Cement decarbonization: CEMS & analytics for low-carbon clinker
Explore the operational challenges behind cement decarbonization and learn how advanced instrumentation improves process stability, performance and compliance.
Introduction
Cement decarbonization: From process emissions to traceable gas analysis
Cement decarbonization relies on reducing CO₂ released during calcination and fuel combustion in the kiln and calciner. These process steps generate most of the plant’s emissions, making reliable measurement critical. A Continuous Emission Monitoring System (CEMS) provides continuous CO₂ and pollutant data, forming the basis of decarbonization and regulatory compliance.
This page explains the technical constraints of cement decarbonization and defines what low‑carbon clinker means from a process perspective. We also outline how continuous gas analysis supports emissions reporting, operational stability and long‑term CO₂ reduction.
Insights
Low‑carbon clinker: Definition and measurable process criteria
Clinker production is the primary driver of a cement plant’s Scope 1 emissions. Lowering CO₂ emissions requires changes in clinker chemistry, kiln operation or combustion behavior. In addition, material strategies such as reduced limestone content or the use of supplementary materials can reduce CO₂ intensity at the product level.
Low‑carbon clinker refers to clinker with a reduced CO₂ emission factor. From a process perspective, it is defined by three quantifiable elements:
- Lower calcination emissions per tonne of clinker
- Reduced fuel-related CO₂
- CO₂ streams suitable for carbon capture technologies
Each element is addressed in the following sections.
Lower calcination emissions per tonne of clinker
While CO₂ emissions from calcination are chemically unavoidable, overall emissions can be reduced through:
- Improved kiln and calciner heat efficiency, avoiding overfiring for the required degree of calcination
- Optimized raw meal chemistry and the use of mineralizers to lower the thermal demand
- Partial substitution of limestone with materials requiring less decarbonation
These measures reduce the specific CO₂ released from CaCO₃ decomposition, even though the chemical reaction itself cannot be eliminated.
Reduced fuel-related CO₂
Fuel-related emissions depend on the carbon content of the heat source and the stability of combustion.
Key pathways include:
- Higher substitution of fossil fuels with alternative fuels such as biogenic fuels and waste-derived fuels (e.g. Refuse-Derived Fuel also known as RDF)
- Maintaining stable O₂/CO behavior to avoid incomplete combustion
- Reducing excess air to limit thermal losses
- Improving calciner efficiency to minimize overall fuel demand
The use of alternative fuels increases variability in combustion, which requires reliable process monitoring and gas analysis to maintain performance and emissions control. A low‑carbon clinker line achieves the same degree of sintering with lower fossil carbon input.
CO₂ streams suitable for carbon capture technologies
Carbon Capture, Utilization and Storage (CCUS) implementation of a clinker process could define an operation as low-carbon in regulatory and market contexts. Before implementation, the operation requires control of the following process parameters:
- Stable and predictable CO₂ concentration in the preheater or calciner exhaust
- Low levels of contaminants such as SO₂, HCl and particulates that affect capture efficiency
- Reliable CEMS data to verify capture performance and reporting accuracy
Plants that deliver a consistent and well-characterized CO₂ exhaust profile are better positioned for future carbon capture integration.
Implementing these decarbonization strategies introduces operational constraints. Alternative fuels can increase combustion variability, while carbon capture requires stable exhaust gas conditions. Plants must therefore balance emission reduction objectives with process stability, clinker quality and production performance. Reliable emissions monitoring is essential to support this transition.
Insights
Critical CEMS process measurement points
Reliable process monitoring in cement production depends on several key measurement points across the kiln, calciner and gas-cleaning systems. Each location provides specific information required for combustion control, alternative fuel operation and regulatory compliance.
The following overview shows how strategic gas analysis at each process stage enables the precision needed for stable, low-carbon clinker production:
- Kiln inlet: Gas analysis at this point captures CO₂, O₂, CO, NOx, SO₂ and HCl. It indicates combustion quality, calcination progress and the intensity of sulfur and chlorine cycles
- Calciner: Measurements here typically include O₂, CO, NOx, SO₂, CO₂ and HCl. They show how alternative fuels burn, how efficiently the calciner operates and how NOx forms under varying combustion conditions
- Preheater outlet: This location provides CO₂, O₂, CO, NOx, SO₂ and HCl values. It reflects the combined pyroprocess gas composition and helps assess CO₂ concentration stability for potential capture
- Coal mill or fuel preparation exhaust: The mill or silo exhaust is monitored for O₂ and CO. These signals detect smouldering, insufficient inerting and other unsafe conditions during fuel preparation
- ESP or stack outlet: Stack measurements include CO₂, NOx, SO₂, HCl, CO and dust. This is the reference dataset used for permits, regulatory compliance and annual CO₂ reporting
This requires measurement at defined points across the kiln and gas-handling system.
Cyclone preheater
Kiln
SNR equipment/clinker cooler
Insights
How CEMS supports your compliance strategy
Cement plants must comply with strict environmental and reporting requirements that define what must be measured and how results must be documented. Traceable data is essential for daily operation, regulatory compliance and long-term decarbonization planning.
What must be reported:
- Scope 1 CO₂ from calcination and fuel combustion
- Specific CO₂ per tonne of clinker
- Emission factors for fuels
- Annual CO₂ totals based on mass balance and CEMS data
Only verified datasets are accepted.
Why CEMS is essential
Certified CEMS provides the continuous emissions data required for reporting and regulatory compliance. It ensures:
- Reliable and traceable measurements
- Compliance with standards such as EN 14181 or MCERTS
- Continuous monitoring of regulated pollutants
- Audit-ready data
Without valid CEMS data, plants risk non-compliance and emissions recalculation.
How measurement enables carbon capture readiness
Carbon capture projects require stable and verifiable process gas data. This depends on:
- Stable CO₂ concentration
- Low contaminant levels
- Continuous and traceable measurement
Insights
Securing the business value of your cement decarbonization
When CO₂, O₂, CO, NOx, SO₂ and HCl data is measured reliably throughout the kiln and calciner system, emission control and fuel use become easier to stabilize. This enables the following improvements:
- Ensure compliance, support Environment Safety and Governance (ESG) and decarbonization targets with continuous and traceable emissions data
- Optimize fuel consumption through stable O₂ and CO behavior that supports efficient combustion and avoids over‑firing
- Stabilize clinker quality as gas trends reveal combustion deviations early and allow timely correction
- Minimize operating and maintenance effort through consistent CEMS performance that reduces troubleshooting and manual verification
FAQ
Frequently asked questions on cement decarbonization with CEMS
This section covers key questions on cement decarbonization, emissions monitoring and process control. It explains the role of CEMS, real-time emission analytics and alternative fuel combustion in maintaining compliance and improving plant performance.
