CO2Valorize
Lead Research Organisation:
Siemens Process Systems Engineering Ltd
Department Name: Research and development
Abstract
Cement production is responsible for 8 % of global CO2 emissions, which mainly come from the processing of limestone. CO2Valorize
proposes a new approach to drastically reduce these emissions by partly replacing some of the limestone content with
supplementary cementitious materials (SCM). Such materials are additionally carbonated using captured CO2, so this partreplacement
process utilises captured CO2. Promising, calcium silicates rich SCM can come from waste materials such as mine tailings
and recycled concrete, all of which are available in large quantities. The carbonation process of such materials is complex and barely
understood to date. Our networks aim to lay the scientific foundations to create fundamental knowledge on the mechanisms,
reaction kinetics, the physico-chemical subprocess, and the performance of the modified cement in order to provide a proof-ofconcept
and show that a CO2 reduction by 50 % per tonne of cement produced is feasible. The project is driven by leading companies
that represent important parts of the value chain and ensure a fast uptake of the results with the potential to commercialise new
equipment, processes and software during and after the project. The structured approach combines complementary research for
each individual project in the academic and industry sector. This is accompanied by a balanced mix of high-level scientific courses
and transferable skills delivered by each partner locally and in dedicated training schools and workshops at network level. This way,
each doctoral candidate builds up deep scientific expertise and interdisciplinary knowledge to deliver game-changing cleantech
innovations during and after the project. CO2Valorize is impact-driven and strives for portfolios of high-class joint publications in
leading journals and patents. The transfer of the results into first-of-its-kind engineering solutions contribute to the next generation
of cement processes that can mitigate climate change.
proposes a new approach to drastically reduce these emissions by partly replacing some of the limestone content with
supplementary cementitious materials (SCM). Such materials are additionally carbonated using captured CO2, so this partreplacement
process utilises captured CO2. Promising, calcium silicates rich SCM can come from waste materials such as mine tailings
and recycled concrete, all of which are available in large quantities. The carbonation process of such materials is complex and barely
understood to date. Our networks aim to lay the scientific foundations to create fundamental knowledge on the mechanisms,
reaction kinetics, the physico-chemical subprocess, and the performance of the modified cement in order to provide a proof-ofconcept
and show that a CO2 reduction by 50 % per tonne of cement produced is feasible. The project is driven by leading companies
that represent important parts of the value chain and ensure a fast uptake of the results with the potential to commercialise new
equipment, processes and software during and after the project. The structured approach combines complementary research for
each individual project in the academic and industry sector. This is accompanied by a balanced mix of high-level scientific courses
and transferable skills delivered by each partner locally and in dedicated training schools and workshops at network level. This way,
each doctoral candidate builds up deep scientific expertise and interdisciplinary knowledge to deliver game-changing cleantech
innovations during and after the project. CO2Valorize is impact-driven and strives for portfolios of high-class joint publications in
leading journals and patents. The transfer of the results into first-of-its-kind engineering solutions contribute to the next generation
of cement processes that can mitigate climate change.
