How close are we to cement without the carbon?Can we make concrete without wrecking the climate?
or, simply: Can we make concrete without wrecking the climate?or, precisely: 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.
Pure Oxyfuel research kiln starts - The 450-tonne-clinker-per-day catch4climate research kiln entered operation after first producing clinker in May; capture and storage at that rate remain unproved. Next up - GeZero targets full capture (expected 2029).
State of playWhere near-zero cement stands right now
The current stage, the honest metric, and the single threshold that gates the next stage. Each threshold is a falsifiable claim with a named next test.How far up the ladder we've climbed, the honest verdict, and the one thing blocking the next step.
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.
Replace the kiln chemistryDrop-In Alternative Binder Next test: A novel-route producer must run a kilotonne-scale plant and publish strength, durability, EPD and cost data.
The thresholds that gate the next stageWhat has to happen next
Each threshold is a falsifiable claim with a named next test; the gap chart shows how far today's metric sits from the goal.Each row is one thing that has to be proven — and how far today's number is from the target.
The record behind the verdict
Major events set large; context events set small but never hidden. Everything below the TODAY rule is a schedule, not a result.
The Clinker Age
The Clinker Age moved the field from portland cement is patented to ransome patents rotary kiln. The results narrowed the next question without closing it.
Measuring Industrial Carbon
Measuring Industrial Carbon begins with modern emissions baseline begins. The result established the next question for the field.
New Binders Emerge
New Binders Emerge begins with calcined-clay concept takes shape. The result established the next question for the field.
Pilots, Standards and Pledges
Pilots, Standards and Pledges moved the field from calera shuts after demonstration to lc3 reaches permanent production. The results narrowed the next question without closing it.
Full-Chain Scale Test
Full-Chain Scale Test moved the field from fortera opens redding plant to announced capacity reaches 35 mt. The results narrowed the next question without closing it.
Events outside the declared eras
Events outside the declared eras moved the field from calcined clay reaches 500 kilotonnes to industry net-zero deadline arrives. The results narrowed the next question without closing it.
Why the meters read the way they do
The learning curves and comparisons that justify each threshold's percentage. Every series is measured, with the source event linked in the timeline above.
Read the evidence more closely
Definitions, system boundaries and experimental caveats behind the headline record.
01What 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.
02H-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.
03The 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.
04What 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.
05Oxyfuel 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.
06Electrification 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.”
07Electric 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.
08Silicate 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
Downstream capabilities, drawn dashed because they depend on results not yet in.
Who is building it-and what the money saysCapital, institutions and the global race
The teams doing the work, where they are based, and whether the money points to real delivery or only a plan.Company finance, public programmes, institutional leadership and market evidence-kept separate from valuations, forecasts and announced capacity.
The field is split between incumbent cement groups adding carbon capture and startups trying to avoid limestone or clinker altogether. The first industrial CCS plant is operating, but most near-zero capacity is still announced rather than producing, and early plants carry a large cost premium.
Who is building itCompanies, laboratories and programmes
Heidelberg Materials
Germany / NorwayOperates Brevik CCS, the first industrial-scale carbon-capture facility attached to a cement plant.
Sublime Systems
USADeveloping ambient-temperature electrochemical cement from non-carbonate rocks and industrial wastes.
Brimstone
USADeveloping a calcium-silicate rock refinery that co-produces Portland cement and other industrial materials.
| Player | Country | What they are doing | Funding | Named investors | Source |
|---|---|---|---|---|---|
| Heidelberg Materialscompany | Germany / Norway | Operates Brevik CCS, the first industrial-scale carbon-capture facility attached to a cement plant. Designed to capture roughly 400,000 tCO2/year, about half of the plant's emissions. | Not disclosed | Not disclosed | Source · heidelbergmaterials.com |
| Sublime Systemscompany | USA | Developing ambient-temperature electrochemical cement from non-carbonate rocks and industrial wastes. The Holyoke commercial-factory schedule remained unachieved and later faced a federal-funding pause. | Strategic investments · $75M combined · Sep 2024 | CRH · Holcim | Source · sublime-systems.com |
| Brimstonecompany | USA | Developing a calcium-silicate rock refinery that co-produces Portland cement and other industrial materials. DOE selected a proposed demonstration for up to $189M cost share; selection is not an operating plant or cumulative company funding. | Not disclosed | Not disclosed | Source · energy.gov |
| LC3 Projectnonprofit | International / Switzerland | Develops and transfers limestone-calcined-clay cement systems that reduce clinker using widely available clays. | Not disclosed | Not disclosed | Source · lc3.ch |
| Ecocemcompany | Ireland / EU | Developing ACT, a low-clinker cement formulation intended to work within existing standards and plants. Its 70% reduction and 2035 scale language are company projections, not sector-wide achieved results. | Not disclosed | Not disclosed | Source · ecocemglobal.com |
Where every number comes from
12 sources — every figure on this page traces to one.
- IEA Breakthrough Agenda 2025: cement and concreteiea.org
- IEA near-zero cement definitionsiea.org
- IEA cement technology trackingiea.org
- GCCA Getting the Numbers Right databasegccassociation.org
- Two-hundred-year Portland cement reviewsciencedirect.com
- LC3 research historylc3.ch
- GCCA 2050 Net Zero Roadmapgccassociation.org
- Brevik CCS openingheidelbergmaterials.com
- First Brevik CO2 storedequinor.com
- Holcim calcined-clay deploymentholcim.com
- Fortera Redding deployment reviewapnews.com
- Sublime Holyoke pausespglobal.com