Christoph Gebald and Jan Wurzbacher were, in the latter’s words, “young, motivated and maybe a bit naïve,” when they decided in 2009 to set up a company based on technology that could capture carbon dioxide from the atmosphere.
The two mechanical engineers, who met while studying at ETH Zürich, had seen first-hand the effects of climate change in the steadily retreating glacier at their favourite skiing destination in France, and they wanted to do something about it. Climeworks, based in Zurich, Switzerland, specialises in direct air capture of carbon dioxide, which is then permanently stored underground.
The general principle of direct air capture is relatively simple. Climeworks’ carbon dioxide collectors, which are around the size of a conventional shipping container, consist of fans which suck the atmosphere over filters made of a granulated, highly porous material. That material consists of chemical compounds called amines, which react with the carbon dioxide and bind it. Once a filter is full, it is heated to around 100 degrees Celsius, which breaks the relatively weak chemical bonds between the amine and carbon dioxide and releases the carbon dioxide, to be captured and liquified.
Capturing carbon dioxide is only half the challenge. Next, you need to store it safely and permanently. To do that, Climeworks has partnered with Icelandic company Carbfix, which developed a technique to dissolve carbon dioxide in water and pump it underground into rocks that react with the carbon dioxide and turn it into stone.
Because Climeworks’ units are modular, the system is scalable. The amines used in the filters are easily sourced and plentiful. The geology that best suits underground storage is widespread. Perhaps most importantly, the system only uses a small amount of energy – renewable, of course – to operate, and its life-cycle emissions equal around ten per cent of the total amount of carbon dioxide it captures.
Climeworks now has 14 direct air capture facilities operating around the world, and opened the Orca plant in Iceland in September, which, with Carbfix’s underground storage, will capture and store around 4,000 tonnes of CO₂ per year. This amounts to around 0.001 per cent of the UK’s emissions for 2019 – barely a drop in the ocean. But it’s a start.
Wurzbacher calculated that for Climeworks to capture one per cent of global CO2 emissions in a year, it would take roughly 750,000 of their units. It sounded like a lot, until he discovered that Shanghai harbour – one of the busiest ports in the world – handles that many shipping containers every two weeks. “It's feasible,” he says. “It's not negligible, but it's certainly doable.”
At that scale, the cost of direct air capture would likely also drop from its current level of around $1,000 per tonne, perhaps even achieving $100 per tonne. This would put direct air capture in “the domain where it's a normal thing for a big corporate to have their emissions reduced,” Wurzbacher says.
Frank Jotzo, director of the Centre for Climate Economics and Policy at the Australian National University in Canberra, Australia, says the steady drop in the price of solar photovoltaics and electric vehicle batteries illustrates the reductions in cost when technologies scale up, and he believes direct air capture will follow the same trajectory. When that happens, direct air capture and other carbon dioxide removal technologies will be vital in negating those last few hard-to-reach emissions that cannot be otherwise avoided with alternative approaches.
“What we do know to be true is there will be some activities that will emit CO2 or other greenhouse gases, [where it] will be so expensive to decarbonise those particular activities that it will actually simply be cheaper to draw down atmospheric CO2 instead,” Jotzo says.
With clients including Microsoft, Stripe, Shopify and Audi now offsetting some of their carbon emissions through Climeworks, the company is scaling up, always with one eye on that retreating glacier in France. “We have to mitigate, but that will not be enough; we will have biological solutions, they won't be enough,” Wurzbacher says. “And so we need technical solutions.”
This article was originally published by WIRED UK
