Updated · July 2026
How close are we to cement without the carbon?Can we make concrete without wrecking the climate?
Can we make concrete without wrecking the climate?How close are we to cement without the carbon?
Cement is about 8% of global CO2; low-clinker chemistries and carbon capture can cut it deeply, but not yet at commodity cost and scale.Making cement pumps out huge amounts of CO2. New recipes and capture can slash it - if they stay cheap enough to use everywhere.
Recorded milestones
Portland cement patented
Industrial CCS enters operation
Open tests · conceptual branches
- OPEN TEST02 ↗Replace the kiln chemistryDrop-In Alternative BinderBrimstone passed ASTM C150 in the lab; Sublime's planned 30,000-tonne plant was paused.Make non-limestone or electrochemical cement that passes mainstream Portland-cement standards and scales beyond a pilot.
- OPEN TEST04 ↗Scale beyond one plantNear-Zero Commercial FleetOnly about 35 Mt/year is announced for 2030, and announced capacity is not production.Operate enough certified near-zero cement plants to supply the roughly 350 Mt/year needed in 2030.
The path shows Industrial CCS enters operation. Open thresholds are separate tests in a conceptual map, not a forecast. No single percentage represents progress.
Where we standWhere we stand
The current stage, the evidence recorded, and the single threshold that gates the next stage.The stage reached, the evidence recorded, and the one test still blocking the next step.
What the evidence has shownWhat the evidence has shown
Making cement pumps out huge amounts of CO2. New recipes and capture can slash it - if they stay cheap enough to use everywhere.Cement is about 8% of global CO2; low-clinker chemistries and carbon capture can cut it deeply, but not yet at commodity cost and scale.
The next testBlocking threshold
Replace the kiln chemistryDrop-In Alternative BinderA novel-route producer must run a kilotonne-scale plant and publish strength, durability, EPD and cost data.A novel-route producer must run a kilotonne-scale plant and publish strength, durability, EPD and cost data.
What would count as proof?What would count as proof?
A clear test, the evidence behind it, and the limits of the claim.A clear test, the evidence behind it, and what it still leaves open.
Use much less clinkerIndustrial Low-Clinker Cement
Holcim's French line is rated for 500,000 tonnes yearly and claims 50% lower CO2 than CEM I.Operate a plant producing at least 100,000 tonnes per year of standards-compliant cement with at least 40% lower cradle-to-gate emissions.
Recorded result The Saint-Pierre-la-Cour calcined-clay line reached industrial nameplate, though delivered tonnes were not disclosed.
Next test Publish third-party EPDs and annual delivered tonnage across multiple calcined-clay plants.
SOURCE RECORD
Holcim calcined-clay deployment ↗Still to demonstrateWhat this does not establishA separate system can still have different conditions and results.The named measurement has no wider implication until the supporting system test is also shown.
View every evidence record
Achieved
Use much less clinkerIndustrial Low-Clinker Cement
Holcim's French line is rated for 500,000 tonnes yearly and claims 50% lower CO2 than CEM I.Operate a plant producing at least 100,000 tonnes per year of standards-compliant cement with at least 40% lower cradle-to-gate emissions.
Recorded result: February 2023 · The Saint-Pierre-la-Cour calcined-clay line reached industrial nameplate, though delivered tonnes were not disclosed.
Next test: Publish third-party EPDs and annual delivered tonnage across multiple calcined-clay plants.
Open test
Replace the kiln chemistryDrop-In Alternative Binder
Brimstone passed ASTM C150 in the lab; Sublime's planned 30,000-tonne plant was paused.Make non-limestone or electrochemical cement that passes mainstream Portland-cement standards and scales beyond a pilot.
Next test: A novel-route producer must run a kilotonne-scale plant and publish strength, durability, EPD and cost data.
Achieved
Store kiln carbon permanentlyFull-Chain Cement CCS
Brevik completed the chain in 2025, but its design addresses about half the plant's emissions.Capture cement-kiln CO2, transport it and inject it into monitored permanent geological storage.
