Drawing CO2 from the air to mineralise it after injecting it deep into the ground. It is called Orca, a name derived from the Icelandic word "orka", meaning "energy". And it is the world's largest plant capable of capturing carbon dioxide from the air.

How CO2 is captured and mineralised

It is located in the Strumsvik area, on a plateau in the south-west of Iceland, and is spread across four units, each made up of two metal boxes resembling shipping containers. Built by Swiss company Climeworks and Icelandic company Carbfix, when operating at full capacity it will be able to absorb 4,000 tonnes of carbon dioxide from the air per year, turning it into rock; according to estimates by the Environmental Protection Agency, the United States environmental protection agency, this is equivalent to the emissions of around 870 cars.

To collect the carbon dioxide, the plant uses fans to draw air into a collector, which contains a filter material inside; once the filter material has been filled with CO2, the collector is closed and the temperature is raised to release the carbon dioxide from the material, after which the highly concentrated gas can be collected; the CO2 is then mixed with water before being injected at a depth of 1,000 metres into the nearby basaltic rock, where it is mineralised.

The shadows are many, from costs to energy consumption

So much for the lights. But the shadows are many. The project comes at a very high cost – Bloomberg reports an investment of between 10 and 15 million dollars – to convert 4,000 tonnes of carbon dioxide, against the billion tonnes that would need to be extracted from the atmosphere to achieve the goal of zero emissions. In practice, Christoph Gebald, one of the Swiss engineers who worked on the project, admitted that "this is about building a market that does not yet exist. The plant we have built is a project to grow further."

Beyond the initial investment, the issue of the costs of the process itself also emerges: at present we are looking at between 600 and 800 dollars per tonne of CO2, whereas the figure would need to come down to 100–150 dollars for the system to become competitive. And it should not be forgotten that Iceland has a particular underground geology and abundant reserves of geothermal energy, which are well suited to a technology of this kind. In essence, the main problem, as the director of the Carbon Mitigation Initiative at Princeton University, Stephen Pacala, has explained, remains that of making the entire project "affordable and replicable."

The race for carbon capture has begun around the world

Orca is only the latest in a long line of multiple projects for carbon capture, the storage of CO2, set up in recent years also thanks to the support of the International Energy Agency, which backs the capture of greenhouse gases on the path towards the energy transition. A prospect also firmly embraced by the United Kingdom, which in its green plan has dedicated one billion out of the twelve made available to this item. More than 20 plants are currently active around the world, drawing in 40 million tonnes of carbon dioxide per year: this amounts to 0.1 per cent of annual global emissions.

In the last four years alone, projects for 30 new plants have been announced. This is the case in Canada, where efforts are under way to produce on a global scale a petrol that emits no new CO2 because it draws in CO2 already present in the atmosphere. Or the project by the University of Illinois, in Chicago, involving a solar cell that captures carbon dioxide and converts it into fuel, reproducing what occurs in nature through photosynthesis. And then there is a Swiss plant that sequesters around 900 tonnes of carbon dioxide from the atmosphere per year, selling it on to a greenhouse to improve the growth of cultivated plants. All things considered, the numbers suggest that this technology still appears too immature for large-scale use; and even if that were to change, the production and business model adopted globally up to now would in any case need to be rethought along more sustainable lines.