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According to the trend of compressor upgrades in hydrogen refueling stations, this article optimizes the single exponential curve of membrane chamber volume and diaphragm stress that performs poorly. First, set the optimization goals as the membrane cavity volume and the arc length of the curve, use the MOPSO algorithm to optimize the curve, and fit the optimization results to obtain a new curve mathematical model. Then, select three curves for comparison. Theoretical calculations and finite element simulations were performed on the membrane cavity volume and diaphragm stress, and the theoretical calculation methods and results were verified with the help of existing experiments. Finally, it was found that the new curve can increase the membrane cavity volume and reduce the diaphragm stress requirement by changing its own parameters, and the new curve has a small amount of cavity volume near the transition point, which has little impact on the membrane cavity volume. Under the same maximum radial stress, the membrane cavity volume of the new curve can be increased by 5.56% compared to the single exponential curve, while under the same membrane cavity volume, the new curve can reduce the maximum stress on the gas side by 8.9% compared with the single exponential curve, and the maximum stress on the oil sides is reduced by 9.8%. [ABSTRACT FROM AUTHOR]

As hydrogen energy, a clean energy source, is to be developed and utilized on a large scale, the construction of long-distance hydrogen pipelines and related stations along the route is also increasing. To study the dispersion patterns of hydrogen leakage under different conditions, a three-dimensional FLACS model of the hydrogen station was established. Simulations of hydrogen leakage and dispersion were conducted under different leakage pressures, leakage apertures, and leakage temperatures in the presence of obstacles. The dispersion ranges of flammable gas clouds were compared, and the influencing factors were analyzed. The results show that obstacles cause changes in the direction of hydrogen leakage, leading to a rapid increase in the dispersion range. In scenario 7, within 7 s (8 s to 15 s), the area of the flammable gas cloud rapidly increases to 73.3% of the entire station area. The increase of leakage pressure and leakage aperture both result in a larger dispersion range of the flammable gas cloud. For low-pressure leakage at 4 MPa, the change in leakage aperture has a more significant impact, while for large aperture leakage at 100 mm, the change in leakage pressure has a more significant impact. When the leakage temperature increases from 293 K to 353 K, the thermal motion of hydrogen molecules accelerates, but the change in leakage temperature does not significantly affect the dispersion range of the gas cloud. This study can provide a reference for the prevention and control of leakage accidents in hydrogen station. [ABSTRACT FROM AUTHOR]

Hydrogen stations are an important component of urban clean energy development. In the event of an accident, they can have a serious impact on the safety and stability of the urban system. This paper identifies and analyzes the main influencing factors of hydrogen station safety resilience based on an improved HFACS model. It establishes a safety resilience evaluation index system from four dimensions: spatial resilience, engineering resilience, management resilience, and social resilience. Subjective index weights are determined through fuzzy analytic hierarchy process, objective index weights are determined through entropy method, and combined index weights are determined based on game theory. A system dynamics model of hydrogen station safety resilience is constructed, and model verification and comparative analysis are conducted. The influence of different dimensions on system safety resilience is analyzed, and quantitative evaluation and prediction research on hydrogen station safety resilience is carried out. Targeted safety resilience improvement suggestions are also proposed. The research results can provide a reference for the safety management of hydrogen stations. • Constructing a resilience evaluation index system using the modified HFACS model. • Modeling the safety resilience evaluation of hydrogen stations from four dimensions. • Simulation and prediction of safety resilience levels for hydrogen stations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Refrigeration is the property of Journal of Refrigeration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A study is conducted on the technology and process of constructing pipeline hydrogen supply station of refinery enterprises relying on by-product hydrogen resources. Optimization design measures have been proposed to simplify process, save investment and reduce energy consumption. Research has found that after cancelling the hydrogen storage bottle group, the control cabinet system, and pre-cooling process of the hydrogenation dispenser in the hydrogen station, it can still meet the safety requirements that the temperature inside the on-board hydrogen cylinder should not exceed 85 °C during filling hydrogen-powered vehicles, and at the same time meet the requirements of hydrogen filling efficiency and better user experience. Compared to the 2,000 kg per 12 hours pipeline hydrogen supply station with the same pressure grade and function in the conventional typical process, the optimized 3,000 kg per 12 hours pipeline hydrogen supply station with 35 MPa pressure grade reduces the investment in major equipment per unit of hydrogen filling scale by more than 50%, decreases the installed power from 1,025 kW to 630 kW, a reduction of 38.5%; the major energy consumption reduces from 6.15 kW • h/kg to 2.52 kW • h/kg, which is more than 50%. [ABSTRACT FROM AUTHOR]

