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The summers of 2020 and 2022 have represented two crossroads in the expectations around the role of hydrogen in the European energy system, setting a target of low-carbon hydrogen supply by 2030 more than twofold compared to the current carbon-intensive levels. While one half of the European supply is planned to be domestically produced within Europe, the other half is envisioned to be sourced from international markets. Projections for low-carbon hydrogen demand in Europe by 2050 range from half the current carbon-intensive demand level to a tenfold increase. Globally, the expected demand for low-carbon hydrogen in 2050 varies from equaling the current carbon-intensive demand level to a sevenfold increase. Factors affecting the scaling of low-carbon hydrogen supply are diverse and vary from the need to enhance the readiness of emerging production technologies to the adoption of mature technologies which lack an economy of scale. Different dynamics surround the hydrogen demand in 2050. Currently, hydrogen is mainly produced and consumed in production plants to refine hydrocarbons, or to produce ammonia and methanol. Current trade mainly concerns the fossil fuels used for its production. In the effort of achieving the net-zero target, hydrogen's role is predicted to extend to demand sectors where it's never been deployed on a large scale and where direct electrification faces limitations, such as heavy-duty transport, aviation, shipping, steel production, and industrial heat generation for the manufacturing of cement and other industrial products. The use of hydrogen relies on the presence of infrastructure to facilitate its transportation between production sites and demand points. Due to hydrogen's low volumetric energy density and high volatility, its derived carriers, i.e. ammonia, methanol, or synthetic hydrocarbons, might be preferred for its transport and as molecules for its final use. The primary goal of this research has been to quantify the hydrogen demand, Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

The challenge in the energy transition lies in the intermittent nature of renewable energy, requiring the development of effective storage methods. E-fuels are considered a promising solution, with potential applications to Homogeneous Charge Compression Ignition (HCCI) engines known for their high thermal efficiency and low nitrogen oxide emissions. However, HCCI engines face limitations such as low power density and a narrow operating range. To overcome these issues, oxygen-enriched combustion is proposed, aiming at enhancing the mixture reactivity and expanding the operating range by decreasing the intake temperature. As the potential of the expansion of the operating range has never been investigated, we performed an experimental campaign using a methane-fuelled HCCI engine at variable oxygen fractions in the oxidizer. To further elucidate the effects of oxy-fuel combustion, we also performed a kinetic analysis of the reactions driving the combustion behaviour. It has been experimentally found that increasing the oxygen content in the mixture, up to 90%, has a significant potential to decrease the needed intake temperature (up to 70 °C) of the charge to keep the Maximum Pressure Rise Rate (MPRR) below the safety threshold of 8 bar/CAD. Despite the notable IMEP increase achieved, operating the engine at high oxygen content presents significant technical challenges. Therefore, to make HCCI engines competitive with other combustion modes, it is essential to combine oxygen enrichment with additional power density enhancement techniques. The kinetic analysis has highlighted that the mixture is less sensitive to intake temperature changes at higher oxygen percentages (above 50%) and that the rates of the main reactions involved in methane and OH consumption are highly enhanced by oxygen addition., SCOPUS: ar.j, info:eu-repo/semantics/published

Energy crops on marginal lands are seen as an interesting option to increase biomass contribution to the primary energy mix. However, in the literature there is currently a lack of integrated assessments of margin land availability, energy crop production potential and supply chain optimisation. Assessing the potential and the cost of these resources in a given region is therefore a difficult task. This work also emphasises the importance on a clear definition and discussion about marginal lands and the related ethical issues embedded in the concept to ensure positive societal impacts of the results. This study proposes a methodology to estimate and analyse, in terms of economic costs, the potential of miscanthus grown on marginal lands from the production to the final point of use. Different datasets are assembled and a supply chain optimisation model is developed to minimize the total cost of the system. Miscanthus is used as a representative energy crop for the Belgian and French case studies. High temperature heat demand is considered as final use. The miscanthus can be traded by truck either in the form of chips or pellets. The results show that the miscanthus on marginal lands could supply high temperature heat up to 38 TWh in France and 1,4 TWh in Belgium with an average cost of around 50 €/t. The different sensitivity analyses showed that the yield variation has the strongest influence on the final cost, together with the distances and the cost of production of miscanthus. The main pattern observed is the local consumption of miscanthus chips and export of the surplus (if any) to the neighbouring regions. Pellets are only of marginal interest for France and are never observed for Belgium. Distances and availability of sufficient feedstocks are the two main parameters impacting the production of pellets.

