The Intergovernmental Panel on Climate Change (IPCC) recognises carbon capture and storage among the solutions for eliminating CO2, without giving it a central place in its models.
"The small DACCS (direct air capture with carbon storage) ecosystem gets more diverse... but we're not exactly sure where this will lead to" in the fight against climate change, said Oliver Geden, an IPCC member and specialist on carbon dioxide removal.
Even if the capacity to capture CO2 reaches two billion tonnes in 2050, compared with just 10,000 today, as suggested by optimistic projections in a report by the University of Oxford, experts are categorical: we must first massively reduce emissions of greenhouse gases like CO2 into the atmosphere and consider carbon capture and storage only for emissions that can't be eliminated.
Companies like Microsoft, Amazon, Airbus and even Lego are already paying upwards of $1,000 per tonne of CO2 captured and stored -- in the form of carbon credits -- to offset their emissions.
- How it works -
Molecules of CO2 in the air pass through large fans and are absorbed by a liquid filter or deposited on a solid filter.
Once the filters are full, the fans close and the filters are heated to high temperatures upwards of 120 degrees Celsius for solid filters and 900 degrees Celsius for liquid filters in order to release pure CO2.
This heating requires substantial use of energy and the development of these technologies on a large scale depends on the availability of electricity or heat from renewable energy.
While the chemical compounds can be reused, the environmental impact of their large-scale production has yet to be studied.
The CO2, in a compressed gaseous form or dissolved in large volumes of water, is then transported and injected into porous rock located hundreds of metres (several thousand feet) below the surface.
- Where its happening -
Three commercial facilities are operational but only Orca in Iceland stores CO2 rather than reusing it as an ingredient in synthetic fuels, construction materials or soft drinks.
Since 2021, Orca has been absorbing 4,000 tonnes of CO2 per year -- the equivalent of a few seconds of global emissions.
Its neighbour Mammoth, also developed by the Swiss start-up Climeworks with Icelandic partners and unveiled on Wednesday, will absorb up to 36,000 tonnes per year.
In comparison, two billion tonnes of CO2 is "eliminated" each year primarily through reforestation and forest protections, according the University of Oxford. That compares to the 40 billion tonnes emitted worldwide last year.
Nearly 30 projects have been commissioned in the United States, United Kingdom, Iceland, Gulf states and Kenya with a capacity to store close to 10 million tonnes of CO2 by 2030, according to the International Energy Agency.
More than 100 others with and without storage are being developed, but lack financial assurances.
The United States has put $3.5 billion on the table but this includes CO2 reutilisation projects.
The European Commission, Canada, the United Kingdom and Japan are also exploring the option.
- The costs -
While carbon capture and reuse by the oil and gas industry dates back to the 1970s, direct capture from the air is a much more recent development, since it was not considered economical.
The cost of these technologies are estimated between $600 and $1,000 per tonne of CO2 captured, according to the IPCC, but could drop between $100 and $300 in the coming years.
Geden applauded the proliferation of start-ups in the sector, but said he believes "a line has been crossed" when pioneering Canadian firm Carbon Engineering was bought by American giant Oxy Petroleum in 2023 for $1.1 billion.
Since then, the fate of carbon capture has been in doubt, since its reuse rather than storage is likely to be more profitable to major oil firms positioning themselves in the expanding market.
New Iceland plant scales up CO2 removal from air
Hellisheidi, Iceland (AFP) May 8, 2024 -
A Swiss start-up unveiled Wednesday its second plant in Iceland sucking carbon dioxide from the air and stocking it underground, scaling up its capacity tenfold with the aim of eliminating millions of tonnes of CO2 by 2030.
Dubbed Mammoth, the plant lies just a few hundred metres (yards) from its little sister Orca, a pioneering facility opened by Swiss start-up Climeworks in September 2021 in the middle of a moss-covered lava field about a half-hour drive from the capital Reykjavik.
Here, 12 containers similar to those used in maritime transport are stacked up against a backdrop of mountains.
In recent days, fans in the containers began drawing in ambient air and releasing it, largely purified of CO2, through vents at the back.
It's all done through a chemical process, and powered by the nearby geothermal plant ON Power.
By the end of the year, 72 units will be installed around the plant where the captured CO2 is compressed and dissolved in fresh water before it is injected under high pressure into the basalt rock underground, locking away the main culprit behind global warming.
At a depth of 700 metres (2,300 feet), the solution fills the rock's cavities and the solidification process begins -- a chemical reaction turning it to calcified white crystals that occurs when the gas comes in contact with the calcium, magnesium and iron in the basalt.
It takes up to two years for the CO2 to petrify, according to the Icelandic group Carbfix that developed the process.
Some 10,000 tonnes of CO2 per year have been stocked using direct air capture with carbon storage (DACCS) techniques around the world, including 4,000 tonnes by Orca with the remainder mostly done at experimental facilities.
- Early days -
When Mammoth is fully operational, it will be able to remove 36,000 tonnes of CO2 from the air per year.
"We started with milligrams of CO2 captured in our lab 15 years ago and now it's kilos, tonnes, thousands of tonnes," said Climeworks founder and co-chief executive Jan Wurzbacher.
Climeworks expects to have a capacity of several million tonnes by 2030, with projects of other start-ups taking total capacity up to around 10 million tonnes per year.
Climeworks hopes it can raise capacity to a billion tonnes per year by 2050.
But that's still a drop in the bucket compared to the 40 billion tonnes of CO2 emitted around the world last year alone.
By pulling CO2 from ambient air, Climeworks' plants are different from more traditional types of CCS projects at highly-polluting industrial smokestacks or those reusing CO2 instead of stocking it.
For each tonne of CO2 stocked, Climeworks creates a carbon credit that enables its clients (including large corporations such as Lego, Microsoft, H&M, Swiss Re, JP Morgan Chase, Lufthansa) to compensate for their greenhouse gas emissions.
The UN's Intergovernmental Panel on Climate Change (IPCC) said in a 2022 report that no matter how much the world slashes greenhouse gas emissions, removing CO2 from the air and oceans will be necessary to avoid climate catastrophe.
However, the technology is not included in most emissions-reducing scenarios yet as it remains extremely costly and is still in the early stages with limited public funding.
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