Net Zero Pathways for the Cement Industry

Cement reaches net zero by stacking several partial levers, not by any single fix: a lower clinker factor, alternative fuels, thermal and electrical efficiency, carbon capture (CCUS), and recarbonation, with the residual balanced by removals across the cement and concrete value chain by 2050. The Global Cement and Concrete Association (GCCA) and the International Energy Agency (IEA) both model this as a lever stack, and in both roadmaps carbon capture is the single largest contributor by mid-century [1][2]. This piece sets out what net zero means for cement, why the sector is structurally hard to decarbonise, and how each lever in the stack contributes.

A note on scope: "net zero concrete" in the GCCA framing covers the whole value chain (clinker, cement, concrete, construction, and end-of-life recarbonation), while "cement decarbonisation" usually means the narrower clinker-and-kiln boundary. This piece works across both, but flags which boundary a number refers to.

What net zero means for cement

Net zero cement means balancing the sector's residual CO2 emissions with an equivalent quantity of removals, so that the net flux to the atmosphere is zero, targeted for 2050 under the GCCA roadmap [1]. It is not zero gross emissions: a fully decarbonised electricity supply and maximum fuel switching still leave the calcination CO2, so the pathway leans on carbon capture and on recarbonation (concrete reabsorbing CO2 over its life) to close the gap [1][3].

Net zero cement: a state in which the CO2 released across the cement and concrete value chain is balanced by an equal quantity of CO2 captured, stored, or reabsorbed (recarbonation), giving a net atmospheric flux of zero. The GCCA targets this for 2050 [1].

The distinction matters for reading any target. A cement producer claiming "net zero" is usually counting captured and reabsorbed CO2 against gross process and combustion emissions, not asserting that the kiln emits nothing. The credibility of the claim rests on whether the capture, storage, and offset volumes are real and verifiable, not on the headline.

Why cement is hard to decarbonise

Roughly half of cement's CO2 comes from the chemistry of making clinker, not from burning fuel, which is why fuel switching alone cannot reach zero. When limestone (calcium carbonate) is heated in the kiln it calcines into lime and CO2; this process CO2 is around 50-60% of cement plant emissions, with fuel combustion contributing most of the remaining ~40% [4][5]. You can decarbonise the fuel completely and still emit the calcination CO2.

Cement and concrete account for approximately 7% of global CO2 emissions, making the sector one of the largest single industrial sources [2]. The process-emission share is the structural problem: steel can in principle switch its reductant (coal to hydrogen), but the calcination reaction releases CO2 regardless of how the heat is supplied. That is why every credible cement roadmap ends up depending on carbon capture for the residual, a point developed in why cement is hard to decarbonise and in the kiln chemistry covered under cement pyroprocessing.

The lever stack: how the roadmaps get to zero

No single lever decarbonises cement, so both the GCCA and IEA roadmaps model a stack of partial reductions that compound to net zero. The largest 2050 contributor in the GCCA roadmap is CCUS at 36% of the sector's planned reductions; the near-term levers (clinker factor, fuels, efficiency) carry more of the load before 2030, when capture is still scaling [1][2]. The table below sets out the main levers, their 2030 milestones, and their 2050 weight.

Read the stack as cumulative. The clinker and fuel levers do most of the work this decade because they are deployable with existing plant; carbon capture overtakes them after 2030 as projects move from demonstration to fleet scale. To stay on the IEA Net Zero Scenario, cement emissions need to fall by roughly 3% per year through 2030 [2].

Lever 1: clinker factor (the fastest near-term lever)

Lowering the clinker-to-cement ratio is the largest reduction the sector can deploy this decade with existing equipment. Clinker is the carbon-intensive component; replacing a share of it with supplementary cementitious materials (SCMs) cuts both the calcination CO2 and the fuel needed per tonne of cement. The GCCA roadmap takes the global clinker/binder ratio from 0.63 today down to 0.58 by 2030 and 0.52 by 2050; the IEA Net Zero Scenario targets 0.65 by 2030, a roughly 1% annual reduction [1][2].

