Conference Agenda

The aluminium industry emits around 1.1 billion tonnes of CO₂-eq annually, constituting roughly 2% of global industrial emissions. Currently, the sector is developing decarbonization pathways to achieve net-zero emissions by 2050. Potential solutions include biomass gasification, power-to-gas, energy storage, direct electrification of furnaces, and carbon capture. However, this involves making decisions today, based on economic assumptions that reflect current market conditions, about technologies that will operate over the coming decades. A situation which results in significant economic uncertainties due to the volatility of energy prices. Historically, price forecasting models have often failed to account for major market disruptions, such as the 2022 energy crisis, due to the unpredictability of geopolitical and market factors. In this context, decision-makers require systematic methodologies to manage uncertainty. In this work, Monte-Carlo Analysis (MCA), is used to evaluate the financial stability of various decarbonization configurations by simulating the effects of fluctuating energy prices over the operational lifetime of the technology. This study applies MCA to two decarbonization pathways for the aluminium industry: a biomass-based option, which relies on biomass gasification to generate syngas for furnaces, and an oxyfuel scenario, which uses electrified furnaces in combination with oxyfuel burners and carbon capture and storage. The biomass pathway was found to have a 63-78% probability of negative incremental Net Present Value (iNPV) over 25 years with reference to the base case. Conversely, the oxyfuel option demonstrates a 54% likelihood of economic loss under similar conditions. Further analysis in this work, introduces the modelling of economic crisis scenarios where sudden price shocks occur during the plant’s lifetime. The results indicate that the oxyfuel solution is 75% more susceptible to financial risk during energy crises than the biomass-based option. This is because the former depends heavily on electricity, whose prices can spike dramatically while the latter demonstrates a diversification of less volatile energy sources such as biomass. This analysis highlights the importance of considering energy price volatility and the need for diversified energy sources when developing decarbonization strategies for the aluminium industry.

The lime industry, essential for construction, steelmaking, and effluent treatment, contributes significantly to CO₂ emissions, accounting for about 1% of global anthropogenic emissions. The calcination process itself emits 0.786 tCO₂ per ton of lime and requires high temperatures (900–1100°C), typically achieved by burning fossil fuels. Depending on the kiln technology, total emissions range from 1 to 1.8 tCO₂ per ton of lime.

The objective of this study is to analyze various pathways for achieving CO₂ emission reduction in the lime sector. For this purpose, a Blueprint (BP) model of the lime sector is developed, consisting of detailed mass and energy balances, as well as economic considerations (i.e., annualized CAPEX and OPEX). This BP model incorporates a superstructure of various energy transition pathways such as fuel switching (towards hydrogen, biogas, solid biomass), kiln electrification (using plasma torches) and CO₂ capture (CC) (via chemical absorption with MEA or oxycombustion (‘NGOxy’)). Furthermore, the OSMOSE tool (an optimization framework), developed at EPFL, is utilized for evaluating the superstructure for three different years (2030, 2040, 2050) and three different energy scenarios based on EnergyVille’s PATHS2050 study, impacting utilities cost and the CO₂ emissions cost. Finally, a comparison between all alternative routes and the base case ’NG’ (natural gas-fired kiln without CC) is performed on the basis of three key performance indicators (KPI): specific energy consumption (kWh/t_lime), specific CO₂ emissions (kgCO₂/t_lime) and specific total cost (€/t_lime).

From results, in 2030, the optimum pathways are ’Biomass-CC’ and ’NGOxy-CC’. Significant CO₂ emissions reduction (-115% compared to ‘NG’) and lower fuel costs result in a specific total cost (STC) reduction of 27% compared to ‘NG’ (€270/t_lime), for ‘Biomass-CC’, despite increased total energy consumption (+120% compared to ‘NG’). The 90% lower CO₂ emissions related to ‘NGOxy-CC’ enable a STC reduction of 16–18% compared to ’NG’, depending on the scenario considered, despite a 16% higher energy consumption. ’Plasma-CC’ comes 3^rd, with a cost reduction of 12–18% due to an energy consumption reduction of 12% and an emission reduction of 93% compared to ’NG’. Similar trends are observed for 2040, with the economically optimal solution remaining ’Biomass-CC’. In 2050, the STC of ’NG’ reaches €476/t_lime. ’Biomass-CC’ remains among the optimal routes with a STC reduction of 61% compared to ‘NG’, while lower electricity prices in 2050 scenarios enable a STC reduction of 51–62% for ’Plasma-CC’. ’NGOxy-CC’ also remains a suitable route with a STC 51–54% lower than ‘NG’. The use of hydrogen in lime kilns, on the other hand, represents one of the most expensive transition pathways for the sector in all scenarios due to higher energy consumption, fuel price and CAPEX than the base case.

In conclusion, this study offers a foundation for decision-making based on specific KPIs for future scenarios. CO₂ capture coupled with biomass-fired kilns, plasma technology or oxycombustion configuration represent the most cost-effective routes for emissions reduction in the lime sector. However, despite relatively low costs, the problems associated with biomass availability and the low TRL of plasma technology should not be overlooked.

