Alternative fuels reduce cement plants’ carbon footprint, but infrastructure challenges limit adoption. Technologies like the HOTDISC® Reactor help overcome these barriers.

Alternative fuels are a relatively straightforward and readily available means of reducing a cement plant’s carbon footprint. The technology is proven and well used worldwide, and with the right controls in place the switch from fossil fuels to waste-derived fuels does not impact the quality of the end product. In some countries, cement plants are achieving near 100 per cent substitution in the calciner and high levels of substitution in the kiln. However, this trend is not universal, and some countries are struggling to achieve a thermal substitution rate (TSR) of 25 per cent. In this article, we will look at the obstacles to alternative fuels use and the technology that is available to overcome them.

Advantages of alternative fuels
Alternative fuels offer three key environmental advantages.
1) A lower carbon alternative to coal or petcoke.
2) A pathway for waste that might otherwise be landfilled, including hazardous waste.
3) An alternative to waste incineration, which is typically done at lower temperatures where emissions tend to be higher.
In addition, the cost of alternative fuels can often be lower than fossil fuels and is not subject to the fluctuations of the energy market.
The sources of alternative fuels are many and varied – to the extent that the supply chain looks vastly different from one region to the next. For example, whereas India has abundant sources of biomass such as rice husk, in Western Europe there are plentiful supplies of refuse-derived fuel (RDF). This is partly a matter of industry and partly of infrastructure. But given the importance of reducing the cement industry’s reliance on coal, a lack of infrastructure must not prevent greater utilisation of alternative fuels – which is why FLSmidth Cement has for some time been developing alternative fuels solutions that reduce the burden of pre-processing and enable cement plants to more easily and more cost-effectively utilise a wide variety of waste streams.

A solution for all waste
Direct calciner injection may seem like the simplest way to replace fossil fuels with alternatives. However, it’s not always the best. The options for alternative fuels are limited by the necessity to pre-process fuel in preparation for burning, which, as stated, requires established infrastructure, or additional facilities at the plant.
Though the CAPEX cost of direct calciner injection is low, the calciner fuel substitution rate is also low, so this method doesn’t enable cement plants to optimise the potential for fuel replacement. Plant operators must also consider the impact on the process of direct injection, which doesn’t allow the long residence time that can be required to reduce process volatility. No plant wants to contend with greater instability or an increase in emissions from adding alternative fuels to the mix. Fortunately, direct calciner injection is not the only option. There are other ways of extracting energy from waste that require no pre-processing at all.
The HOTDISC® Reactor can handle a wide variety of solid waste in sizes up to 1.2m – from sludge or grains to whole truck tyres. There’s no need for expensive shredding or pre-drying, or any pre-processing, which removes one of the obstacles to adopting alternative fuels. The broad range of accepted fuel types also means cement plants are free to shop the market and not tied into one supplier. This makes it a very cost-effective solution because cement plants can select the lowest cost fuel without worrying about the quality.

How does the HOTDISC® work?
The HOTDISC® is a moving hearth furnace that is integrated into the pyroprocess below the calciner bottom and above the kiln riser. Coarse alternative fuels are fed onto a slowly rotating disc. Hot tertiary air is directed into the HOTDISC to provide an oxidising atmosphere for the alternative fuel to burn. As the alternative fuel slowly travels around approximately 270 degrees on the rotating disc, almost all of it fully combusts. Depending on the nature of the alternative fuel (size, heat content, moisture, etc.), the rotational speed of the HOTDISC can be adjusted to optimise the residence time (up to 45 minutes) and combustion rate. In addition, the temperature inside the HOTDISC is controlled by directing a portion of the preheated raw meal into the HOTDISC. The HOTDISC operation generates a controlled mix of hot gases, combustion residue (ash) and calcined raw meal that exits the HOTDISC. The combustion gases and finer materials are carried with the hot gases into the bottom of the calciner, while the coarser residues meet a scraper at the end of the 270 degrees rotation, where they are directed down into the riser duct. From there, this material falls into the kiln and is incorporated into the clinker.
The HOTDISC is designed to achieve a calciner substitution rate in the range of 50 to 80 per cent – or even higher – of the calciner fuel. Results vary by the specific plant conditions and fuel specification, but based on over 20 years of plant data it is possible to predict the substitution rate in each application.
The HOTDISC was originally designed for use with In-Line Calciners (ILCs), but new models are now available for use with Separate Line Calciners (SLCs), enabling the HOTDISC to be installed under the calciner and still deliver the same benefits. The HOTDISC-S is installed in the bottom part of the SLC calciner on the ground, the reject will be cooled and transported to a container or back into the system, gas flow and AF flow operates counter current.
For cement plants that wanted to utilise a wide range of alternative fuels, the HOTDISC®-S is a cost-saving solution that avoids the expense of changing the SLC to an ILC while enabling a high substitution of alternative fuels. Another model, the HOTDISC®-HMT (Hot Material Transport), enables quicker and easier installation of the HOTDISC in existing plants. Instead of directly integrating the exit of the HOTDISC reactor to the calciner and riser duct, the new layout allows the HOTDISC reactor to be mounted two to five metres away. It is then connected to the calciner and riser duct via a hot material transport chute for gas flows and combustion ashes.

