of the excess CO 2 from the atmo-
sphere. Growing forests, or improving
farmland, is often a good idea for other rea-
sons, and can certainly store some carbon.
But it is not a particularly reliable way of
doing so. Forests can be cut back down, or
burned—and they might also die off if,
overall, mitigation efforts fail to keep the
climate cool enough for their liking.The chronic complexity of
carbon capture
DRAX, YORKSHIRE
Climate policy depends on being able to trap carbon dioxide in exhaust gases and
from the atmosphere. It is not being doneBriefing Negative emissions