Hungary

Direct CO₂ hydrogenation to hydrocarbons is a promising method of reducing CO2 emissions along with producing value-added products. However reactor design and performance have remained a challenging issue because of low olefin efficiency and high water production as a by-product. Accordingly a one-dimensional non-isothermal mathematical model is proposed to predict the membrane reactor performance and statistical analysis is used to assess the effects of important variables such as temperatures of reactor (Tr:A) shell (Ts:B) and tube (Tt:C) as well as sweep ratio (θ:D) and pressure ratio (φ:E) and their interactions on the products yields. In addition the optimized operating conditions are also obtained to achieve maximum olefin yields. Results reveal that interacting effects comprising AB (TrTs) AC (TrTt) AE (Trφ) BC (TsTt) CE (Ttφ) CD (Ttθ) and DE (θφ) play important roles on the product yields. It is concluded that higher temperatures at low sweep and pressure ratios can maximize the yields of olefins while simultaneously the yields of paraffins are minimized. In this regard optimized values for Tr Ts Tt θ and φ are determined as 325 °C 306.96 °C 325 °C 1 and 1 respectively.

Climate change and global warming as well as growing global demand for hydrocarbons in industrial sectors make great incentives to investigate the utilization of CO₂ for hydrocarbons production. Therefore finding an in-depth understanding of the CO₂ hydrogenation reactors along with simulating reactor responses to different operating conditions are of paramount importance. However the reaction mechanisms for CO₂ hydrogenation and their corresponding kinetic parameters have been disputable yet. In this regard considering the previously proposed Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism which considered CO₂ hydrogenation as a combination of reverse water gas shift (RWGS) and Fischer-Tropsch (FT) reactions and using a one-dimensional pseudo-homogeneous non-isothermal model kinetic parameters of the rate expressions are estimated via fitting experimental and modelling data through a novel swarm intelligence optimization technique called dragonfly algorithm (DA). The predicted reactants conversion using DA algorithm are closer to the experimental data (with about 4% error) comparing to those obtained by the artificial bee colony (ABC) algorithm and are in significant agreement with available literature data. The proposed model is used to assess the effect of reactor configuration on the performance and temperature fluctuations. Results show that axial flow spherical reactor (AFSR) and radial flow spherical reactor (RFSR) exhibiting the same surface area with that of the cylindrical reactor (CR) i.e. AFSR-2 and RFSR-2-i are the most efficient exhibiting hydrocarbons selectivity of 40.330% and 40.286% at CO₂ conversion of 53.763% and 53.891%. In addition it is revealed that the location of the jacket has an essential role in controlling the reactor temperature.

Although hydrogen is considered to be one of the most promising green fuels its efficient and safe storage and use still raise several technological challenges. Physisorption in porous materials may offer an attractive means of  storage but the state-of-the-art capacity of these kinds of systems is still limited. To overcome the present drawbacks a deeper understanding of the adsorption and surface diffusion mechanism is required along with new types of adsorbents developed and/or optimised for this purpose. In the present study we compare the hydrogen adsorption behaviour of three carbon gels exhibiting different porosity and/or surface chemistry. In addition to standard adsorption characterisation techniques neutron spin-echo spectroscopy (NSE) has been also applied to explore the surface mobility of the adsorbed hydrogen. Our results reveal that both the porosity and surface chemistry of the adsorbent play a significant role in the adsorption of  in these systems.

Deriving biohydrogen from dark fermentation is a practically suitable pathway for scaling-up and envisaged mass production. However a common issue with these systems is the incomplete conversion of feedstock as a result of which a process effluent with notable organic strength is left behind. The main components of dark fermentation effluents are volatile fatty acids that can be utilized by integrated applications involving bioelectrochemical systems particularly microbial fuel cells (MFCs) to generate electrical energy. In this work MFCs deployed to treat dark fermentative H₂ production effluents are assessed to take a look into the current standing of this specific research area and address what MFC design and operating features (reactor configuration mode of operation anode surface and reactor size) seem favorable towards improved working efficiency (e.g. power density Coulombic efficiency COD removal). Furthermore promising technological implementations are outlined and suggestions conclusions for future studies for this field are given.

Hungary’s National Hydrogen Strategy (hereinafter referred to as: Strategy) is ambitious but provides a realistic vision of the future as it opens the way for the establishment of a hydrogen economy therefore contributing to the achievement of decarbonisation goals and providing an opportunity for Hungary to become an active participant of the European hydrogen sector. On the long term the Strategy focuses on “green” hydrogen but in addition to hydrogen based on electricity generated using renewable resources primarily solar energy Hungary does not ignore opportunities for hydrogen production based on carbon-free energy accessed either through a nuclear basis or from the network. Additionally in the short and medium term a rapid reduction in emissions and the establishment of a viable hydrogen market will also require low-carbon hydrogen.

