Rajesh Kumar Nayma, Associate General Manager – Environment and Sustainability, Wonder Cement, in conversation with Kanika Mathur about CCUS technology.

Wonder Cement Limited (WCL), a leading player in the cement industry, is committed to sustainable practices and innovation in its operations. Rajesh Kumar Nayma, Associate General Manager – Environment and Sustainability at WCL, shares insights into the company’s efforts to integrate Carbon Capture, Utilisation, and Storage (CCUS) technology to combat climate change. Through advanced processes and renewable energy initiatives, WCL is paving the way for a greener cement industry.

How is your company incorporating CCUS technology into its operations to promote sustainability?
To combat climate change and achieve Net Zero emissions by 2060, Carbon Capture, Utilisation, and Storage (CCUS) technology will play a pivotal role. Wonder Cement Limited (WCL) is actively collaborating with various technology providers to support this journey. Efforts include segregating greenhouse gas (GHG) emissions from stacks, implementing oxy-fuel technology, electrifying kilns, utilising 100 per cent solar energy within plants, and eliminating fossil fuel consumption.
WCL has conducted a comprehensive GHG inventory aligned with India’s COP26 commitments, aiming to achieve net-zero emissions. Technological innovations such as the installation of a 45 MW Waste Heat Recovery System (WHRS) and an additional 15 MW WHRB have been key milestones. These systems capture excess heat from production processes, converting it into energy and reducing carbon footprints. The company has also introduced advanced burner technology to lower NOx emissions and optimise energy consumption. Currently, WCL achieves less than 47 KWh/tonne of clinker and an SEC of less than 685 Kcal/kg of clinker—benchmarks among the best in the cement industry. These achievements reflect the company’s dedication to lowering environmental footprints through technological enhancements.

What challenges do you face in implementing CCUS in the cement manufacturing process, and how do you address them sustainably?
For India, CCUS is still an emerging concept. While some European companies have successfully implemented CCUS, the associated costs in the Indian context are currently prohibitive, approximately 2.5 to 3 times the cost of a cement plant. This makes large-scale implementation challenging. Some of the key challenges are:

• High project costs: The cost of implementing CCUS is 2-3 times higher than the cost of a cement plant.
• Energy-intensive operations: Operating CCUS facilities can double energy consumption, increasing operational expenses.
• Space requirements: CCUS infrastructure demands substantial space.
• Storage accessibility: Many Indian plants are located inland, far from oceans, complicating carbon storage options.

WCL is advocating for further research to optimise the utilisation of captured carbon, which could lower project and operational costs over time. The company is committed to exploring CCUS feasibility for its future projects and collaborating with technology providers to address these challenges sustainably.

How do you see CCUS contributing to achieving net-zero emissions?
CCUS is indispensable for achieving Net Zero emissions in the cement industry. Even with 100 per cent electrification of kilns and renewable energy utilisation, CO2 emissions from limestone calcination—a key raw material—remain unavoidable. The cement industry is a major contributor to GHG emissions, making CCUS critical for sustainability.
Integrating CCUS into plant operations ensures significant reductions in carbon emissions, supporting the industry’s Net Zero goals. This transformative technology will also play a vital role in combating climate change and aligning with global sustainability standards.

Any specific investments or partnerships made in CCUS research or deployment to support sustainable practices?
WCL has implemented several innovative technologies and process optimisations to minimise GHG emissions. Key initiatives include:

• Installation of WHRS and maximising renewable energy usage.
• Exploring the production of lower clinker cements such as LC3 and PLC, alongside increasing the share of blended cement like PPC.
• Engaging with consultants and technology providers to develop a comprehensive Net Zero and ESG roadmap.

Any success stories or pilot projects involving CCUS that have significantly impacted your sustainability goals?
We have invested in renewable energy projects to significantly reduce its carbon footprint. Key examples include:

• Solar power installations at Nimbahera Integrated Plant and Jhajjar Grinding Unit.
• 15 MW windmills at Pratapgarh.
• Renewable Power Purchase Agreements for grinding units in Aligarh, Uttar Pradesh, and Dhule, Maharashtra, replacing 50 to 60 per cent of energy demand from the grid and reducing GHG emissions.