Il existe de nombreuses manières de concevoir la transition écologique et sociale, et de les ordonner les unes par rapport aux autres. Du point de vue heuristique, une façon commode de les penser consiste à les ranger le long d’un spectre dont les extrémités sont incarnées respectivement par l’État et par la société, dans un cadre de pensée politique qui conçoit celui-ci et celle-là comme des instances séparées l’une de l’autre (Castoriadis, 2007). D’un côté, il y aurait une transition « par le haut », à partir de l’État ou du centre, par le recours aux outils de la réglementation juridique, des incitants économiques (taxes et subsides) ou de la planification. De l’autre côté, se situerait la transition « par le bas », à partir d’initiatives locales conduites par des hommes et des femmes ordinaires, dans des contextes spécifiques, le plus souvent à petite échelle. Entre les deux, il y aurait place pour une transition par les mécanismes du marché, sous la forme d’une « croissance verte » ou d’un « capitalisme vert », de la responsabilité sociétale des entreprises ou de l’investissement socialement responsable.

European Green Deal sets the EU’s target towards becoming the world’s first climate-neutral continent by 2050. To achieve the 2050 Green Deal target, multi-combined actions are required, such as increasing renewable energy (RE) production in the EU, enhancing efficiency, and importing RE. The limited area, high population density, and geographical position constrain the EU’s RE self-sufficiency; in fact, the energy import dependency of the European Union (EU-27) reached 58.4% and 60.7% in 2018 and 2019, respectively. Interestingly, the final energy consumption by fuel comprises 23% of electricity and 77% of molecules. Consequently, a sustainable energy system requires not only green electricity but green molecules as well to move from fossil to electrified chemical industry (chemistree). In this context, the work analyses the LCOE of importing RE from Morocco, Algeria, Egypt, and Saudi Arabia to selected locations in the EU namely Rome, Madrid, and Cologne, since they have both a well-established energy importing/exporting network with the EU and a high potential of RE sources. A promising LCOE of H2 is found in all importing scenarios with an average of 5.20 €/kgH2. Hydrogen transport via pipelines (0.14 €/kg/1000 km) is found to be the optimal solution for the studied cases. Further investigation is required for importing RE via other types of molecules and e-fuels such as ammonia, methanol, and methane from the Middle East and North Africa (MENA) to the EU.

The control and characterization of the fracture behavior of thin films and 2D materials, in the era of continuous device miniaturization, are of paramount importance for the design and integrity assessment of many coatings and microelectronics devices towards more reliable devices. However, the available test methods suffer from many limitations mainly when the film rests on a substrate due to different constraints that are difficult to deconvolute and or with the introduction of an initial sharp precrack in freestanding configurations. In this context, the objective of this research is to develop a robust on-chip fracture technique for freestanding thin films and 2D materials. This crack-on-chip method consists of actuator beams produced by lithography undergoing large internal stress attached to a notched specimen beam. Both actuators and specimens are deposited on top of a Si substrate. The etching of a part of this substrate induces the release of the test structure, with the actuators then contracting and pulling on the test specimen. If the applied displacement is large enough, a crack initiates at the notch root and propagates. The design has been selected such as to involve a decrease of the crack driving force after some amount of crack growth leading to crack arrest, avoiding the problem of notch opening of the precrack. The technique can also be used to investigate the environmentally-assisted cracking in thin-film materials. The fracture toughness of SiO2 (142 nm), SiN (50 nm), Al2O3 (190 nm), and CVD-grown monolayer graphene was extracted. It was found that Al2O3 films are more prone to subcritical aging compared to SiN, while simultaneously exhibiting larger resistance to environmental cracking than thermally-grown SiO2 films. For single-layer graphene, fracture strain, Young’s modulus, strength, and Weibull modulus were determined with, for the first time, statistically representative data., (FSA - Sciences de l'ingénieur) -- UCL, 2022

