Korea, Republic of
Secure Hydrogen Production Analysis and Prediction Based on Blockchain Service Framework for Intelligent Power Management System
Nov 2023
Publication
The rapid adoption of hydrogen as an eco-friendly energy source has necessitated the development of intelligent power management systems capable of efficiently utilizing hydrogen resources. However guaranteeing the security and integrity of hydrogen-related data has become a significant challenge. This paper proposes a pioneering approach to ensure secure hydrogen data analysis by integrating blockchain technology enhancing trust transparency and privacy in handling hydrogen-related information. Combining blockchain with intelligent power management systems makes the efficient utilization of hydrogen resources feasible. Using smart contracts and distributed ledger technology facilitates secure data analysis (SDA) real-time monitoring prediction and optimization of hydrogen-based power systems. The effectiveness and performance of the proposed approach are demonstrated through comprehensive case studies and simulations. Notably our prediction models including ABiLSTM ALSTM and ARNN consistently delivered high accuracy with MAE values of approximately 0.154 0.151 and 0.151 respectively enhancing the security and efficiency of hydrogen consumption forecasts. The blockchain-based solution offers enhanced security integrity and privacy for hydrogen data analysis thus advancing clean and sustainable energy systems. Additionally the research identifies existing challenges and outlines future directions for further enhancing the proposed system. This study adds to the growing body of research on blockchain applications in the energy sector specifically on secure hydrogen data analysis and intelligent power management systems.
Spatiotemporal Analysis of Hydrogen Requirement to Minimize Seasonal Variability in Future Solar and Wind Energy in South Korea
Nov 2022
Publication
Renewable energy supply is essential for carbon neutrality; however technologies aiming to optimally utilize renewable energy sources remain insufficient. Seasonal variability in renewable energy is a key issue which many studies have attempted to overcome through operating systems and energy storage. Currently hydrogen is the only technology that can solve this seasonal storage problem. In this study the amount of hydrogen required to circumvent the seasonal variability in renewable energy supply in Korea was quantified. Spatiotemporal analysis was conducted using renewable energy resource maps and power loads. It was predicted that 50% of the total power demand in the future will be met using solar and wind power and a scenario was established based on the solar-to-wind ratio. It was found that the required hydrogen production differed by approximately four-times depending on the scenarios highlighting the importance of supplying renewable energy at an appropriate ratio. Spatially wind power was observed to be unsuitable for the physical transport of hydrogen because it has a high potential at mountain peaks and islands. The results of this study are expected to aid future hydrogen research and solve renewable energy variability problems.
Safety Issues of a Hydrogen Refueling Station and a Prediction for an Overpressure Reduction by a Barrier Using OpenFOAM Software for an SRI Explosion Test in an Open Space
Oct 2022
Publication
Safety issues arising from a hydrogen explosion accident in Korea are discussed herein. In order to increase the safety of hydrogen refueling stations (HRSs) the Korea Gas Safety Corporation (KGS) decided to install a damage-mitigation wall also referred to as a barrier around the storage tanks at the HRSs after evaluating the consequences of hypothetical hydrogen explosion accidents based on the characteristics of each HRS. To propose a new regulation related to the barrier installation at the HRSs which can ensure a proper separation distance between the HRS and its surrounding protected facilities in a complex city KGS planned to test various barrier models under hypothetical hydrogen explosion accidents to develop a standard model of the barrier. A numerical simulation to investigate the effect of the recommended barrier during hypothetical hydrogen explosion accidents in the HRS will be performed before installing the barrier at the HRSs. A computational fluid dynamic (CFD) code based on the open-source software OpenFOAM will be developed for the numerical simulation of various accident scenarios. As the first step in the development of the CFD code we conducted a hydrogen vapor cloud explosion test with a barrier in an open space which was conducted by the Stanford Research Institute (SRI) using the modified XiFoam solver in OpenFOAMv1912. A vapor cloud explosion (VCE) accident may occur due to the leakage of gaseous hydrogen or liquefied hydrogen owing to a failure of piping connected to the storage tank in an HRS. The analysis results using the modified XiFoam predicted the peak overpressure variation from the near field to the far field of the explosion site through the barrier with an error range of approximately ±30% if a proper analysis methodology including the proper mesh distribution in the grid model is chosen. In addition we applied the proposed analysis methodology using the modified XiFoam to barrier shapes that varied from that used in the test to investigate its applicability to predict peak overpressure variations with various barrier shapes. Through the application analysis we concluded that the proposed analysis methodology is sufficient for evaluating the safety effect of the barrier which will be recommended through experimental research during VCE accidents at the HRSs.