Recorded result: August 2025 · The first Brevik cargo was injected 2,600 metres beneath the North Sea.
Next test: Brevik must publish a full-year captured and stored total against its 400,000 t/year design.
Open test
Scale beyond one plantNear-Zero Commercial Fleet
Only about 35 Mt/year is announced for 2030, and announced capacity is not production.Operate enough certified near-zero cement plants to supply the roughly 350 Mt/year needed in 2030.
Next test: Track final investment decisions, commissioning and certified output for the 35 Mt project pipeline.
The record behind the verdictThe record behind the verdict
Major milestones and smaller context events share one source-linked record. Scheduled targets are marked separately from recorded events.Milestones, smaller events and setbacks share one sourced record. Scheduled targets are marked separately from recorded events.
Event key
The Clinker Age
This record spans “Portland cement is patented” to “Ransome patents rotary kiln”.
Measuring Industrial Carbon
Recorded event: “Modern emissions baseline begins”.
New Binders Emerge
Recorded event: “Calcined-clay concept takes shape”.
Pilots, Standards and Pledges
This record spans “Calera shuts after demonstration” to “LC3 reaches permanent production”.
Full-Chain Scale Test
This record spans “Fortera opens Redding plant” to “Announced capacity reaches 35 Mt” and includes scheduled targets.
Additional records
This record spans “Calcined clay reaches 500 kilotonnes” to “Industry net-zero deadline arrives” and includes scheduled targets.
The data behind the verdictThe data behind the verdict
Read each measure with its units, conditions, uncertainty and source; targets remain distinct from observations.Read each chart with its conditions, limits and source. Future targets remain distinct from recorded results.
GNR-based global average estimate · 762 kgCO2e/t cement · 1990 · verification unspecified
View every data figure
GNR-based global average estimate · 762 kgCO2e/t cement · 1990 · verification unspecified
Independent records
Net CO2 intensity of conventional cement linear scale · kgCO2/t cementitious material
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Independent records
Landmark low-clinker and alternative-binder nameplate log scale · t product/year
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Independent records
Cement-sector CO2 capture project nameplate log scale · tCO2/year
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
ConditionHeidelberg Materials planned 2029 capture nameplate
Conditionthyssenkrupp planned 2029 capture nameplate
Independent records
Announced near-zero cement capacity for 2030 linear scale · Mt cement/year
Conditionsite, project or pathway record; nameplate and operating conditions differ
Conditionsite, project or pathway record; nameplate and operating conditions differ
Independent records
Kiln thermal energy intensity pathway linear scale · GJ/t clinker
ConditionIEA historical kiln-energy baseline, 2015
ConditionIEA historical kiln-energy baseline, 2022
ConditionIEA 2030 pathway milestone
ConditionIEA 2050 pathway milestone
Each square = 5 kgCO2e/t
Each square = 10 Mt/year
Each square = 20,000 tCO2/year
Each square = 5 %
Methods & conditions
Under the measurement.
The boundary of a measurement changes what it means.
What near-zero excludes
Method and conditions
“Near-zero” is not synonymous with “low-carbon.” The IEA ceiling slides from 125 kgCO₂e/t at 100% clinker to 40 kgCO₂e/t at low clinker ratios, and its principles require a physical pathway without offsets or emissions-reduction credits.
Source notes
Technical notes and sources
Each note keeps its authored method, conditions and citations available for review.
What near-zero excludes
“Near-zero” is not synonymous with “low-carbon.” The IEA ceiling slides from 125 kgCO₂e/t at 100% clinker to 40 kgCO₂e/t at low clinker ratios, and its principles require a physical pathway without offsets or emissions-reduction credits.
H-UKR remains above near-zero
Hoffmann’s H-UKR is clinker-free but its 2025 cradle-to-gate EPD reported 141 kgCO₂e/t, down from 188 kgCO₂e/t in its earlier EPD. It is therefore a major reduction, but not within the IEA’s roughly 40 kgCO₂e/t low-clinker near-zero limit.
