Here, we present a methodology for the generalized quantification of the carbon (C)-formation risk in hydrocarbon mixtures based on the normalized chemical activity. An open-source computational thermodynamics tool is coupled to a solid oxide fuel cell (SOFC) stack model to apply and validate this approach with literature data based on methane-fueled SOFC systems with anode off-gas recirculation. Two- and three-dimensional C-formation risk maps valid for all C-H-O mixtures are proposed for a practical, accurate, and meaningful assessment of the trade-off between C-deposition risk and SOFC performance. Compared to conventional risk evaluation methods such as steam-to-carbon ratio (SCR), oxygen-to-carbon ratio (OCR), or C-H-O ternary-phase diagrams, this approach allows a system-agnostic evaluation of different designs operated at varying conditions at a constant C-formation risk margin. The generalized formulation allows integration into process optimization workflows to obtain high-performance system designs with extended stack operating windows.

The electrolysis of CO₂ converts CO₂ into value-added products and has the potential to reduce the use of fossil feedstocks by serving as a circular alternative in chemical processes. However, existing literature lacks comprehensive and quantitative analyses of economic, environmental, and governmental factors that can hinder or support its deployment. This study addresses this gap by exploring the potential of CO₂ electrolysis for the production of synthesis gas, syngas, through a supply chain design that integrates long-term decisions on location and infrastructure and medium-term decisions on capacity expansion and aggregate production planning. We identify and quantify time-dependent and uncertain parameters using the Delphi method and employ multi-period planning and robust optimization approaches to consider them, respectively. Moreover, since the environmental impact of syngas is highly dependent on electricity consumption, renewable electricity is utilized with battery support alongside grid electricity. Accordingly, we propose a mixed integer linear programming model to design a supply chain that can serve as a benchmark to make CO₂ electrolysis financially and environmentally viable for syngas production. We conduct a case study on the Benelux region, analyzing different scenarios to derive managerial and design insights. The results show that a design that takes uncertainty into account can reduce syngas production costs by up to 22%. Additionally, although renewable electricity supply variability and different grid characteristics across countries can lead to different strategic decisions with higher costs, increased battery installations and higher government financial support for renewable electricity can help eliminate differences in designs.

Syngas production via high-temperature co-electrolysis of CO₂ (CO₂E) shows great potential to reduce the reliance on fossil fuels within the chemical industry. This paper presents an optimization model (MILP) to investigate syngas production from CO₂ in the European chemical sector. The model assesses the economic performance of CO₂E in prospective supply chains and explores alternative supply chain configurations under different syngas market sizes. The results reveal that the optimal placement of the CO₂ electrolysis plant in the supply chain is co-located or decentralized at the product location. This configuration reduces the need for syngas transportation by delivering CO₂ to the demand site, which is typically more cost-effective. At a syngas market fulfillment of 2 %, the lowest levelized cost of syngas is achieved at 673 EUR₂₀₁₈/tonne, with electrolysis plants averaging a production capacity of 100 ktonne syngas/year. This levelized cost is between 1.5 and 4 times higher than the fossil-based reference.

Sustainability transition to a climate neutral economy requires the rapid development, testing and scaling of emerging technologies currently in their infancy. Carbon dioxide electrolysis is one such promising emerging technology to produce fossil-free fuels and chemicals for a sustainable chemical industry. This paper investigates enablers and barriers shaping this technology within a European context by combining a technological innovation system (TIS) lens with political economy perspectives. Evidence from over forty semi-structured interviews, policy documents, and an expert consultation workshop reveals a fast-emerging TIS enabled by R&D, legitimisation and advocacy of carbon capture and utilisation as an emission reduction pathway, and complementary technological developments. However, factors such as availability of renewable electricity and carbon dioxide, and a policy bias towards mature technologies to meet urgent emission reduction targets are barriers to its future development. The TIS in this early formative phase, is in a state of flux and vulnerable to shifts in actor strategies, which can result in discontinuities in the learning process. We identify a need for technology-specific policies to support iterative upscaling through long-term projects, encourage niche market formation and strategically manage knowledge. In contrast to the current fit and conform narrative dominated by cost comparison with fossil fuels, we propose a need to empower carbon dioxide electrolysis with a stronger stretch and transform framing by imagining its role in a carbon neutral economy. Our methodology complements existing techno-economic assessments by bringing forth a rich narrative of underlying innovation processes and offers important policy insights for governing emerging technology development.