Economic Analysis of P2G Green Hydrogen Generated by Existing Wind Turbines on Jeju Island
Dec 2022
Publication
Every wind turbine is subject to fluctuations in power generation depending on climatic conditions. When electricity supply exceeds demand wind turbines are forced to implement curtailment causing a reduction in generation efficiency and commercial loss to turbine owners. Since the frequency and amount of curtailment of wind turbines increases as the amount of renewable energy become higher on Jeju Island in South Korea Jeju is configuring a Power to Gas (P2G) water electrolysis system that will be connected to an existing wind farm to use the “wasted energy”. In this study economic analysis was performed by calculating the production cost of green hydrogen and sensitivity analysis evaluated the variance in hydrogen cost depending on several influential factors. Approaches to lower hydrogen costs are necessary for the following reasons. The operating company needs a periodical update of hydrogen sale prices by reflecting a change in the system margin price (SMP) with the highest sensitivity to hydrogen cost. Technical development to reduce hydrogen costs in order to reduce power consumption for producing hydrogen and a decrease in annual reduction rate for the efficiency of water electrolysis is recommended. Discussions and research regarding government policy can be followed to lower the hydrogen cost.
Urban Hydrogen Production Model Using Environmental Infrastructures to Achieve the Net Zero Goal
Dec 2022
Publication
Land available for energy production is limited in cities owing to high population density. To reach the net zero goal cities contributing 70% of overall greenhouse gas emissions need to dramatically reduce emissions and increase self-sufficiency in energy production. Environmental infrastructures such as sewage treatment and incineration plants can be used as energy production facilities in cities. This study attempted to examine the effect of using environmental infrastructure such as energy production facilities to contribute toward the carbon neutrality goal through urban energy systems. In particular since the facilities are suitable for hydrogen supply in cities the analysis was conducted focusing on the possibility of hydrogen production. First the current status of energy supply and demand and additional energy production potential in sewage treatment and incineration plants in Seoul were analyzed. Then the role of these environmental infrastructures toward energy self-sufficiency in the urban system was examined. This study confirmed that the facilities can contribute to the city’s energy self-sufficiency and the achievement of its net-zero goal.
Experimental Analysis of the Effects of Ship Motion on Hydrogen Dispersion in an Enclosed Area
Apr 2023
Publication
This study aims to experimentally quantify the hydrogen diffusion characteristics by ship motion. Hydrogen leakage experiments were conducted under various ship motion conditions and the corresponding hydrogen concentrations for each sensor were expressed by an equation. The experimental facility was a scale model of the hydrogen fuel storage room of a ship. An experiment was conducted by implementing the roll and pitch motions of the ship as well as motion direction using a ship simulator. In the equation describing the hydrogen concentration the minimum and maximum root mean square deviations were 0.987 and 0.707 respectively and the correlations were 0.000109 and 0.0012289. Although the results differed as per the sensor location the hydrogen concentration was affected by the motion period of the ship. The experimental results and prediction equations can be useful for sensor and vent location selection by predicting the concentration when hydrogen leaks in ships in motion.
