Captain Drawdown’s daily logbook on every CDR story, paper, and expert voice — so you don’t have to read them all.
Which matters more to a carbon removal project’s economics: the pathway or the postcode? Four preprints on CDRXIV this cycle let me test that question with an unusually clean pairing. One trial spreads crushed rock on smallholder maize plots in Kenya. Another models turning fire-prone California forest into structural timber. The chemistry in each case is well understood. What differs is everything around it, and my read is that the “everything around it” is where the business model actually lives.
Subject one: enhanced rock weathering in Kenya. Enhanced rock weathering (ERW) spreads finely ground silicate rock on farmland, where it reacts with CO2 and, as a side effect, can improve soil chemistry. Haque et al. report a maize trial testing ERW’s agronomic performance in a tropical smallholder system in Kenya. The headline is not the carbon. It is the yield question. In a smallholder context, whether the rock helps the crop is the variable that determines whether anyone spreads it at all. Separate evidence points the same direction: Jordan et al. studied smallholder rice farmers in India, at Mati Carbon deployments across Madhya Pradesh, Chhattisgarh, and Jharkhand, and found increased yields from ERW. Different country, different crop, same lesson from the Global South end of the land ladder. I wrote a primer on the underlying chemistry in What Is Enhanced Weathering?
Subject two: cross-laminated timber from California’s burn zones. Bose et al. assess the life-cycle carbon footprint and total production potential of cross-laminated timber (CLT), an engineered structural wood product, sourced from California’s wildland-urban interface, the zone where housing meets flammable forest. Here the carbon storage rides on two local pressures: the need to thin fuel loads before they burn, and a formal construction sector that can absorb the resulting material. Kane et al. supply the matching infrastructure, a framework for ground-up life-cycle assessment of carbon-storing building materials. That kind of accounting apparatus only earns its keep where large-scale formal construction exists to use it.
The comparison, on four dimensions:
| Dimension | Kenya ERW | California CLT |
|---|---|---|
| Core co-benefit | Crop yield on smallholder plots | Wildfire fuel reduction, building material substitution |
| Who plausibly pays | Carbon buyers plus agronomic value | Construction demand, fire-risk mitigation budgets |
| Land context | Fragmented smallholder agriculture | Wildland-urban interface forest |
| What geography supplies | Tropical weathering conditions, farmers as deployment network | Fuel-load crisis, formal construction sector |
Where they converge. The surprising similarity is that neither project is really sold as carbon first. Both preprints spend their effort on the co-benefit: agronomic performance in Kenya, fuel-load and material substitution in California. The tonne of CO2 is almost the passenger. That echoes an argument I made in Why Carbon Removal Needs More Than Trees: single-value carbon projects are fragile, stacked-value ones are not.
Where they diverge. The consequential difference is that the co-benefit stacks are not portable. Kenya’s stack, yield gains on smallholder farms, has no meaning in Sonoma County. California’s stack, wildfire liability and building codes, has no meaning in Kisumu. You cannot arbitrage between them. To be clear, that portability claim is my inference from reading these papers side by side, not a finding either team tests. But it follows directly from what each paper chose to measure. Nobody runs a maize yield trial or a CLT production model unless the local co-benefit is the load-bearing wall.
So what. For the sector’s trajectory, I think the California result matters more in the near term, because it plugs into existing industrial demand, while the Kenya and India results matter more for ultimate scale, because that is where the weathering-friendly farmland and the farmers are. For buyers and developers, the practical shift is this: stop asking which pathway is cheapest per tonne and start asking which pathway’s co-benefits match the jurisdiction’s political economy. Portfolios built on pathway logic will misprice both of these projects. Portfolios built on the geography of co-benefits will not.
What I am watching next: whether the coming rounds of large offtake agreements price co-benefits differently by geography, or keep treating a tonne in Kisumu and a tonne in Sonoma as interchangeable. These four preprints suggest they are not.
Citations
- Cdrxiv — Haque et al.
- Cdrxiv — Jordan et al.
- Cdrxiv — Bose et al.
- Cdrxiv — Kane et al.