Biomass is a key renewable resource for energy transition and climate change mitigation. It can be used for either energy purposes (production of heat, electricity, and fuel) or non- energy demand (e.g., chemicals). This raises the question of the optimal use of biomass in energy systems. In the literature, this optimal use is often determined for one specific situation in terms of greenhouse gas emissions and rarely considering the non-energy demand. The non-energy demand is defined as the demand for energy products used as raw materials. Given the expected simultaneous changes in all industrial sectors, it is important to include the non-energy demand in the models of energy systems as they will share common resources. This paper 1) studies the optimal use of lignocellulosic biomass within an energy system including the non-energy demand and 2) analyzes the evolution of its role throughout the energy transition. Belgium is taken as a case study as it presents a non-energy demand corresponding to ~15% of its primary energy mix. The energy system is modeled with EnergyScope TD which optimizes whole-energy systems in terms of costs under greenhouse gas emission constraints. Local and imported biomass is considered with two potential scenarios. Fourteen biomass-converting technologies are included in the model. It is shown that high-temperature heat remains a significant application for biomass in all scenarios and increases when moving toward carbon neutrality. For greenhouse gas savings below 50%, biomass is largely used for low-temperature heat. However, when aiming at reducing greenhouse gas further (>50% reduction), biomass is substantially exploited for the non-energy demand. Electricity from biomass also appears, to a lesser extent, for large greenhouse gas savings only. The integration of the non-energy demand in the simulations impacts the allocation of biomass in the system, depending on the scenario of potential considered.

The high-quality two-dimensional (2D) crystals possess remarkable mechanical behaviour which offers exciting opportunities for new material selection and design, like the combination of extremely high in-plane stiffness and bending flexibility. For this reason, nanomechanical testing of 2D layers and their 3D heterostructures is vital in order to prove that they can be practical and useful in different applications. In this work, different nanomechanical testing including membrane deflection, nanoindentation and tensile tests have been performed with various techniques such as atomic force microscopy, nanoindentation and lab-on-chip developed in UCLouvain, respectively. The elastic and plastic behaviour of graphene as well as its effect on the mechanical response of copper thin film have been investigated by using these methods. For each technique, some challenges are required to be faced and some uncertainties needed to be considered in order to extract the mechanical response precisely. Membrane deflection on single and bilayer graphene has been performed in order to extract Young’s modulus and fracture strength of these layers by considering the uncertainties and errors that can occur regarding the device calibration and experimental procedure. The effect of CVD-graphene on the plastic behaviour of Cu thin film in two different configurations has been investigated by nanoindentation in two different modes which are complementary to each other limitations. In this configuration, graphene acted as a perfect barrier against the movement and propagation of dislocations underneath the indent. In the last part, lab-on-chip (LOC) technique has been used to evaluate the effect of graphene on the fracture and creep behaviour of thin film of copper. Although convincing and reliable experimental data could not be generated, a well-defined, adapted process for Cu/Gr specimens with Ni actuators has been proposed and the solutions for most of the challenges in each step have b, (FSA - Sciences de l'ingénieur) -- UCL, 2022

The use of microbial fuel cells (MFCs) as a bioelectrochemical system (BES) for the treatment of textile wastewater has attracted attention due to the ability to produce bioelectricity from wastewater treatment. However, textile wastewater is far from being an ideal electrolyte for an electrochemical process. It can generate biofouling on electrodes and separators (membranes), affecting greatly the efficiency in such systems. In recent years, different types of membranes have been explored as separators in MFCs, although to our knowledge no nanofiltration membranes have ever been used in such systems. Nanofiltration membranes share advantages with porous and non-porous membranes. In addition, the wide variety of nanofiltration membranes, high oxygen retention, and lower electrical resistance compared to ion-selective membranes normally used in BES, made these types of membranes potential separators. In this work, an integrated process is proposed, including three technologies, i.e., membrane technology, an advanced oxidation process, and microbial fuel cells. Antifouling and self-cleaning membranes are developed as efficient separators for a new generation of osmotic systems (nanofiltration microbial fuel cells) in textile wastewater treatment. A new method of modification of bio-inspired membranes with commercial catalysts (TiO2 and ZnO) showed that the modified membranes acquired antibacterial, self-cleaning, and antifouling properties, improved when the catalysts were combined. The application of this method on low-cost membranes exhibited a significant improvement in COD and color removal, as well as an improvement in bioelectricity production in the MFCs. In order to further improve the activation efficiency of the photocatalysts under visible light and the antifouling properties of the membranes, a new catalyst (ZnO Er/Al) was synthesized, which demonstrated high photocatalytic and antibacterial activity. The new membranes also demonstrated efficient resistanc, (FSA - Sciences de l'ingénieur) -- UCL, 2022