Impacts of Green Energy Expansion and Gas Import Reduction on South Korea’s Economic Growth: A System Dynamics Approach
Jun 2023
Publication
South Korea ranking ninth among the largest energy consumers and seventh in carbon dioxide emissions from 2016 to 2021 faces challenges in energy security and climate change mitigation. The primary challenge lies in transitioning from fossil fuel dependency to a more sustainable and diversified energy portfolio while meeting the growing energy demand for continued economic growth. This necessitates fostering innovation and investment in the green energy sector. This study examines the potential impact of green energy expansion (through integrating renewable energy and hydrogen production) and gas import reduction on South Korea’s economic growth using a system dynamics approach. The findings indicate that increasing investment in green energy can result in significant growth rates ranging from 7% to 35% between 2025 and 2040. Under the expansion renewable energy scenario (A) suggests steady but sustainable economic growth in the long term while the gas import reduction scenario (B) displays a potential for rapid economic growth in the short term with possible instability in the long term. The total production in Scenario B is USD 2.7 trillion in 2025 and will increase to USD 4.8 trillion by 2040. Scenario C which combines the effects of both Scenarios A and B results in consistently high economic growth rates over time and a substantial increase in total production by 2035–2040 from 20% to 46%. These findings are critical for policymakers in South Korea as they strive for sustainable economic growth and transition to renewable energy.
Techno-economic Analysis of High-power Solid Oxide Electrolysis Cell System
Jan 2023
Publication
Water electrolysis using solid oxide electrolysis cells is a promising method for hydrogen production because it is highly efficient clean and scalable. Recently a lot of researches focusing on development of high-power stack system have been introduced. However there are very few studies of economic analysis for this promising system. Consequently this study proposed 20-kW-scale high-power solid oxide electrolysis cells system config urations then conducted economic analysis. Especially the economic context was in South Korea. For com parison a low-power system with similar design was used as a reference; the levelized cost of hydrogen of each system was calculated based on the revenue requirement method. Furthermore a sensitivity analysis was also performed to identify how the economic variables affect the hydrogen production cost in a specific context. The results show that a high-power system is superior to a low-power system from an economic perspective. The stack cost is the dominant component of the capital cost but the electricity cost is the factor that contributes the most to the hydrogen cost. In the first case study it was found that if a high-power system can be installed inside a nuclear power plant the cost of hydrogen produced can reach $3.65/kg when the electricity cost is 3.28¢/kWh and the stack cost is assumed to be $574/kW. The second case study indicated that the hydrogen cost can decrease by 24% if the system is scaled up to a 2-MW scale.
Photocatalytic Water Splitting: How Far Away Are We from Being Able to Industrially Produce Solar Hydrogen?
Oct 2022
Publication
Solar water splitting (SWS) has been researched for about five decades but despite successes there has not been a big breakthrough advancement. While the three fundamental steps light absorption charge carrier separation and diffusion and charge utilization at redox sites are given a great deal of attention either separately or simultaneously practical considerations that can help to increase efficiency are rarely discussed or put into practice. Nevertheless it is possible to increase the generation of solar hydrogen by making a few little but important adjustments. In this review we talk about various methods for photocatalytic water splitting that have been documented in the literature and importance of the thin film approach to move closer to the large-scale photocatalytic hydrogen production. For instance when comparing the film form of the identical catalyst to the particulate form it was found that the solar hydrogen production increased by up to two orders of magnitude. The major topic of this review with thin-film forms is discussion on several methods of increased hydrogen generation under direct solar and one-sun circumstances. The advantages and disadvantages of thin film and particle technologies are extensively discussed. In the current assessment potential approaches and scalable success factors are also covered. As demonstrated by a film-based approach the local charge utilization at a zero applied potential is an appealing characteristic for SWS. Furthermore we compare the PEC-WS and SWS for solar hydrogen generation and discuss how far we are from producing solar hydrogen on an industrial scale. We believe that the currently employed variety of attempts may be condensed to fewer strategies such as film-based evaluation which will create a path to address the SWS issue and achieve sustainable solar hydrogen generation.
