Korea, Republic of

During the last decade developing more sustainable transportation modes has become a primary objective for car manufacturers and governments around the world to mitigate environmental issues such as climate change the continuous increase in greenhouse gas (GHG) emissions and energy depletion. The use of hydrogen fuel cell technology as a source of energy in electric vehicles is considered an emerging and promising technology that could contribute significantly to addressing these environmental issues. In this study the effects of Hydrogen Fuel Cell Battery Electric Vehicles (HFCBEVs) on global GHG emissions compared to other technologies such as BEVs were determined based on different relevant factors such as predicted sales for 2050 (the result of the developed prediction model) estimated daily traveling distance estimated future average global electricity emission factors future average Battery Electric Vehicle (BEV) emission factors future global hydrogen production emission factors and future average HFCBEV emission factors. As a result the annual GHG emissions produced by passenger cars that are expected to be sold in 2050 were determined by considering BEV sales in the first scenario and HFCBEV replacement in the second scenario. The results indicate that the environmental benefits of HFCBEVs are expected to increase over time compared to those of BEVs due to the eco-friendly methods that are expected to be used in hydrogen production in the future. For instance in 2021 HFCBEVs could produce more GHG emissions than BEVs by 54.9% per km of travel whereas in 2050 BEVs could produce more GHG emissions than HFCBEVs by 225% per km of travel.

The development of a Clean Hydrogen Standard based on life-cycle greenhouse gas (GHG) emissions is gaining prominence on the international agenda. Thus a framework for assessing life-cycle GHG emissions for clean hydrogen pathways is necessary. In this study the comprehensive datasets and effects of various scenarios encompassing hydrogen production carriers (liquid hydrogen ammonia methylcyclohexane) carbon capture and storage (CCS) target analysis year (2021 2030) to reflect trends of greening grid electricity and potential import countries on aggregated life-cycle GHG emissions were presented. South Korea was chosen as a case study region and the low-carbon alternatives were suggested for reducing aggregated emissions to meet the Korean standard (5 kgCO2e/kgH2). First capturing and storing nearly entire (>90%) CO2 from fossil- and waste-based production pathways is deemed essential. Second when repurposing the use of hydrogen that was otherwise used internally applying a penalty for substitution is appropriate leading to results notably exceeding the standard. Third for electrolysis-based hydrogen using renewable or nuclear electricity is essential. Lastly when hydrogen is imported in a well-to-point-of-delivery (WtP) perspective using renewable electricity during hydrogen conversion into a carrier and reusing the produced hydrogen for endothermic reconversion reaction are recommended. By implementing the developed calculation framework to other countries' cases it was observed that importing hydrogen to regions having scope of WtP or above (e.g. well-to-wheel) might not meet the threshold due to additional emissions from importation processes. Additionally for hydrogen carriers undergoing the endothermic reconversion the approach to reduce WtP emissions (reusing produced hydrogen) may conflict with the approach to reduce well-to-gate (WtG) emission (using external fossilbased fuel). The discrepancy highlights the need to set a broader scope of emissions assessment to effectively promote the life-cycle emission reduction efforts of hydrogen importers. This study contributes to the field of clean hydrogen GHG emission assessment offering a robust database and calculation framework while addressing the effects of greening grid electricity and CCS implementation proposing low-carbon alternatives and GHG assessment scope to achieve global GHG reduction.

Hydrogen is deemed as a crucial component in the transition to a carbon-free energy system and researchers are actively working to realize the hydrogen economy. While hydrogen derived from renewable energy sources is a promising means of providing clean energy to households and industries its practical usage is currently hindered by difficulties in transportation and storage. Due to the extreme operating conditions required for liquefying hydrogen various hydrogen carriers are being considered which can be transported and stored at mild operating conditions and provide hydrogen at the site of usage. Among various candidates green hydrogen carriers obtained via carbon dioxide utilization have been proposed as an economically and environmentally feasible option. Herein the potential of using methanol and formic acid as green hydrogen carriers are evaluated regarding various production and dehydrogenation pathways within a hydrogen distribution system including the recycle of carbon dioxide. Recent progress in carbon dioxide utilization processes especially conversion of carbon dioxide captured in amine solutions have demonstrated promising results for methanol and formic acid production. This study analyzes seven scenarios that consider carbon dioxide utilization-based thermocatalytic and electrochemical methanol and formic acid production as well as different dehydrogenation pathways and compares them to the scenario of delivering liquefied hydrogen. The scenarios are thoroughly analyzed via techno-economic analysis and life cycle assessment methods. The results of the study indicate that methanol-based options are economically viable reducing the cost up to 43% compared to liquefied hydrogen delivery. As for formic acid only the electrochemical production method is profitable retaining 10% less cost compared to liquefied hydrogen delivery. In terms of environmental impact all of the scenarios show higher global warming impact values than liquefied hydrogen distribution. However results show that in an optimistic case where wind electricity is widely used electrochemical formic acid production is competitive with liquefied hydrogen distribution retaining 39% less global warming impact values. This is because high conversion can be achieved at mild operating conditions for the production and dehydrogenation reactions of formic acid reducing the input of utilities other than electricity. This study suggests that while methanol can be a shortterm solution for hydrogen distribution electrochemical formic acid production may be a viable long-term option.