The accounting behind evoZero
Heidelberg’s accounting distinguishes physically identical cement volumes: conventional Brevik cement is listed at 451 kgCO₂e/t, proportionally allocated evoBuild at 230, and freely allocated single-site mass-balance evoZero at 46. Products are not physically segregated; a separate non-physical variant transfers Brevik attributes to locally produced cement and claims zero through certificates.
What the first certificates covered
DNV’s first disclosed assurance period covered 12,088.322 t of clinker produced under capture conditions and 2,389.099 tCO₂ confirmed injected. Each certificate carried 307.3 kgCO₂ reduction per tonne of clinker, net of capture, transport, storage and infrastructure impacts.
Oxyfuel is not storage
Pure Oxyfuel burns fuel in oxygen rather than air, avoiding nitrogen dilution and producing a concentrated CO₂ stream. The catch4climate kiln demonstrates that process integration; it does not itself prove permanent storage.
Electrification leaves process emissions
Fully electric clinker heating removes combustion emissions but does not remove limestone’s calcination CO₂. SaltX’s design aims to concentrate that stream for capture; “fully electrified” therefore does not mean “zero-emission cement.”
Electric cement’s scaling constraints
Cambridge Electric Cement substitutes already-decarbonated recovered paste for lime flux in steel recycling. EAF temperatures drive off problematic sulfate and chloride species and favour reactive alite, but scale depends on clean paste separation, scrap chemistry and EAF capacity.
Silicate cement’s theoretical floor
For silicate-derived Portland cement, a 2026 analysis estimated theoretical-minimum emissions of 49 kgCO₂/t, versus 609 kgCO₂/t from limestone. Its illustrative proven-unit-process route, however, requires 6.2 GJ/t, versus about 2.9 GJ/t for current limestone cement; the low-energy result remains theoretical, not achieved industrial performance.
If the remaining tests pass.If the remaining tests pass.
Downstream capabilities remain conditional on results that are not yet in.These are possible next capabilities, conditional on results that are not yet in.
- PASSED · February 202301 ↗Use much less clinkerIndustrial Low-Clinker CementHolcim's French line is rated for 500,000 tonnes yearly and claims 50% lower CO2 than CEM I.Operate a plant producing at least 100,000 tonnes per year of standards-compliant cement with at least 40% lower cradle-to-gate emissions.
- PASSED · August 202503 ↗Store kiln carbon permanentlyFull-Chain Cement CCSBrevik completed the chain in 2025, but its design addresses about half the plant's emissions.Capture cement-kiln CO2, transport it and inject it into monitored permanent geological storage.
- OPEN TEST02 ↗Replace the kiln chemistryDrop-In Alternative BinderBrimstone passed ASTM C150 in the lab; Sublime's planned 30,000-tonne plant was paused.Make non-limestone or electrochemical cement that passes mainstream Portland-cement standards and scales beyond a pilot.
- OPEN TEST04 ↗Scale beyond one plantNear-Zero Commercial FleetOnly about 35 Mt/year is announced for 2030, and announced capacity is not production.Operate enough certified near-zero cement plants to supply the roughly 350 Mt/year needed in 2030.
Possible, if the open tests pass.
Lower-carbon urbanization
This is a possible benefit only if lower-carbon urbanization works safely, reliably and at useful scale.Potential benefit only if the stated use (Lower-carbon urbanization) is demonstrated with evidence for safety, reliability, affordability and scale.
Durable carbon-storing infrastructure
This is a possible benefit only if durable carbon-storing infrastructure works safely, reliably and at useful scale.Potential benefit only if the stated use (Durable carbon-storing infrastructure) is demonstrated with evidence for safety, reliability, affordability and scale.
Cleaner megaproject construction
This is a possible benefit only if cleaner megaproject construction works safely, reliably and at useful scale.Potential benefit only if the stated use (Cleaner megaproject construction) is demonstrated with evidence for safety, reliability, affordability and scale.
Meet the builders.Meet the builders.