Publications
Varnier L
(2025)
Combined electrification and carbon capture for low-carbon cement: techno-economic assessment of different designs
in Journal of Cleaner Production
| Description | Global production of cement and concrete from raw materials is responsible for 7-8% of global CO2 emissions. These are considered hard-to-abate because (1) the conversion of limestone to lime (the most important intermediate in the cement process) produces vast amounts of CO2, and (2) this reaction requires high temperatures typically achieved through the combustion coal. The research & development activity funded through this UKRI award has resulted in a set of mathematical models for the techno-economic analysis of alternative lower-carbon cement production processes. More specifically, they were used to explore electrically heating the calciner (one of the key high temperature reactors), in combination with capturing CO2 from the process. Researchers found that (1) CO2 avoidance rate is larger than 98% when renewable electricity is supplied. (2) The cost per tonne of CO2 avoided for this technology ranges between 217 and 234 €/tCO2. It is mainly driven by electricity cost. (3) Current electricity prices of 125 €/MWh make the technology economically unviable. (4) Affordable and low-carbon electricity is crucial to ensure cost-effectiveness. |
| Exploitation Route | Policymakers can use it to inform decisions related to attempt the decarbonization of the cement industry. Technology providers can use it to predict the impact of new technology on their designs. |
| Sectors | Environment Manufacturing including Industrial Biotechology Other |
| URL | https://www.sciencedirect.com/science/article/pii/S0959652625003798 |
| Title | Cement Pyroprocess Plant Flowsheet |
| Description | A flowsheet model of a conventional cement pyroprocessing plant was created by utilizing the model library developed in the initial part of the project. The flowsheet model has proven to provide qualitatively reasonable results for key output variables around the process, such as operating temperatures, degree of calcination, gas and solids compositions, fuel consumption and overall CO2 emissions. The digital flowsheet model has been simulated in gPROMS® Advanced Process Modelling Environment and simulations can be performed both in steady sate and dynamic mode by providing the appropriate initial and boundary conditions needed. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2024 |
| Provided To Others? | No |
| Impact | Clinker production comprises some high temperature and carbon intensive processes, which occur in the pyroprocessing section of a cement plant. The chemical and physical phenomena occurring in such processes are rather complex and to this day, these processes have mostly been examined and modelled in literature as standalone unit operations. As a result, there is a lack of holistic model-based approaches on flowsheet simulations of cement plants in literature. This model could provide valuable insights on important technical and environmental Key Performance Indicators (KPIs), like the specific CO2 emissions and energy consumption per tonne of clinker produced and the fuel consumption per tonne of clinker produced. Another important potential application of such a model, would be the integration of decarbonization technologies in it, so that the technical and economical impact of different decarbonization technologies can be evaluated and tested on the same basis. Such a concept has already been applied by our research group, specifically the substitution of the coal fuel used in the reference case with different types of alternative sustainable fuels that originate from biomass. Potential implications of such a technology in the overall cement pyro process performance have been assessed and the most important environmental gains can be extracted (f.e. CO2 reduction potential). |
| Title | Cement Pyroprocess Production Model Library |
| Description | First principles mathematical models for the simulation the four main clinker production processes have been developed; more specifically the preheating cyclones, the calciner, the rotary kiln and the grate cooler. The models are PDAE systems of either index-1 or index-2 and they are integrated and solved numerically in Siemens' gPROMS® Advanced Process Modelling software. The first model simulates the process behaviour of the pre-heating cyclones of a cement plant, which are used to preheat the solid raw material through the flue gas of latter processes. The model incorporates mass and energy conservation balances, heat-transfer phenomena between the gas-wall-solid phases and can be used to predict important key performance indicators (KPIs) of the process such as average temperature, heat loss, pressure drop (KPIs linked to energy consumption and carbon intensity of the process) and outlet mass flowrates, compositions and temperatures for the solid and gas streams. The accurate prediction of the outlet conditions of the exhaust gas (flowrate, temperature, CO2, O2 and H2O content) is crucial, since it is the stream that contains almost all the CO2 generated inside a cement plant. Therefore, in potential end-of-pipe carbon capture applications this would be the CO2 source stream, and its conditions will directly affect the performance and size of the carbon capture plant. The second model simulates the behaviour of a cement pre-calciner, the most carbon-intensive unit operation