The company is actively exploring CCUS installation for upcoming projects, assessing its viability in the Indian context.

Beyond CCUS, what other sustainable practices or innovations is your company implementing to reduce its environmental footprint?
WCL’s sustainability initiatives include:

Energy efficiency: Installing Variable Frequency Drives (VFDs), optimising differential pressures across bag filters, and enhancing kiln operations.

• 3R principles: Emphasising reduce, reuse and recycle to optimise resource utilisation and waste management.
  Waste co-processing: Utilising over 50,000 tonnes of RDF/plastic waste and ensuring proper disposal of hazardous waste like used oil and lead-acid batteries.
• Alternative raw materials: Substituting natural resources with industrial by-products like red mud, chemical gypsum and ETP sludge.
• Plastic waste management: Increasing recycled content in PP bags and achieving Extended Producer Responsibility (EPR) targets.
• Carbon sequestration: Planting over 250,000 trees, sequestering 5,000-10,000 tonnes of CO2 annually.
• Water conservation: Operating as a water-positive organisation, with a focus on rainwater harvesting and groundwater recharge.

How do you balance the cost challenges of CCUS with your commitment to sustainable development?
WCL prioritises environmental stewardship alongside financial sustainability. While CCUS implementation involves high costs, WCL sees opportunities in mechanisms such as Carbon Border Adjustment Mechanism (CBAM), carbon trading, and Renewable Energy Certificate (REC) trading. These avenues provide financial incentives to offset the initial investment in green technologies.

ICR discusses India’s rapid advances in renewable energy, on track to exceed its 2030 targets, even as the rising energy demands challenge complete reliance on sustainable sources.

The cement industry, a cornerstone of infrastructure development, has long been associated with high emissions, particularly of CO2. This sector alone is responsible for approximately 8 per cent of global carbon dioxide emissions, primarily due to the energy-intensive processes of clinker production and calcination. Beyond carbon emissions, cement production also generates particulates, nitrogen oxides (NOx), sulphur oxides (SOx), and other pollutants, contributing to environmental degradation and health risks. With the global push towards sustainable practices and carbon neutrality, addressing emissions in the cement industry has become imperative.
According to Climate Change Performance Index, India ranks 7 in 2024. India receives a high ranking in the GHG Emissions and Energy Use categories, but a medium in Climate Policy and Renewable Energy, as in the previous year. While India is the world’s most populous country, it has relatively low per capita emissions. Data shows that in the per capita GHG category, the country is on track to meet a benchmark of well below 2°C.
India’s situation underscores the complexity of transitioning to sustainable energy systems in the face of rising and fluctuating energy needs. International support is crucial for India to access advanced technologies, financial resources, and best practices that can accelerate its transition to a sustainable energy future. Our analysis shows that with current policies, India will overachieve its conditional NDC targets of achieving 50 per cent non-fossil capacity by 2030, so it could set stronger targets. India has ambitious renewable energy plans as outlined in the National Electricity Plan 2023 (NEP2023) aiming for a share of installed capacity of 57 per cent and 66 per cent in 2026-27 and 2031-32, respectively. Share of renewable energy capacity in India reached 44 per cent, ranked fourth in the world in renewable energy capacity installations in 2023, after China, the US and Germany. The NEP2023 is reflected in the lower bound of our current policy and action pathway.
India has seen a steady increase in renewable energy deployment, including both utility-scale and rooftop solar, leading to the share of coal capacity dropping below 50 per cent for the first time. However, this increase in renewable energy capacity is barely able to keep up with the surging demand. As a result, the electricity generation share of renewable energy, including large hydro, remains at around 18 per cent, showing no improvement since last year. Investment in renewable energy projects in India are projected to increase by over 83 per cent to around USD 16.5 bn in 2024, with fossil fuel companies also diversifying their investments into the renewable sector. Despite this, India has not committed to phasing out coal power or fossil gas.
The National Electricity Plan indicated a temporary halt in coal capacity addition, but current under-construction capacity exceeds the threshold stated in these plans. While new gas power projects have been abandoned, the utilisation of existing gas power plants has increased to meet energy demand driven by severe heat stress.