Alternative carbon sources (ACS) are increasingly considered necessary for the defossilisation of fossil-based chemicals. However, the potential and impacts of integrating ACS-based processes in existing petrochemical clusters are often overlooked. This paper aims to systematically analyse key techno-economic and environmental indicators associated with producing bio-based isobutene as an option to defossilise the production of methyl-tert-butyl-ether (MTBE) in the Port of Rotterdam, the Netherlands. The assessment is conducted at process and cluster levels. For this, the bio-isobutene (bio-IBN) process (358 kt/y of product), along with the existing fossil-based processes involved in MTBE production (i.e. the MTBE cluster), were modelled in Aspen Plus v12. The results show that under current conditions, although bio-IBN production could defossilise the MTBE cluster by c.a. 80 %, it is not cost-competitive compared to the current fossil-based process. Furthermore, deploying the bio-IBN process would significantly change the structure of the existing MTBE cluster, increasing by a factor of two or larger electricity, cooling water and bare land requirements. These requirements would affect the economic and environmental performance of the full cluster. The results emphasise the critical role of strategic change of new processes within existing petrochemical clusters.

The rising pressure to defossilize the chemical industry has driven research toward producing chemicals that use alternative carbon sources (ACS). However, the challenges and impacts of replacing already implemented processes and symbiotic relationships remain largely underexplored. This paper systematically assesses the impacts of defossilizing existing processes, both individually and simultaneously, in a propylene cluster in the Port of Rotterdam, the Netherlands. Nine fossil-based processes and three ACS-based processes (i.e., CO₂-based polyol, biopropylene glycol (bio-PG), and biomethyl-tert-butyl-ether (bio-MTBE)) were included in the assessment. Integrating a single ACS-based process enlarges the propylene cluster and results in an excess of upstream chemicals that are no longer required by the ACS processes. Still, relatively simple technologies can reduce total energy and water use, resulting in lower direct CO₂emissions and water consumption of the cluster. Deploying multiple processes in parallel can drive the full defossilization of the cluster, but it requires a complete overhaul. The results illustrate the extent to which combining ACS-based processes could change the layout of an existing petrochemical cluster, affecting its performance. The paper stresses the importance of assessing such deployments, considering the existing conditions in industrial clusters.

Electrochemical ammonia synthesis via the nitrogen reduction reaction (NRR) has been poised as one of the promising technologies for the sustainable production of green ammonia. In this work, we developed extensive process models of fully integrated electrochemical NH ₃ production plants at small scale (91 tonnes per day), including their techno-economic assessments, for (Li-)mediated, direct and indirect NRR pathways at ambient and elevated temperatures, which were compared with electrified and steam-methane reforming (SMR) Haber-Bosch processes. The levelized cost of ammonia (LCOA) of aqueous NRR at ambient conditions only becomes comparable with SMR Haber-Bosch at very optimistic electrolyzer performance parameters (FE > 80% at j ≥ 0.3 A cm ⁻²) and electricity prices (<$0.024 per kW h). Both high temperature NRR and Li-mediated NRR are not economically comparable within the tested variable ranges. High temperature NRR is very capital intensive due the requirement of a heat exchanger network, more auxiliary equipment and an additional water electrolyzer (considering the indirect route). For Li-mediated NRR, the high lithium plating potentials, ohmic losses and the requirement for H ₂, limits its commercial competitiveness with SMR Haber-Bosch. This incentivises the search for materials beyond lithium.

The present study utilizes a value sensitive design (VSD) inspired approach to contribute to the design and implementation of CO₂ electrolysis (CO₂E) within the framework of carbon capture and utilization (CCU) technologies, which convert CO₂ into valuable products. The focus of this study is on a low technology readiness level (TRL) technology, yet likely relevant to reach climate neutrality by 2050. We examine the perspectives of stakeholders along the supply chain and proactively identify relevant sustainability-related values and potential conflicts among them. Thus the current work highlights the importance of considering a broad range of stakeholders and their values in the early stages of technological design. The research approach is consisting of various steps inspired by value sensitive design (VSD): identifying relevant values and norms associated with CO2 electrolysis through literature analysis, conducting qualitative interviews with relevant stakeholders to triangulate the results. Subsequently, a value-based alignment network analysis was employed to examine shared values that are central for the design of the technology. The findings indicate that sustainability-related values such as concern for nature, climate change mitigation, the use of renewable energy, critical raw materials, cost, and return on investment, albeit with potential differences in interpretation, are increasingly becoming central considerations in the decision-making processes of individuals, businesses, and governments alike. Based on these findings, specific aspects of technology design, namely scale, location, integration, and synthesized product, that can impact a wide range of identified values, are discussed.

