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A simple economic analysis has revealed that in order for wind energy to be a viable alternative, wind-turbines (convertors of wind energy into electrical energy) must be able to operate for at least 20 years, with only regular maintenance. However, wind-turbines built nowadays do not generally possess this level of reliability and durability. Specifically, due to the malfunction and failure of drive-trains/gear-boxes, many wind-turbines require major repairs after only three to five years in service. The paper aims to discuss these issues.

The subject of the present work is the so-called white etch cracking, one of the key processes responsible for the premature failure of gear-box roller-bearings. To address this problem, a multi-physics computational methodology is developed and used to analyze the problem of wind-turbine gear-box roller-bearing premature-failure. The main components of the proposed methodology include the analyses of: first, hydrogen dissolution and the accompanying grain-boundary embrittlement phenomena; second, hydrogen diffusion from the crack-wake into the adjacent unfractured material; third, the inter-granular fracture processes; and fourth, the kinematic and structural response of the bearing under service-loading conditions.

The results obtained clearly revealed the operation of the white-etch cracking phenomenon in wind-turbine gear-box roller-bearings and its dependence on the attendant loading and environmental conditions.

The present work attempts to make a contribution to the resolution of an important problem related to premature-failure and inferior reliability of wind-turbine gearboxes.

Spark ignition (SI) engines are used in a wide area in the transportation industry, from road vehicles to piston-prop aircraft. On the other hand, the decrease in reserves of fossil fuels used in SI engines and the increase in greenhouse gas emissions makes the use of alternative fuels inevitable. In this paper, optimization of in-cylinder combustion and engine performance parameters by intake-charge conditions [i.e. intake-air temperature, injection timing and exhaust gas recirculation (EGR)] in a hydrogen (H₂)-fueled small SI engine is performed.

Experimental studies were performed at a 1,600 rpm engine speed of a single-cylinder, air-cooled engine having a stroke volume of 476.5 cm³, maximum output power of 13 HP and torque of 25 Nm. The hydrogen-fueled SI engine was operated by a lean air-fuel mixture (ϕ = 0.6) under wide-open throttle (WOT) conditions.

The findings of the paper show that improvements can be achieved in in-cylinder combustion, indicated engine performance, exhaust NO_x emissions with optimum intake-air temperature, the start of H₂ injection and the ERG rate.

It has been determined that a 32°C intake-air temperature, 395°C (bTDC) start of H₂ injection, and 5%–10% EGR rates are the most suitable values for the examined hydrogen fueled SI engine.

Hydrogen is a usable alternative fuel for SI engines used in a wide area from road vehicles to piston-prop aircraft engines. However, a number of problems remain that limit hydrogen fueled SI engines to some extent, such as backfire, a decrease of engine power, and high NO_x emissions. Therefore, it is appropriate to examine the effects of intake-charge conditions on in-cylinder combustion, engine performance, and NO_x emissions parameters in a hydrogen fuelled SI engine.

Acute shortage of potable water and energy supplies is expected to raise in developing countries in the near future. One solid way to address these issues is to exploit renewable energy resources efficiently. Hence, this study aims to investigate wind and solar energy use in the coastal areas of southern Iran for renewable-powered seawater desalination and hydrogen production systems.

To accomplish the aforementioned purpose, five areas most prone to the problems in Iran, namely, Mahshahr, Jask and Chabahar ports and Kish and Hormoz islands were scrutinized. To ascertain the amount of wind and solar energy available in the areas, Weibull distribution function, Angstrom–Prescott equation and HOMER software were used.

The findings indicated that wind energy density in Kish was 2,014.86 (kWh/m².yr) and solar energy density in Jask equaled to 2,255.7 (kWh/m².yr) which possessed the best conditions among the areas under study. Moreover, three commercial wind turbines and three photovoltaic systems were examined for supplying energy needed by the water desalination and hydrogen production systems. The results showed that application of wind turbines with rated power of 660, 750 and 900 kWh in Kish could result in desalting 934,145, 1,263,339 and 2,000,450 (m³/yr) of seawater or producing 14,719, 20,896 and 31,521 (kg/yr) of hydrogen, respectively. Additionally, use of photovoltaic systems with efficiency of %14.4, %17.01 and %21.16 in Jask could desalinate 287, 444 and 464 (m³/yr) of seawater or generate 4.5, 7 and 7.3 (kg/yr) of hydrogen, respectively.

