Take on a podcast episode from Ground Cover, originally published Wed, 19 Au. Listen: https://player.whooshkaa.com/shows/ground-cover

TL;DR

  • Biochar as durable carbon removal on-farm: 1 tonne biomass → ~1/3 biochar, 2/3 syngas. Useful mass-balance framing rarely stated so plainly.
  • Guest cites ~2.7 tCO₂e sequestered per tonne of biochar (80% carbon). Standard figure, worth internalizing.
  • Claim: biochar is currently the largest deployed carbon sequestration method. Defensible on delivered durable tonnes today, but worth checking against CDR.fyi.
  • Own-farm data: soil carbon doubled in top 100mm over 10 years including through the 2019-20 drought. Anecdotal, single site, no control — treat as directional.
  • Economics hinge on monetizing the syngas, not the char. This is the real CDR-relevant insight.

Australian ag podcast Ground Cover (host Pippa Jones) interviews John Winter, a chemical engineer turned Glen Innes cattle producer and inventor behind SEATA Group’s pyrolysis pilot. The episode is pitched at farmers, but there’s enough on unit economics and durability accounting to make it worth 45 minutes for a CDR practitioner working on biomass pathways.

What’s worth knowing. Winter is unusually clear about why standalone biochar economics are painful: you need 3 tonnes of biomass to make 1 tonne of char, and if you flare or heat-dump the syngas (the other two-thirds by mass), you’ve thrown away most of the energy value. At ~18 GJ/tonne biomass and Australian gas around $20/GJ, the syngas fraction is where the project either pencils or doesn’t. His pitch is a distributed model of regional pyrolysis hubs sized to aggregate ag residues, council green waste (he cites ~14 Mt/yr identified by Bioenergy Australia), and biosolids, with syngas piped or trucked to centralized synthesis. This is the same conclusion the serious biochar developers have reached — char alone is a byproduct business; the system has to sell heat, power, or synthesis gas to work.

The durability accounting deserves scrutiny. Winter uses the ~2.7 tCO₂e per tonne biochar multiplier (from ~80% fixed carbon), which matches methodology assumptions in Puro.earth and Isometric biochar protocols — but only if the char is produced above ~500°C under anaerobic conditions with adequate H:C ratios. He flags this explicitly: “biochar has to be made under anaerobic conditions… at a lower enough temperature, somewhere around 500° plus or minus, to retain its functional groups.” Below-spec char behaves like ordinary charcoal and doesn’t earn century-plus permanence. Buyers should note this is exactly where field measurement, reporting, and verification (MRV) gets contested.

CDR context. Biochar is now the largest-volume delivered durable removal category by tonnes retired — see CDR.fyi for the running count against DAC (direct air capture), enhanced weathering, and marine pathways. Frontier and Stripe have both bought biochar (Charm, Exomad, others); the debates worth tracking are permanence class (100 vs 1000 years), feedstock additionality, and the syngas/heat co-product allocation that Winter is essentially describing. Stephen Joseph’s 2021 GCB Bioenergy review, referenced in the show notes, remains the standard mechanism paper. Nothing in the episode contradicts the mainstream view; it’s a ground-level articulation of why the co-product problem is the whole problem.

Useful for CDR practitioners evaluating distributed pyrolysis models, feedstock-side project developers, or buyers pressure-testing biochar supplier claims about temperature regime and permanence. Skip if you want durability protocol detail — this is farmer-facing, not MRV-facing.