Enhanced rock weathering

Based on a Technology Deep Dive presentation by Jim Mann, CEO of UNDO, in February 2023


  • Enhanced rock weathering (ERW) removes CO2 from the atmosphere by spreading large quantities of selected and finely ground rock material onto extensive land areas. 
  • ERW mimics and accelerates (50,000 x) the natural weathering processes of silicate rocks.
  • The carbon removal takes place over a 50-year “weathering curve”; with approximately 13% of removals taking place in the first year, and 90% over 20 years.
  • The rock is a waste by-product of mining and quarrying – it needs to be ground to dust.
  • Basalt generally has low heavy metal content and can be spread on agricultural land.
  • Other approaches use olivine that weathers more quickly but contains heavy metals.
  • Suitable locations depend on: rock mineralogy, weathering conditions and proximity of quarry/mine to suitable land.
  • The UNDO ERW value chain includes: quarry/mine owners, haulage companies, agricultural contractors and land-owners/farmers.


UNDO has the ambition to contract a GT of removals by 2030. Scale possible because:

  • rock waste is a vast resource – <10% of basalt mined annually needed to get to GT scale
  • uses existing mining, quarrying and agricultural processes and infrastructure
  • offers significant co-benefits (increased crop yield, jobs in rural areas, use of waste, ocean alkalinity)
Leverages existing infrastructureOpen system makes it hard to measure
High permanenceExtensive analysis of rock mineralogy needed
Huge scalability potentialRemoval takes place over multiple years
Cost reduction – potential to get to < $100/TAll OPEX costs are upfront – negative cash-flow
Very low energy requirementsValidation hard because science is new
Abundantly available rockLong education process for buyers
Clear co-benefits 
Use of by-product 
Can be developed in Global South 

Costs (UNDO)

  • Currently from $101/T to $160/T, excluding MRV
  • Current MRV costs are $70-80/T, but targeting single $/T costs once models validated
  • Targeting a selling price of <$150/T within the next few years
  • UNDO has undertaken a project to define a pathway to $100/T


Silicate rock powders increase crop yield (up to 40%) and help to mitigate soil nutrient depletion.2Zero Hunger
Projects can done with small-scale farmers and provide a cheap alternative to traditional fertilisers.8Decent work/economic growth
Can bring agronomic benefits for farmers, supporting regenerative practices, and recycles mine waste12Responsible consumption & production
Scalabale, affordable, permanent carbon removal13Climate action
Assists with ocean alkalinisation and improve the nitrogen cycle.14Life below water
Improves soil health and mitigates land degradation associated with BAU farming practices.15Life on land

Market maturity

  • A dozen companies globally working on ERW
  • UNDO is market leader having sold approximately 30,000 tonnes of (pre-methodology) removals.
  • The rest of the market has sold approximately 6-7KT of removals (Lithos, Eion, Greensand).
  • Buyers are “climate forward” companies (eg Stripe, Microsoft and XTX Markets) and resellers, including SuperCritical, Wren, Ceezer and Cur8.
  • UNDO is aiming to contract approximately 1MT of removals by the end of 2024 and spread enough rock to capture those 1MT by the end of 2025.


  • Standards are critical to identify high quality projects, offer assurance to buyers, identify bad actors.
  • Measurement is done through a modelling process, reflecting many different scenarios.  Model outputs need to be calibrated, or “trued up” with field data.
  • Life-cycle analysis (LCA) accounts for grinding, transport and spreading to get net removals.
  • Measuring carbonate storage in solid form is easier; measuring dissolved bicarbonates is more challenging – UNDO is working on measurement innovations.
  • Current MRV costs are high – associated with truing up the model; insurance can lower costs.
  • Identifying third-party verifiers with the right background is a challenge.