The reaction conditions in industrial scale chemical reactors can differ markedly from the ones in a small laboratory scale reactor. The differences are both conceptual and practical, and can at best be analysed by studying a full reactor, which requires an analytical method capable of quantifying the distribution of reactants and products in a running reactor. For this, we introduce non-destructive operando neutron imaging in combination with modelling. As a representative reaction, we studied the hydrogenation of carbon dioxide to methane selected due to the large neutron cross-section of hydrogen and hydrogen-containing species. The integration of the measurement setup/reactor into the neutron beamline enables the temporally resolved measurement of the distribution of adsorbed water on the catalyst under operating conditions (p, T). The resulting quantitatively determined partial pressure of the water thus indirectly enables the spatial and temporal conversion of the processes. The knowledge gained from this experimental approach, combined with modelling, allows the design of reactor dimensions under optimized reaction conditions. The good agreement between simulation and experimental neutron imaging warrants the method as a reliable instrument for reactor characterization and design, with the prospect of its application on reactors on the industrial scale.

Growing demand for air travel and limited scalable solutions pose significant challenges to the mitigation of aviation’s climate change impact. Direct air capture (DAC) may gain prominence due to its versatile applications for either carbon removal (direct air carbon capture and storage, DACCS) or synthetic fuel production (direct air carbon capture and utilization, DACCU). Through a comprehensive and time-dynamic techno-economic assessment, we explore the conditions for synthetic fuels from DACCU to become cost-competitive with an emit-and-remove strategy based on DACCS under 2050 CO2 and climate neutrality targets. We find that synthetic fuels could achieve climate neutrality at lower cost than an emit-and-remove strategy due to their ability to cost-effectively mitigate contrails. Under demand reductions, contrail avoidance, and CO2 neutrality targets the cost advantage of synthetic fuels weakens or disappears. Low electricity cost (€0.02 kWh-1) and high fossil kerosene prices (€0.9 l-1) can favor synthetic fuels’ cost-competitiveness even under these conditions. Strategic interventions, such as optimal siting and the elimination of fossil fuel subsidies, can thus favor a shift away from fossil-reliant aviation.

Hydrogen is a volatile element, both as a molecular gas and as atomic hydrogen in materials. A method is described for the detection of the corresponding dynamic hydrogen in matter, as opposed to the relatively stable bond hydrogen (“static hydrogen”). The method is based on laser-stimulated hydrogen desorption using nanosecond laser pulses in the UV optical range. The principle, already established for surface hydrogen on nonabsorbent metals has been extended to hydrogen affine bulk systems. The feasibility of the idea is demonstrated by quantifying hydrogen in hydrogen-permeable metal membranes. Model experiments, such as HD exchange, provide input to the model to extract the surface hydrogen concentration of dynamic hydrogen from laser-stimulated hydrogen desorption while eliminating the influence of the laser-matter interaction on the quantification. An estimate of the limit of detection is given.

To reduce environmental impacts from the shipping industry, the FuelEU Maritime Regulation has set a binding 80 % reduction target for well-to-wake (WTW) greenhouse gas (GHG) emissions by 2050. This article presents a prospective life cycle assessment (LCA) comparing the environmental impacts of e-ammonia, e-methanol, e-Fischer Tropsch (FT) diesel, and e-liquefied natural gas (LNG)—for maritime applications in Europe. In addition to e-fuels, traditional propulsion technologies using very low sulfur fuel oil (VLSFO) and LNG are assessed, both with and without integrating ship-based carbon capture (SBCC) systems. Key factors considered include the impact of different production locations in Europe, electrolysis technology choices, and global climate policies. Beyond analysing the environmental footprints, the study examines the economic and externality costs associated with each fuel option, contextualizing these findings within the GHG mitigation targets set by the FuelEU Maritime regulation.The results indicate that e-ammonia, e-FT diesel, and e-methanol could meet the 2050 FuelEU Maritime target, but e-LNG and SBCCS could not. Although it is the most immature technology, e-ammonia could be the cheapest option with the lowest overall environmental impacts. E-LNG shows higher life cycle climate change impacts due to ship-level methane slip but has lower impacts across other environmental categories because of low NOx emissions. E-methanol has higher toxicity risks over the life cycle and higher costs.