Hydrogen fuel has shown promise as a clean, alternative fuel aiding in the reduction of fossil fuel dependence within the transportation sector. However, hydrogen refueling stations and infrastructure remains a barrier and are a prerequisite for consumer adoption of low-cost and low-emission fuel cell electric vehicles (FCEVs). The costs for FCEV fueling include both station capital costs and operation and maintenance (O&M) costs. Contributing to these O&M costs, unscheduled maintenance is presently more costly and more frequent than for similar gasoline fueling infrastructure and is asserted to be a limiting factor in achieving FCEV customer acceptance and cost parity. Unscheduled maintenance leads to longer station downtime, therefore, causing an increase in missed fueling opportunities, which forces customers to seek refueling at other operable stations that may be significantly farther away. This research proposes a framework for a hydrogen station prognostics health monitoring (H2S PHM) model that can minimize unexpected downtime by predicting the remaining useful life for primary hydrogen station components within the major station subsystems. The H2S PHM model is a data-driven statistical model, based on O&M data collected from 34 retail hydrogen stations located in the U.S. The primary subcomponents studied are the dispenser, compressor, and chiller. The remaining useful life calculations are used to decide whether or not maintenance should be completed based on the prediction and expected future station use. This paper presents the background, method, and results for the H2S PHM model as for a means for improving station availability and customer confidence in FCEVs and hydrogen infrastructure. • Hydrogen station reliability is a key contributor to market success. • Mean fills between failure and station availability are lower than conventional technologies. • A prognostics health monitoring system can improve hydrogen station availability. • Estimated remaining useful life of primary components assists in maintenance decisions. [ABSTRACT FROM AUTHOR]

In order to reduce various environmental pollutants and green house gas emissions caused by the use of fossil fuels, countries around the world are making various efforts to revitalize the supply of eco-friendly vehicles such as FCEVs(fuel cell electric vehicles) and electric vehicles. As a policy to revitalize the supply of eco- friendly cars, it is pushing for purchase subsidies and tax reduction policies, and aims to supply 6.7 million fuel cell electric vehicles and 310 hydrogen charging stations by 2022. Meanwhile in order for eco-friendly cars to be activated, various policies such as subsidies, vehicle price reduction, easing various regulatory policies, and promoting incentive policies are needed, but above all, installing charging facilities is important to revitalize eco-friendly vehicles. In this study, the current status of the FCEV industry and the promotion strategy according to the supply of FCEVs were presented to revitalize the supply of the FCEVs suitable for the situation in Gyeongsangbuk-do. The first, practical hydrogen utilization measures should be prepared first in purchasing business vehicles through a plan to supply FCEVs, expand subsides to revitalize the supply of FCEVs, and secure subsidies for operation of hydrogen charging stations. The second, it is necessary to build a hydrogen production base in Gyeongsangbuk-do to expand the FCEV infrastructure, build an institutional plan to revitalize FCEVs, and reduce hydrogen costs through green hydrogen production and production base construction. The third, it is necessary to train professionals, in the hydrogen industry and promote the transformation of local people’s perception of hydrogen and hydrogen charging stations. Therefore, Gyeongsangbuk-do can secure competitiveness in the hydrogen industry by supplying FCEVs and expanding hydrogen charging stations, and contribute for forstering the hydrogen economy, a key driving force for future innovation growth and energy conversion.