inside a cement plant, responsible for 70-80 % of total carbon dioxide emissions. The model incorporates mass and energy conservation balances and takes into account the limestone decomposition kinetics (heat and mass transfer limitations, diffusion limitations, CO2 partial pressure effects and pore efficiency). The resulting system of Partial Differential Algebraic Equations (PDAE) was implemented and solved in gPROMS for various reactor geometries and operating conditions. The simulation results are validated against published data, demonstrating the ability to predict accurately operating temperatures, degree of calcination, gas and solids mass fractions, pressure drop and fuel consumption. Most of the output variables calculated from the models are directly linked to economic and environmental KPI's and will be used for performing technoeconomic and environmental assessment of these processes, looking for potential process improvements that could result in mitigation of the process CO2 emissions. The third model simulates the behaviour of a rotary kiln, the heart of a cement plant in which all the clinkerization reactions occur and the final clinker product is created. For the rotary kiln system, the process model is divided into three sub-models that refer to: a) the motion of solid bed inside the rotating drum, b) the heat transfer phenomena between the solid bed, gas phase and rotating wall and shell, c) the chemical reactions occurring during clinkerization and fuel combustion. The first sub-model is used to calculate accurately the height of the bed, the residence time and velocity of the solids inside the kiln and the cross sectional and contact areas between the bed-gas-wall system, that are essential for the heat transfer model calculations. For the chemical reaction sub-model, the four main clinker formation reactions are assumed, and generic pseudo-homogeneous reaction kinetics are assigned. The resulting system of Partial Differential Algebraic Equations (PDAE) was implemented and solved in gPROMS for various kiln geometries and operating conditions. The simulation results are validated against published data, demonstrating the ability to predict accurately operating temperatures of all the phase involved in the system (gas-bed-wall-shell), and composition of the gas and solid clinker phases. The fourth model simulates the behaviour of a clinker cooler, the final unit of the pyroprocess. The unit is modelled as a 2-D heat transfer model between cooling air and a moving bed (of the hot clinker coming out of the kiln). The respective heat transfer areas and coefficients are estimated though heat transfer modelling corellations. The resulting system of Partial Differential Algebraic Equations (PDAE) was implemented and solved in gPROMS for various cooler geometries and operating conditions. The simulation results are validated against published data, demonstrating the ability to predict accurately 2-D distribution of the cooling air and clinker bed temperature. Consecutively the flowrates and temperatures of the secondary air and tertiary air supplied to the kiln and the calciner can be calculated respectively. Finally the energy efficiency and heat losses can be evaluated. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2024 |
| Provided To Others? | No |
| Impact | The development of the model library described above, is the first step in the research group's attempt to build a digital toolkit for the simulation of cement production plants. These models will be the basis on which a detailed flowsheet of a conventional cement plant will be built, in which several decarbonization strategies and technologies will be integrated. The final objective is to perform technoeconomic and environmental evaluation between different decarbonization levers (based on the reference case - conventional plant), compare them and ultimately identify the benefits and drawbacks of each technology. Moreover, potential synergies and application of a combination of decarbonization technologies could be identified and tested virtually in the digital simulation environment created. |
| Title | Model Library for Mineral Carbonation Reactors |
| Description | Mineral carbonation refers to the reaction of CO2 with calcium or magnesium bearing minerals, for the conversion of their calcium/magnesium oxide content to their respective carbonates. The process can be performed under a range of different temperature and pressure conditions; from ambient to elevated (e.g. from 25-65oC to 500-700oC). Depending on the process conditions selected, different reactor types are suitable to accommodate carbonation. The model library developed includes standardized mathematical models for the simulation and design of different carbonation reactors depending on the materials and process configuration. Each model consists of several sub models incorporating material and energy conservation equations, the major heat and mass transfer phenomena, reaction kinetics, and thermodynamic property estimation. The parameters and input variables of each sub-model can be modified/calibrated for specific use cases with experimental input. The main functionalities and expected outputs of the models are the estimation of the gaseous and solid species evolution throughout the reactor, carbonation reaction progress and temperature distribution between the different phases. These results can then lead to the calculation of the most important process Key Performance Indicators (KPIs) like the CO2 capture efficiency, degree of solid conversion and carbonated material composition. The simulations can be performed either in dynamic or steady-state manner, depending on the objective of the analysis performed each time. Preliminary determination of the reactor size and dimensions for a specific process CO2 throughput and capture efficiency, as well as evaluation of the required process utilities, is one of the main functionalities and end uses of the aforementioned models, when properly calibrated and delivered with experimental information. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2025 |