Combining intermittent renewable electricity (IRE) with carbon capture and utilisation is urgently needed in the chemical sector. In this context, microbial electrosynthesis (MES) has gained attention. It can electrochemically produce hexanoic acid, a value-added chemical, from CO₂. However, there is a lack of understanding regarding how the intermittency of renewable electricity could impact the design of a MES plant. We studied this using Aspen Plus models. A MES plant that was powered by constant grid electricity could operate from 100% down to 70% of its nominal capacity, at which point the heat exchangers and the internal geometrical design of the distillation towers became bottlenecks. The levelised production cost of hexanoic acid (LPC_C6A) was estimated at 4.0 €/kg. Switching to IRE supply increased LPC_C6A to 5.3 €/kg (for wind electricity) and 4.7 €/kg (for hybrid renewable electricity). A battery energy storage system (BESS) was deployed. The lowest LPC_C6A was found at a BESS installation of 29 GJ/h for wind electricity (5.1 €/kg) and at 12 GJ/h for hybrid renewable electricity (4.7 €/kg). In both situations, the volume flexibility of the MES plant was not improved. At the investigated market and operating conditions, coupling IRE to the MES plant was economically infeasible.

Microbial electrosynthesis (MES) is a novel carbon utilisation technology aiming to contribute to a circular economy by converting CO₂ and renewable electricity into value-added chemicals. This study presents a cradle-to-gate life cycle assessment (LCA) of hexanoic acid (C6A) production using MES, comparing this production with alternative technologies. It also includes a cradle-to-grave LCA for potentially converting C6A into a neat sustainable aviation fuel (SAF). On a cradle-to-gate basis, MES-based C6A exhibits a carbon footprint at 5.5 t CO₂eq/tC6A, similar to fermentation- and plant-based C6A. However, its direct land use is more than one order of magnitude lower than plant-based C6A. On a cradle-to-grave basis, MES-based neat SAF emits 325 g CO₂eq/MJ neat SAF, which is significantly higher than the counterparts from currently certified routes and conventional petroleum-derived jet fuel. However, its negligible indirect land use change emissions might potentially make it competitive against neat SAFs originating from first-generation biomass.

Different alternative carbon sources like CO₂, biomass and plastic waste, can be used to replace fossil carbon as feedstock in the production of methanol. Based on current literature, the plastic-based methanol route is the most competitive one among the three based on price indicator, but there is still a lack of comprehensive understanding of the techno-economic differences between alternative feedstock technologies. In this study, three technologies from each alternative feedstock were assessed to evaluate the techno-economic trade-offs between them. The research shows that even though currently the plastic-based route is comparatively cost competitive with the conventional route of producing methanol, the CO₂-based methanol route can also be competitive with green hydrogen prices in the range of 1400-1100 EUR/t. While the biomass-based route showed superior energy performance compared to the other two.

The production of base chemicals by electrochemical conversion of captured CO₂ has the potential to close the carbon cycle, thereby contributing to a future energy transition. With the feasibility of low-temperature electrochemical CO₂ conversion demonstrated at lab scale, research is shifting toward optimizing electrolyser design and operation for industrial applications, with target values based on techno-economic analysis. However, current techno-economic analyses often neglect experimentally reported interdependencies of key performance variables such as the current density, the faradaic efficiency, and the conversion. Aiming to understand the impact of these interdependencies on the economic outlook, we develop a model capturing mass transfer effects over the channel length for an alkaline, membrane electrolyser. Coupling the channel scale with the higher level process scale and embedding this multiscale model in an economic framework allows us to analyze the economic trade-off between the performance variables. Our analysis shows that the derived target values for the performance variables strongly depend on the interdependencies described in the channel scale model. Our analysis also suggests that economically optimal current densities can be as low as half of the previously reported benchmarks. More generally, our work highlights the need to move toward multiscale models, especially in the field of CO₂ electrolysis, to effectively elucidate current bottlenecks in the quest toward economically compelling system designs.