TRL 7–8. Cement kilns and power boilers. Air separation unit is the key capital item.
Oxy-fuel combustion replaces the air used in conventional combustion with pure oxygen (95–99% O₂ purity) produced by an Air Separation Unit (ASU). When fuel is burned in pure oxygen rather than air, the nitrogen that typically dilutes the flue gas to 10–15% CO₂ is absent. The result is a flue gas consisting predominantly of CO₂ and water vapour — typically 80–95% CO₂ after water condensation — which requires no chemical separation step. The CO₂ is simply dried and compressed for transport and storage.
A portion of the flue gas (typically 60–70%) is recycled back to the combustion chamber to moderate the flame temperature, which would otherwise be excessively high in pure oxygen. This recycle flue gas replaces the temperature-moderation function that nitrogen provides in air combustion. The net result is a process that produces a near-pure CO₂ stream at essentially the same energy output as the original air-fired process, with an oxygen production energy penalty rather than a solvent regeneration energy penalty.
The primary capital cost driver for oxy-fuel combustion is the Air Separation Unit — a cryogenic distillation system that separates atmospheric air into oxygen, nitrogen, and argon streams. For large plants, the ASU is a proven, commercially available technology from Linde, Air Products, Air Liquide, and Praxair. The cost of oxygen production under Indian electricity prices — which vary significantly between grid power and captive coal generation — is the dominant economic variable in oxy-fuel feasibility assessments.
India is the world's second-largest cement producer at approximately 380 MT/year, and cement production is growing at 5–7% annually to support India's infrastructure development programme. Cement's CO₂ emissions are uniquely challenging: approximately 60% comes from the chemical decomposition of limestone (calcination) — CaCO₃ → CaO + CO₂ — a reaction that cannot be avoided by fuel switching, electrification, or efficiency improvement. The only way to eliminate calcination CO₂ is to capture it.
Oxy-fuel combustion is particularly attractive for cement because it captures both the calcination CO₂ and the fuel combustion CO₂ in a single concentrated stream, without requiring two separate capture systems. The Heidelberg Materials ANRAV project in Brevik, Norway — the world's first full-scale carbon capture plant at a cement factory — uses oxy-fuel-adjacent technology to capture 400,000 tonnes/year and provides the primary reference design that NCM uses for Indian cement feasibility assessments.
India's major cement producers — UltraTech (120 MT/year capacity), ACC, Shree Cement, Ambuja, Dalmia Bharat, and JK Cement — collectively represent one of the world's largest concentrations of cement production. The CBAM exposure for Indian cement exporters is significant, and NCM has conducted preliminary oxy-fuel screening assessments for facilities in Rajasthan, Andhra Pradesh, and Madhya Pradesh — India's primary cement production clusters.
India's annual cement production — second largest globally and growing at 5–7%/year
Share of cement CO₂ from limestone calcination — unavoidable without carbon capture
CO₂ concentration in oxy-fuel flue gas after water removal — vs. 14–33% in conventional flue gas
Technology readiness at industrial demonstration scale — approaching commercial readiness
Each project provides specific lessons applied to Indian oxy-fuel feasibility and design.
The world's most comprehensive oxy-fuel coal power demonstration. 30 MW thermal oxy-fuel boiler. Demonstrated full cycle operability, ASU integration, and CO₂ compression train performance. NCM's Australian operational team includes engineers who worked on Callide — lessons directly applied to Indian coal boiler assessments.
World's first full-scale cement carbon capture installation. 400,000 t/year CO₂ captured. Demonstrates industrial-scale oxy-fuel-adjacent technology for the global cement sector — primary reference for NCM's Indian cement oxy-fuel feasibility work.
Vattenfall's oxy-fuel pilot plant — the first demonstration of oxy-fuel technology on a coal power plant connected to the electricity grid. Key data source for NCM's coal power oxy-fuel retrofit assessments.
NCM's oxy-fuel feasibility assessments begin with a detailed energy integration study — because the ASU electricity consumption is the dominant variable in oxy-fuel economics under Indian conditions. We evaluate three electricity supply scenarios for each site: grid power at state industrial tariff, dedicated captive coal power, and waste heat recovery from the host industrial process. The optimal scenario varies significantly by site and location.
For cement plants, NCM evaluates both full oxy-fuel kiln retrofit and partial oxy-fuel options — where the kiln calciner is converted to oxy-fuel (capturing the 60% calcination CO₂) while the main kiln continues on air-fired operation. This partial oxy-fuel approach can reduce capital cost by 35–45% compared to full kiln conversion while still capturing the majority of cement's unavoidable process emissions.
All oxy-fuel assessments are integrated with NCM's storage advisory — because oxy-fuel produces a high-purity CO₂ stream with minimal impurities, it has specific compression train design requirements and CO₂ quality specifications that differ from post-combustion capture streams. Our end-to-end advisory ensures that capture, compression, transport, and storage system specifications are consistent from the outset.
Whether you are a government body seeking policy advice, an industrial company facing CBAM exposure, or an investor seeking CCUS project opportunities — our team is ready to engage.