This study investigates the cost and climate change mitigation potentials of fuels and chemicals from CO2 and low-carbon hydrogen produced in four sites with favorable conditions for renewable energy generation, located in Iceland, The Netherlands, Spain, and Chile. We investigate eight different chemicals, i.e., Fischer–Tropsch fuels, methanol, methane, dimethyl ether, ammonia, urea, olefins, and aromatics, considering two temporal horizons, i.e., the near future (by 2035) and the long-term future (post-2035). For hydrogen production, we explore alkaline water electrolysis, proton exchange membranes, and solid oxide electrolyzer cells. As carbon feedstock, we focus on CO2 produced via low-temperature solid adsorption direct air capture (LT DAC). Additionally, we investigate CO2 from high-temperature aqueous absorption DAC and point-source capture. We find that optimal renewable energy sites like the ones considered in this study have the potential to offer competitive costs for carbon capture and utilization (CCU) processes. These routes, when compared to the current price of their fossil-based counterparts, could achieve long-term future cost ratios ranging from 1 to 6.5 times, with a cost per ton of CO2eq avoided estimated between 150 and 750 €/t. In conclusion, this research provides valuable insights into the techno-economic feasibility of relying on fuels and chemicals via CCU processes as an energy policy strategy.

Low-carbon fuels (LCFs) are crucial for achieving net-zero CO2 emission goals in integrated assessment model (IAM) and energy system model (ESM) scenarios. The absence of a standardized LCF classification system and inconsistencies in modeling approaches have obscured the integration of various LCFs within these models and makes a meaningful comparison of scenario outcomes difficult. This study addresses these issues by conducting a comprehensive critical review of the representation of LCFs in IAMs and ESMs, focusing on the fuel's role in shaping net-zero emission futures. We categorize LCFs into key groups, including electrification, hydrogen, synfuels, and biofuels. Our analysis reveals substantial gaps in technical modeling, lifecycle emissions data, incomplete modeling of environmental impacts beyond CO2 emission, and discrepancies in LCF applications across sectors. To enhance the accuracy of future scenarios, we recommend adopting a unified LCF classification system, standardized input data, and more detailed sectoral applications. Additionally, we advocate for the integration of Life Cycle Assessment (LCA) into IAMs and ESMs to improve the evaluation of LCFs' full environmental impacts, providing a more comprehensive foundation for net-zero emission pathways.

Key stakeholders and researchers gather for productive discussions on sustainable fuels

Complex modeling of periodic excitation combined with time-resolved product detection is used to describe the complex response function of a catalytic system. We describe this concept of catalytic impedance spectroscopy (CIS) and the underlying general experimental approach and a concrete setup. The feasibility of CIS is experimentally demonstrated along the catalytic CO2 methanation reaction. The measurements confirm the theoretically anticipated rate-determining step of HCO* → CH* on Ni catalysts. Limitations and prospects of CIS to unravel reaction mechanisms are discussed.

Sustainable jet fuel plays a crucial role in reducing aviation’s carbon footprint, offering a promising approach toward net-zero emissions in the aviation sector. This work investigates pathways for producing jet fuels directly from CO2. Given the early stage of many direct CO2 utilization technologies, identifying promising pathways is essential. Our investigation focuses on the three most important routes for jet fuel production, each of which employs a distinct intermediate compound. These routes are the reverse water–gas shift and Fischer–Tropsch (RWGS-FT) route, the methanol route, and the CO2 electrolysis route, which employ syngas, methanol, and ethylene as key intermediates, respectively. By performing comprehensive process simulations and analyzing the resulting energy intensity and thermal and CO2 efficiency of each route, these findings provide quantitative early-stage evaluations and allow us to identify key technical development requirements.

Experts from research and industry discussed the technical and regulatory challenges of implementing sustainable fuels and platform chemicals at the first annual conference of the SWEET consortium reFuel.ch.

A decision has been made on the call for proposals “Sustainable Fuels and Platform Chemicals”: The reFuel.ch consortium led by Empa will receive project funding.

Developing robust supply paths for sustainable fuels and basic chemicals for Switzerland is the aim of the "reFuel.ch" consortium funded by the Swiss Federal Office of Energy (SFOE), which held its kick-off event on 8 December 2023. The consortium comprises nine Swiss universities, universities and research institutes from various disciplines as well as an industrial partner. As time is pressing for climate-friendly solutions, political decision-makers will also be involved.