Further advances in alternative fuels technologies
Low or varying quality alternative fuels can be another inhibitor to substitution, given the requirements of the relatively delicate cement pyro process. FLSmidth Cement has expended considerable R&D effort developing solutions that can accommodate a wide range of fuel types, knowing that this is the easiest path to greater substitution and ultimately the near-elimination of fossil fuels. The FUELFLEX® Pyrolyzer was one result of this effort and offers an exciting prospect for cement plants wishing to achieve near – 100 per cent substitution in the calciner and minimise NOx emissions.

The FUELFLEX® Pyrolyzer utilises hot meal from the lower preheater cyclones (yellow arrows) to dry and pyrolyze RDF or biomass. Either part or the full stream of hot meal from a lower preheater cyclone is admitted to the Pyrolyzer via the U-Lock (controlled by two dividing gates). The U-Lock fluidises the hot meal, forming a U-shaped gas lock that prevents pyrolysis gases from flowing backwards through the process. Subsequently the hot meal stream flows into the Pyrolyzer vessel, which also has a U-shaped lower aerated section to contain the hot fluidised meal. Fuel is pneumatically fed to the pyrolyzer vessel wherein through contact with the hot meal, it is dried, heated and pyrolyzed to form reactive gases and char. The gases push upwards into the main pyrolyzer vessels while the char falls down into the fluidised meal bed, before being reunited and fed as a very reactive stream into the calciner. Aeration panels are used to fluidise the hot meal and drain gates are used to drain out debris and meal from the pyrolyzer to the kiln system in a controlled manner. The reactive stream of pyrolysis products reacts with rotary kiln NO by so-called ‘re-burning’ reactions, utilising pyrolysis gases to convert NO into free N2 in the reduction zone prior to mixing with preheated combustion air in the calciner. In addition, the full fuel pyrolysis preceding the calciner helps limit calciner NOx formation by limiting access to oxygen when burning.

By using the FUELFLEX® Pyrolyzer, cement plants can achieve up to 100 per cent fossil fuel replacement in the calciner, with the following benefits:

• Reduced CO2 emissions, as net CO2 emissions from alternative fuels generally are lower than from fossil fuels.
• Increased utilisation of local waste streams, avoiding the need to dispose of or store this waste in other ways.
• Reduced fuel costs, especially in times of fluctuating energy prices.
• Reduced fossil fuel use saves the associated environmental impact of fossil fuel extraction and transport.

Conclusion
The challenge is on: cement plants must reduce carbon emissions now, and continue to do so for the next several decades until the target of net zero is met. While there are some solutions that are not ready yet – i.e. carbon capture – alternative fuels offer a valuable means of reducing the cement industry’s environmental impact immediately, with the added benefit of providing a controlled means of waste disposal. New and proven technologies will help the cement industry to overcome alternative fuel supply chain problems and achieve a dramatic reduction in fossil fuel use.

(Communication by the management of the company)

Swapnil Jadhav, Director, SIDSA Environmental, discusses transforming waste into valuable resources through cutting-edge technology and innovative process solutions.

