Physics / mechanism
Mineralisation for carbon removal exploits the thermodynamic stability of carbonate and bicarbonate minerals. CO₂ reacts with alkaline metal cations—primarily Ca²⁺ and Mg²⁺ sourced from silicate rocks or industrial feedstocks—to form solid carbonates (CaCO₃, MgCO₃) or dissolved bicarbonates. Heirloom accelerates natural weathering by cycling limestone through a calcination-rehydration loop: CaCO₃ → CaO + CO₂ (captured) → Ca(OH)₂ → re-exposed to air → CaCO₃ again, ~12-day cycle. 44.01 injects CO₂-saturated seawater into peridotite, mineralising in situ within months. Key parameters: mineralisation rate (kg CO₂/m²/day), energy penalty of calcination (~3–4 GJ/t CO₂), permanence (>10,000 yr for solid carbonates). Heirloom claims ~$300/t today, targeting sub-$100/t at scale.
Competitive landscape
Direct air capture (DAC) via liquid solvents (Carbon Engineering/Oxy) and solid sorbents (Climeworks, Global Thermostat) compete on cost and energy intensity. Enhanced weathering (UNDO, Eion) spreads crushed silicates on agricultural land—lower capex, harder to verify. Ocean alkalinity enhancement (Planetary, Ebb Carbon) overlaps with 44.01’s subsurface/marine approach. Bioenergy with CCS (BECCS) competes on policy subsidy capture.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.