Korea, Republic of

The average temperature of the Earth has risen due to the accumulation of greenhouse gases emitted from the usage of fossil fuels. The consequential climate changes have caused various problems fueling the growing demand for environmentally friendly energy sources that can replace fossil fuels. Batteries and hydrogen have thus been utilized as substitute energy sources for automobiles to reduce fossil fuel consumption. Consequently the number of hydrogen refueling stations is increasing due to an increase in the number of hydrogen-powered vehicles. However several incidents have been reported in the United States of America and Japan where hydrogen refueling stations have been operating for a long time. A risk assessment of hydrogen refueling stations operating in urban areas was performed in this study by calculating the risk effect range using a process hazard analysis tool (PHAST) v8.7 from DNV-GL and a hydrogen risk assessment model (HyRAM) from Sandia National Laboratories (SNL). The societal risk was assessed through a probit model based on the calculation results. The assessment results showed that the risk caused by jet fire and overpressure in an incident is lower than the ‘as low as reasonably practicable’ (ALARP) level.

This study introduced the methodology for integrating ethylene glycol/water mixture (GW) systems which supply heat energy to the liquid hydrogen (LH2 ) fuel gas supply system (FGSS) and manage the temperature conditions of the battery system. All systems were designed and simulated based on the power demand of a 2 MW class platform supply vessel assumed as the target ship. The LH2 FGSS model is based on Aspen HYSYS V14 and the cell model that makes up the battery system is implemented based on a Thevenin model with four parameters. Through three different simulation cases the integrated GW system significantly reduced electric power consumption for the GW heater during ship operations achieving reductions of 1.38% (Case 1) 16.29% (Case 2) and 27.52% (Case 3). The energy-saving ratio showed decreases of 1.86% (Case 1) 21.01% (Case 2) and 33.80% (Case 3) in overall energy usage within the GW system. Furthermore an examination of the battery system’s thermal management in the integrated GW system demonstrated stable cell temperature control within ±3 K of the target temperature making this integration a viable solution for maintaining normal operating temperatures despite relatively higher fluctuations compared to an independent GW system.

To meet the global climate goals agreed upon regarding the Paris Agreement governments and institutions around the world are investigating various technologies to reduce carbon emissions and achieve a net-negative energy system. To this end integrated solutions that incorporate carbon utilization processes as well as promote the transition of the fossil fuel-based energy system to carbon-free systems such as the hydrogen economy are required. One of the possible pathways is to utilize CO2 as the base chemical for producing a liquid organic hydrogen carrier (LOHC) using CO2 as a mediating chemical for delivering H2 to the site of usage since gaseous and liquid H2 retain transportation and storage problems. Formic acid is a probable candidate considering its high volumetric H2 capacity and low toxicity. While previous studies have shown that formic acid is less competitive as an LOHC candidate compared to other chemicals such as methanol or toluene the results were based on out-of-date process schemes. Recently advances have been made in the formic acid production and dehydrogenation processes and an analysis regarding the recent process configurations could deem formic acid as a feasible option for LOHC. In this study the potential for using formic acid as an LOHC is evaluated with respect to the state-of-the-art formic acid production schemes including the use of heterogeneous catalysts during thermocatalytic and electrochemical formic acid production from CO2 . Assuming a hydrogen distribution system using formic acid as the LOHC each of the production transportation dehydrogenation and CO2 recycle sections are separately modeled and evaluated by means of techno-economic analysis (TEA) and life cycle assessment (LCA). Realistic scenarios for hydrogen distribution are established considering the different transportation and CO2 recovery options; then the separate scenarios are compared to the results of a liquefied hydrogen distribution scenario. TEA results showed that while the LOHC system incorporating the thermocatalytic CO2 hydrogenation to formic acid is more expensive than liquefied H2 distribution the electrochemical CO2 reduction to formic acid system reduces the H2 distribution cost by 12%. Breakdown of the cost compositions revealed that reduction of steam usage for thermocatalytic processes in the future can make the LOHC system based on thermocatalytic CO2 hydrogenation to formic acid to be competitive with liquefied H2 distribution if the production cost could be reduced by 23% and 32% according to the dehydrogenation mode selected. Using formic acid as a LOHC was shown to be less competitive compared to liquefied H2 delivery in terms of LCA but producing formic acid via electrochemical CO2 reduction was shown to retain the lowest global warming potential among the considered options.

Environmental emissions global warming and energy-related concerns have accelerated the advancements in conventional vehicles that primarily use internal combustion engines. Among the existing technologies hydrogen fuel cell electric vehicles and fuel cell hybrid electric vehicles may have minimal contributions to greenhouse gas emissions and thus are the prime choices for environmental concerns. However energy management in fuel cell electric vehicles and fuel cell hybrid electric vehicles is a major challenge. Appropriate control strategies should be used for effective energy management in these vehicles. On the other hand there has been significant progress in artificial intelligence machine learning and designing data-driven intelligent controllers. These techniques have found much attention within the community and state-of-the-art energy management technologies have been developed based on them. This manuscript reviews the application of machine learning and intelligent controllers for prediction control energy management and vehicle to everything (V2X) in hydrogen fuel cell vehicles. The effectiveness of data-driven control and optimization systems are investigated to evolve classify and compare and future trends and directions for sustainability are discussed.

