Ashok Kumar Dembla, President & Managing Director, Humboldt Wedag India, talks about the key areas where carbon emission reduction is feasible and how they are pioneering solutions that would drive sustainability while maintaining operational efficiency.

Tell us about the prominent areas in the cement manufacturing process where carbon emission reduction is greatly possible.
Cement production emerges as one of the highest-emitting industries, accounting for approximately 7 per cent of global CO2 emissions. As the world strives to achieve net-zero emissions by 2050 to combat climate change effectively, rapid decarbonisation of the cement and concrete industry becomes imperative.
The conventional production process of cement relies heavily on fossil fuels, primarily coal, which releases substantial CO2 emissions into the atmosphere. Therefore, reducing the reliance on fossil fuels by substituting them with low-carbon alternative fuels, such as biomass and waste-derived fuels and incorporating alternative raw materials in cement production is the way forward.
Cement manufacturers are already exploring alternatives such as fly ash, metal slag, or calcined clay to replace clinker in their production processes. Blended cement production offers a solution to mitigate carbon emissions and high energy consumption related to clinker production. Replacing a portion of the clinker with fly ash or blast furnace slag, lowers the clinker/cement ratio without compromising the properties of Portland cement.

As technology leaders for the cement industry, what are the products and solutions offered by you that can make cement manufacturing sustainable?
KHD offers a wide variety of technologies that can be utilised to reduce carbon emissions. The technologies are developed with the aim of following decarbonisation pathways set out by Global Cement and Concrete Association to help cement plants become cleaner alongside reducing the operation cost.
Oxyfuel: Oxyfuel technology increases the concentration of CO2 in the exhaust gas and so makes it simpler and less costly to capture. It’s thus currently the most techno-commercially feasible pathway to carbon capture at scale. CO2 concentration of standard cement plant exhaust gases is low (mostly below 20 per cent), which reduces the efficacy of capture technologies. Raising the concentration of CO2 in the exhaust gas is therefore an important step toward establishing commercially viable CCUS solutions at scale and this is where KHD’s oxyfuel combustion concept comes into play.
Clay Calcination: Cement producers around the world are pursuing clay calcination projects as part of efforts to reduce the carbon intensity of their cement but how best to implement these projects depends on a range of site-specific factors.
KHD ProMax®: KHD ProMax is a suite of Cloud-based digital solutions that connects to and delivers real-world optimisation of cement plant equipment and processes. KHD ProMax® is customisable and grows as per the customer’s requirements. We are also continuously developing new functionalities in response to customer’s requests. It begins, however, with a secure connection from the plant to the Cloud via KHD ProMax Edge.
Pyrorotor®: The Pyrorotor® is our most advanced technology for utilising alternative fuels. Its innovative design enables very high thermal substitution rates with almost no fuel pre-processing, even when dealing with low-quality alternative fuels. Available as a modular add-on to any calciner, the Pyrorotor® delivers unmatched fuel flexibility and reduces fuel costs. It also helps cut carbon emissions associated with the combustion of fossil fuels. The results are good for the bottom line and support the pathway
to decarbonisation.
Roller Press: When compared to other grinding options, the roller press is simply the most energy-efficient of the lot. It is also flexible and can be used to grind various feed materials, supporting the use of alternative cementitious materials and the production of lower-carbon composite cements.

Are your solutions customisable as per your customer’s requirements?
Yes, we always understand the basic requirements of the customer and then based on feasibility, we are offering them what best suits them to achieve their goal. For example, the client has to provide the composition and granulometry of AFR and percentage planned to be used along with its calorific Value and moisture, we accordingly design our pyro-process system including the need of by-pass required and design of calciner and PH fan etc. In case a higher percentage of AFR is envisaged, we incorporate the pyro-rotor from the project stage itself.

Which are the key parameters where the cement industry can use decarbonisation consultation?
Consultants can be useful to do complete surveys of availability of alternative fuels and their quality. Accordingly, consultants can make complete feasibility of using AFR keeping logistic costs involved and long-term agreement with producers of AFR. Consultants can also be useful to identify alternative binding materials like slag and fly-ash which are very useful to reduce clinker consumption in final product e.g. slag cement, fly-ash cement etc. However, technology related to preparation of alternative fuels and firing is available with various technology suppliers and consultants have limited role in technology areas.

