Avant de rentrer d’Islande, j’ai visité l’entreprise islandaise @Carbfix, qui transforme le CO₂ en pierre. Alors que nous bâtissons une économie propre et agissons pour le climat au pays, nous continuerons de travailler avec des experts du monde entier – et d’apprendre d’eux. pic.twitter.com/C4Ve7YQ795
— Justin Trudeau (@JustinTrudeau) June 26, 2023
Carbfix doesn’t simply freeze carbon dioxide—that’s dry ice, and that will evaporate right away even on the coldest day in Reykjavik (which is actually relatively mild, thanks to the Gulf Stream, but I’m distracting myself). Instead, Carbfix dissolves carbon dioxide in water, then injects that Perrier into basalts and other rock formations that react with the carbonated water and form new minerals. Here’s Carbfix’s simple explanation:
Trees and vegetation are not the only form of carbon drawdown from the atmosphere. Vast quantities of carbon are naturally stored in rocks. Carbfix imitates and accelerates these natural processes, where carbon dioxide is dissolved in water and interacts with reactive rock formations, such as basalts, to form stable minerals providing a permanent and safe carbon sink. The Carbfix process captures and permanently removes CO2. The technology provides a complete carbon capture and injection solution, where CO2 dissolved in water – a sparkling water of sorts – is injected into the subsurface where it reacts with favorable rock formations to form solid carbonate minerals via natural processes in about 2 years. For the Carbfix technology to work, one needs to meet three requirements: favorable rocks, water, and a source of carbon dioxide.
Carbonated water is acidic. The more carbon you can pack into water, the more acidic the fluid will become. Carbfix’s carbonated water reacts with rocks underground and releases available cations such as calcium, magnesium and iron into the water stream. Over time, these elements combine with the dissolved CO2 and form carbonates filling up the empty space (pores) within the rocks. The carbonates are stable for thousands of years and can thus be considered permanently stored. The timescale of this process initially surprised scientists. In the CarbFix pilot project, it was determined that at least 95% of the injected CO2 mineralizes within two years, much faster than previously thought.
The injected carbonated water is denser than the surrounding water in the geological formation and therefore has the tendency to sink after it has been injected. This differs from more conventional methods of carbon capture and storage, which depend on cap rock to prevent possible leakage of gaseous CO2 injected into deep formations. Young basaltic rocks are highly fractured and porous such that water seeps easily through the interconnected cracks and empty spaces underground [Carbfix, “How It Works,” retrieved 2023.07.02].
Carbfix says the basalts that work best with its process are found, among other places, on ocean ridges, and Iceland is the protruding crown of the Mid-Atlantic Ridge. Carbfix provides this map showing in chalky yellow the places where its carbon-fixing process would find the most fertile rock formations:
Summit Carbon Solutions plans to pipe carbon dioxide from ethanol plants across the upper Midwest up to North Dakota, which appears to have no good rock for this carbon-fixing process. But Minnesota and Iowa do:
Maybe Kristi Noem’s rich Iowa Republican pals are running their pipeline the wrong way. Instead of shipping CO2 to the North Dakota oil fields (where they’re just going to sequester the gas, not use it for fracking), perhaps Summit Carbon Solutions needs to reverse its current, add Carbfix to its list of partners, and plow that CO2 right into that big strip of good carbon-fixing rock running west of Des Moines from Omaha to Albert Lea.
Of course, Carbfix’s fixing also takes a lot of water. Carbfix is working on using seawater for its process, so perhaps the most forward-looking route for Summit Carbon Solutions and other CO2 pipeliners would be to ship their gas down to that friendly yellow geology down by the Gulf of Mexico or out in the Cascade Mountains, where they could use seawater instead of dwindling prairie aquifers for carbon mineralization.
Scaling up and deploying Carbfix’s technology in the Midwest wouldn’t get rid of the carbon dioxide pipelines that are causing so much consternation among landowners and the John Birch Society. Summit Carbon Solutions would still want pipelines to carry carbon dioxide from South Dakota’s ethanol plants to whatever carbon-friendly rock formations they can find in Iowa, Minnesota, or farther-flung locales. But maybe the ethanol industry could look at Carbfix’s process and maps and focus its production in places where it could plow its carbon emissions right back into ground and lock that CO2 up in local rock.