Carbon Capture Economics: Dollars per Tonne CO2 in Cement

Carbon capture in cement costs roughly USD 40-160 per tonne of CO2, depending on the capture technology, plant size, and whether the figure is quoted per tonne captured or per tonne avoided. Oxyfuel combustion sits at the low end and post-combustion amine absorption at the high end [1][2][3]. Cement is one of the more expensive industrial sectors to capture from, because its flue gas is dilute and roughly 60% of its CO2 comes from the chemistry of making clinker rather than from burning fuel [4]. This piece sets out the $/tCO2 ranges by technology, the capex and opex behind them, and what actually moves the number.

A note on scope: "cost of carbon capture" here means the capture and compression cost at the plant gate. CO2 transport and permanent storage are separate line items, added on top.

What carbon capture costs in cement, per tonne of CO2

Cement carbon capture costs roughly USD 40-160 per tonne of CO2 across the main technologies, with most credible estimates clustering between USD 60 and USD 120 per tonne [1][2][3]. The IEA places "dilute" capture sources, which include cement and power, at USD 40-120 per tonne of CO2, against USD 15-25 per tonne for concentrated streams such as gas processing or ethanol [1]. Cement does not have a concentrated stream to work with, so it lives at the higher end.

Two structural facts put cement near the top of the cost range. First, kiln flue gas is dilute: the CO2 has to be separated from a large volume of nitrogen and excess air, and the more dilute the stream, the more energy and equipment the separation takes. Second, around 60% of a cement plant's CO2 is process emission released when limestone is calcined to lime, not combustion emission from fuel [4]. That share cannot be removed by switching fuels or electrifying; for those tonnes, capture is the only scalable route, which is why the sector's cost discussion is unavoidable rather than optional. The wider emissions picture is covered in cement industry emissions, and the four capture pathways themselves in carbon capture in the cement industry.

Cost of CO2 captured: the total cost of running a capture plant divided by the tonnes of CO2 it collects, ignoring the extra CO2 generated by the energy the capture plant itself consumes [5].

Captured vs avoided: why the same plant has two numbers

Every capture plant has two cost figures, because capturing CO2 consumes energy, and that energy generates its own CO2 [5][6]. Cost of CO2 captured divides the cost by tonnes collected. Cost of CO2 avoided divides it by the net reduction after subtracting the emissions caused by running the capture plant. Because some energy is always spent capturing, compressing, and moving CO2, avoided tonnes are always fewer than captured tonnes, so the cost per tonne avoided is always higher than the cost per tonne captured [5][6].

Cost of CO2 avoided: the incremental cost of capture divided by the net CO2 reduction, after subtracting the additional emissions caused by the energy the capture plant consumes. Always higher than the cost per tonne captured [5][6].

The gap matters when reading any quoted number. A study of cement capture put the same configuration at CAD 50-150 per tonne captured but CAD 45-205 per tonne avoided, a wide spread driven entirely by which basis is used [6]. When a vendor or a press release quotes a single low figure, the first question is which basis it is on. The avoided figure is the honest one for a plant deciding whether capture closes its emissions gap, because it reflects the real reduction the plant pays for.

$/tCO2 by capture technology

Across the main cement capture routes, oxyfuel combustion is currently the cheapest per tonne avoided and post-combustion amine absorption the most expensive, with calcium looping competitive when its surplus heat is sold [2][3][7]. The table below gives representative ranges on a cost-of-CO2-avoided basis. Figures are general industry estimates from the cited sources, not Oswal numbers, and they move with plant size, energy price, and study assumptions.

Two patterns sit inside that table. The first is plant scale. IEAGHG estimated post-combustion capture at EUR 107 per tonne avoided (about USD 161) for a 1 Mt/y European plant, but only EUR 59 (about USD 88) for a 3 Mt/y Asian plant, and oxyfuel at EUR 40 (about USD 60) versus EUR 23 (about USD 34) on the same comparison [2]. Larger plants and lower-cost regions roughly halve the per-tonne figure. The second is the trade between maturity and cost: amine post-combustion is the only route demonstrated at full industrial scale in cement, but it is also the most expensive, while oxyfuel and calcium looping are cheaper on paper yet less proven [2][3][7].

