Selecting hydrogen production methods using fuzzy analytic hierarchy process with opportunities,costs, and risks

In this study, we evaluated six hydrogen-producing methods using a fuzzy analytic hierarchy process (AHP) under benefits, opportunities, costs, and risks concepts. Twelve factors were set up, and the weights of each factor were appraised using the fuzzy AHP method. We conclude that steam methane reforming is the optimal method for hydrogen production in Korea; equipment investment cost and market size are the most important factors, while the indirect benefits such as spillover effect, human resource development, and environmental contribution are less important. The results show that achieving economic feasibility and lowering risks are very important. Therefore, considering stable natural gas prices and unconventional gas production, steam methane reforming is a promising option for hydrogen production.     

Fuzzy Delphi method for evaluating hydrogen production technologies

The purpose of this research is to establish an evaluation model for selecting the most appropriate technology for development in Taiwan, based on 14 evaluation criteria. Due to the inherent uncertainty and imprecision associated with the mapping of decision makers’ perception to crisp values, linguistic variables are used to assess the weights of the criteria and the ratings of each technology with respect to each criterion. The criteria weights and technology ratings are collected through a seven-point linguistic scale using a Delphi questionnaire. The linguistic scores are then converted into fuzzy numbers, and a consensus of the decision makers’ opinions on weights and ratings is mathematically derived using fuzzy Delphi methodology. We have used the model to evaluate seven different hydrogen production technologies. The results indicate that hydrogen production via electrolysis by wind power and that via electrolysis by photovoltaic electricity are the two technologies that should be chosen for further development.     

An assessment of exploiting renewable energy sources with concerns of policy and technology

In recent years, the Taiwanese government has vigorously promoted the development of renewable energy to engage the challenges of gradual depletion of fossil fuels and oil, as well as the intensification of the greenhouse effect. Since the Sustainable Energy Policy Principles were announced in 2008, Taiwanese government has declared that the development of renewable energy should take into account goals that pertain to energy, the environment, and the economy (3E goals). This study aims to assess the 3E goals and renewable energy sources regulated by the Renewable Energy Development Bill that passed in 2009. The fuzzy analytic hierarchy process (FAHP) is used to resolve the multi-goal problem for achieving our research purposes. That is, this research attempts to reveal the suitable renewable energy sources for the purposes of meeting the 3E policy goals. The results first show that environmental goal is the most important to the development of various renewable energy technologies in Taiwan, followed by the economic and energy goals. Additionally, hydropower, solar energy, and wind energy would be the renewable energy sources utilized in meeting the 3E policy goals.     

Multi-criteria evaluation of hydrogen storage systems for automobiles in Korea using the fuzzy analytic hierarchy process

In this paper, five hydrogen storage systems for automobiles are evaluated using the fuzzy analytic hierarchy process (AHP) in respect to eight criteria. The hydrogen storage systems for automobiles to be evaluated are 350 bar compressed gas hydrogen, 700 bar compressed gas hydrogen, liquefied hydrogen, metal hydride and chemical hydride. The selected criteria used in the evaluation of five hydrogen storage systems are weight efficiency, volume efficiency, system cost, energy efficiency, cycle life, refueling time, safety and infrastructure. According to the evaluation, compressed gas hydrogen ranks the highest in classification in Korea. Liquefied hydrogen ranks higher than metal hydride and chemical hydride. If the infrastructure for liquefied hydrogen were good in Korea, liquefied hydrogen may rank the highest in classification. Also, it should be noted that the rank of hydrogen storage systems can be changed according to the future technological developments.     

Sustainability of hydrogen supply chain. Part II: Prioritizing and classifying the sustainability of hydrogen supply chains based on the combination of extension theory and AHP

The purpose of this study is to develop a method for prioritizing and classifying the sustainability of hydrogen supply chains and assist decision-making for the stakeholders/decision-makers. Multiple criteria for sustainability assessment of hydrogen supply chains are considered and multiple decision-makers are allowed to participate in the decision-making using linguistic terms. In this study, extension theory and analytic hierarchy process are combined to rate the sustainability of hydrogen supply chains. The sustainability of hydrogen supply chains could be identified according to the synthesis correlation degrees to each classical domain. Finally, an illustrative case is studied by the proposed method, and the results show that the proposed method is feasible for prioritizing and classifying the sustainability of hydrogen supply chains.     