Tell us more about the carbon capture technology for cement plants.
The type of fuel used in cement manufacture directly impacts on CO2 emissions, with coal accounting for around 60 per cent to 70 per cent of CO2 emissions from cement installations. Therefore, the large amount of carbon dioxide emitted during the cement manufacturing process accounts for 5 per cent of the total emissions of CO2 from stationary sources worldwide and is a cause of great concern and must be tackled in order to comply with current legislation.
Several technologies are available and have been proposed for the separation of CO2 from the flue gases from new and existing plants with retrofit capture units.
Amine-Scrubbing: Amine-based carbon capture is a regenerative process using an amine solvent to remove CO2 from flue gas. Reversing the reaction releases pure CO2 for capture and frees up the solvent for re-use. The technology uses an amine solvent to scrub CO2 from the flue gas. The flue gas is initially fed into an absorption column, where the solvent selectively removes the CO2. The CO2-rich solvent is then fed into a desorber column, where it is heated to release the CO2, which is captured before being sent for geological storage or onward use. This regeneration process is highly energy intensive, however, posing an economic and environmental challenge.
The regenerated solvent is cooled and returned to the absorption column.
Oxy-firing: In oxy-firing technology, the combustion air is replaced by reasonably pure oxygen from an air separation unit (ASU), with the CO2-rich flue gas being recycled to moderate the flame temperature. Because of the high percentage of CO2 in flue gas originating from the calcination process, combustion in a CO2/O2 atmosphere looks like the best option for CO2 reduction in a cement plant. The main advantage of oxy-firing for cement plants is the low oxygen consumption with only 1/3rd of the amount of oxygen needed per tonne of CO2 captured compared to a coal-fired boiler.
Calcium looping: Calcium looping technology is also known as the regenerative carbon cycle. This process works on two reversible chemical reactions: carbonation and calcination. It removes CO2 from the flue gases of a cement plant using a Calcium oxide (CaO) sorbent.
These are still under evolution phase and all stakeholders are actually pushing the stakes.

How important is it for cement plants to become modernised and digitally equipped today?
Digitalisation can help achieve material cost savings, reduce inventory carrying costs, increase equipment uptime and availability, reduce maintenance planning time and costs, improve health, safety and environmental (HSE) compliance, enable faster real time decisions, data driven problem solving, and establish clear linkages to initiatives, performance, and accountability. While digitalisation serves numerous advantages, care needs to be administered while implementing the solutions to realise its true potential. It becomes critically important to define the objectives at the beginning- starting small through pilot projects and scaling up gradually through a designated reference factory.
Digitalisation is imperative for a highly commoditised and competitive industry of cement. Steep decline in the cost of computing technology, data storage and network bandwidth have streamlined the implementation of pilot projects and scaling up technological solutions. Digitalising the value chain could be a game changer for the cement companies and improve profitability while realising a sustainable competitive advantage.

What are the major challenges that you face in context to providing decarbonisation solutions?
Decarbonising cement and concrete production face several challenges and barriers that hinder the transition to low-carbon practices. Technological challenges and research gaps exist, as developing and scaling up innovative technologies for carbon capture, alternative materials and energy-efficient processes requires further research and development. Investment and financing constraints pose another barrier, as the upfront costs of adopting decarbonisation technologies and implementing sustainable practices can be substantial. Resistance to change and industry practices rooted in traditional methods and established norms can impede the adoption of new technologies and practices. Additionally, a lack of awareness and education among industry stakeholders about the benefits and feasibility of decarbonisation can slow down progress. Overcoming these challenges requires collaborative efforts, increased research funding, supportive policies and educational campaigns to drive the necessary transformation in the cement and concrete industry.

How do you envision the future of carbon emissions from the cement industry?
The cement and concrete industry have established new targets to lower and even eliminate emissions, such as those set by the Global Cement and Concrete Association (GCCA). These targets aim for a 20 per cent reduction of CO2 per metric ton of cement and a 25 per cent reduction of CO2 per cubic meter of concrete by 2030 compared to 2020 levels. The GCCA calls for complete decarbonisation by 2050. All the parties involved are maximising their resources and approach to achieve these benchmarks.

• –Kanika Mathur