UNDO Enhanced Rock Weathering: status and timeline

UNDO Enhanced Rock Weathering

Remove CO2 from the air permanently and cheaply by speeding up natural rock weathering on farmland. Nature already removes about a billion tonnes a year this way; spreading crushed rock makes it happen far faster.

DeployStage 4 of 5

Rock spread on 444 farms across 61,000 acres in the UK and Canada; corporate offtakes growing.

Updated 24 Sep 2025Checked 11 Oct0 updates this week

Milestones

No announced next step

First Microsoft deal: 5,000 t of CO22023Complete.
Microsoft follow-on: 15,000 t (UK basalt, Canadian wollastonite)Sep 2024Complete.
Barclays deal: 6,538 t on 10,000 acres in OntarioSep 2025Complete.

Most important updates

Current obstacles

Measuring removal on real farmsRemoval must be inferred from rock, soil and water data over years; methods are still being refined with academic partners.
Transport emissionsHauling heavy rock emits CO2; UNDO tracks trucks by GPS and subtracts it, so long hauls cut net removal.

Physics limits

Weathering speed is set by natureHow fast rock dissolves depends on rainfall, temperature, soil chemistry and grain size. Cool, dry fields weather slowly, so credits for removal accrue over years, not at spreading.
A lot of rock per tonne of CO2Several tonnes of rock are needed per tonne of CO2 removed, so crushing and trucking costs and emissions decide where the method makes sense.

How it works

4 parts

Spread

Crushed rock on fields

Finely crushed basalt (UK) or wollastonite (Ontario) is spread on farmland, much like farmers spread lime.

Weather

Rain turns CO2 into bicarbonate

Rain absorbs CO2 and forms a weak acid that dissolves the rock, converting the CO2 into dissolved bicarbonate.

Store

Carried to the ocean

Bicarbonate drains through soils and rivers to the sea, where carbon stays for tens of thousands of years or more.

Soil

Minerals for crops

The rock releases calcium, magnesium and potassium and can raise soil pH; trials with Newcastle University saw yield gains.

Spec sheet

Spec	UNDO Enhanced Rock Weathering
Rock spread to date	358,340 t^R (reported)
Area spread	61,310 acres^R (reported)
Farms	444^R (reported)
CO2 removal expected	78,835 t^R (reported)
Carbon efficiency, basalt	~95% (after operating emissions)^R (reported)
Carbon efficiency, wollastonite	~90%^R (reported)

^R reported by the company

Update log

2 updates

Wed 24 Sep 2025

Minor: Barclays makes its first carbon removal purchase: 6,538 tonnes from UNDO's rock weathering in OntarioPressCommercial

Thu 26 Sep 2024

Major: Microsoft expands its deal with UNDO to remove 15,000 tonnes of CO2 by rock weathering in the UK and CanadaPressCommercial

About UNDO

The team behind UNDO Enhanced Rock Weathering

UNDO

Enhanced rock weathering on farmland, carbon removal

London company that spreads crushed basalt and wollastonite on farmland in the UK and Canada so rain slowly turns CO2 into dissolved bicarbonate, and sells the carbon removal to buyers such as Microsoft.

358,000 t of rock spread on 444 farms; 78,800 t of CO2 removal expected (company figures).
Buyers include Microsoft (15,000 t deal, 2024) and Barclays (6,538 t, 2025).
Uses basalt in the UK and Canadian wollastonite in Ontario.

un-do.com (opens un-do.com)Company profile →

Founded: 20224 yrs
Headquarters: United Kingdom
Status: Private
Valuation: private
Works in: AgricultureSoil carbon & rock weathering
Coverage: 1 program · 2 updateslatest 24 Sep 2025checked 11 Oct
Customers: MicrosoftBarclays

Spec

UNDO Enhanced Rock Weathering

Rock spread to date

358,340 t^R (reported)

Area spread

61,310 acres^R (reported)

Farms

444^R (reported)

CO2 removal expected

78,835 t^R (reported)

Carbon efficiency, basalt

~95% (after operating emissions)^R (reported)

Carbon efficiency, wollastonite

~90%^R (reported)