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CO2 emissions associated with hydrogen production can be reduced replacing steam methane reforming with electrolysis using renewable electricity with a trade-off of increasing energy consumption, water consumption and cost. In this research, a linear programming optimization model of a hydrogen production system that considers simultaneously energy consumption, water consumption, CO2 emissions and cost on a cradle-to-gate basis was developed. The model was used to evaluate the impact of CO2 intensity on the optimum design of a hydrogen production system for Japan considering different stakeholders’ priorities. Hydrogen is produced using steam methane reforming and electrolysis. Electricity sources include grid, wind, solar photovoltaic, geothermal and hydro. Independent of the stakeholders’ priorities, steam methane reforming dominates hydrogen production for cradle-to-gate CO2 intensities larger than 9 kg CO2/kg H2, while electrolysis using renewable electricity dominates for lower cradle-to-gate CO2 intensities. Reducing the cradle-to-gate CO2 intensity increases energy consumption, water consumption and specific cost of hydrogen production. For a cradle-to-gate CO2 intensity of 0 kg CO2/kg H2, the specific cost of hydrogen production varies between 8.81 and 13.6 USD/kg H2; higher than the specific cost of hydrogen production targeted by the Japanese government in 2030 of 30 JPY/Nm3, 3.19 USD/kg H2.

Culminating two decades of industrial planning, China is now officially moving full steam ahead towards realizing a hydrogen economy under the country’s first ever Medium and Long-term Plan of the Hydrogen Industry (2021–2035). Among the relevant benchmarks established is the goal of developing a regulatory framework by 2025. This raises the question of how best to achieve a regulatory framework for China’s emerging hydrogen economy. To answer this question, the discussions of this paper are further broken-down and organized across four independent, but correlated, academic questions. One, relying on the fragmented authoritarianism model, what are the impacts of China’s current model of industrial development on an emerging regulated industry? Two, through a scientific and technological review, what are the characteristics of the hydrogen supply-chain most likely to present a regulatory challenge for China? Three, by analogy to the comparable experiences of China’s other regulated industries, what are the possible regulatory solutions? Four, and most importantly, how best to reconcile the findings to the above questions as they relate to the regulatory challenge of developing China’s emerging hydrogen economy. The results of the discussions reveal, that not all policy solutions and recommendations to the regulatory framework of the hydrogen economy should be treated equally. Rather, an integrated view of the core academic question revealed a procedural relationship among the regulatory solutions identified from the analysis above. Therefore, recognizing that each solution should synergize and correspond to different phases of regulatory development, a three-step regulatory pathway towards the hydrogen economy is proposed.

Hydrogen energy, as clean and efficient energy, is considered significant support for the construction of a sustainable society in the face of global climate change and the looming energy revolution. Hydrogen is one of the most important chemical substances on earth and can be obtained through various techniques using renewable and nonrenewable energy sources. However, the necessity for a gradual transition to renewable energy sources significantly hampers efforts to identify and implement green hydrogen production paths. Therefore, this paper’s objective is to provide a technological review of the systems of hydrogen production from solar and wind energy utilizing several types of water electrolyzers. The current paper starts with a short brief about the different production techniques. A detailed comparison between water electrolyzer types and a complete illustration of hydrogen production techniques using solar and wind are presented with examples, after which an economic assessment of green hydrogen production by comparing the costs of the discussed renewable sources with other production methods. Finally, the challenges that face the mentioned production methods are illuminated in the current review.

The paper is structured in three parts: the first contains some reflections on the essence of the circular economy concept; the second reviews the European Union positions vis-à-vis the circular economy and the large scale utilization of hydrogen, with reference in particular to the most recent strategic documents (European Green Deal, EU New Industrial Strategy for Europe, EU Strategy for Energy System Integration, EU Hydrogen Strategy, European Clean Hydrogen Alliance); the third part evaluates the feasibility and implications of the transition to a hydrogen based economy and the relation of this transition to the circular economy. The conclusions state that the adoption by the European Union of a hydrogen strategy represents a significant step towards a true circular economy

Numerous reviews on hydrogen storage have previously been published. However, most of these reviews deal either exclusively with storage materials or the global hydrogen economy. This paper presents a review of hydrogen storage systems that are relevant for mobility applications. The ideal storage medium should allow high volumetric and gravimetric energy densities, quick uptake and release of fuel, operation at room temperatures and atmospheric pressure, safe use, and balanced cost-effectiveness. All current hydrogen storage technologies have significant drawbacks, including complex thermal management systems, boil-off, poor efficiency, expensive catalysts, stability issues, slow response rates, high operating pressures, low energy densities, and risks of violent and uncontrolled spontaneous reactions. While not perfect, the current leading industry standard of compressed hydrogen offers a functional solution and demonstrates a storage option for mobility compared to other technologies.