The widespread use of fossil fuels in automobiles has become a concern particularly in light of recent frequent natural disasters prompting a shift towards eco-friendly vehicles to mitigate greenhouse gas emissions. This shift is evident in the rapidly increasing registration rates of hydrogen vehicles. However with the growing presence of hydrogen vehicles on roads a corresponding rise in related accidents is anticipated posing new challenges for first responders. In this study computational fluid dynamics analysis was performed to develop effective response strategies for first responders dealing with high-pressure hydrogen gas leaks in vehicle accidents. The analysis revealed that in the absence of blower intervention a vapor cloud explosion from leaked hydrogen gas could generate overpressure exceeding 13.8 kPa potentially causing direct harm to first responders. In the event of a hydrogen vehicle accident requiring urgent rescue activities the appropriate response strategy must be selected. The use of blowers can aid in developing a variety of strategies by reducing the risk of a vapor cloud explosion. Consequently this study offers a tailored response strategy for first responders in hydrogen vehicle leak scenarios emphasizing the importance of situational assessment at the incident site.

An energy source transition is necessary to realize carbon neutrality emphasizing the importance of a hydrogen economy. The transportation sector accounted for 27% of annual carbon emissions in 2019 highlighting the increasing importance of transitioning to hydrogen vehicles and establishing hydrogen refueling stations (HRSs). In particular HRSs need to be prioritized for deploying hydrogen vehicles and developing hydrogen supply chains. Thus research on HRS is important for achieving carbon neutrality in the transportation sector. In this study we improved the efficiency and scaled up the capacity of an on-site HRS (based on steam methane reforming with a hydrogen production rate of 30 Nm3/h) in Seoul Korea. This HRS was a prototype with low efficiency and capacity. Its efficiency was increased through thermodynamic analysis and heat exchanger network synthesis. Furthermore the process was scaled up from 30 Nm3/h to 150 Nm3/h to meet future hydrogen demand. The results of exergy analysis indicated that the exergy destruction in the reforming reactor and heat exchanger accounted for 58.1% and 19.8% respectively of the total exergy destruction. Thus the process was improved by modifying the heat exchanger network to reduce the exergy losses in these units. Consequently the thermal and exergy efficiencies were increased from 75.7% to 78.6% and from 68.1% to 70.4% respectively. The improved process was constructed and operated to demonstrate its performance. The operational and simulation data were similar within the acceptable error ranges. This study provides guidelines for the design and installation of low-carbon on-site HRSs.

The global trend towards decarbonization and the demand for energy security have put hydrogen energy into the spotlight of industry politics and societies. Numerous governments worldwide are adopting policies and strategies to facilitate the transition towards hydrogen-based economies. To assess the determinants of such transition this study presents a comparative analysis of the technological innovation systems (TISs) for hydrogen technologies in Germany and South Korea both recognized as global front-runners in advancing and implementing hydrogen-based solutions. By providing a multi-dimensional assessment of pathways to the hydrogen economy our analysis introduces two novel and crucial elements to the TIS analysis: (i) We integrate the concept of ‘quality infrastructure’ given the relevance of safety and quality assurance for technology adoption and social acceptance and (ii) we emphasize the social perspective within the hydrogen TIS. To this end we conducted 24 semi-structured expert interviews applying qualitative open coding to analyze the data. Our results indicate that the hydrogen TISs in both countries have undergone significant developments across various dimensions. However several barriers still hinder the further realization of a hydrogen economy. Based on our findings we propose policy implications that can facilitate informed policy decisions for a successful hydrogen transition.