In the automotive sector the zero emissions area has been dominated by battery electric vehicles. However prospective users cite charging times large batteries and the deployment of charging stations as a counter-argument. Hydrogen will offer a solution to these areas in the future. This research focuses on the development of a prototype three-wheeled vehicle that is named Neumann H2. It integrates state-of-the-art energy storage systems demonstrating the benefits of solar- battery- and hydrogen-powered drives. Of crucial importance for the R&D platform is the system’s ability to record its internal states in a time-synchronous format providing valuable data for researchers and developers. Given that the platform is equipped with the ROS2 Open-Source interface the data are recorded in a standardized format. Energy management is supported by artificial intelligence of the “Reinforcement Learning” type which selects the optimal energy source for operation based on different layers of high-fidelity maps. In addition to powertrain control the vehicle also uses artificial intelligence to detect the environment. The vehicle’s environment-sensing system is essentially designed to detect distinguish and select environmental elements through image segmentation using camera images and then to provide feedback to the user via displays.

In this paper the effects of hydrogen on the transport of natural gas-hydrogen mixture in a high-pressure natural gas transmission system are investigated in detail. Our research focuses on the decrease in transferable energy content under identical operating conditions as hydrogen is blended in the gas transmission network. Based on the extensive literature review the outstanding challenges and key questions of using hydrogen in the natural gas system are introduced. In our research the transmissible energy factor - TEF - is defined that quantifies the relative energy capacity of the pipeline caused by hydrogen blending. A new equation is proposed in this paper to find the value of TEF at specific pressure and temperature conditions for different hydrogen concentrations. This practical equation helps the natural gas system operators in the decision-making process when hydrogen emerges in the gas transmission system. In this paper the change of the compression power requirement which increases significantly with hydrogen blending is investigated in detail.

Beside steam reforming methane pyrolysis is an alternative method for hydrogen production. ‘Turquoise’ hydrogen with solid carbon is formed in the pyrolysis process contrary to ‘grey’ or ‘blue’ hydrogen via steam methane reforming where waste carbon dioxide is produced. Thermal pyrolysis is conducted at higher temperatures but catalytic decomposition of methane (CDM) is a promising route for sustainable hydrogen production. CDM is generally carried out over four types of catalyst: nickel carbon noble metal and iron. The applied reactors can be fixed bed fluidized bed plasma bed or molten-metal reactors. Two main advantages of CDM are that (i) carbon-oxide free hydrogen ideal for fuel cell applications is formed and (ii) the by-product can be tailored into carbon with advanced morphology (e.g. nanofibers nanotubes). The aim of this review is to reveal the very recent research advances of the last two years achieved in the field of this promising prospective technology.

The on-board hydrogen storage of mobile applications is a key area of global industrial transformation to hydrogen technology. The research work provides an overview about the principle of hydrogen fuel cell vehicles with a focus on the widespread on-board hydrogen storage technologies. In this work type IV composite pressure vessels in particular are reviewed. The key challenges of polymeric liners are deeply investigated and liner collapse was identified as a critical failure of type IV vessels. Different factors of liner collapse were categorized and relevant material properties - such as permeability physical characteristics and surface properties - were explained in more detail to lay the foundation for further research on high barrier durable polymeric liner materials.

This study explores the performance and emissions characteristics of a dual-fuel internal combustion engine operating on a blend of hydrogen and gasoline. This research began with a baseline simulation of a conventional gasoline engine which was subsequently validated through experimental testing on an AVL testbed. The simulation results closely matched the testbed data confirming the accuracy of the model with deviations within 5%. Building on this validated model a hydrogen–gasoline dual-fuel engine simulation was developed. The predictive simulation revealed an approximately 5% increase in overall engine efficiency at the optimal operating point primarily due to hydrogen’s combustion properties. Additionally the injected gasoline mass and CO2 emissions were reduced by around 30% across the RPM range. However the introduction of hydrogen also resulted in a slight reduction (~10%) in torque attributed to the lower volumetric efficiency caused by hydrogen displacing intake air. While CO emissions were significantly reduced NOx emissions nearly doubled due to the higher combustion temperatures associated with hydrogen. This research demonstrates the potential of hydrogen–gasoline dual-fuel systems in reducing carbon emissions while highlighting the need for further optimization to balance performance with environmental impact.