Advertisement

Climate's magic rabbit: Pulling CO2 out of thin air

From BBC - November 14, 2017

UN climate negotiators are meeting in Bonn amid a welter of reports indicating that concentrations of carbon dioxide in the atmosphere have broken records, while international attempts to curb greenhouse gases are not doing enough to avoid dangerous levels of warming. Our environment correspondent Matt McGrath has travelled to Switzerland to see if technology to remove CO2 from the air could be the answer to this ongoing carbon conundrum.

While CO2 concentrations are now higher than they have been in at least 800,000 years, the gas still only accounts for a tiny 0.04% of our atmosphere.

However, extracting carbon dioxide from well mixed air is not just technically difficult, it's expensive as well.

A half-hour outside Zurich stands one of the frontline attempts to develop a commercial approach to sucking down CO2.

On the roof of a large recycling centre at Hinwil stand 18 metal fans, stacked on top of each, each about the size of a large domestic washing machine.

These fans suck in the surrounding air and chemically coated filters inside absorb the CO2. They become saturated in a few hours so, using the waste heat from the recycling facility, the filters are heated up to 100C and very pure carbon dioxide gas is then collected.

This installation, called a direct-air capture system, has been developed by a Swiss company called Climeworks.

It can capture about 900 tonnes of CO2 every year. It is then pumped to a large greenhouse a few hundred metres away, where it helps grow bigger vegetables.

This is not supposed to be a demonstration of a clever technology - for the developers, making money from CO2 is critical.

"This is the first time we are commercially selling CO2; this is the first of its kind," co-founder Jan Wurzbacher told BBC News.

"It has to be for business; CO2 capture ca not work for free."

Right now Climeworks is selling the gas to the vegetable growers next door for around $600 per tonne, which is very expensive.

But the company says that this is because it has built its extraction devices from scratch - everything is bespoke. The firm believes that like solar and wind energy, costs will rapidly fall once production is scaled up.

"The magic number we always say is $100 per tonne," said Jan Wurzbacher.

"We have drawn a road down to the region of $100 and that is something we think is feasible. We can do it by scaling up the mass production of our components. I'd say half of the way to go there - we know what to do. We just have to do it over the next two or three years."

One of the things about CO2 that makes it attractive for developers is that it has many uses in the world.

From fish food to concrete; from car seats to toothpaste - entrepreneurs are trying to use carbon dioxide as a raw material. There's also a roaring trade in CO2 in the US, where it's being used, without irony, to boost the extraction of oil from wells.

One of the most ambitious plans is to extract CO2 and turn it into fuel.

A couple of years ago, car manufacturer Audi announced it had developed what it called "e-diesel", a liquid fuel made from water and CO2. Climeworks supplied some of the CO2 for the trials.Driving down the price of capturing CO2 is key to making this idea work.

"If you have to pay $100 per tonne of CO2 that makes roughly 25 cents per litre of gasoline," said Jan Wurzbacher.

"It is a reasonable amount per litre or per kilogramme of natural gas."

Making fuel or other products out of CO2 might help but it wo not achieve the type of large scale take-down from the atmosphere that many scientists now fear will be necessary over the next 20-30 years if the goals of the Paris climate agreement are to be met.

'Natural' solution

The terms of the pact state that there needs to be a "balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases" in the second half of this century. To reach that balance, many experts believe we will have to resort to technological means of taking carbon out of the air.

"There are some things we can do in the real near-term but to get to zero emissions we will probably need some technologies to remove carbon from the atmosphere," Dr Glen Peters from the Centre for International Climate and Environmental Research told BBC News.

'Magical techno-fixes'

Question of time

Advertisement

Continue reading at BBC »