Among the alternative fuels enabling the energy transition, hydrogen-based transportation is a sustainable and efficient choice. It finds application both in light-duty and heavy-duty mobility. However, hydrogen gas has unique qualities that must be taken into account when employed in such vehicles: high-pressure levels up to 900 bar, storage in composite tanks with a temperature limit of 85 °C, and a negative Joule–Thomson coefficient throughout a wide range of operational parameters. Moreover, to perform a refueling procedure that is closer to the driver's expectations, a fast process that requires pre-cooling the gas to −40 °C is necessary. The purpose of this work is to examine the major phenomena that occur during the hydrogen refueling process by analyzing the relevant theory and existing modeling methodologies. [ABSTRACT FROM AUTHOR]

BACKGROUND: This study is concerned with the development of the hydrogen gas dispenser used in hydrogen stations for fuel cell vehicles (FCV). Most of the current flexible hoses suppling the high-pressure hydrogen gas to FCV are made of rubber and resin-based materials. They are required to have the characteristics of resistance to permeation of the gas and to inhibit the internal fractures known as blisters. If the materials can be replaced with metal materials, those difficulties may be resolved. OBJECTIVE: The relationship between the internal pressure strength of flexible metal tubes and their convolution shapes is investigated by experiments and computer-aided engineering (CAE) analyses. METHODS: Two kinds of stainless steels with high Ni equivalent are used for flexible tubing. The U-shaped bellows and the compressed bellows made by compressing them in the axial direction are fabricated, and then CAE analyses of their internal pressure strength are performed Internal pressure rupture tests are also carried out on both bellows. RESULTS: The internal pressure strength of the compressed bellows with a pitch of 1.6 mm was more than twice that of the U-shaped bellows with a pitch of 4.3 mm. CONCLUSION: It was found that the smaller the pitch of the bellows, the larger the internal pressure strength. [ABSTRACT FROM AUTHOR]

The present paper analyzes an innovative energy system based on a hydrogen station, as the core of a smart energy production center, where the produced hydrogen is then used in different hydrogen technologies adopted and installed nearby the station. A case study analysis has been proposed and then investigated, with a station capacity of up to 360 kg of hydrogen daily generated, located close to a University Campus. A hydrogen mobility network has been included, composed of a fuel cell hydrogen fleet of 41 vehicles, 43 bicycles, and 28 fuel cell forklifts. The innovative proposed energy system needs to meet also a power and heat demand for a student housing 5400 m2 building of the University Campus. The performance of the system is presented and investigated, including technical and economic analyses, proposing a hydrogen refueling station as an innovative alternative fuel infrastructure, called Multi-modular Hydrogen Energy Station, marking its great potential in future energy scenarios. [Display omitted] • Presentation of a new concept of Multi-modular Hydrogen Energy Station. • Hydrogen Mobility based on FCEVs, forklifts, and hydrogen bicycles. • Fuel Cell-based cogeneration system for heat and power generation. • 360 kg of daily hydrogen for 41 vehicles, 43 bicycles, and 28 fuel cell forklifts. • LCOH of 10.39 €/kg and ROI of 14.43% for the hydrogen facility. [ABSTRACT FROM AUTHOR]

Among the alternative fuels enabling the energy transition, hydrogen-based transportation is a sustainable and efficient choice. It finds application both in light-duty and heavy-duty mobility. However, hydrogen gas has unique qualities that must be taken into account when employed in such vehicles: high-pressure levels up to 900 bar, storage in composite tanks with a temperature limit of 85 °C, and a negative Joule–Thomson coefficient throughout a wide range of operational parameters. Moreover, to perform a refueling procedure that is closer to the driver’s expectations, a fast process that requires pre-cooling the gas to −40 °C is necessary. The purpose of this work is to examine the major phenomena that occur during the hydrogen refueling process by analyzing the relevant theory and existing modeling methodologies.