Compared to the huge extent of water shortage and environmental pollution, there has not been conducted enough studies to obtain broader view regarding use of renewable energies to solve these issues in Iran. Therefore, this study tries to close this gap and to give other developing nations the idea of water desalination and hydrogen production via renewable energies.

Alternating current (AC) corrosion is a type of corrosion that occurs in buried pipelines under AC stray current interference, which can increase the hydrogen embrittlement sensitivity of pipelines. However, rare research works have been conducted on the hydrogen permeability characteristics of pipeline steel under AC stray current interference. The purpose of this paper is to study hydrogen permeation behavior of X80 steel under AC stray current interference.

In this paper, the hydrogen permeation behavior of X80 steel under AC interference is studied by AC hydrogen charging experiment in a dual electrolytic cell. The relationship between hydrogen evolution rate and hydrogen permeation flux is studied using the gas collection method. The difference between AC hydrogen permeability and direct current (DC) hydrogen permeability is also discussed.

The anodic dissolution caused by AC corrosion promotes the chemical desorption reaction of the adsorbed hydrogen atoms on the surface, reducing the hydrogen atom absorption ratio by 70%. When the AC is smaller than 150░ A/m², the hydrogen permeation process is controlled by the hydrogen atom generation rate, and the hydrogen permeation flux increases with the increase in hydrogen atom generation rate. When the AC exceeds 400░ A/m², the hydrogen permeation process is controlled by the absorption ratio. The hydrogen permeation flux decreases with the decrease in the absorption ratio. Under AC interference, there is a maximum hydrogen permeation flux that linearly correlates to the H⁺ concentration in the solutions.

The high-strength steel is very sensitive to hydrogen embrittlement, and X80 steel has been widely used in oil and gas pipelines. To date, no research has been conducted on the hydrogen permeation behavior of pipeline steel under AC interference, and the hydrogen permeability characteristics of pipeline steel under AC interference are not clear. The research results of this paper are of great significance for ensuring the intrinsic safety of high-strength pipelines under AC stray current interference.

The purpose of this paper is the definition and the implementation of a simplified mathematical model to estimate the hazard and the risk related to the use of high‐pressurized hydrogen pipeline.

This study aims to investigate the effects of different hydrogen operations conditions and to tackle with different release or failure scenarios. Based on the combination of empirical relations and analytical models, this paper sets the basis for suitable models for consequence analysis in terms of estimating fire length and of predicting its thermal radiation. The results are compared either with experimental data available in the literature, thus by setting the same operations and failure conditions, or with other conventional gaseous fuel currently used.

The findings show that the release rate increasingly varies according to the supply pressure. Regarding the effect of the hole diameter, it hugely affects the amount of hydrogen escaping from the leak, up to a value of approximately 0.3 m, after which the release rate remains fixed at a maximum of 43 Kg/s. For failure consequences related to jet flame, the leak dimension has a strength impact on the flame length.

This paper represents a helpful engineering tool, to establish the safety requirements that are related to define adequate safety buffer zones for the hydrogen pipeline in order to ensure safety to people, as well the environment.

The paper attempts to highlight and discuss the limitations of the current discourse around the role of hydrogen‐based energy in a more sustainable future.

The paper draws upon preliminary findings from qualitative fieldwork in three case studies. Focus groups were conducted with members of the public in three different areas of the UK where hydrogen projects are being planned and/or developed. Findings are connected to evidence gathered in other similar studies addressing the relationship between publics and new technologies.

In the case of hydrogen energy and its role in a future economy, questions about safety were present but did not dominate the debate. Participants in our focus groups were not only concerned about the technical and economic aspects of hydrogen technologies, but they also wanted to understand what hydrogen as an energy carrier and fuel would mean for them and in their daily lives; whether it would deliver the promise of realising a better future, for the global environment and the people; and whether it would disrupt people's lifestyles and require a significant change in collective and individual behaviour. Moreover, a frequent issue raised by many people was their ambivalence about what, and whom, to trust in the provision of information about hydrogen.

This research on public attitudes to a future hydrogen economy provides empirical insights about the socio‐cultural contexts in which lay understandings of new, unfamiliar technologies and technological systems are developed, and what issues are raised by members of the general public when an informed debate is encouraged. The research attempts to contribute to the wider debate about public engagement in technological change.

This paper aims to study the mechanism of hydrogen embrittlement in 12Cr2Mo1R(H) steel, which will help to provide valuable information for the subsequent hydrogen embrittlement research of this kind of steel, so as to optimize the processing technology and take more appropriate measures to prevent hydrogen damage.