The organisations, their approaches, and the evidence behind them.The teams doing the work, the money around them, and what the record can support.
Germany / Norway · company
Heidelberg Materials
Operates Brevik CCS, the first industrial-scale carbon-capture facility attached to a cement plant.
Capital is context, not a demonstration.
Company source ↗View every builder record
Heidelberg Materials
Germany / Norway · company · Operates Brevik CCS, the first industrial-scale carbon-capture facility attached to a cement plant.
Funding: Funding not recorded in this record.
Designed to capture roughly 400,000 tCO2/year, about half of the plant's emissions.
Company source ↗Sublime Systems
USA · company · Developing ambient-temperature electrochemical cement from non-carbonate rocks and industrial wastes.
Funding: Strategic investments · $75M combined · Sep 2024
Named investors: CRH · Holcim
The Holyoke commercial-factory schedule remained unachieved and later faced a federal-funding pause.
Company source ↗Brimstone
USA · company · Developing a calcium-silicate rock refinery that co-produces Portland cement and other industrial materials.
Funding: Funding not recorded in this record.
DOE selected a proposed demonstration for up to $189M cost share; selection is not an operating plant or cumulative company funding.
Company source ↗LC3 Project
International / Switzerland · nonprofit · Develops and transfers limestone-calcined-clay cement systems that reduce clinker using widely available clays.
Funding: Funding not recorded in this record.
Company source ↗Ecocem
Ireland / EU · company · Developing ACT, a low-clinker cement formulation intended to work within existing standards and plants.
Funding: Funding not recorded in this record.
Its 70% reduction and 2035 scale language are company projections, not sector-wide achieved results.
Company source ↗Follow the evidence.Follow the evidence.
50 sources — every figure on this page traces to one.50 sources — every figure on this page traces to one.
- 01
IEA Breakthrough Agenda 2025: cement and concrete
Read source ↗iea.orgUsed on this pageScope: Not recorded. Limit: Not recorded.
- 02
IEA near-zero cement definitions
Read source ↗iea.orgUsed on this pageAll 6 uses across 5 destinations
Scope: Not recorded. Limit: Not recorded.
- 03
IEA cement technology tracking
Read source ↗iea.orgScope: Not recorded. Limit: Not recorded.
- 04
GCCA Getting the Numbers Right database
Read source ↗gccassociation.orgScope: Not recorded. Limit: Not recorded.
- 05
Two-hundred-year Portland cement review
Read source ↗sciencedirect.comUsed on this pageAll 6 uses across 4 destinations
Scope: Not recorded. Limit: Not recorded.
- 06
LC3 research history
Read source ↗lc3.chScope: Not recorded. Limit: Not recorded.
- 07
GCCA 2050 Net Zero Roadmap
Read source ↗gccassociation.orgUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 08
Brevik CCS opening
Read source ↗heidelbergmaterials.comUsed on this pageAll 5 uses across 3 destinations
Scope: Not recorded. Limit: Not recorded.
- 09
Scope: Not recorded. Limit: Not recorded.
- 10
Holcim calcined-clay deployment
Read source ↗holcim.comUsed on this pageAll 6 uses across 5 destinations
Scope: Not recorded. Limit: Not recorded.
- 11
Scope: Not recorded. Limit: Not recorded.
- 12
Scope: Not recorded. Limit: Not recorded.
- 13
Scope: Not recorded. Limit: Not recorded.
- 14
Timeline · Ransome patents rotary kiln
Read source ↗patents.google.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 15
Timeline · Brevik tests amine capture
Read source ↗sintef.noUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 16
Timeline · Clinker-free plant is commissioned
Read source ↗live.euronext.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 17
Timeline · Alternative route meets C150
Read source ↗businesswire.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 18
Timeline · Cement-free concrete enters a building
Read source ↗news.mit.eduUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 19
Timeline · Electric arc furnace reclinkers cement
Read source ↗nature.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 20
Scope: Not recorded. Limit: Not recorded.