In a hydrogen station that operates with direct fueling through the use of a 700 bar boost compressor, the outlet hydrogen temperature can significantly increase, stressing the chiller system. This paper evaluates improvements that can be made to the auxiliary cooling system integrated with the compressor. Both theoretical modeling and experiments were performed at Cal State LA Hydrogen Research and Fueling Facility. The findings suggest that adjusting the auxiliary closed-loop cooling system from 15 °C to 10 °C reduced the station energy consumption and decreased the demand on the station chiller that needed to provide −20 °C hydrogen at the hose. The overall energy consumption for a single fueling reduced by between 2.86 and 9.43% for the set of experiments conducted. After the temperature of the closed-loop cooling system was reduced by 5 °C, the boost compressor outlet temperature dropped from 46-50 °C–40 °C and consequently at the hose the hydrogen temperature declined by 3 °C. Results were scaled up with a forecast on the number of daily refueling events. With a low number of daily fuelings, the proposed set-up showed a minor influence on the overall station energy consumption. However, the benefits were more pronounced for a connector station with sales at 180 kg/day, where the energy efficiency improved by between 1.4 and 5.5%, and even more so for a higher capacity station at 360 kg/day, where the improvement was between 2.9 and 8%. [Display omitted] • Hydrogen Station with two booster compressors and a hydrogen chiller. • Water process chiller tuning-up and new-set-up. • Hydrogen Refueling Process Energy Reduction. • Results scaled up by forecasting the number of fueling events. • Pilot, Connector, and Main Stations Evaluation. [ABSTRACT FROM AUTHOR]

The dissemination of fuel-cell vehicles requires cost reduction of hydrogen refueling stations. The temperature of the supplied hydrogen has currently been cooled to approximately −40 °C. This has led to larger equipment and increased electric power consumption. This study achieves a relaxation of the precooling temperature to the −20 °C level while maintaining the refueling time. (1) Adoption of an MC formula that can flexibly change the refueling rate according to the precooling temperature. (2) Measurement of thermal capacity of refueling system parts and re-evaluation. Selection from multiple refueling control maps according to the dispenser design (Mathison, et al., 2015). (3) Calculation of the effective thermal capacity and reselection of the map in real time when the line is cooled from refueling of the previous vehicle (Mathison, and Handa, 2015). (4) Addition of maps in which the minimum assumed pressures are 10 and 15 MPa. The new method is named MC Multi Map. • Compatible hydrogen refueling protocol to the current existing station. • Cold dispenser control and thermal mass management are merged in a simple control map selection method. • A refueling with −20C precooling is possible even in summer. [ABSTRACT FROM AUTHOR]

In this paper, a novel model of electric-hydrogen integrated charging station (ICS) is proposed, which is composed of battery swapping station (BSS) and hydrogen station (HS). The BSS model, which mainly includes user adaptive response model, battery allocation and scheduling strategy, is established to realize the reasonable management and allocation of batteries. The HS model mainly includes hydrogen production module, hydrogen storage module, hydrogen charging module, fuel cell module and hydrogen scheduling strategy to optimize scheduling from hydrogen production to use. In addition, the BSS can provide energy for HS, and both BSS and HS can feed back the stored energy to the power system during peak load, which is beneficial to the stable operation of the power system. Simulation shows the rationality and correctness of the proposed optimization model. The proposed model and optimization strategy can improve the flexibility and economy of ICS, and help the power system to cut peak and fill valley. [Display omitted] • A model of electric-hydrogen integrated charging station is proposed. • The battery swapping station and hydrogen station are jointly optimized. • The energy transfer of the integrated charging station is more flexible. • The integrated charging station can provide auxiliary services for the power grid. [ABSTRACT FROM AUTHOR]