The hydrogen diffusion coefficient of 12Cr2Mo1R(H) steel was measured by the hydrogen permeation technique of double electrolytic cells. Moreover, the influence of hydrogen traps in the material and experimental temperature on hydrogen diffusion behavior was discussed. The first-principles calculations based on density functional theory were used to study the occupancy of H atoms in the bcc-Fe cell, the diffusion path and the interaction with vacancy defects.

The results revealed that the logarithm of the hydrogen diffusion coefficient of the material has a linear relationship with the reciprocal of temperature and the activation energy of hydrogen atom diffusion in 12Cr2Mo1R(H) steel is 23.47 kJ/mol. H atoms stably exist in the nearly octahedral interstices in the crystal cell with vacancies. In addition, the solution of Cr/Mo alloy atom does not change the lowest energy path of H atom, but increases the diffusion activation energy of hydrogen atom, thus hindering the diffusion of hydrogen atom. Cr/Mo and vacancy have a synergistic effect on inhibiting the diffusion of H atoms in α-Fe.

This article combines experiments with first-principles calculations to explore the diffusion behavior of hydrogen in 12Cr2Mo1R(H) steel from the macroscopic and microscopic perspectives, which will help to establish a calculation model with complex defects in the future.

Long life and high hydrogen sensitivity are the crucial performance parameters for an optical fiber hydrogen sensing membrane, and these are the fundamental areas of study for an optical fiber hydrogen sensor. Considering that a traditional optical fiber hydrogen sensor based on pure palladium cannot meet the expectations for long life and rapid sensitivity simultaneously, the experiment in this paper designed a kind of reflective optical fiber bundle hydrogen gas sensor based on a Pd_0.75–Ag_0.25 alloy to achieve a hydrogen sensing system. This paper aims to discuss the issues with this system.

A reflective optical fiber bundle hydrogen sensor was made up of an optical fiber bundle and a Pd_0.75–Ag_0.25 alloy hydrogen membrane. A combination of optical fiber light intensity measurements and the reference calculation method were used to extract the hydrogen concentration information from within the optical fiber, and the relationship between the hydrogen concentration changes and the reflective light intensity in the optical fiber was established.

The reflective optical fiber bundle hydrogen gas sensor based on a Pd–Ag alloy membrane was shown to provide an effective way to detect hydrogen concentrations. The experimental results showed that a 20-30-nm-thick Pd_0.75–Ag_0.25 alloy membrane could reach high hydrogen absorption and sensitivity. Key preparation parameters which included sputtering time and substrate temperature were used to prepare the hydrogen membrane during the DC sputtering process, and the reflectivity of the Pd–Ag alloy membrane was enough to meet the requirements of long life and high hydrogen sensitivity for the optical fiber hydrogen sensor.

This paper seeks to establish a foundation for optimizing and testing the performance of the Pd–Ag alloy hydrogen sensing membrane for an optical fiber bundle hydrogen sensor. To this end, the optimal thickness and key preparation parameters for the Pd–Ag alloy hydrogen sensing membrane were discussed. The results of this research have proved that the reflective optical fiber hydrogen sensor based on a Pd_0.75–Ag_0.25 alloy is an effective approach and precisely enough for hydrogen gas monitoring in practical engineering measurements.

The purpose of this paper is to estimate delivered hydrogen cost including both transport and expected accidents cost comparing compressed gas or liquid hydrogen road transport. The model allows to determine whether, in a given context, the risk of accidents is an influencing variable in the selection of the hydrogen transport mode. It also helps to select the lowest cost transport mode and route.

Transportation cost models are developed and integrated with a risk analysis model to determine expected accidents cost so that an overall delivered hydrogen cost can be computed. Alternative transport modes are compared on the basis of hydrogen demand, delivery distance and route type.

While safety cost in many cases can be considered negligible with respect to overall hydrogen transport cost, there are cases (high flow rate, long distance) where accident cost is relevant, especially in routes through densely populated areas. In such cases, factoring in accidents cost may significantly affect the break even point between CH2 and LH2 transport alternatives.

The paper only deals with proven road transportation methods (CH2 and LH2). Inclusion of alternative transport modes such as pipeline or hydrides is a future research goal.

Decision makers can examine the costs implied by hydrogen transportation alternatives in different economic scenarios factoring in safety costs to make informed decision.

Available hydrogen transportation cost models neglect any safety issue, while risk assessment models only consider accident consequences costs. This work integrates both views.