What drives the cost: capex vs opex

Two things dominate cement capture cost: the capital cost of the capture island and the energy (opex) to regenerate the solvent or run the air-separation unit [2][8]. Both scale with the volume of flue gas and the mass of CO2 to be separated, which is why upstream plant efficiency feeds directly into capture economics.

On the capital side, a post-combustion retrofit adds an absorber, a stripper, compression, and, specific to cement, a purpose-built auxiliary boiler. A cement plant has no spare steam to regenerate the solvent the way a power station does, so that heat has to be raised from scratch [8]. That auxiliary boiler is both a capex item and a running-emissions item, and it is one reason cement post-combustion lands at the high end.

On the operating side, the dominant cost is the heat to strip CO2 back out of the amine. Reboiler thermal duty for conventional amine capture runs about 3.95-4.65 GJ per tonne of CO2, of which roughly 50-70% is the energy to break the chemical bond between the solvent and the CO2 [8]. Advanced solvents and heat integration can cut that toward 2.2 GJ per tonne, which is the main lever on amine opex [8]. Oxyfuel shifts the energy burden to the air-separation unit that supplies near-pure oxygen, trading reboiler heat for electrical power. The kiln-side energy context is in specific fuel consumption in cement kilns and the broader heat path in cement pyroprocessing.

Energy penalty: the additional energy a plant must consume to capture, regenerate, and compress CO2. It raises operating cost and creates the gap between tonnes captured and tonnes avoided [5][8].

The upstream-savings argument: cheap tonnes before captured tonnes

The cheapest tonne of CO2 is the one a plant never emits, so kiln energy efficiency, including false air control, lowers both fuel CO2 and the size, and cost, of any downstream capture plant [1][8]. Capture capex and opex both scale with flue-gas volume and CO2 mass flow. Anything that shrinks those before the capture island shrinks the bill.

False air is the clearest example. Air drawn into the kiln system through worn seals, hood interfaces, and inspection ports dilutes the flue gas and raises the load on the induced-draft fan, which means a capture plant downstream has to process more gas to recover the same CO2. Cutting false air lowers specific fuel consumption, which cuts fuel CO2 directly, and it keeps the flue gas less diluted, which is exactly the condition that makes separation cheaper. None of this captures CO2 by itself; it lowers how much capture has to be paid for. The mechanism and the fuel cost of leakage are set out in false air in cement kilns, and the sealing-plus-monitoring approach in Oswal's integrated false air control system.

What this means for a plant evaluating capture

A plant scoping capture should fix its baseline energy efficiency first, size the project against avoided rather than captured tonnes, and treat transport and storage as a separate line item [5][6]. Three further points shape the number a plant will actually face.

First, clinker substitution lowers the tonnage that needs capturing at all. Replacing a share of clinker with supplementary cementitious materials cuts process CO2 at source, so less remains for the expensive capture step. Second, the headline $/tCO2 rarely closes on its own; a carbon price or capital subsidy usually bridges the gap between capture cost and the value of the avoided emission, which is why most demonstration projects are publicly co-funded. Third, scale realism matters. Brevik CCS in Norway, the world's first industrial-scale cement capture plant, captures around 400,000 tonnes of CO2 per year, about 50% of that plant's emissions, and entered operation in 2025 after reaching mechanical completion in late 2024 [9]. It captures half the plant's CO2, not all of it, which is a useful anchor for what a first capture investment realistically delivers.

For an operator, the sequence is the point: drive down fuel and process CO2 first, then capture what remains, and read every cost figure on an avoided basis before committing capital.

If you are scoping carbon capture and want to wring the cheap tonnes out first, our engineering team works through kiln energy efficiency and false air control as the upstream step before any capture plant is sized. Contact us to review your kiln's sealing and false-air profile against your decarbonisation plan, and how it feeds into capture economics for your cement operation.