Updated hydrogen production costs and parities for conventional and renewable technologies

This paper provides first a review of the production costs of hydrogen from conventional, nuclear and renewable sources, reported in the literature during the last eight years. In order to analyze the costs on a unified basis, they are updated to a common year (2009), taking into account the yearly inflation rates. The study also considers whether the hydrogen has been produced in centralized or distributed facilities. From these data, the expected future costs for conventional production of hydrogen are calculated considering several scenarios on carbon emission taxations. Based on these estimations, together with the predicted future costs (2019–2020 and 2030) for hydrogen from alternative sources, several hydrogen cost-parity analyses are exposed for renewable and nuclear energies. From the comparison between these alternative technologies for hydrogen production and the conventional ones (steam methane reforming and coal gasification), several predictions on the time-periods to reach cost parities are elaborated.     

Large-vscale hydrogen production and storage technologies: Current status and future directions

Over the past years, hydrogen has been identified as the most promising carrier of clean energy. In a world that aims to replace fossil fuels to mitigate greenhouse emissions and address other environmental concerns, hydrogen generation technologies have become a main player in the energy mix. Since hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating these systems with other renewable energy systems is becoming very feasible. For example, the coupling of wind or solar systems hydrogen fuel cells as secondary energy sources is proven to enhance grid stability and secure the reliable energy supply for all times. The current demand for clean energy is unprecedented, and it seems that hydrogen can meet such demand only when produced and stored in large quantities. This paper presents an overview of the main hydrogen production and storage technologies, along with their challenges. They are presented to help identify technologies that have sufficient potential for large-scale energy applications that rely on hydrogen. Producing hydrogen from water and fossil fuels and storing it in underground formations are the best large-scale production and storage technologies. However, the local conditions of a specific region play a key role in determining the most suited production and storage methods, and there might be a need to combine multiple strategies together to allow a significant large-scale production and storage of hydrogen.     

Evaluation of hydrogen production methods using the Analytic Hierarchy Process

In this paper, seven common hydrogen production processes are evaluated using the Analytic Hierarchy Process (AHP) in respect to five criteria. The processes to be evaluated are steam methane reforming (SMR), partial oxidation of hydrocarbons (POX), coal gasification (CG), biomass gasification (BG), the combination of photovoltaics and electrolysis (PV–EL), the combination of wind power and electrolysis (W–EL) and the combination of hydropower and electrolysis (H–EL). The selected criteria that were used in the evaluation, for each of the seven hydrogen production processes are CO₂ emissions, operation and maintenance costs, capital cost, feedstock cost and hydrogen production cost. According to the evaluation, the processes that combine renewable energy sources with electrolysis (PV–EL, W–EL and H–EL) rank higher in classification than conventional processes (SMR, POX, CG and BG).     

Efficiency of hydrogen production systems using alternative nuclear energy technologies

Nuclear energy can be used as the primary energy source in centralized hydrogen production through high-temperature thermochemical processes, water electrolysis, or high-temperature steam electrolysis. Energy efficiency is important in providing hydrogen economically and in a climate friendly manner. High operating temperatures are needed for more efficient thermochemical and electrochemical hydrogen production using nuclear energy. Therefore, high-temperature reactors, such as the gas-cooled, molten-salt-cooled and liquid-metal-cooled reactor technologies, are the candidates for use in hydrogen production. Several candidate technologies that span the range from well developed to conceptual are compared in our analysis. Among these alternatives, high-temperature steam electrolysis (HTSE) coupled to an advanced gas reactor cooled by supercritical CO₂ (S-CO₂) and equipped with a supercritical CO₂ power conversion cycle has the potential to provide higher energy efficiency at a lower temperature range than the other alternatives.     