Role of a Unitized Regenerative Fuel Cell in Remote Area Power Supply: A Review
Aug 2023
Publication
This manuscript presents a thorough review of unitized regenerative fuel cells (URFCs) and their importance in Remote Area Power Supply (RAPS). In RAPS systems that utilize solar and hydrogen power which typically include photovoltaic modules a proton exchange membrane (PEM) electrolyzer hydrogen gas storage and PEM fuel cells the cost of these systems is currently higher compared to conventional RAPS systems that employ diesel generators or batteries. URFCs offer a potential solution to reduce the expenses of solar hydrogen renewable energy systems in RAPS by combining the functionalities of the electrolyzer and fuel cell into a single unit thereby eliminating the need to purchase separate and costly electrolyzer and fuel cell units. URFCs are particularly well-suited for RAPS applications because the electrolyzer and fuel cell do not need to operate simultaneously. In electrolyzer mode URFCs function similarly to stand-alone electrolyzers. However in fuel cell mode the performance of URFCs is inferior to that of stand-alone fuel cells. The presented review summarizes the past present and future of URFCs with details on the operating modes of URFCs limitations and technical challenges and applications. Solar hydrogen renewable energy applications in RAPS and challenges facing solar hydrogen renewable energy in the RAPS is discussed in detail.
Frequency Regulation of an Islanded Microgrid Using Hydrogen Energy Storage Systems: A Data-Driven Control Approach
Nov 2022
Publication
Hydrogen energy storage (HES) systems have recently received attention due to their potential to support real-time power balancing in a power grid. This paper proposes a data-driven model predictive control (MPC) strategy for HES systems in coordination with distributed generators (DGs) in an islanded microgrid (MG). In the proposed strategy a data-driven model of the HES system is developed to reflect interactive operations of an electrolyzer hydrogen tank and fuel cell and hence the optimal power sharing with DGs is achieved to support real-time grid frequency regulation (FR). The MG-level controller cooperates with a device-level controller of the HES system that overrides the FR support based on the level of hydrogen. Small-signal analysis is used to evaluate the contribution of FR support. Simulation case studies are also carried out to verify the accuracy of the data-driven model and the proposed strategy is effective for improving the real-time MG frequency regulation compared with the conventional PI-based strategy.
Numerical Investigation of the Initial Charging Process of the Liquid Hydrogen Tank for Vehicles
Dec 2022
Publication
Liquid hydrogen has been studied for use in vehicles. However during the charging process liquid hydrogen is lost as gas. Therefore it is necessary to estimate and reduce this loss and simulate the charging process. In this study the initial charging process of a vehicle liquid hydrogen tank under room temperature and atmospheric pressure conditions was numerically investigated. A transient thermal-fluid simulation with a phase-change model was performed to analyze variations in the volume pressure mass flow rate and temperature. The results showed that the process could be divided into three stages. In the first stage liquid hydrogen was actively vaporized at the inner wall surface of the storage tank. The pressure increased rapidly and liquid droplets were discharged into the vent pipe during the second stage. In the third stage the mass flow rates of liquid and hydrogen gas at the outlet showed significant fluctuations owing to complex momentum generated by the evaporation and charging flow. The temperatures of the inner and outer walls and insulation layer decreased significantly slower than that of the gas region because of its high heat capacity and insulation effect. The optimal structure should be further studied because the vortex stagnation and non-uniform cooling of the wall occurred near the inlet and outlet pipes.
Charpy Impact Properties of Hydrogen-Exposed 316L Stainless Steel at Ambient and Cryogenic Temperatures
May 2019
Publication
316L stainless steel is a promising material candidate for a hydrogen containment system. However when in contact with hydrogen the material could be degraded by hydrogen embrittlement (HE). Moreover the mechanism and the effect of HE on 316L stainless steel have not been clearly studied. This study investigated the effect of hydrogen exposure on the impact toughness of 316L stainless steel to understand the relation between hydrogen charging time and fracture toughness at ambient and cryogenic temperatures. In this study 316L stainless steel specimens were exposed to hydrogen in different durations. Charpy V-notch (CVN) impact tests were conducted at ambient and low temperatures to study the effect of HE on the impact properties and fracture toughness of 316L stainless steel under the tested temperatures. Hydrogen analysis and scanning electron microscopy (SEM) were conducted to find the effect of charging time on the hydrogen concentration and surface morphology respectively. The result indicated that exposure to hydrogen decreased the absorbed energy and ductility of 316L stainless steel at all tested temperatures but not much difference was found among the pre-charging times. Another academic insight is that low temperatures diminished the absorbed energy by lowering the ductility of 316L stainless steel
A Study on the Characteristics of Academic Topics Related to Renewable Energy Using the Structural Topic Modelling and the Weak Signal Concept
Mar 2021
Publication
It is important to examine in detail how the distribution of academic research topics related to renewable energy is structured and which topics are likely to receive new attention in the future in order for scientists to contribute to the development of renewable energy. This study uses an advanced probabilistic topic modeling to statistically examine the temporal changes of renewable energy topics by using academic abstracts from 2010–2019 and explores the properties of the topics from the perspective of future signs such as weak signals. As a result in strong signals methods for optimally integrating renewable energy into the power grid are paid great attention. In weak signals interest in large-capacity energy storage systems such as hydrogen supercapacitors and compressed air energy storage showed a high rate of increase. In not-strong-but-well-known signals comprehensive topics have been included such as renewable energy potential barriers and policies. The approach of this study is applicable not only to renewable energy but also to other subjects.