SIDSA Environmental brings decades of experience and expertise to the important niche of waste treatment and process technologies. As a global leader that is at the forefront of sustainable waste management, the company excels in recycling, waste-to-energy solutions and alternative fuel production. In this conversation, Swapnil Jadhav, Director, SIDSA Environmental, shares insights into their advanced shredding technology, its role in RDF production for the cement industry and emerging trends in waste-to-energy solutions.

Can you give us an overview of SIDSA Environmental’s role in waste treatment and process technologies?
SIDSA is a leading innovator in the field of waste treatment and process technologies, dedicated to delivering sustainable solutions that address the growing challenges of waste management.
SIDSA is a more than 52-year-old organisation with worldwide presence and has successfully realised over 1100 projects.
Our expertise is in the engineering and development of cutting-edge systems that enable the conversion of waste materials into valuable resources. This includes recycling technologies, waste-to-energy (W2E) systems, and advanced methods for producing alternative fuels such as refuse derived fuel (RDF). The organisation prioritises environmental stewardship by integrating energy-efficient processes and technologies, supporting industrial sectors—including the cement industry—in reducing their carbon footprint. Through our comprehensive approach, we aim to promote a circular economy where waste is no longer a burden but a resource to be harnessed.

How does SIDSA Environmental’s shredding technology contribute to the cement industry, especially in the production of RDF?
SIDSA’s shredding technology is pivotal in transforming diverse waste streams into high-quality RDF. Cement kilns require fuel with specific calorific values and uniform composition to ensure efficient combustion and operational stability, and this is where our shredding systems excel. In India, we are segment leaders with more than 30 projects including over 50 equipment of varied capacity successfully realised. Some of the solutions were supplied as complete turnkey plants for high capacity AFR processing. Our esteemed client list comprises reputed cement manufacturers and chemical industries. Our technology processes various types of waste—such as plastics, textiles and industrial residues—breaking them down into consistent particles suitable for energy recovery.

Key features include:

• High efficiency: Ensures optimal throughput for large volumes of waste.
• Adaptability: Handles mixed and heterogeneous waste streams, including contaminated or complex materials.
• Reliability: Reduces the likelihood of operational disruptions in RDF production. By standardising RDF properties, our shredding technology enables cement plants to achieve greater energy efficiency while adhering to environmental regulations.

What are the key benefits of using alternative fuels like RDF in cement kilns?
The adoption of RDF and other alternative fuels offers significant advantages across environmental, economic and social dimensions:

• Environmental benefits: Cement kilns using RDF emit fewer greenhouse gases compared to those reliant on fossil fuels like coal or petroleum coke. RDF also helps mitigate the issue of overflowing landfills by diverting waste toward energy recovery.
• Economic savings: Alternative fuels are often more cost-effective than traditional energy sources, allowing cement plants to reduce operational expenses.
• Sustainability and resource efficiency: RDF facilitates the circular economy by repurposing waste materials into energy, conserving finite natural resources.
• Operational flexibility: Cement kilns designed to use RDF can seamlessly switch between different fuel types, enhancing adaptability to market conditions.

What innovations have been introduced in waste-to-energy (W2E) and recycling solutions?
SIDSA’s machinery is meticulously engineered to handle the complex requirements of processing hazardous and bulky waste.

This includes:

• Robust construction: Our equipment is designed to manage heavy loads and challenging waste streams, such as industrial debris, tires and large furniture.
• Advanced safety features: Intelligent sensors and automated controls ensure safe operation when dealing with potentially harmful materials, such as chemical waste.
• Compliance with standards: Machinery is built to adhere to international environmental and safety regulations, guaranteeing reliability under stringent conditions.
• Modular design: Allows for customisation and scalability to meet the unique needs of various waste management facilities.

How does your organisation customised solutions help cement plants improve sustainability and efficiency?
We consistently push the boundaries of technology to enhance waste management outcomes.
General innovations and new product development focus on:

• Energy-efficient shredders: These machines consume less power while maintaining high throughput, contributing to lower operational costs.
• AI-powered sorting systems: Utilise advanced algorithms to automate waste classification, increasing material recovery rates and minimising errors.
• Advanced gasification technologies: Convert waste into syngas (a clean energy source) while minimising emissions and residue.
• Closed-loop recycling solutions: Enable the extraction and repurposing of materials from waste streams, maximising resource use while reducing environmental impact.