Prioritizing the weights of hydrogen energy technologies in the sector of the hydrogen economy by using a fuzzy AHP approach

KIER, government supported research institute, establishes a long-term strategic energy technology development roadmap essentially with selection and specialization of energy technology R&D and for Korea's national security. In this paper, we establish a strategic hydrogen energy technology roadmap taking economic impact, commercial potential, inner capacity, and technical spin-off into account. We suggest a methodology to prioritize the relative weights of hydrogen energy technologies of hydrogen energy technology roadmap (ETRM) as we allocate R&D budget effectively using a fuzzy analytic hierarchy process (AHP), which reflects the vagueness of human thoughts instead of crisp numbers efficiently. In the sector of the hydrogen ETRM which is composed of 6 hydrogen energy technologies, PEMFC technology is the most preferred and technology (0.29), followed by DEFC tech (0.28), SOFC tech (0.24), Hydrogen separation & storage tech (0.10), and Hydrogen production tech (0.09).     

Power management control for off-grid solar hydrogen production and utilisation system

Climate change concerns, increasing global energy demand, coupled with pending peak supply of fossil fuels, calls for development of new power source. The rapid price drops for solar technologies and combined with international and national policy changes makes solar energy more affordable and accessible for widespread adoption. Solar energy also contributes towards the reduction of greenhouse gas emissions. The combination of electrolysis of water and fuel cells, which use hydrogen as an energy carrier extends the utility of the solar energy. For an integrated solar powered hydrogen production, storage and utilisation system, one of the elements that needs to be designed carefully is the power management system. Power management strategy has a complex function in this type of solar hydrogen system. This paper presents a power management strategy based on fuzzy logic technology to address the problems.     

Exergoeconomic analysis of hydrogen production using a standalone high-temperature electrolyzer

The conventional hydrogen production methods, primarily steam methane reforming and coal gasification, produce massive amounts of greenhouse gas emissions which significantly cause impacts on the environment. An alternative hydrogen production method is high-temperature electrolysis using Solid Oxide Electrolyzer that combines both high conversion efficiency and saleable high purity hydrogen production. The produced hydrogen can feed the various industrial processes at different scales in addition to offering an environmentally friendly storage option. The scope of this paper is to examine the economic feasibility of this technology through the utilization of the exergoeconomic concept, which traces the flow of exergy through the system and price both waste and products. Therefore, a standalone solid oxide electrolyzer of a 1MWe is considered for hydrogen production using renewably generated electricity. Having the detailed exergy analysis conducted in earlier studies, the focus of this article is on the costing of each exergy stream to determine the exergy cost and the potential changes outcomes as a result of the system operating or design parameters optimization. It is found that the cost of hydrogen production through the modular high-temperature electrolyzer varies between $3-$9/kg with an average of about $5.7/kg, respectively.     

The portfolio of renewable energy sources for achieving the three E policy goals

Renewable energy is considered by many policy-makers to contribute to achieving at least three major policy goals: the energy goal, the environmental goal, and the economic goal (3E goals). As an innovation-oriented island country with scarce natural resources, Taiwan announced the Sustainable Energy Policy Principles in 2008 that stated that Taiwan’s renewable energy policy should accomplish the 3E goals. Several studies point out that specific renewable energy policy goals lead to specific renewable energy sources and technologies because each type of renewable energy has different features. In order to achieve the renewable energy policy goals, this research aims to examine how different policy goals lead to corresponding renewable energy sources. The relative importance of each goal is evaluated by using analytic hierarchy process (AHP). The weight of each policy goal is adjusted separately to construct policy scenarios by the sensitivity analysis. According to the results, non-pumped storage hydropower, wind energy, and solar energy are three sources that could meet the three policy goals at the same time.     

Hydrogen production and End-Uses from combined heat,hydrogen and power system by using local resources

To address the problem of fossil fuel usage at the Missouri University of Science and Technology campus, using of alternative fuels and renewable energy sources can lower energy consumption and hydrogen use. Biogas, produced by anaerobic digestion of wastewater, organic waste, agricultural waste, industrial waste, and animal by-products is a potential source of renewable energy. In this work, we have discussed Hydrogen production and End-Uses from CHHP system for the campus using local resources. Following the resource assessment study, the team selects FuelCell Energy DFC1500™ unit as a molten carbonate fuel cell to study of combined heat, hydrogen and power (CHHP) system based on a molten carbonate fuel cell fed by biogas produced by anaerobic digestion. The CHHP system provides approximately 650 kg/day. The total hydrogen usage 123 kg/day on the university campus including personal transportation applications, backup power applications, portable power applications, and other mobility applications are 56, 16, 29, 17, and 5 respectively. The excess hydrogen could be sold to a gas retailer. In conclusion, the CHHP system will be able to reduce fossil fuel usage, greenhouse gas emissions and hydrogen generated is used to power different applications on the university campus.     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