This review examines the central role of hydrogen, particularly green hydrogen from renewable sources, in the global search for energy solutions that are sustainable and safe by design. Using the hydrogen square, safety measures across the hydrogen value chain—production, storage, transport, and utilisation—are discussed, thereby highlighting the need for a balanced approach to ensure a sustainable and efficient hydrogen economy. The review also underlines the challenges in safety assessments, points to past incidents, and argues for a comprehensive risk assessment that uses empirical modelling, simulation-based computational fluid dynamics (CFDs) for hydrogen dispersion, and quantitative risk assessments. It also highlights the activities carried out by our research group SaRAH (Safety, Risk Analysis, and Hydrogen) relative to a more rigorous risk assessment of hydrogen-related systems through the use of a combined approach of CFD simulations and the appropriate risk assessment tools. Our research activities are currently focused on underground hydrogen storage and hydrogen transport as hythane.

A general rise in environmental and anthropogenically induced greenhouse gas emissions has resulted from worldwide population growth and a growing appetite for clean energy, industrial outputs, and consumer utilization. Furthermore, well-established, advanced, and emerging countries are seeking fossil fuel and petroleum resources to support their aviation, electric utilities, industrial sectors, and consumer processing essentials. There is an increasing tendency to overcome these challenging concerns and achieve the Paris Agreement’s priorities as emerging technological advances in clean energy technologies progress. Hydrogen is expected to be implemented in various production applications as a fundamental fuel in future energy carrier materials development and manufacturing processes. This paper summarizes recent developments and hydrogen technologies in fuel refining, hydrocarbon processing, materials manufacturing, pharmaceuticals, aircraft construction, electronics, and other hydrogen applications. It also highlights the existing industrialization scenario and describes prospective innovations, including theoretical scientific advancements, green raw materials production, potential exploration, and renewable resource integration. Moreover, this article further discusses some socioeconomic implications of hydrogen as a green resource.

Green hydrogen production is essential to meeting the conference of the parties’ (COP) decarbonization goals; however, this method of producing hydrogen is not as cost-effective as hydrogen production from fossil fuels. This study analyses an off-grid photovoltaic energy system designed to feed a proton-exchange membrane water electrolyzer for hydrogen production to evaluate the optimal electrolyzer size. The system has been analyzed in Baghdad, the capital of Iraq, using experimental meteorological data. The 12 kWp photovoltaic array is positioned at the optimal annual tilt angle for the selected site. The temperature effect on photovoltaic modules is taken into consideration. Several electrolyzers with capacities in the range of 2–14 kW were investigated to assess the efficiency and effectiveness of the system. The simulation process was conducted using MATLAB and considering the project life span from 2021 to 2035. The results indicate that various potentially cost-competitive alternatives exist for systems with market combinations resembling renewable hydrogen wholesale. It has been found that the annual energy generated by the analyzed photovoltaic system is 18,892 kWh at 4313 operating hours, and the obtained hydrogen production cost ranges from USD 5.39/kg to USD 3.23/kg. The optimal electrolyzer capacity matches a 12 kWp PV system equal to 8 kW, producing 37.5 kg/year/kWp of hydrogen for USD 3.23/kg.

The overuse of fossil fuels has caused a serious energy crisis and environmental pollution. Due to these challenges, the search for alternative energy sources that can replace fossil fuels is necessary. Hydrogen is a widely acknowledged future energy carrier because of its nonpolluting properties and high energy density. To realize a hydrogen economy in the future, it is essential to construct a comprehensive hydrogen supply chain that can make hydrogen a key energy carrier. This paper reviews the various technologies involved in the hydrogen supply chain, encompassing hydrogen production, storage, transportation, and utilization technologies. Then, the challenges of constructing a hydrogen supply chain are discussed from techno-economic, social, and policy perspectives, and prospects for the future development of a hydrogen supply chain are presented in light of these challenges.