What future trends do you foresee in waste management and alternative fuel usage in the cement sector?
Looking ahead, several trends are likely to shape the future of waste management and alternative fuels in the cement industry:

• AI integration: AI-driven technologies will enhance waste sorting and optimise RDF production, enabling greater efficiency.
• Bio-based fuels: Increased use of biofuels derived from organic waste as a renewable and low-carbon energy source.
• Collaborative approaches: Strengthened partnerships between governments, private industries and technology providers will facilitate large-scale implementation of sustainable practices.
• Circular economy expansion: The cement sector will increasingly adopt closed-loop systems, reducing waste and maximising resource reuse.
• Regulatory evolution: More stringent environmental laws and incentives for using alternative fuels will accelerate the transition toward sustainable energy solutions.

(Communication by the management of the company)

Driving sustainable logistics with EV-powered supply chains, Pushpank Kaushik, CEO, Jassper Shipping, explains the correlation between reduced carbon emissions and efficient deliveries.

Jassper Shipping is advancing green logistics by integrating electric vehicles (EVs) into its supply chain and leveraging a transportation management system (TMS) to track and reduce carbon emissions at the shipment level. In this interview, Pushpank Kaushik, CEO, Jassper Shipping, tells us about the gameplan to achieve the goal of net-zero carbon emissions by 2035, and being a pioneer in shaping the future of eco-friendly logistics in India.

How is Jassper Shipping integrating green logistics into its shipping operations?
Jassper Shipping’s green logistics are being integrated by expanding its fleet of EV, with 58 already in operation. Emission-reduction strategies and carbon offset programmes are being implemented in sea logistics to reduce environmental impact. With a strategically mapped network of 380 locations across India, including both major states and smaller towns, sustainable and accessible logistics solutions are being ensured supported by partnerships with FMCG brands and pharmaceutical companies as well as supermarket chains like D-Mart and Big Basket.
A transportation management system is also used to track and measure carbon dioxide emissions on a cargo basis. Jassper Shipping’s efforts remain focused on creating a future-ready, sustainable logistics network.

What sustainable practices are you implementing to reduce carbon emissions?
Jassper Shipping prioritises sustainability, with several measures in place to reduce carbon emissions. The inclusion of electric vehicles (EVs) into the distribution network represents a significant advancement, with 58 EVs currently operational. This change not only decreases the company’s carbon footprint, but it also improves operating efficiency, eliminates fuel cost uncertainty, and helps delivery partners by lowering costs. Collaboration with clients enhances sustainability efforts by producing eco-friendly supply chain solutions with low environmental effect. A transportation management system helps track and measure carbon dioxide emissions at the shipment level, ensuring a data-driven approach to sustainability. Participation in carbon offset programmes further contributes to reducing the environmental impact of shipments.

Are you investing in energy-efficient vessels or alternative fuels?
No, currently we are not investing in energy-efficient vessels or alternative fuels. Instead, our focus at Jassper Shipping is on developing EV fleets and strengthening a sustainable supply chain network in India to support green commerce solutions.

How does technology help Jassper optimise eco-friendly logistics solutions?
Technology is critical to our eco-friendly logistics. Our transportation management system (TMS) monitors and assesses carbon emissions,
allowing for more environmentally responsible operations. The growth of our electric vehicle (EV) fleet decreases environmental impact while assuring efficient transportation.

What challenges do you face in making shipping more environmentally sustainable?
The main challenge in making shipping more environmentally sustainable is the lack of global agreement and consistent efforts. Different countries and organisations have varying levels of commitment and policies, making it difficult to implement uniform sustainable solutions. Without widespread cooperation, progress toward greener shipping practices remains slow.

What are Jassper Shipping’s long-term goals for achieving greener logistics in Asia?
Jassper Shipping is dedicated to reducing carbon footprints, including those of clients. Emission-reduction plans and carbon offset investments aim to achieve net-zero carbon emissions by 2035. Over the next two quarters, the number of EVs in the fleet will increase from 58 to 150. The last-mile delivery supply chain is becoming more sustainable and efficient with EV integration while maintaining high-quality service.