Conference Agenda

The European chemical industry plays a critical role in the region's economy, producing essential chemicals for numerous sectors. However, its environmental footprint is substantial, with high energy consumption, significant greenhouse gas emissions, and the release of harmful chemicals. However, previous research on the environmental performance of the chemical industry is often limited to specific processes or activities, lacking a comprehensive sector-wide perspective.

To address this gap, this study evaluates the sector's environmental performance against the planetary boundaries (PB) framework, which defines the ecological limits within which humanity can safely operate. By comparing the sector's environmental impacts to these boundaries, we assess its absolute sustainability and identify key areas of transgression. To do this, we consider the 19 highest-volume chemicals as representative of the entire European chemical sector. These chemicals account for 80% of the industry’s energy consumption and 75% of its greenhouse gas emissions, highlighting their critical role in both production volume and environmental impact. Given that each of these chemicals can be manufactured through multiple processes, our analysis incorporates data from 32 processes across 23 datasets, sourced from the ecoinvent 3.5 database. To avoid double counting impacts, we explore the links between these 23 activities and adjust production volumes accordingly.

Our findings reveal that the European chemical industry significantly exceeds the safe operating limits for multiple PBs, particularly for climate change, ocean acidification, and biosphere integrity. The industry's contribution to atmospheric CO2 concentration and energy imbalance at the top of the atmosphere exceeds safe levels by 15 and 16 times, respectively, while impacts on ocean acidification are 6 times greater than acceptable. The biosphere integrity boundary, assessed here via functional diversity, is also slitghly transgressed (3%). Five high-volume chemicals —ammonia, polypropylene, high-density polyethylene, styrene, and benzene— are responsible for 50% of the sector's overall environmental burden across all PBs.

We also explore various mitigation pathways, including the deployment of carbon capture and storage (CCS) technologies, the use of renewable energy, and green hydrogen. Our results indicate that CCS could enable the sector to meet all PBs concurrently; however, burden-shifting to other environmental areas remains a concern. This highlights the necessity of holistic approaches to sustainability, where solutions are evaluated not only within the chemical industry but also in interconnected sectors, such as energy.

In conclusion, while technological solutions such as CCS and green chemistry innovations hold promise, they must be implemented in conjunction with broader systemic changes, including policy interventions and cross-sector collaboration. This study emphasizes the need for integrated, multi-disciplinary strategies to ensure that the European chemical industry can transition toward sustainability within the ecological limits of the planet.

As the United States advances its decarbonization goals through electrification initiatives, significant engineering challenges related to the reliance on rare earth elements and many other critical minerals will have to be overcome. Recovery of these critical minerals, either from ores or unconventional feedstocks such as end-of-life products, involves processes where chemical equilibrium calculations are essential. Chemical equilibria problems are typically solved in one of two ways¹: either by minimizing the Gibbs free energy of the system (the GEM approach) or by solving a system of equations involving the equilibrium constants (the law of mass action approach, LMA).

However, despite the widespread use and popularity of the LMA approach, it tends to fail when many species are involved, as simultaneous satisfaction of equilibrium between all in-solution and precipitated species is not always possible. Software such as PHREEQC² and MINTEQ³ which utilize LMA approaches, make use of different heuristics based on saturation indices to arrive at a solution⁴ The newer GEM methods are more stable, but they also rely on thermodynamic data that is not always available.

In this work, we present an optimization-based approach for solving precipitation/dissolution reactions utilizing equilibrium relations. Our approach models the precipitation reactions as inequality constraints, which relaxes the typical requirement of equilibrium between all precipitated and in-solution species. The objective function is set to minimize the square of the difference between the ion product QP , defined over the actual concentration in solution, and the equilibrium constants Keq or solubility products Ksp, defined over the equilibrium concentrations in solution. This choice of objective function allows the identification of the species that should precipitate (i.e., QP = Ksp) and those that should not (i.e., QP ≤ Ksp) without the need for saturation indices heuristics. We hypothesize that this model may have advantages over current LMA-based software packages in certain applications as it (i) makes use of commonly available data such as solubility products Ksp and equilibrium constants Keq, and (ii) can be more easily embedded in unit operations’ optimization problems.

As a proof of concept, we apply our model to a novel REE recovery process developed by the Critical Materials Innovation Hub (CMI) to determine whether experimental results reported in the literature for that process could be successfully replicated. The CMI process uses a series of dissolution and precipitation reactions to recover rare earth elements as rare earth oxalates from end-of-life rare earth permanent magnets.^5,6 The relative complexity and configurability of the process—having multiple stages and unit operations—makes it an ideal case for study, as the model could have direct impacts for licensees as they scale-up and mature the process.

Acknowledgments: This effort was funded by the U.S. Department of Energy’s Process Optimization and Modeling for Minerals Sustainability (PrOMMiS) Initiative, supported by the Office of Fossil Energy and Carbon Management’s Office of Resource Sustainability.