Understanding Emissions in Cement Production
Primary Sources of Emissions: Cement production emissions stem mainly from three sources: calcination, fuel combustion, and electricity use. During calcination, limestone is heated to produce clinker, releasing CO2 as a by-product. This process alone accounts for roughly 60 per cent of emissions in cement manufacturing. The remaining emissions result from burning fossil fuels in kilns to achieve the high temperatures needed for calcination and from electricity consumption across production stages.
Raju Ramchandran, SVP Manufacturing (Cluster Head – Central), Nuvoco Vistas, says, “We consistently track air emissions from fuel combustion in our cement manufacturing and power generation operations. The burning of fossil fuels releases pollutants such as Oxides of Sulphur (SOx), Oxides of Nitrogen (NOx), and Particulate Matter (PM), which require stringent monitoring.”
“We ensure compliance with regulatory standards by using the Continuous Emission Monitoring System (CEMS) to monitor these emissions. For the FY 23-24, both our stack and fugitive emissions have stayed within the permissible limits set by Pollution Control Boards. Moreover, our ongoing monitoring of fugitive emissions ensures that we meet the prerequisite air quality standards,” he adds.
In addition to CO2, the cement industry releases various pollutants that pose risks to air quality and public health. These include particulate matter, NOx, and SOx, which can lead to respiratory and cardiovascular issues, acid rain, and ecosystem imbalances.
Governments worldwide are setting increasingly stringent regulations to curb industrial emissions. Standards such as the EU Emissions Trading System and India’s National Action Plan on Climate Change encourage cement manufacturers to adopt cleaner technologies. Many countries now impose limits on NOx, SOx and particulate emissions, with the aim of minimising the industry’s environmental impact.

Challenges in Reducing Emissions
High carbon intensity of cement production: Cement’s high carbon intensity largely stems from the chemical reactions involved in transforming limestone into clinker, making emissions difficult to reduce without altering core processes. Additionally, achieving the necessary kiln temperatures requires significant energy, often derived from coal or natural gas.
Operational limitations: Altering the traditional cement production process can compromise the quality and durability of the end product. Adapting existing production lines for lower emissions involves extensive R&D and technical trials to ensure the finished cement meets industry standards.
Financial constraints: The cost of implementing green technology is high, creating economic challenges, particularly for smaller cement manufacturers. Equipment upgrades, energy-efficient kilns, and carbon capture facilities require considerable investment, which many companies find difficult to justify without strong financial incentives.
Balancing market demands and environmental goals: With global infrastructure demands rising, the cement industry faces pressure to meet growing production needs while simultaneously working to reduce emissions. Balancing these competing demands requires innovation, efficient resource management, and support from stakeholders.

Technological Innovations for Emission Reduction
Alternative fuels and energy sources: One of the most effective ways to reduce emissions is by replacing fossil fuels with alternatives like waste-derived fuels, biomass, or biofuels. Some manufacturers are incorporating solar and wind energy to power auxiliary processes, further reducing reliance on traditional energy sources.
Sudhir Pathak, Head- Central Design & Engg (CDE), QA, Green Hydrogen, Hero Future Energies, says, “The cement industry is one of the largest consumers of grid power (Scope 2) and also a guzzler of in-process fossil CO2 (Scopem1) including process-based CO2 through limekilns. Decarbonisation can be achieved only up to 50 per cent to 60 per cent through plain hybrid solar and wind. However, for achieving balance 40 per cent, storage is essential, be it chemical or mechanical. Today, HFE is ready to provide such bespoke storage solutions as is evident through several complex RTC tenders that we have won in the last 6-8 months floated by agencies like SECI, NTPC and SJVN. These include tenders for FDRE projects, peak power, load following, etc. Further, regarding green hydrogen and its derivatives, we are ready to apply these for decarbonising industrial heating and mobility.”
Carbon Capture and Storage (CCS): CCS technology captures emissions at the source, storing CO2 to prevent it from entering the atmosphere. Recent advancements in CCS technology make it a viable option for large-scale cement plants, although high costs and infrastructure requirements remain obstacles to widespread adoption.
Clinker Substitution: Reducing clinker content is a promising method for emission reduction, achieved by using supplementary cementitious materials (SCMs) such as fly ash, slag, and calcined clay. These materials not only reduce CO2 emissions but also enhance the durability and performance of cement. SCMs are gradually becoming industry-standard components, especially in eco-friendly and green cement products.
Rajesh Kumar Nayma, Assistant General Manager – Environment, Wonder Cement, says, “The use of AFR plays a critical role in our strategy to reduce the environmental footprint of cement production. By substituting traditional fossil fuels with waste-derived alternatives like biomass, refuse-derived fuel (RDF) and industrial by-products, we significantly lower CO2 emissions and reduce the demand for natural resources. The utilisation of supplementary cementitious materials (SCMs), such as fly ash, helps in reducing clinker consumption, which is a major source of carbon emissions in cement production. This not only decreases our reliance on energy-intensive processes but also promotes waste recycling and resource efficiency. AFR adoption is an integral part of our commitment to the circular economy, ensuring that we minimise waste and optimise the use of materials throughout the production cycle, ultimately contributing to a more sustainable and eco-friendly cement industry.”
“WCL is exploring transitioning from fossil fuels to cleaner alternatives like biofuels or hydrogen or RDF/plastic waste/other hazardous waste. Till date, 5 per cent TSR has been achieved, while the intent is to achieve more than 20 per cent TSR. WCL is utilising the hazardous and other waste as an alternative fuel or raw material. We have used more than 3 lakh metric tonne of hydrogen waste and other waste in FY-2023-24,” he adds.
Improving energy efficiency is critical for emissions reduction. Technologies like high-efficiency kilns, heat recovery systems, and process optimisation techniques are helping manufacturers achieve more output with less energy. These measures reduce the carbon footprint while lowering operational costs.

