Captain Drawdown’s daily logbook on every CDR story, paper, and expert voice — so you don’t have to read them all.
The rock-based carbon removal pathway has quietly stopped being a science project and started being a mining-industry pivot. Three announcements in three weeks, on three continents, all point to the same insight: tailings piles are the new feedstock asset class for durable CDR.
Start with Quebec. The Quebec Surficial Mineralization Hub launched with Frontier backing, and the framing is what matters. Frontier called Quebec’s industrial legacy, meaning its mining tailings, “one of the world’s biggest carbon removal opportunities.” Liability becomes feedstock. The throughput numbers are not small either. “Not spreading, either aerating large piles or using reactors. You do end up getting more mass at the end than you dig up due to carbonation, but we still expect on the order of >30k tons CO2 stored per acre.” - Zeke Hausfather (@hausfath.bsky.social on Bluesky). Per-acre density at that level is what separates a serious feedstock thesis from a boutique demo.
Now layer in Arca’s partnership with Carbon Direct to scale industrial mineralization. Arca’s pitch is straightforward: operate on active mine sites, convert ultramafic tailings into permanent CO2 storage as part of routine mining workflow. Carbon Direct, a buyer-side advisor, signing on is the validation signal. Mine-integrated mineralization is now considered bankable, not bench-scale. For background on why this pathway works chemically, our earlier explainer on enhanced weathering covers the basics.
Third data point: Carbonyx raised $1.2M to turn mining waste into usable materials. The CEO’s framing flips the business model. The pitch is to “make carbon capture economically viable again” by monetizing mining waste co-products. Materials-first, with carbon as a by-product credit. Same feedstock, different revenue stack.
A fourth confirmation arrived from Europe. Co-reactive opened a demo plant turning industrial mineral residues into carbon-negative concrete. Cement-bound mineralization using residue streams is now at demo scale in the building-materials sector. Four companies, one feedstock thesis.
Here is the tension. CDR discourse this quarter has been dominated by Microsoft’s procurement pause and the question of whether buyers come back. While that conversation runs in circles on the demand side, four different operators are quietly assembling the supply-side answer using a feedstock the mining industry has historically treated as a contamination problem. The buyers’ panic and the builders’ pivot are happening in parallel, and they are not talking to each other.
There is one important caveat from the same scientist. “If we continue to emit 40 GtCO2 per year all CDR will be a useless waste of money. The goal of this hub is to test different technologies to be deployed in a future where we need CDR because we are succeeding at mitigation.” - Zeke Hausfather (@hausfath.bsky.social on Bluesky). The tailings pivot only pays off in a world where fossil phase-out actually happens. CDR remains for hard-to-abate residual emissions. It is not a license to keep burning.
So what does this mean if you write checks or build projects in CDR? The cheapest durable tonnes in the next decade may not come from purpose-built DAC plants or bespoke spreading operations on farmland. They may come from operators who already have ultramafic rock crushed, piled, and sitting on permitted industrial land with grid power and rail access. That changes three things at once: unit economics (no mining CapEx, the rock is already broken), permitting timelines (industrial sites already zoned), and the competitive set. Every durable pathway, including DAC, now has to price against tailings-based mineralization. For buyers building portfolios like the CUR8 and Isometric 2030 offering, that reshapes the durable allocation math.
It also means the next major CDR offtake announcements may not be signed with climate-native startups. They may be signed with mining companies who realized they were sitting on the asset.
What to watch: a CDR offtake or joint venture from a mining major. Glencore, Vale, BHP, or Rio Tinto signing a multi-year CDR agreement, or taking equity in an Arca-style operator, would confirm the feedstock pivot has crossed from CDR-native startups into the mining sector itself. That is the moment the supply curve actually bends. Two quarters is a reasonable window. If it happens, the durable CDR market in 2027 looks very different from the one we are pricing today.