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(References and Disclaimer missing per limit in length of abstract)

Life Cycle Assessment (LCA) evaluates the environmental effects of products and processes. Life Cycle Impact Assessment methods such as TRACI and ReCiPE were developed to quantify impacts^{1, 2}. They employ midpoint indicators relating the impact of an activity to specific environmental sectors. For example, kg SO₂-eq relates to acidification in TRACI v2.1². ReCiPe uses endpoint indicators, a linear combination of midpoint indicators with weights assigned based on relative impact. Endpoint indicators aggregate relevant midpoint indicators to reflect broader societal impacts, such as human health, ecosystem quality, and resource depletion. While these endpoint indicators have a physical basis, their weights are mostly subjective and may not align with stakeholder interests. One example is the United Nations Human Development Index (HDI), where three indicators (life expectancy, education index, and income per capita) are grouped into the HDI with a fixed weight³. These weights can change between regions and the stakeholders’ preferences. Therefore, we need an endpoint indicator that considers the environmental impacts important to stakeholders. This metric is essential for setting policy that prevents burden-shifting between different environmental impacts. A data-driven, multi-stakeholder framework has been developed to enable the creation of LCA endpoint metrics that accommodate the diverse needs of stakeholders, including businesses, governments, and the public.

To generate stakeholder preferences, a mass allocation approach based on emissions is used for businesses. Government reports are employed to determine gaseous emissions, wastewater generation, and solid waste generation. Scaled ordinal rankings based on mass allocation for the emissions estimated in each indicator are then established. Government stakeholder preferences are estimated from state emission regulations. Public preferences are determined using public survey data, and companies’ preferences are considered to correspond to their profitability.

A risk-based approach and a stakeholder satisfaction approach are used for optimization. In the risk-based approach, there is a probabilistic guarantee that in the worst-case scenario, the stakeholder’s worst option is minimized. To do so, an optimization problem using downside risk as the objective function is proposed. The stakeholder satisfaction approach minimizes deviation from stakeholders’ preferred solutions⁴. The objective function can be formulated as a risk measure that shapes the distribution of stakeholder dissatisfaction. Specifically, Conditional Value at Risk penalizes high dissatisfaction levels in the (1-α) tail of the distribution. By minimizing dissatisfaction, the model selects a solution that satisfies the top (α) percentile of stakeholders. A case study focusing on the state of Delaware is presented. From the government emissions reports, primary stakeholders are identified and their environmental preferences characterized. The optimization framework is used to calculate LCA endpoint metrics and compare them using these different approaches.

References:

(1) Huijbregts, M. A. J.; et al. Int J Life Cycle Assess 2017, 22 (2), 138-147. DOI: 10.1007/s11367-016-1246-y

(2) Bare, J. C. Journal of Industrial Ecology 2002, 6 (3‐4), 49-78.

(3) Programme, U. N. D. Human Development Report 2023/2024; United Nations, 2024. DOI: https://doi.org/10.18356/9789213588703.

(4) Dowling, A. W.; et al. Computers & Chemical Engineering 2016, 90. DOI: 10.1016/j.compchemeng.2016.03.034.

The reduction and recovery of household organic waste fraction is one of the major challenges for contemporary society. Waste management requires the establishment of one or more strategies that are both economically viable and environmentally sustainable. In 2022, Parisians generated approximately 2.2 million tons, or 410 kg/capita/year, of household waste. 300 kg/capita/year of them were residual household waste (RHW)¹, a non-recyclable fraction that is typically incinerated or landfilled, resulting in over 1.75 million tons burned for that year alone¹. This RHW consist of approximately 30% organic waste which could be recycled. Following a path of circular economy in 2018 the European Union introduced different obligations the new Regulation on Packaging and Packaging waste, replacing the Waste Framework Directive². As a result, since 2024, separate collection of biowaste is mandatory across Europe. To optimize and evaluate the environmental impact of this regulatory change, the overall performance of the biowaste treatment system needs to be assessed. The aim of our research is to propose physico-chemical predictive models to enable these assessments.

To build our system simulation, two processes were studied and modelled: i) composting and ii) incineration. Both are sub-systems (represented in their superstructure, Figure 1) that contribute to the Paris waste management system. Due to the lack of an open-access composting model in the literature, and to address common EU objectives, we developed a predictive model to evaluate and simulate the system. The complex matrix of 'biowaste' was described as consisting of different sub-fractions equal to macrocomponents, compostable bags, and inert material due to improper sorting. Data collected over several years from 85 zones in Greater Paris, provided by our municipal partner, were used to estimate waste composition.