• Hybrid electric vehicle charging and hydrogen fueling station is investigated. • Multi-criteria decision-making method is introduced to find optimal system design. • Optimal system is affordable, sustainable, and socio-politically acceptable. • Optimal system is economically feasible compared to the grid after 59.6 km. • Optimal system design reduced 942 tons of carbon emission annually. The world is facing severe climate threats due to continuous increases in greenhouse gas emissions. Around one-fifth of global emissions are produced by the transport sector alone. Electric vehicles, as a potential replacement for conventional vehicles, can reduce global emissions. Pakistan is among the few countries severely affected by climate change impact. Therefore, Pakistan announced a national policy to increase the electric vehicles market share, calling for the development of electric vehicles charging stations nationwide. This work addresses this urgency by investigating renewable-based electric vehicles charging and hydrogen fueling stations (ECHFS). Seven possible ECHFS configurations are introduced. Then, a four-level sustainable design framework is developed, with the help of pre-feasibility analysis, HOMER optimization tool, and a multi-criteria decision-making method, to identify the most optimal ECHFS configuration. Solar PV with biogas generator configuration emerged as an optimal ECHFS, which is cost-effective (0.475 $/kWh cost of energy and 3.62 $/kg cost of hydrogen), reliable (unmet electric and hydrogen loads are 0.14 % and 0 %), eco-friendly (reduced 942 tons CO 2 annually), and socio-politically acceptable. Sensitivity analysis showed that the optimal system is economically sensitive to simultaneously increasing charging and hydrogen fueling demands. The breakeven distance is estimated to be 59.6 km compared to the grid. The outcome of this work contributes to United Nations sustainability goals 7a, 8, 11, 13, and 13.2 and holds the potential to aid the sustainable development of ECHFS infrastructure. [Display omitted] [ABSTRACT FROM AUTHOR]

Models based on too many parameters are complex and burdensome, difficult to be adopted as a tool for sizing these technologies, especially when the goal is not the improvement of electrochemical technology, but the study of the overall energy flows. The novelty of this work is to model an electrolysis hydrogen production process, with analysis and prevision of its electrical and thermal energy expenditure, focusing on the energy flows of the whole system. The paper additionally includes investigation on auxiliary power consumption and on thermal capacity and resistance as functions of the stack power. The electrolysis production phase is modeled, with a zero-dimensional, multi-physics and dynamic approach, both with alkaline and polymer membrane electrolyzers. Models are validated with experimental data, showing a good match with a root-mean-square percentage error under 0.10. Results are scaled-up for 180 kg/day of hydrogen, performing a comparison with both technologies. • Mathematical model development for PEM and Alkaline Water electrolysis. • Energy flows, auxiliaries, electricity and heat demand are the core of the model. • Model validated with experimental data from literature. • Scaling up of the results to a "connector hydrogen infrastructure. • Comparison between PEM and Alkaline energy performance. [ABSTRACT FROM AUTHOR]

The focus of this research is on refueling process from a buffer and a cascade storage bank. A thermodynamic analysis is developed to investigate the filling process of fuel transmission from a storage bank to hydrogen cylinder. Refueling Process from Buffer and Cascade Storage Banks is the subject of this research. Filling the hydrogen cylinder to the required final condition is influenced by the volume and pressure of storage bank. For both buffer and cascade storage banks, ambient temperature is also an important parameter that affects the initial condition, the final condition and the refueling process. Comparison of buffer and cascade storage banks showed that refueling time using buffer storage bank is 200 s less than the cascade storage bank. However, the energy required for gas storage is higher in buffer storage system. As shown by the study, reduction in the final temperature of the filling process can be achieved by controlling the ambient temperature, the initial pressure and the fuel charging rate. • The subject is the performance of transmission fuel from buffer and cascade banks. • Method of Buffer storage banks has short refueling time. • Cascade storage bank method requires less energy. • Ambient temperature and initial pressure are fundamental parameters in this study. [ABSTRACT FROM AUTHOR]

Abstract Fuel cell electric vehicles (FCEVs) have now entered the market as zero-emission vehicles. Original equipment manufacturers such as Toyota, Honda, and Hyundai have released commercial cars in parallel with efforts focusing on the development of hydrogen refueling infrastructure to support new FCEV fleets. Persistent challenges for FCEVs include high initial vehicle cost and the availability of hydrogen stations to support FCEV fleets. This study sheds light on the factors that drive manufacturing competitiveness of the principal systems in hydrogen refueling stations, including compressors, storage tanks, precoolers, and dispensers. To explore major cost drivers and investigate possible cost reduction areas, bottom-up manufacturing cost models were developed for these systems. Results from these manufacturing cost models show there is substantial room for cost reductions through economies of scale, as fixed costs can be spread over more units. Results also show that purchasing larger quantities of commodity and purchased parts can drive significant cost reductions. Intuitively, these cost reductions will be reflected in lower hydrogen fuel prices. A simple cost analysis shows there is some room for cost reduction in the manufacturing cost of the hydrogen refueling station systems, which could reach 35% or more when achieving production rates of more than 100 units per year. We estimated the potential cost reduction in hydrogen compression, storage and dispensing as a result of capital cost reduction to reach 5% or more when hydrogen refueling station systems are produced at scale. Highlights • Accelerated roll-outs of hydrogen stations in many countries in Europe, Asia and North America. • Discussion of manufacturing analysis of key parts in the hydrogen stations. • Reduction of the hydrogen station cost could play role in reducing the cost of hydrogen at the pump. • U.S. based manufacturers have advantages of the long experience and low energy cost. • Storage bank and compressors are the key cost contributor in the hydrogen station. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