Nitrogen oxides (NOx and N2O) are harmful atmospheric pollutants, mostly emitted by high-temperature combustion processes [1]. Extensive research activity on NOx control is being driven by increasingly stricter emission limits and the need of fuel flexible combustion systems. In this context, Coke Oven Gas (COG), a valuable by-product of coal carbonization, remains an attractive energy source [2,3]. After being cleaned from tar residues and other impurities; COG mostly contains H2, CH4, CO and small percentages of aromatic compounds, of which benzene is the most abundant one [2,4]. The proper exploitation of COG in combustion processes requires a detailed kinetic characterization, to assess both the combustion efficiency and pollutants emissions. This work aims to shed light on the effect of benzene on NOx formation in low pressure premixed H2/CH4/CO-air flames doped with benzene (0 to 1% in the fuel), as COG surrogates. A joint experimental and numerical study was performed at three different equivalence ratios (0.8, 1 and 1.2).

The exponential growth of technology opened the door for a new generation of locomotion assistive devices (e.g. prostheses and exoskeletons) to emerge. The latest generation is lighter weight due to the emergence of smart and composite materials, and advanced actuators and sensors. Controlling these devices to compensate for limb loss or walking disorder requires the generation of various gait patterns for different locomotion tasks like stairs ascending, descending, and level ground walking. However, this requires that these devices be able to detect the actions and intentions of their human user when traversing from one type of terrain to another. Such transition requires switching to the new task in a timely manner; otherwise, the user is more vulnerable to falls and injuries. Typical solutions to detect a new locomotion task are based either on sensors that measure the user’s kinematics or on a voluntary action of the user, such has tilting their chest or pushing a button. While the former suffers from a delay, the latter provides an unnatural way of behaving during locomotion. Recently, alternative methods have been proposed that uses wearable ranging sensors or camera. However, the implemented approaches for terrain identification with such sensors have been only validated in single indoor and/or outdoor path(s). Also, the system detection ability in a path being partially occluded by other walkers has not been addressed yet. Last but not least, the detection results are obtained based on a pre-specified region of interest in front of the user, without applying extra processing to predict the terrain information for several upcoming steps. In this thesis, we introduce a computer vision-based terrain detection algorithm that relies on a depth camera attached to the user’s chest. The camera, therefore, could capture the scene in front of the user in a point cloud data format, while the algorithm applies several steps on the captured data in order to achieve envi, (FSA - Sciences de l'ingénieur) -- UCL, 2022

What a pleasant feeling to stay in one’s comfort zone: working on a model of energy systems (EnergyScope) using sources, conversion technologies, and demands. But what a disturbing realization when one looks at the boundaries of such models: What is the realistic potential of renewables?, How would the demand for transport evolve?, What is the intrinsic link between energy and economy? Through several PhD theses, we have started addressing these questions. In this presentation, we will give you the first results and future directions.

