At a Canadian facility, attempts are under way to produce on a global scale a petrol that emits no new CO2 — drawing in CO2 already present in the atmosphere. Some doubts remain, however, about a process that is currently highly energy-intensive.
A fossil fuel that produces no new greenhouse gas emissions because it uses gases that have already been emitted, only to release them back into the atmosphere. And recycle them again, in a cycle that could potentially go on indefinitely. For around fifteen years now, in various parts of the world, researchers have been studying ways to "draw in" CO2 from the atmosphere in order to produce fuel using special plants; as if they were vacuum cleaners capable of purifying the air of excess carbon dioxide and using it to produce a zero-emission fuel.
The main stumbling block, until now, has been economic: all studies on DAC (Direct Air Capture) technology estimated that as much as 600 dollars (around 519 euros) would be needed for every tonne of CO2 captured — a price unsustainable for large-scale development. Now, however, a study conducted by Carbon Engineering and recently published in the scientific journal Joule completely overturns the outlook: the company's Canadian plant is able to extract one tonne of CO2 from the atmosphere at an average cost of 100 dollars per tonne (around 86 euros). The facility then converts the captured carbon dioxide into various types of liquid fuels, at a production cost of one dollar per litre — slightly higher than that of current fuels, but certainly not prohibitive.
It all began in 2015 in Squamish, in the Canadian province of British Columbia, on the initiative of David Keith, professor of applied physics at Harvard University; an investment of 30 million dollars, several heavyweight backers (chief among them Microsoft founder Bill Gates), and a three-year timeframe to understand the true potential of this technology.
The results have been better than expected, to the point that the experimental plant could soon be transformed into a fully operational facility, capable of capturing one million tonnes of CO2 per year — twice Italy's emissions — and of producing 200 barrels of "recycled" fuel per day. If everything goes to plan, by the end of 2021 American motorists — starting with those living in states such as California, which through a regulated market incentivise the use of sustainable products — will be able to choose between a traditional fuel or one that has emitted no greenhouse gases during its production phase, branded Carbon Engineering.
DAC technology uses large banks of suction fans to draw in air: a series of subsequent steps allows the captured CO2 to be separated and stabilised with an alkaline solution. The liquid can be pressurised and injected underground, where it is stored and then converted into a fuel through a series of chemical processes: the result is a synthetic fossil fuel that, once used in engines, produces no new CO2 because it releases into the atmosphere the same CO2 that was drawn in. This is a decidedly energy-intensive process which, in this initial phase, the company has managed by using electricity produced by some of the region's hydroelectric dams; for a large-scale plant, however, alternative solutions will necessarily have to be found: some doubts therefore remain about the real sustainability of this technology from an energy-balance perspective.
What is certain is that we may be facing a revolution: the transport sector accounts for around 20 per cent of global greenhouse gas emissions, and further development of DAC technology would bring a double benefit. On the one hand, carbon dioxide could be permanently removed from the atmosphere: the plant envisaged by Carbon Engineering would alone eliminate one fortieth of the CO2 produced worldwide in a year. On the other hand, it would launch the production of a fuel compatible with today's engines, without having to convert the entire existing vehicle fleet to electric.