Scenario-Based Techno-Economic Analysis of Steam Methane Reforming Process for Hydrogen Production
Jun 2021
Publication
Steam methane reforming (SMR) process is regarded as a viable option to satisfy the growing demand for hydrogen mainly because of its capability for the mass production of hydrogen and the maturity of the technology. In this study an economically optimal process configuration of SMR is proposed by investigating six scenarios with different design and operating conditions including CO2 emission permits and CO2 capture and sale. Of the six scenarios the process configuration involving CO2 capture and sale is the most economical with an H2 production cost of $1.80/kg-H2. A wide range of economic analyses is performed to identify the tradeoffs and cost drivers of the SMR process in the economically optimal scenario. Depending on the CO2 selling price and the CO2 capture cost the economic feasibility of the SMR-based H2 production process can be further improved.
A Comprehensive Review of Microbial Electrolysis Cells (MEC) Reactor Designs and Configurations for Sustainable Hydrogen Gas Production
Nov 2015
Publication
Hydrogen gas has tremendous potential as an environmentally acceptable energy carrier for vehicles. A cutting edge technology called a microbial electrolysis cell (MEC) can achieve sustainable and clean hydrogen production from a wide range of renewable biomass and wastewaters. Enhancing the hydrogen production rate and lowering the energy input are the main challenges of MEC technology. MEC reactor design is one of the crucial factors which directly influence on hydrogen and current production rate in MECs. The rector design is also a key factor to upscaling. Traditional MEC designs incorporated membranes but it was recently shown that membrane-free designs can lead to both high hydrogen recoveries and production rates. Since then multiple studies have developed reactors that operate without membranes. This review provides a brief overview of recent advances in research on scalable MEC reactor design and configurations.
Options for Methane Fuel Processing in PEMFC System with Potential Maritime Applications
Nov 2022
Publication
Proton-exchange membrane fuel cells (PEMFCs) are low-temperature fuel cells that have excellent starting performance due to their low operating temperature can respond quickly to frequent load fluctuations and can be manufactured in small packages. Unlike existing studies that mainly used hydrogen as fuel for PEMFCs in this study methane is used as fuel for PEMFCs to investigate its performance and economy. Methane is a major component of natural gas which is more economically competitive than hydrogen. In this study methane gas is reformed by the steam reforming method and is applied to the following five gas post-treatment systems: (a) Case 1—water– gas shift only (WGS) (b) Case 2—partial oxidation reforming only (PROX) (c) Case 3—methanation only (d) Case 4—WGS + methanation (e) Case 5—WGS + PROX. In the evaluation the carbon monoxide concentration in the gas did not exceed 10 ppm and the methane component which has a very large greenhouse effect was not regenerated in the post-treated exhaust gas. As a result Case 5 (WGS and PROX) is the only case that satisfied both criteria. Therefore we propose Case 5 as an optimized post-treatment system for methane reforming gas in ship PEMFCs.