The Role of SCMs
SCMs serve as partial replacements for clinker, providing a dual benefit of reduced carbon emissions and improved product resilience. The use of materials like fly ash and slag also helps mitigate industrial waste, contributing to a circular economy. Fly ash, slag, and silica fume are among the most widely used SCMs. Each has unique properties that contribute to cement’s strength, workability, and durability. By incorporating SCMs, manufacturers can produce cement with a lower environmental footprint without compromising quality.
While SCMs are effective, several obstacles hinder their widespread adoption. Supply chain constraints, material variability, and lack of technical standards are challenges that manufacturers face. Additionally, geographic limitations impact access to certain SCMs, creating disparities in their usage across regions.

Policy and Industry Collaboration
Policies play a critical role in driving green transitions within the cement industry. Carbon credits, tax incentives, and funding for R&D are some measures governments have introduced to support emission reduction. India’s Perform, Achieve, and Trade (PAT) scheme is an example of a policy incentivising industrial energy efficiency.
Collaborations between government entities, private corporations, and research institutions foster innovation and accelerate the adoption of sustainable practices. Partnerships can also help address funding gaps, allowing companies to explore new technologies without bearing the full financial burden.
International frameworks such as the Paris Agreement and industry-led efforts like the Global Cement and Concrete Association (GCCA) are setting targets for sustainable cement production. These initiatives encourage the sector to adopt environmentally friendly practices and set a roadmap toward achieving net-zero emissions.

Towards a Net-Zero Future
Reaching net-zero emissions is an ambitious but necessary goal for the cement industry. Realistic targets, set with interim milestones, allow companies to gradually transition to greener processes while maintaining production efficiency. Continued investment in R&D is crucial for discovering new methods of emission reduction. Emerging technologies such as carbon-negative materials, alternative binders, and low-carbon clinkers hold promise for the future, potentially transforming cement production into a more sustainable process.
Increasingly, consumers and investors are prioritising sustainability, placing pressure on companies to reduce their environmental impact. This shift in consumer sentiment is driving the cement industry to adopt green practices and focus on transparency in emissions reporting.

Conclusion
The journey toward reducing environmental impact in the cement industry is complex and multifaceted, requiring a combination of innovation, policy support, and industry collaboration. By adopting alternative fuels, implementing carbon capture technology, integrating SCMs, and improving energy efficiency, the industry can take significant strides in minimising its carbon footprint. Achieving sustainability in cement production is essential not only for the industry’s future but also for the planet’s well-being. Together, industry players, policymakers, and consumers can support the transition to a net-zero future, ensuring that cement remains a vital yet sustainable component of global infrastructure.