When a retail hydrogen station operates using booster compressors to directly fill cars, a need for an additional high-pressure buffer volume is present, in order to mitigate potential pressure pulsations in the system. In the case of the Cal State LA Hydrogen Fueling Station, pulsations with a magnitude up to 6.7 MPa were observed with no buffer volume during 70 MPa fueling. Thus the focus was placed on determining the minimum buffer volume required to ensure pulsation free operation to the entire downstream system (booster compressors, piping and the vehicle hydrogen hardware). A mathematical model of volumes involved has been developed and compared to experimental measurements. The station configuration allows isolating one or more of the four high-pressure buffer tanks with which the station was upgraded to reduce pulsations. Each tank has a volume of 0.05 m 3 . A relatively simple model developed shows a strong correlation with the experiments in determining the maximum pulse and the minimum additional high-pressure buffer volume. Effectively, one buffer tank would have provided a proper operation of the station by keeping the pressure pulsation magnitude under 0.2 MPa. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The utilization of fuel cell vehicles can significantly reduce the greenhouse gas emissions in urban areas. However, huge investments are needed to construct the hydrogen infrastructure to produce, store and distribute hydrogen fuel to fuel cell vehicles. The present study conducted an analysis of a roll-out strategy to introduce fuel cell vehicles and hydrogen stations in Shenzhen, China between 2016 and 2025. An accurate estimation to develop hydrogen economy in Shenzhen in the near-term was provided. Three different scenarios of fuel cell vehicle penetration rate in the new car sales market were employed to predict the number of fuel cell vehicles and daily hydrogen demand in Shenzhen. The capital investment and operation/maintenance cost of on-site steam methane reforming hydrogen fueling stations was estimated. For a station with 100, 500 and 1000 kg/day capacity, the capital investment is $1.04, 4.15 and 7.84 million, respectively, while the corresponding hydrogen fuel price at 20 years of return on investment (ROI) is 7.7, 7.0 and 6.8 $/kg, respectively. A roll-out strategy of ten hydrogen stations in Shenzhen by 2020 was proposed, taking into consideration the population density, average income, locations of grocery stores and shopping malls, and locations of existing gas stations. The total capital investment required to construct 10 hydrogen stations is $19.7 million. The fuel costs and life cycle greenhouse gas emissions of hydrogen, gasoline and electricity vehicles were assessed to justify the benefits of introducing fuel cell vehicles in Shenzhen. Local industry and government can use the results to make decisions about possible future H 2 utilization and infrastructure construction. [ABSTRACT FROM AUTHOR]

The Korean government is planning to increase the number of its hydrogen stations from 20 in 2016 to 100 by 2020, to enhance the use of hydrogen fuel cell electric vehicles and to reduce greenhouse gas (GHG) emissions. This article looks at the public willingness to pay (WTP) for implementing the expansion policy. To this end, a contingent valuation survey of 1000 Korean households was implemented. To mitigate the response effect in eliciting the WTP and to increase the statistical efficiency of the analysis of the WTP data, we employed a one-and-one-half-bounded dichotomous choice question format. Furthermore, we used a spike model to model the WTP responses with zero observations. The mean yearly WTP for the policy implementation is computed to be KRW 2258 (USD 2.04) per household, which is statistically significant at the 1% level. The national annual value amounts to KRW 42.8 billion (USD 38.6 million). This value can be taken as an indication of the external benefit of the reduction in GHG emissions by means of the expansion. [ABSTRACT FROM AUTHOR]