A predictive model of composting was developed and validated with experimental data. Hydrolysis and bioconversion were considered by different classes of microorganisms: bacteria, actinomycetes, and fungi, into the final product. Constraints included microbial growth and death rates, oxygen quantity, temperature, substrate availability, and humidity (Figure 2). For incineration, the modified Dulong equation was used for the estimation of the lower heating value (LHV) of the biowaste using the specialized process engineering software ProSimPlus®. The outcomes of both processes were compared in different municipal configurations, with scenarios exploring the importance of biowaste purity and the impact of mis-sorted materials, with regards to the performance in the environmental and techno-economic dimensions of sustainability.

REFERENCES

¹ Rapport d'activité Syctom, 2022

https://www.syctom-paris.fr/fileadmin/user_upload/Syctom_RA_2022.pdf

² Packaging and Packaging Waste Regulation, 2024

https://environment.ec.europa.eu/topics/waste-and-recycling/packaging-waste_en

As global decarbonization efforts accelerate, hydrogen is increasingly recognized as a crucial energy carrier for the transition to a low-carbon future. However, the environmental assessment of hydrogen supply chains, including both production and transportation, within the framework of planetary boundaries (PB), remains insufficiently explored on a global scale.

This study addresses this gap by evaluating the environmental impacts of 800 potential hydrogen supply chains, combining 32 production methods and 25 transportation options. Production methods include steam reforming, water electrolysis with bioenergy and carbon capture and storage (WE-BECCS), and aluminum combustion, while transportation methods cover options like compressed hydrogen, liquid hydrogen, and Liquid Organic Hydrogen Carriers (LOHCs) such as ammonia and methanol. Each alternative is evaluated in six regions before results are aggregated at the global level, thus capturing the influence of regional factors while providing a global perspective on hydrogen’s environmental performance.

Using the PB framework in conjunction with Life Cycle Assessment, the study evaluates the global impacts of these potential hydrogen supply chains on nine Earth-system processes. Key findings reveal that current hydrogen demand contributes significantly to several planetary boundaries. Notably, on-site hydrogen production accounts for approximately 22% of total global impacts on CO₂ concentration, primarily driven by steam reforming of natural gas and coal gasification. More importantly, if hydrogen demand continues to rise, the current decentralized production might shift to a centralized model. Considering that transporting compressed hydrogen via pipelines over long distances increases energy consumption and greenhouse gas emissions by 15-25% compared to localized production, this shift could further exacerbate impacts on climate change and atmospheric aerosol loading boundaries.

Among the 32 production methods, WE-BECCS emerged as one of the most promising hydrogen alternatives, reducing CO2 emissions by up to 90% compared to conventional steam reforming. Despite its benefits, it also introduces trade-offs, using 20-30% more land than other alternatives, which impacts the land-system change boundary.

Regional discrepancies also influence technological preferences. For instance, dark fermentation is a better option than autothermal reforming of biogas in China, while the opposite holds true in the USA. These differences are due to variations in electricity generation and in waste management practices, alongside distinct processes to obtain the raw materials for hydrogen production.

On the transportation side, ammonia and methanol are very promising alternatives if used directly as fuels, with contributions from transport on pair with those from compressed or liquid hydrogen, but at a lower cost. However, if hydrogen needs to be regenerated at destination, their impacts increase by 15-48%, indicating that this step is the bottleneck for these pathways.

Given these findings, hydrogen policy must not only focus on production but also address the environmental impacts of transportation, as they could offset production gains. This study highlights the wide range of green hydrogen production alternatives and emphasizes the importance of exploiting domestic resources while applying circular economy principles to meet future hydrogen demand. This approach would allow for maintaining a decentralized production model, diversifying methods, and reducing the risks associated with long-distance transportation.

Space exploration demands the integration of multiple scientific and engineering disciplines, with chemical engineering and process systems engineering playing pivotal roles. This paper examines thecritical contributions to propulsion systems, life support mechanisms, and advanced materials essential for space missions. Recent advancements in chemical propellants and rocket fuels, illustrated by SpaceX and NASA missions, have significantly improved propulsion efficiency and safety. Chemical engineering is vital in developing air purification, water recycling, and bioregenerative life support systems, ensuring astronaut survival and mission sustainability. Additionally, creating heat-resistant, lightweight materials enhances spacecraft durability under extreme space conditions. Process systems engineering (PSE) complements these efforts by integrating, simulating, and controlling complex systems. PSE ensures reliable subsystem integration and uses predictive analytics and advanced modeling for mission planning and risk mitigation. Automation and control systems are essential for maintaining operations with minimal human intervention. The synergy between these fields is evident in in-situ resource utilization (ISRU) technologies, which extract and process local resources on extraterrestrial bodies, reducing reliance on Earth supplies and enhancing mission viability. Despite significant progress, challenges remain. Addressing harsh space environments, ensuring long-duration mission sustainability, and advancing energy sources and materials are ongoing research areas. This presentation underscores the indispensable roles of chemical and process systems engineering in overcoming space exploration challenges.