– Kanika Mathur

Dr SB Hegde, Professor, Jain College of Engineering and Technology, Hubli, and Visiting Professor, Pennsylvania State University, USA, helps us understand the red river formation in cement kiln operations, its causes, impacts and mitigation strategies.

Red river formation in cement kilns, where molten clinker flows uncontrollably in the cooler, is a costly problem for cement plants. The phenomenon not only affects clinker quality but also leads to significant operational disruptions, increased energy consumption and accelerated wear on kiln refractory bricks. Understanding the factors that cause red river formation and implementing strategies to prevent it are critical to maintaining operational efficiency and clinker quality.
This paper explores the causes of red river formation, the operational impacts it has on kiln performance, and the various mitigation strategies that cement plants can adopt. Additionally, safety considerations associated with the prevention and handling of red river formation are discussed, with practical insights from case studies of successful plant interventions in India and globally.

Causes of red river formation
Red river formation is primarily caused by improper kiln operations, including fluctuating kiln temperatures, oxygen levels, and cooler inefficiency. The following parameters are essential contributors:
Kiln temperature: Inconsistent temperature control in the kiln’s burning zone, often exceeding 1500°C, creates an imbalance between the solid and molten clinker phases, leading to red river formation. Maintaining temperatures within a more stable range of 1470-1490°C ensures that the clinker remains solid as it moves into the cooler.
Oxygen levels and CO concentrations: Oxygen levels above 2.5 per cent increase the risk of over-combustion, while elevated CO levels above 0.3 per cent indicate incomplete combustion, both contributing to excessive clinker melting. Optimising oxygen levels to 1.8-2.0 per cent minimises the risk.
Raw mix composition: The raw mix plays a vital role in clinker formation. A high liquid phase due to improper ratios of silica, alumina, and iron oxide can lead to excessive melting. Controlling the silica modulus (SM: 2.3-2.7) and alumina modulus (AM: 1.3-1.8) ensures a more stable clinker and reduces the risk of red river formation. If the raw mix is improperly proportioned, red river formation becomes more likely due to high fluxing compounds that melt at lower temperatures.
Kiln speed and torque: Kiln speeds that fluctuate below 3.4 rpm can cause material buildup, while kiln torque exceeding 50-60 per cent indicates stress that can lead to clinker instability.
Cooler efficiency: Inefficiencies in the clinker cooler, with efficiency levels below 78 per cent, can exacerbate red river formation. Clinker that is not cooled properly will remain molten for longer, allowing it to flow uncontrollably. Coolers should maintain exit temperatures between 180-200°C to prevent red river incidents.
Impact on clinker quality and kiln performance
The occurrence of red river has numerous negative impacts on both clinker quality and kiln performance:
Clinker quality: Red river formation results in poor clinker grindability, higher variability in free lime content and inconsistent cement properties. Poor clinker reactivity reduces both early and late strength development in the final cement product.
Increased heat consumption: Red river typically increases specific heat consumption by 3-5 per cent, resulting in higher fuel usage. These inefficiencies can significantly affect the plant’s cost structure, driving up operational expenses.
Refractory damage: The molten clinker accelerates the wear of refractory bricks in the kiln, especially in the burning zone and cooler transition areas. Brick life can decrease by 25-30 per cent, leading to more frequent replacements and higher maintenance costs.
Equipment and instrumentation damage: The uncontrolled molten flow of clinker during red river incidents can damage cooler plates, kiln discharge systems, and even temperature sensors and thermocouples, leading to costly repairs and prolonged downtime.

Mitigation strategies
Mitigating red river formation requires a multi-faceted approach combining operational optimisation, automation and staff training:
Kiln temperature control: Maintaining stable burning zone temperatures in the 1470-1490°C range is key to preventing excessive melting of clinker. Advanced temperature monitoring systems can help regulate temperature fluctuations.
Cooler efficiency optimisation: To ensure proper cooling, cooler efficiency must be maintained at 78-80 per cent, with clinker exit temperatures not exceeding 200°C. Real-time airflow adjustments in grate coolers improve cooling performance, solidifying the clinker at the appropriate stage.
Automation and data analytics: Advanced Process Control (APC) systems using data analytics can monitor critical kiln parameters—such as temperature, oxygen levels, and torque—in real-time, allowing for predictive maintenance and early intervention when red river signs appear. This technology has been implemented successfully in leading plants globally to prevent red river formation.