| Provided To Others? | Yes |
| Impact | The work described above provides a consistent modelling framework that can help towards the understanding of the performance of carbonation reactors. The models library developed will be used as the basis for the following studies of the CO2Valorize consortium, related to the process design, flowsheet integration and technoeconomic analysis of mineral carbonation processes. |
| Title | Model for the Simulation of Alternative Fuel Combustion |
| Description | Our research group has developed a mechanistic model that is capable of simulating and predicting the performance of alternative fuel fired calciners. The model is agnostic of the fuel type, so any type of fuel can be simulated (from municipal solid waste and solid recovered fuels to sawdust, mean and bone meals and others) if their chemical and physical properties are specified (f.e. ultimate, proximate and ash analysis, particle size and heating value among others). The combustion characteristics and performance of the fuels in the calciner, as well as their influence on the calcination reaction and temperature of the reactor, can be evaluated in a systematic way. The model is an index-1 PDAE system similar in structure to the conventional coal fired calciner model developed in the initial part of the project with the added feature of simulating a wide range of fuel types. Its versatility also lies to the fact that a varying particle size distribution can be specified from the user to capture the large variability of this parameter in alternative fuel firing projects. |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2024 |
| Provided To Others? | No |
| Impact | Internal fuel combustion is responsible for 40% of the CO2 emissions associated with cement production. The most common fuels used in the calciner, and the rotary kiln are the fossil-based pulverized coal or petcoke. However, the utilization of solid alternative fuels is becoming a more and more popular approach. According to the Global Cement & Concrete Association fuel switching is one of the most important decarbonisation levers and can contribute towards a 10% reduction in the emissions of the cement and concrete value chain. In order to achieve this, the combustion behavior of these different fuels has to be studied and predicted so it doesn't affect the operation of the cement plant. Based on their source and nature, alternative fuels have different chemical and mechanical properties which affect directly their performance upon combustion. By utilizing the model described above and the already developed flowsheet model of the cement plant it is possible to capture the effect of fuel substitution in the plant's operation. moreover, required adjustments in the design and operation of the processes can be identified. Furthermore, the model is able to predict the flowrate, temperature and composition of the final flue gas, information very important in potential end-of-pipe carbon capture installations, with good precision. |
| Description | Coolaboration between Siemens and CAPE Lab from the University of Padova for Process Modelling and Technoeconomic Assessment of Low Carbon Cement Plants |
| Organisation | University of Padova |
| Department | Department of Industrial Engineering |
| Country | Italy |
| Sector | Academic/University |
| PI Contribution | Siemens has provided the available tools, resources and training for the partner institution, while our research group is actively engaged and with the partners, contributing in the parts of software and methodology development. A thermodynamic property estimation model for the properties of solid cementitious materials that has been created in the first part of the project has also been supplied to the partner organization as well. Furthermore, Leonardo Varnier (PhD Researcher form the partner institution) is hosted by Siemens in our Hammersmith office in London for one year, in which he is working actively together with our research group. |
| Collaborator Contribution | Based on the training, consulting and resources provided from our organization, our partners conceptualized and developed several processes and configurations of electrified cement plants and then performed a technoeconomic analysis of the modelled plants. The partner organization conducted a sensitivity analysis on the results of the study. |