- 21
Timeline · Ghana scales calcined clay
Read source ↗heidelbergmaterials.comUsed on this pageAll 4 uses across 3 destinations
Scope: Not recorded. Limit: Not recorded.
- 22
Timeline · Captured-carbon cement reaches customers
Read source ↗heidelbergmaterials.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 23
Scope: Not recorded. Limit: Not recorded.
- 24
Timeline · Electric process makes Portland clinker
Read source ↗saltxtechnology.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 25
Timeline · Pure Oxyfuel research kiln starts
Read source ↗heidelbergmaterials.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 26
Timeline · GeZero targets full capture
Read source ↗heidelbergmaterials.comUsed on this pageAll 4 uses across 3 destinations
Scope: Not recorded. Limit: Not recorded.
- 27
Timeline · Announced capacity reaches 35 Mt
Read source ↗iea.orgUsed on this pageAll 5 uses across 4 destinations
Scope: Not recorded. Limit: Not recorded.
- 28
Metric · GNR participating-producer net intensity
Read source ↗worldcement.comUsed on this pageAll 4 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 29
Metric · Approximate GCCA target implied by a 20% cut from its roughly 594 kg/t 2020 level
Read source ↗gccassociation.orgUsed on this pageAll 2 uses across 1 destination
Scope: Not recorded. Limit: Not recorded.
- 30
Series · Landmark low-clinker and alternative-binder nameplate
Read source ↗sublime-systems.comUsed on this pageScope: Not recorded. Limit: Not recorded.
- 31
Series · Landmark low-clinker and alternative-binder nameplate
Read source ↗forteraglobal.comUsed on this pageScope: Not recorded. Limit: Not recorded.
- 32
Series · Cement-sector CO2 capture project nameplate
Read source ↗heidelbergmaterials.comUsed on this pageScope: Not recorded. Limit: Not recorded.
- 33
Series · Cement-sector CO2 capture project nameplate
Read source ↗thyssenkrupp.comScope: Not recorded. Limit: Not recorded.
- 34
Engineer note · H-UKR remains above near-zero
Read source ↗ciments-hoffmann.comScope: Not recorded. Limit: Not recorded.
- 35
Engineer note · The accounting behind evoZero
Read source ↗evozero.comScope: Not recorded. Limit: Not recorded.
- 36
Engineer note · What the first certificates covered
Read source ↗evozero.comScope: Not recorded. Limit: Not recorded.
- 37
Engineer note · Electrification leaves process emissions
Read source ↗saltxtechnology.comScope: Not recorded. Limit: Not recorded.
- 38
Engineer note · Silicate cement’s theoretical floor
Read source ↗nature.comScope: Not recorded. Limit: Not recorded.
- 39
companies · Sublime Systems
Read source ↗sublime-systems.comUsed on this pageAll 2 uses across 1 destination
Scope: Not recorded. Limit: Not recorded.
- 40
Scope: Not recorded. Limit: Not recorded.
- 41
Scope: Not recorded. Limit: Not recorded.
- 42
Scope: Not recorded. Limit: Not recorded.
- 43
people · Leah Ellis
Read source ↗sublime-systems.comUsed on this pageAll 2 uses across 2 destinations
Scope: Not recorded. Limit: Not recorded.
- 44
Scope: Not recorded. Limit: Not recorded.
- 45
Scope: Not recorded. Limit: Not recorded.
- 46
Heidelberg Materials official site
Read source ↗heidelbergmaterials.comScope: Not recorded. Limit: Not recorded.
- 47
Sublime Systems official site
Read source ↗sublime-systems.comScope: Not recorded. Limit: Not recorded.
- 48
Brimstone official site
Read source ↗brimstone.comScope: Not recorded. Limit: Not recorded.
- 49
LC3 Project official site
Read source ↗lc3.chScope: Not recorded. Limit: Not recorded.
- 50
Ecocem official site
Read source ↗ecocemglobal.comScope: Not recorded. Limit: Not recorded.
Sources describe evidence. Inclusion is not endorsement.