Indian case studies
Case Study 1: Cement Plant in South India – Optimisation of Kiln Parameters
A cement plant in South India faced recurrent red river issues due to high kiln temperatures and low cooler efficiency. After comprehensive process audits, the plant optimised its kiln temperature to 1480°C, reduced oxygen levels to 1.9 per cent, and upgraded its cooler to an efficiency of 80 per cent. These changes reduced red river incidents by 85 per cent, saving the plant Rs 10 million in energy costs annually and improving clinker quality by
15 per cent.

Case Study 2: Cement Plant in North India – Cooler Upgrade and Automation
A northern India plant increased cooler efficiency from 70 per cent to 78 per cent by installing an advanced grate cooler. This reduced clinker exit temperatures to 190°C, preventing red river formation. Automation systems provided real-time adjustments, decreasing the frequency of incidents by 75 per cent and saving `12 million annually.

Global Case Studies
Case Study 1: European Plant – Automation Success
A German cement plant, experiencing red river issues due to fluctuating oxygen levels, installed an advanced data-driven automation system. The system stabilised oxygen at 1.9 per cent and maintained kiln temperature at 1,475-1,485°C, reducing red river by 90 per cent. Clinker quality improved by 10 per cent, with a reduction in specific heat consumption by 4 per cent.

Case study 2: US Plant – Operator Training and Process Optimisation
A US cement plant reduced red river occurrences by 70 per cent through kiln speed optimisation (3.8 rpm) and comprehensive operator training. Improved monitoring of kiln torque and cooler exit temperatures led to higher cooler efficiency (75 per cent) and an annual savings of $2 million.

Safety Aspects
Safety is a paramount concern in red river incidents. When molten clinker flows uncontrollably, it poses a significant risk to personnel working near the kiln and cooler areas.

To mitigate these risks:

• Clearance zones: Kiln and cooler areas should have strict clearance zones for personnel when red river incidents are detected.
• Protective gear and training: Personnel should be equipped with proper protective equipment (PPEs) and trained to handle emergencies involving molten clinker. Emergency shutdown procedures should be well-documented and rehearsed.
• Automation and early warning systems: Automation can provide early warning systems that alert operators to potential red river formation before it becomes critical, ensuring safe intervention.

Conclusion
Red river formation remains a major operational challenge for cement plants, but it can be effectively mitigated through proper kiln temperature control, cooler efficiency optimisation and the use of advanced automation systems.
The case studies highlight the importance of process improvements and staff training in reducing red river occurrences, improving clinker quality, and lowering operational costs. Additionally, safety
measures must be prioritised to protect personnel from the risks posed by molten clinker. By incorporating these strategies, cement plants can ensure consistent kiln performance and enhanced operational efficiency.

References
1. Duda, W. H. (1985). Cement Data Book. International Process Engineering in the Cement Industry. Bauverlag GmbH.
2. Javed, I., & Sobolev, K. (2020). “Use of Automation in Modern Cement Plants.” Cement and Concrete Research, 130, 105967.
3. Tamilselvan, P., & Kumar, R. (2023). “Optimisation of Kiln and Cooler Systems in Indian Cement Plants.” Indian Cement Review, 34(7), 42-48.
4. Martin, L. (2019). “Case Studies of Red River Mitigation in European Cement Plants.” International Journal of Cement Production, 12(2), 63-78.
5. Schorr, H. (2021). “Advanced Process Control in Cement Manufacturing.” Cement International, 19(3), 30-37.
6. Singh, V. K., & Gupta, A. (2022). “Impact of Raw Mix on Clinker Formation and Kiln Operations.” Global Cement Magazine, 14(4), 22-29.

About the author: Dr SB Hegde brings over thirty years of leadership experience in the cement industry in India and internationally. He has published over 198 research papers and holds six patents, with four more filed in the USA in 2023. His advisory roles extend to multinational cement companies globally and a governmental Think Tank, contributing to research and policy. Recognised for his contributions, he received the ‘Global Visionary Award’ in 2020 from the Gujarat Chambers of Commerce and Industry.