At each stage, the leftover chemical residues are recycled back in the process, forming a closed reaction that repeats endlessly with no waste materials. These limestone flakes are sieved off and heated in a third chamber, called a calciner, until they decompose, giving off pure CO2, which is captured and stored.

The lime seizes hold of the dissolved CO2, producing small flakes of limestone. The potash absorbs CO2 from the air, after which the liquid is piped to a second chamber and mixed with calcium hydroxide (builder's lime). There are several ways to do it, but the one that Carbon Engineering's system uses fans to draw air containing 0.04% CO2 (today's atmospheric levels) across a filter drenched in potassium hydroxide solution – a caustic chemical commonly known as potash, used in soapmaking and various other applications. The science of direct air capture is straightforward. 'We need to pull 800 gigatonnes out of the atmosphere. Yet he admits the scale of the task ahead is dizzying. 'Once one is done, it's a cookie cutter model, you simply build replicas of that plant,' says Oldham. But the firm is drawing up blueprints for a much larger plant in the oil fields of west Texas, which would fix 1 million tonnes of CO2 annually. That's where direct air capture comes in.Ĭarbon Engineering's plant in Squamish is designed as a testbed for different technologies. Nor can it address the CO2 that is already in the air. But this is impractical for small, numerous point sources like the planet's billion or so automobiles. Most carbon capture focuses on cleaning emissions at the source: scrubbers and filters on smokestacks that prevent harmful gases reaching the atmosphere.

'With DAC, you can remove any emission, anywhere, from any moment in time. 'We have a climate change problem and it's caused by an excess of CO2,' says Carbon Engineering chief executive Steve Oldham. It is a small start, and a somewhat larger plant in Texas is in the works, but this is the typical scale of a DAC plant today. When it becomes operational in September, Carbon Engineering's prototype direct air capture plant will begin scrubbing a tonne of CO2 from the air every year. If the world is to meet Paris Agreement goals of limiting global warming to 1.5C by 2100, sights like this may be necessary by mid-century.īut step back for a moment to 2021, to Squamish, British Columbia where, against a bucolic skyline of snowy mountains, the finishing touches are being put to a barn-sized device covered in blue tarpaulin. Now the legacy of those fossil fuels – the CO2 in our air – is being pumped back into the emptied reservoirs. This Texan landscape was made famous for the billions of barrels of oil pulled out of its depths during the 20th Century. Together, they're trying to cool the planet by sucking carbon dioxide out of the air. You're looking at a direct air capture (DAC) plant, one of tens of thousands like it across the globe. You think to yourself that it looks like a gigantic air conditioning unit, blown up to incredible proportions. Behind the wall, you glimpse the snaking pipes and gantries of a chemical plant.Īs you get closer you see the wall is moving, shimmering – it is entirely made up of huge fans whirring in steel boxes. In the distance, they lap at a colossal grey wall five storeys high and almost a kilometre long. The land here is mirrored: the choppy silver-blue waves of an immense solar array stretch out in all directions. Walk out of the Permian Basin Petroleum Museum in Midland, Texas, and drive north across the sun-baked scrub where a few remaining oil pumpjacks nod lazily in the heat, and then you'll see it: a glittering palace rising out of the pancake-flat ground.

Blue planet carbon capture