Gasification is a thermochemical conversion process of biomass. Gasification is used for heat and power generation applications. This process is promising in a West African environment where energy needs are significant and where biomass potential is considerable. The aim of this study is the valorization by gasification of agricultural residues especially rice husk. It resulted to a design and a manufacture of a gasification reactor suitable for small-scale industrial units in the agricultural processing sector. This study is divided into several stages, namely a design methodology of the prototype, an equilibrium modelling of the gas composition, a simulation of the process heat losses and an experimental study of the prototype. Several parameters have been studied experimentally, namely the equivalence ratio, the air injection levels as well as the fuel supply mode. The produced gas was analyzed in order to determine the operating conditions to obtain the best yield of gasification. The best experimental results were carried out at an equivalence ratio of 0.32 for a thermal power of 50 kWth[LHV] and a global efficiency of 46 %. The composition of the produced gas is 14.62 % of CO, 12.89 % of CO2, 2.89 % of CH4 and 6.84 % of H2. These results with a relatively low yield are explained by the low process temperatures and a cold reduction zone. In fact, the heat losses estimated at 8 % of the energy balance of the exiting entities of the reactor, but they are probably higher. Some operational difficulties such as the homogenization of the bed during gasification lead to the formation of bypass where the pyrolysis gases are entrained towards the outlet. This also explains the proportions of the gas obtained with low CO and H2 contents. The experimental campaign carried out on the gasifier allows to issue perspectives to improve yields for future work., (SC - Sciences) -- UCL, 2022

The minimization of nitrogen oxides (NOx) emissions is among the major concerns of combustion-related processes, together with the adverse effects related to the emission of greenhouse gases. NOx emission control can become very challenging for those combustion processes which require high temperatures, and/or involve the exploitation of non-conventional fuel mixtures. This PhD thesis work aims to shed light on NOx formation during combustion of Coke Oven Gas (COG) and particularly to understand the role that aromatic chemical compounds could play during NOx formation. COG is an attractive energy source derived from the coal carbonization, due to its high H2 content and calorific value. It has been widely investigated as a fuel directly burnt in-situ to sustain the energy requirement of the integrated steel production processes, or as an important source of valuable compounds (i.e. H2, CH4, syngas, methanol, etc). The residual presence of aromatic compounds in COG, downstream the raw COG purification line, can potentially affect both its combustion efficiency and pollutant emissions. Therefore, a fundamental understanding of the interactions between NOx formation and aromatic species oxidation is required to both valorize the use of COG as energy carrier, and to highlight promising strategies for the minimization of NOx emissions during the combustion of COG in coke making plants. Benzene (C6H6) has been considered as the representative aromatic compound. The effect of its addition on NO formation chemistry, during combustion of COG surrogate fuel blends has been investigated, under different stoichiometric conditions. A hierarchical approach was used in this thesis work to achieve this objective. Indeed, NOx formation during combustion of a COG surrogate mixture (H2/CH4/CO) has been investigated at i) lab-scale, in low-pressure flat premixed laminar flames through a joint experimental and kinetic modeling study, and at ii) semi-industrial scale, in a 20-kW semi-ind, Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

Biomass is a key renewable resource for energy transition and climate change mitigation. It can be used for either energy purposes (production of heat, electricity, and fuel) or non-energy demand (e.g. chemicals). This raises the question of the optimal use of biomass in energy systems. In the literature, this optimal use is often determined for one specific situation in terms of greenhouse gas emissions and rarely considering the non-energy demand. The non-energy demand is defined as the demand for energy products used as raw materials. Given the expected simultaneous changes in all industrial sectors, it is important to include the non-energy demand in the models of energy systems as they will share common resources. This paper 1) studies the optimal use of lignocellulosic biomass within an energy system including the non-energy demand and 2) analyzes the evolution of its role throughout the energy transition. Belgium is taken as a case study as it presents a non-energy demand corresponding to ∼15% of its primary energy mix. The energy system is modeled with EnergyScope TD which optimizes whole-energy systems in terms of costs under greenhouse gas emission constraints. Local and imported biomass is considered with two potential scenarios. Fourteen biomass-converting technologies are included in the model. It is shown that high-temperature heat remains a significant application for biomass in all scenarios and increases when moving toward carbon neutrality. For greenhouse gas savings below 50%, biomass is largely used for low-temperature heat. However, when aiming at reducing greenhouse gas further (>50% reduction), biomass is substantially exploited for the non-energy demand. Electricity from biomass also appears, to a lesser extent, for large greenhouse gas savings only. The integration of the non-energy demand in the simulations impacts the allocation of biomass in the system, depending on the scenario of potential considered., SCOPUS: ar.j, info:eu-repo/semantics/published