Technology Portfolio Assessment for Near-zero Emission Iron and Steel Industry in China
May 2023
Publication
China aims to peak CO2 emissions before 2030 and to achieve carbon neutrality before 2060; hence industrial sectors in China are keen to figure out appropriate pathways to support the national target of carbon neutrality. The objective of this study is to explore near-zero emission pathways for the steel industry of China through a detailed technology assessment. The innovative technology development has been simulated using the AIM-China/steel model developed by including material-based technologies and optimal cost analysis. Six scenarios have been given in terms of different levels of production output emission reduction and carbon tax. Near-zero emission and carbon tax scenarios have shown that China’s steel industry can achieve near-zero emission using electric furnaces and hydrogen-based direct reduction iron technologies with policy support. Based on these technologies minimised production costs have been calculated revealing that the steel produced by these technologies is cost-effective. Moreover the feedstock cost can play a key role in these technology portfolios especially the cost of scrap iron ore and hydrogen. In addition the feedstock supply can have strong regional effects and can subsequently impact the allocation of steelmaking in the future. Therefore China can achieve near-zero emissions in the steel industry and electric furnace and hydrogen-based direct reduction iron technologies are crucial to achieving them.
A Theoretical Study on the Hydrogen Filling Process of the On-board Storage Cylinder in Hydrogen Refueling Station
May 2023
Publication
With the development of the hydrogen fuel automobile industry higher requirements are put forward for the construction of hydrogen energy infrastructure the matching of parameters and the control strategy of hydrogen filling rate in the hydrogen charging process of hydrogen refueling stations. At present the technological difficulty of hydrogen fueling is mainly reflected in the balanced treatment of reducing the temperature rise of hydrogen and shortening the filling time during the fast filling process. Vehicle hydrogen storage cylinder (VHSC) is one of the important components of hydrogen fuel cell vehicles. This study proposed a theoretical model for calculating the temperature rise in the VHSC during the high pressure refueling process and revealed the hydrogen temperature rise during refueling. A hydrogen temperature rise prediction model was constructed to elucidate the relationship between filling parameters and temperature rise. The filling process of VHSC was analyzed from the theoretical method. The theoretical analysis results were consistent with the simulation and experimental analysis results which provided a theoretical basis for the current hydrogen temperature control algorithm of the gas source in the hydrogen refueling station and then reduced the energy consumption required for hydrogen cooling in the hydrogen refueling station.
Energy, Exergy and Thermoeconomic Analyses on Hydrogen Production Systems Using High-temperature Gas-cooled and Water-cooled Nuclear Reactors
Dec 2023
Publication
The use of nuclear energy is inevitable to reduce the dependence on fossil fuels in the energy sector. High-temperature gas-cooled reactors (HTGRs) are considered as a system suitable for the purpose of reducing the use of fossil fuels. Furthermore eco-friendly mass production of hydrogen is crucial because hydrogen is emerging as a next-generation energy carrier. The unit cost of hydrogen production by the levelized cost of energy (LCOE) method varies widely depending on the energy source and system configuration. In this study energy exergy and thermoeconomic analyses were performed on the hydrogen production system using the HTGR and high-temperature water-cooled nuclear reactor (HTWR) to calculate reasonable unit cost of the hydrogen produced using a thermoeconomic method called modified production structure analysis (MOPSA). A flowsheet analysis was performed to confirm the energy conservation in each component. The electricity generated from the 600 MW HTGR system was used to produce 1.28 kmol/s of hydrogen by electrolysis to split hot water vapor. Meanwhile 515 MW of heat from the 600 MW HTWR was used to produce 8.10 kmol/s of hydrogen through steam reforming and 83.6 MW of electricity produced by the steam turbine was used for grid power. The estimated unit cost of hydrogen from HTGR is approximately USD 35.6/GJ with an initial investment cost of USD 2.6 billion. If the unit cost of natural gas is USD 10/GJ and the carbon tax is USD 0.08/kg of carbon dioxide the unit cost of hydrogen produced from HTWR is approximately USD 13.92/GJ with initial investment of USD 2.32 billion. The unit cost of the hydrogen produced in the scaled-down plant was also considered.
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