With an increase in the use of eco-friendly vehicles such as hybrid electric and hydrogen vehicles in response to the global climate crisis accidents related to these vehicles have also increased. Numerical analysis was performed to optimize the safety of first responders responding to hydrogen vehicle accidents wherein hydrogen jet flames occur. The influence range of the jet flame generated through a 1.8-mm-diameter nozzle was analyzed based on five discharge angles (90 75 60 45 and 30◦ ) between the road surface and the downward vertical. As the discharge angle decreases toward the road surface the risk area that could cause damage moves from the center of the vehicle to the rear; at a discharge angle of 90◦ the range above 9.5 kW/m2 was 1.59 m and 4.09 m to the front and rear of the vehicle respectively. However at a discharge angle of 30◦ it was not generated at the front but was 10.39 m to the rear. In response to a hydrogen vehicle accident first responders should perform rescue activities approaching from a diagonal direction to the vehicle front to minimize injury risk. This study can be used in future hydrogen vehicle design to develop the response strategy of the first responders.

This review explores the recent advancements in catalyst technology for hydrogen production emphasizing the role of catalysts in efficient and sustainable hydrogen generation. This involves a comprehensive analysis of various catalyst materials including noble metals transition metals carbon-based nanomaterials and metal–organic frameworks along with their mechanisms and performance outcomes. Major findings reveal that while noble metal catalysts such as platinum and iridium exhibit exceptional activity their high cost and scarcity necessitate the exploration of alternative materials. Transition metal catalysts and single-atom catalysts have emerged as promising substitutes demonstrating their potential for enhancing catalytic efficiency and stability. These findings underscore the importance of interdisciplinary approaches to catalyst design which can lead to scalable and economically viable hydrogen production systems. The review concludes that ongoing research should focus on addressing challenges related to catalyst stability scalability and the integration of renewable energy sources paving the way for a sustainable hydrogen economy. By fostering innovation in catalyst development this work aims to contribute to the transition towards cleaner energy solutions and a more resilient energy future.

Hydrogen tractors are being developed necessitating consideration of the variation in the center of gravity depending on the arrangement of components such as power packs and cooling modules that replace traditional engines. This study analyzes the effects of component arrangement on stability and rollover angle in hydrogen tractors through simulations and proposes an optimal configuration. Stability is evaluated by analyzing rollover angles in various directions with rotations around the tractor’s midpoint. Based on the analysis of rollover angles for Type 1 Type 2 and Type 3 hydrogen tractors Type 2 demonstrates superior stability compared to the other types. Specifically when comparing lateral rollover angles at 0◦ rotation Type 2 exhibits a 2% increase over Type 3. Upon rotations at 90◦ and 180◦ Type 2 consistently displays the highest rollover angles with differences ranging from approximately 6% to 12% compared to the other types. These results indicate that Type 2 with its specific component arrangement offers the most stable configuration among the three types of tractors. It is confirmed that the rollover angle changes based on component arrangement with a lower center of gravity resulting in greater stability. These findings serve as a crucial foundation for enhancing stability in the future design and manufacturing phases of hydrogen tractors.

With the world-wide decision to reduce carbon emissions through the Paris Agreement (2015) the demand for hydrogen-fuelled vehicles has been increasing. Although hydrogen is not a toxic gas it has a wide flammable range (4e75%) and can explode due to static electricity. Therefore studies on hydrogen safety are urgently required. In this study an explosion was induced by applying fire to the lower part of a fuel cell electric vehicle (FCEV). Out of three compressed hydrogen storage tanks installed in the vehicle two did not have hydrogen fuel and one was filled with compressed gaseous hydrogen of 700 bar and forcedly deactivated its temperature-activated pressure relief device. The side-on overpressure transducers were installed by distance in main directions to measure the side-on overpressure generated by the vehicle explosion. A 10 m-long protective barrier was installed on which reflected overpressure displacement and acceleration were measured to examine the effect of attenuation of explosion damage in the event of an accident. The vehicle exploded approximately 11 min after ignition generating a blast wave fireballs and fragments. The results of the experiment showed that the protective barrier could almost completely block explosive pressure smoke and scattering generated during an explosion. Through Probit function analysis the probabilities of an accident occurring were derived based on peak overpressure peak impulse and scattering. The results of this study can be used to develop standard operating procedures (SOPs) for firefighters as the base data for setting the initial operation location and deriving the safe separation distance.