| Impact | This collaboration aims to provide technical and economical insights on the integration of decarbonization technologies in cement plants; more specifically electrification and cryogenic carbon capture. The main outputs from this partnership so far, are related to the technology of electrification of cement plants. We have studied the concept of combined electrification and amine based carbon capture. A techno-economic analysis was conducted on four distinct process alternatives, which differed by the type of electrified calciner use, and the heat recovery strategy. The low-carbon processes studied increased electrical energy demand by 5.6-6.2 times compared to a benchmarked traditional cement plant. All alternatives achieved competitive capture rates of approximately 97.5%, and CO2 concentrations met the required quality specifications without the need for additional purification. Under an EU-27 energy mix, the low-carbon processes reached a CO2 avoidance rate of 70-72%, which was lower than other promising decarbonisation technologies such as oxyfuel and calcium looping. However, when low-carbon electricity is supplied, the CO2 avoidance rate improved to 98%, making these processes competitive with both oxyfuel and calcium looping technologies. From an economic perspective, the most favorable configuration resulted in a cost of clinker of 213.4 €/tclk and a cost of avoided CO2 of 217.4 €/tCO2, primarily due to the lower CAPEX of the electrified calciner and amine capture system. The other scenarios showed comparable economic performance, with cost of avoided CO2 values between 231 and 234 €/tCO2. These values observed in the baseline scenario revealed that these technologies are not yet economically viable, mainly due to the current electricity price in the EU. A sensitivity analysis through a response surface model highlighted that the competitiveness of low carbon cement plants is strongly influenced by electricity price and grid carbon intensity. |
| Start Year | 2024 |
| Description | CO2Valorize & DETOCS Online Training Schools |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Postgraduate students |
| Results and Impact | Our research group participated into 3 online training schools, two organized by CO2Valorize partners and one organized from the DETOCS project, another MSCA doctoral network. A series of talks from industry, policymaking and academic experts were given, touching upon many interesting topics. The talks focused on a broad range of technical subjects like industrial approaches in the design of chemical reactors (by FLSmidth), the costs related with carbon capture applications in cement industries (by John Kilne Consulting), and the characterization standards and techniques for carbonated materials and supplementary cementitious materials (by KIT). Moreover, other talks focused on the development of several soft skills like organization and management of a PhD project, presentation and visualization research results and datasets and tips for writing a PhD thesis. |
| Year(s) Of Engagement Activity | 2024,2025 |
| Description | CO2Valorize - DETOCS Training School |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | This was an collaborative event co-organized from CO2Valorize and DETOCS, both EU funded MSCA projects, held between 23-26 September 2024 in Padova, Italy. The main purpose of this activity was to bring together doctoral candidates (22 in total) that work on similar fields (decarbonization of the cement and concrete value chain) but in different consortiums. In the first two days, the doctoral students had the opportunity to present their research topic and results, while exchanging opinions and ideas on the very important topics of clinker substitution and emerging Supplementary Cementitious Materials (SCMs). The last two days were dedicated to intensive training on the topics of Machine Learning and Industry 4.0 standards and what is the current state and applications in the cement industry. This workshop was a first opportunity for the research group to communicate important results and investigate potential synergies and collaborations within the consortium. |
| Year(s) Of Engagement Activity | 2024 |
| Description | CO2Valorize Panel |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | The CO2Valorize Doctoral Network has established a formal working group which comprises of 8 young researchers (one of them coming from the UK side) and their respective supervisors (two of them coming from the UK side). The working group is actively discussing progress, exchanges ideas and establishes collaborations and synergies between research projects. The UK research group funded by UKRI, has established synergies with University of Padova, with which an additional working group has been formed. This working group works towards the modelling, design and technoeconomic assessment of cement decarbonization technologies (Project Work Package 3). |
| Year(s) Of Engagement Activity | 2023,2024 |
| Description | CO2Valorize Training School 2 |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | The research group hosted two doctoral training schools, providing a wide range of training courses to the Doctoral Network. The trainings focused on modelling and coding principles related to Siemens' gPROMS® Advanced Process Modelling Software and covered both introductory (first online training school) and advanced (second in-person training school) topics. The researchers gained new skills and knowledge that could benefit their research. Furthermore, during the second training school hosted by the research group, the project's midterm review took place, in which project management related matters were discussed and technical presentations of the Doctoral Candidates' work took place, while there was an overall assessment of the project's status from the EU's Project Officer. |
| Year(s) Of Engagement Activity | 2023 |