South Korea has drawn up plans to reduce greenhouse gases by 29.7 million tons by supplying 4.5 million electric and hydrogen cars by 2030 to implement the “2050 carbon neutrality” goal. This article gathers data on public preferences for electric cars (ECs) over hydrogen cars (HCs) in the commercial vehicle transportation sector through a survey of 1000 people. Moreover the strength of the preference was evaluated on a five-point scale. Of all respondents 60.0 percent preferred ECs and 21.0 percent HCs the former being 2.86 times greater than the latter. On the other hand the strength of the preference for HCs was 1.42 times greater than that for ECs. Factors influencing the preference for ECs over HCs were also explored through adopting the ordered probit model which is useful in examining ordinal preference rather than cardinal preference. The analyzed factors which are related to respondents’ characteristics experiences and perceptions can be usefully employed for developing strategies of promoting carbon neutrality in the commercial vehicle transportation sector and preparing policies to improve public acceptance thereof.

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.

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.

The integration of hydrogen energy systems into nearly zero-emission buildings (nZEB) is emerging as a viable strategy to curtail greenhouse gas emissions associated with energy use in these buildings. However the indoor or outdoor placement of certain hydrogen system components or equipment necessitates stringent safety measures particularly in confined environments. This study aims to investigate the dynamics of hydrogen dispersion within an enclosure featuring forced ventilation analyzing the interplay between leakage flow rates and ventilation efficiency both experimentally and numerically. To simulate hydrogen's behavior helium gas which shares similar physical characteristics with hydrogen was utilized in experiments conducted at leakage flows of 4 8 and 10 L/min alongside a ventilation rate of 30 air changes per hour (ACH). The experiments revealed that irrespective of the leakage rate the oxygen concentration returned to its initial level approximately 11 min post-leakage at a ventilation rate of 30 ACH. This study also encompasses a numerical analysis to validate the experimental findings and assess the congruence between helium and hydrogen behaviors. Additionally the impact of varying ACH rates (30 45 60 75) on the concentrations of oxygen and hydrogen was quantified through numerical analysis for different hydrogen leakage rates (4 8 10 20 L/min). The insights derived from this research offer valuable guidance for building facility engineers on designing ventilation systems that ensure hydrogen and oxygen concentrations remain within safe limits in hydrogen-utilizing indoor environments.

The war in Ukraine caused Europe to more than double its imports of liquefied natural gas (LNG) in only one year. In addition imported LNG remains a crucial source of energy for resource-poor countries such as Japan where LNG imports satisfy about a quarter of the country’s primary energy demand. However an increasing number of countries are formulating stringent decarbonization plans. Liquefied hydrogen and liquefied ammonia coupled with carbon capture and storage (LH2-CCS LNH3-CCS) are emerging as the front runners in the search for low-carbon alternatives to LNG. Yet little is currently known about the full environmental profile of LH2-CCS and LNH3-CCS because several characteristics of the two alternatives have only been analyzed in isolation in previous work. Here we show that the potential of these fuels to reduce greenhouse gas (GHG) emissions throughout the supply chain is highly uncertain. Our best estimate is that LH2-CCS and LNH3-CCS can reduce GHG emissions by 25%–61% relative to LNG assuming a 100 year global warming potential. However directly coupling LNG with CCS would lead to substantial GHG reductions on the order of 74%. Further under certain conditions emissions from LH2-CCS and LNH3-CCS could exceed those of LNG by up to 44%. These results question the suitability of LH2-CCS and LNH3-CCS for stringent decarbonization purposes.

In response to the urgent need to mitigate climate change via net-zero targets many nations are renewing their interest in clean hydrogen as a net-zero energy carrier. Although clean hydrogen can be directly used in various sectors for deep decarbonization the relatively low energy density and high production costs have raised doubts as to whether clean hydrogen development is worthwhile. Here we improve on the GCAM model by including a more comprehensive and detailed representation of clean hydrogen production distribution and demand in all sectors of the global economy and simulate 25 scenarios to explore the costeffectiveness of integrating clean hydrogen into the global energy system. We show that due to costly technical obstacles clean hydrogen can only provide 3%–9% of the 2050 global final energy use. Nevertheless clean hydrogen deployment can reduce overall energy decarbonization costs by 15%–22% mainly via powering ‘‘hard-to-electrify’’ sectors that would otherwise face high decarbonization expenditures. Our work provides practical references for cost-effective clean hydrogen planning.