Thermo-economic analysis of a hydrogen production system by sodium borohydride (NaBH4)

In the spectrum of current energy possibilities, hydrogen represents a solution of great interest toward a future sustainable energy system. No single technology can sustain the energy needs of the whole society, but integration and hybridization are two key strategic features for viable energy production based in hydrogen economy.In the present work, a hydrogen energy model is analyzed. In this model hydrogen is produced through the electrolysis of water, taking advantage of the electrical energy produced by a renewable generator (photovoltaic panels). The produced hydrogen is chemically stored by the synthesis of sodium borohydride (NaBH₄). NaBH₄ promising features in terms of safety and high volumetric density are exploited for transportation to a remote site where hydrogen is released from NaBH₄ hydrolysis and used for energy production.This model is compared from an economic standpoint with the traditional hydrogen storage and transportation technology (compressed hydrogen in tanks).This paper presents a thermodynamic and economic analysis of the process in order to determine its economic feasibility. Data employed for the realization of the model have been gathered from recent important progresses made on the subject.The innovative plant including NaBH₄ synthesis and transportation is compared from an economic standpoint with the traditional hydrogen storage and transportation technology (compressed hydrogen in tanks). As a final point, the best technology and the components' optimal sizes are evaluated for both cases in order to minimize production costs.     

Sensitivity analysis of technological,economic and sustainability evaluation of power plants using the analytic hierarchy process

Technological, economic and sustainability evaluation of power plants by use of the analytic hierarchy process and nine end node criteria for a reference scenario based on subjective criteria weighting has been presented in a previous paper by authors. However, criteria weight variations may substantially modify overall evaluations and rankings of power plants.     

Fuzzy Multi-actor Multi-criteria Decision Making for sustainability assessment of biomass-based technologies for hydrogen production

The purpose of this paper is to develop a sustainability assessment method to rank the prior sequence of biomass-based technologies for hydrogen production. A novel fuzzy Multi-actor Multi-criteria Decision Making method which allows multiple groups of decision-makers to use linguistic variables to assess the biomass-based technologies for hydrogen production has been developed. Fifteen criteria relevant to in economic, environmental, technological and social-political aspects have been used in sustainability assessment. Four biomass-based technologies including pyrolysis, conventional gasification, supercritical water gasification and fermentative hydrogen production have been studied by the proposed method, and biomass gasification has been considered as the most sustainable scenario and can be chosen for further development.     

PEM electrolysis for production of hydrogen from renewable energy sources

PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyzer for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyzer in the renewable energy systems are addressed, such as sizing of electrolyzer, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.     

Performance evaluation of a photoelectrochemical hydrogen production reactor under concentrated and non-concentrated sunlight conditions

In this paper, we present the experimental performance evaluations of a newly developed photoelectrochemical (PEC) reactor for the production of hydrogen under no-light and concentrated solar radiation conditions. With a newly developed experimental setup, the solar light is concentrated about ten times, and the spectrum is divided using cold mirrors for better sunlight utilization. The photoelectrochemical reactor is examined at different applied potentials and the hydrogen production quantities are measured. Copper oxide, which is used as a light-sensitive material, is electrochemically coated on the cathode metal plate to increase the rate of hydrogen evolution under illumination. The present experiments are conducted to investigate the variation of reactor performance with intensified light conditions and the obtained results are compared with the dark conditions. The results of this study reveal that the hydrogen evolution rate was 41.34 mg/h for concentrated light measurement and 34.73 mg/h for no-light measurements at 2.5 V applied potential. The corresponding photocurrent generated under concentrated light at 2.5 V is found to be 0.63 mA/cm². Under the concentrated sunlight, the hydrogen production rates increase considerably which is led by the positive effect of the photocurrent contribution.