Decarbonizing industries could significantly increase electricity demand, necessitating strategic
grid expansion. This study evaluates the impact of decarbonizing the Pulp and Paper Sector under
four 2050 scenarios: carbon capture, biomass-based, direct electrification, and indirect electrifi-
cation. A bottom-up approach is employed to estimate 2020 final energy demand by heat grade
and subsector. Both final and primary energy demand systems are modeled, accounting for the
efficiencies of end-use technologies and primary energy transformation processes. The analysis
compares primary renewable energy demand (electricity and biomass) normalized per ton of
equivalent CO2 avoided against a business-as-usual scenario. It also considers the requirements
for wood residues, organic waste, and CO2 storage. The carbon capture scenario, while low in
electricity demand, requires significant organic waste for renewable natural gas production and
2.6 Mt of CO2 storage to offset direct and indirect emissions, making it the least feasible due to
uncertainties around carbon storage in Quebec. Among the remaining scenarios, the direct elec-
trification stands out by offering the lowest primary energy demand. It combines heat pumps with
electric boilers for steam production and lime kilns are converted to a plasma-based solution. The
study also includes a sensitivity analysis highlighting the potential of energy efficiency measures
to ease the burden of decarbonization.

Cement production is one of the largest sources of global industrial CO₂ emissions. To achieve ambitious target of net-zero emissions by 2050, conventional CO₂ capture technologies alone are considered insufficient. In fact, although chemical absorption is a mature technology, it suffers from significant issues due to solvent regeneration process and incomplete carbon separation. For this reason, novel CO₂ capture and mineralization approaches must be implemented, which can also provide minerals and additives, thus increasing the economic attractiveness and sustainability of the overall process. In this work, the performance of the process integration between a chemical absorption process and a cement plant is compared to that of a novel CO₂ capture and sequestration system based on ex-situ CO₂ mineralization. CO₂ mineralization offers the potential for permanent carbon sequestration by converting captured CO₂ into stable carbonates, utilizing industrial by-products such as slags, fly ash, and other waste materials.

A superstructure-based methodology is developed to explore and evaluate multiple solutions, e.g. chemical absorption, Oxycombustion, as well as CO₂ mineralization, injection and calcium looping. Evaluated key performance indicators include total annualized costs (€/t_cement), CO₂ emissions (t_CO2/t_cement), and specific energy consumption (GJ/t_cement), with each pathway evaluated under future energy scenarios: 2030, 2040, and 2050, dased on EnergyVille’s PATHS2050, aiming to reflect the evolving commodity prices and carbon pricing. Preliminary results indicate that CO₂ mineralization may become more cost-effective than chemical absorption by 2050, particularly due to its lower energy requirements and the ability to produce marketable by-products. In a near term (2030), chemical absorption remains competitive due to its established infrastructure and relatively higher capture efficiency. Yet, as CO₂ pricing escalates and renewable electricity becomes more affordable by 2050, solutions shift towards mineralization technology. The integration of CO₂ capture with mineralization in cement kilns, combined with renewable energy, could offer a more economically viable and environmentally sustainable solution, considering twofold benefit of emission reduction and generation of useful materials for other sectors, such as construction.

By comparing emerging technologies like mineralization with traditional chemical absorption, this study identifies key trade-offs between costs, emissions reduction potential, and technology readiness. The insights generated will assist policymakers and industry stakeholders in formulating long-term strategies for achieving climate targets in the cement sector.

A growing number of circular engineering projects are being developed. They propose to reduce, reuse, recycle or recover resources. Their aim is to contribute to the transition to more sustainable systems. However, they are embedded in an economic, social and environmental context. This context will impact the project (e.g. social acceptability), which in turn will impact it (e.g. CO2 emissions). Depending on the context, the project will not necessarily improve the global sustainability. It may be necessary to rethink elements of this context, particularly socio-economic ones. In this case, the project is part of a transition to a circular economy, going beyond the scope of circular engineering. A question to be asked in engineering project management is: How to support the development of projects really contributing to a transition to a more circular economy and thus to more sustainable systems?

Indicators are central decision-making tools, useful including in computer-aided tool. There are numerous indicators relating to the circular economy. However, most of them are specific, biased by an aggregation method and incomplete (De Pascale et al., 2021). So, what aspects should these indicators represent to support the transition? how? and how can they be adapted to the specificities of a given context?

Studies in ecological economics show that stakeholder participation improve (i) the consistence between the indicator and the context ; and (ii) there usage in decision-making (Fraser et al., 2006). Defining indicators is then also a way to co-define which system to aim for and how to get there. This involvement of stakeholders in the decision-making process seems necessary for real and desirable transitions. But how to support this participatory process?

This study proposes a tool-based participatory method for developing indicators aiming to support decision-making on projects of transition to a circular economy. The method aims to be generic (industrial sector, scale). Indicator sets developed are context-specific, multi-scale, multi-stakeholders and aim for strong sustainability. The tools used are multidisciplinary (e.g. economy, management, industrial engineering). The central tool of the method is a database of 370 non-aggregated indicators classified in a framework. Both the database and the framework were deduced from the literature. The frame categories are aspects to be potentially considered. Indicators are examples of how these aspects can be represented. The method was tested on a project to set up a food processing plant.

De Pascale, A., Arbolino, R., Szopik-Depczyńska, K., Limosani, M., Ioppolo, G., 2021. A systematic review for measuring circular economy: The 61 indicators. Journal of Cleaner Production 281, 124942. https://doi.org/10.1016/j.jclepro.2020.124942

Fraser, E.D.G., Dougill, A.J., Mabee, W.E., Reed, M., McAlpine, P., 2006. Bottom up and top down: Analysis of participatory processes for sustainability indicator identification as a pathway to community empowerment and sustainable environmental management. Journal of Environmental Management 78, 114–127. https://doi.org/10.1016/j.jenvman.2005.04.009