Clinker factor (clinker/binder ratio): the mass fraction of clinker in finished cement. A factor of 0.63 means 63% clinker and 37% other binders or fillers. Lowering it directly lowers the CO2 per tonne of cement, because clinker carries the calcination and most of the fuel emissions [1].

The substitutes are the standard SCMs: fly ash, ground granulated blast-furnace slag, calcined clay, and limestone filler. Their availability is the constraint; as coal power and blast-furnace steel decline, fly ash and slag supply tighten, which is why calcined clay (the basis of LC3 cement) is the SCM most roadmaps lean on for new capacity. The blended-cement families that carry these substitutions are covered in OPC vs PPC vs PSC cement, and the materials themselves in supplementary cementitious materials.

Lever 2: fuels and efficiency

Alternative fuels and energy efficiency attack the combustion side, the ~40% of emissions that come from heating the kiln rather than from calcination [4]. Replacing fossil fuels (coal, petcoke) with waste-derived fuels, biomass, and eventually hydrogen lowers the combustion CO2; the GCCA roadmap raises the alternative-fuel share of thermal input from about 6% today to 22% by 2030 and 43% by 2050 [1]. Efficiency squeezes the energy demand the fuels have to meet: the IEA Net Zero Scenario targets average thermal intensity below 3.4 GJ/t clinker and electrical intensity below 90 kWh/t cement by 2030 [2].

Efficiency and fuel substitution interact with day-to-day kiln operation. A kiln running near its thermal-intensity floor depends on a tight combustion-air path; uncontrolled air ingress (false air) raises the fuel needed per tonne of clinker and works directly against the efficiency lever. The size of that penalty is set out in specific fuel consumption in cement kilns and in false air in cement kilns. Alternative fuels also raise the stakes on combustion control, because their variable calorific value and moisture make a stable, well-sealed kiln atmosphere harder to hold.

Lever 3: CCUS (the largest 2050 contributor)

Carbon capture, utilisation, and storage (CCUS) is the single largest lever in the 2050 picture, accounting for 36% of the sector's planned reductions in the GCCA roadmap, because it is the only lever that addresses the calcination CO2 directly rather than reducing the clinker that produces it [1]. The IEA estimates the Net Zero Scenario needs around 180 Mt of cement CO2 captured per year by 2030, against roughly 0.1 Mt captured today, the steepest scaling demand in the stack [2].

The first industrial-scale proof point is now operating. Heidelberg Materials' Brevik CCS plant in Norway opened in June 2025 and captures around 400,000 tonnes of CO2 per year, about 50% of that plant's emissions, with the captured CO2 liquefied, shipped, and stored under the North Sea [6]. Brevik is the reference case for the next wave of cement CCS, but a single plant at 0.4 Mt/yr against an 180 Mt/yr target shows the scale of deployment still required. The capture technologies (amine scrubbing, oxy-fuel, calcium looping) and their energy penalties are compared in carbon capture in the cement industry.

Where kiln integrity fits the pathway

Every efficiency-side number in these roadmaps assumes a kiln that is not leaking, so kiln sealing is a precondition for the fuel and efficiency levers, not a decarbonisation lever in itself. False air drawn in through worn inlet and outlet seals raises specific fuel consumption and pulls the kiln away from the IEA thermal-intensity target; the tighter a roadmap drives the energy budget, the less headroom there is to waste on uncontrolled air ingress [4].

This is the practical link between sealing and decarbonisation. Oswal's kiln sealing systems and integrated false air control keep the combustion-air path controlled so that the fuel saved by efficiency measures is not given back through seal-face leakage. For the cement industry specifically, holding false air low is the unglamorous baseline that makes the rest of the efficiency lever measurable. It does not capture carbon or cut the clinker factor; it stops the kiln undoing the gains those levers deliver.

If you are working through the efficiency side of a cement decarbonisation plan, our engineering team maps each kiln position to a sealing approach so the fuel saved by efficiency measures is not lost to false air. Contact us to review your kiln's sealing and false-air profile.