Institution of Gas Engineers & Managers

This study presents a comprehensive 4E (energy exergy economic and exergo-environmental) analysis of a solar-powered multi-generation system (MGS) that integrates parabolic trough collectors (PTCs) thermal energy storage (TES) an organic Rankine cycle (ORC) an absorption refrigeration cycle (ARC) a proton exchange membrane electrolyzer (PEME) and a reverse osmosis (RO) unit to simultaneously produce electricity cooling potable water and hydrogen. A complete thermodynamic model is developed in Engineering Equation Solver (EES) to evaluate the system from technical economic and environmental perspectives. Results indicate that the MGS can convert solar energy into multiple outputs with energy and exergy efficiencies of 12.2% and 4.3% respectively. The highest and lowest energy efficiencies are found in PEME (58.6%) and ORC (7.4%) while the highest and lowest exergy efficiencies are related to PEME (57.4%) and PTC (11.9%) respectively. Despite notable environmental impacts from the complex subsystems (particularly PTC and PEME) the system demonstrates strong economic performance with a net present value of approximately USD 8 million an internal rate of return of 30% and a payback period of 3.8 years. Sensitivity analysis shows that increasing solar radiation reduces the number of required PTCs and shortens payback time with less effect on energy and exergy efficiencies due to increased thermal and radiative losses.

The exploitation of fossil fuels in various sectors such as power and heat generation and the transportation sector has been the primary source of greenhouse gas (GHG) emissions which are the main contributors to global warming. Qatar's oil and gas sector notably contributes to CO2 emissions accounting for half of the total emissions. Globally it is essential to transition into cleaner fossil fuel production to achieve carbon neutrality on a global scale. In this paper we focus on clean hydrogen considering carbon capture to make hydrogen a viable low carbon energy alternative for the transition to clean energy. This paper systematically reviews emerging technologies in carbon capture and conversion (CCC). First the road map stated by the Intergovernmental Panel on Climate Change (IPCC) to reach carbon neutrality is discussed along with pathways to decarbonize the energy sector in Qatar. Next emerging CO2 removal technologies including physical absorption using ionic liquids chemical looping and cryogenics are explored and analyzed regarding their advancement and limitations CO2 purity scalability and prospects. The advantages limitations and efficiency of the CO2 conversion technology to value-added products are grouped into chemical (plasma catalysis electrochemical and photochemical) and biological (photosynthetic and non-photosynthetic). The paper concludes by analyzing pathways to decarbonize the energy sector in Qatar via coupling CCC technologies for low-carbon hydrogen highlighting the challenges and research gaps.

The signing of the Paris Agreement in 2016 established the goals of countries around the world for the transition from traditional fossil energy to sustainable energy in the 21st century. Reduce carbon emissions using new sustainable energy sources while safeguarding the energy needs of social development. The advantages of hydrogen fuel cell vehicles such as no carbon emissions long battery life and short hydrogenation time make them the development direction of new energy vehicles in many countries. Many countries such as the United Kingdom China and Japan have formulated hydrogen energy development plans. As the hub and supply station of the hydrogen energy transportation network the hydrogen refueling station is crucial to the development of the hydrogen economy. This paper summarizes the current main hydrogen storage methods and the existing risks analyzes the main security threats of hydrogen refueling stations and discusses the security system to prevent hydrogen embrittlement and hydrogen explosion. Finally the hydrogen refueling station is compared with the petrol station and the future security development and management pattern of the hydrogen refueling station is summarized. The security assessment of the hydrogen refueling station is carried out in this paper which provides theoretical support for the development of hydrogen refueling stations from the perspective of security.

In order to solve the problem of large-scale offshore wind power consumption the development of an offshore wind power hydrogen supply chain has become one of the trends. In this study 10 feasible options are proposed to investigate the economics of an offshore wind hydrogen supply chain for offshore hydrogen refueling station consumption from three aspects: offshore wind hydrogen production storage and transportation and application. The study adopts a levelized cost analysis method to measure the current and future costs of the hydrogen supply chain. It analyses the suitable transport modes for delivering hydrogen to offshore hydrogen refueling stations at different scales and distances as well as the profitability of offshore hydrogen refueling stations. The study draws the following key conclusions: (1) the current centralised wind power hydrogen production method is economically superior to the distributed method; (2) gas-hydrogen storage and transportation is still the most economical method at the current time with a cost of CNY 32.14/kg which decreases to CNY 13.52/kg in 2037 on a par with the cost of coal-based hydrogen production using carbon capture technology; and (3) at the boundaries of an operating load factor of 70% and a selling price of CNY 25/kg the offshore hydrogen refueling station. The internal rate of return (IRR) is 21% showing good profitability; (4) In terms of the choice of transport mode for supplying hydrogen to the offshore hydrogen refueling station gas-hydrogen ships and pipeline transport will mainly be used in the near future while liquid organic hydrogen carriers and synthetic ammonia ships can be considered in the medium to long term.

Given the urgent need to decarbonize the global energy system green hydrogen has emerged as a key alternative in the transition to renewables. However its production via electrolysis demands high water quality and raises environmental concerns particularly regarding reject water discharge. This study employs an experimental and analytical approach to define optimal water characteristics for electrolysis focusing on conductivity as a key parameter. A pilot water treatment plant with reverse osmosis and electrodeionization (EDI) was designed to simulate industrial-scale pretreatment. Twenty water samples from diverse natural sources (surface and groundwater) were tested selected for geographical and geological variability. A predictive algorithm was developed and validated to estimate useful versus reject water based on input quality. Three conductivity-based categories were defined: optimal (0–410 µS/cm) moderate (411–900 µS/cm) and restricted (>900 µS/cm). Results show that water quality significantly affects process efficiency energy use waste generation and operating costs. This work offers a technical and regulatory framework for assessing potential sites for green hydrogen plants recommending avoidance of high-conductivity sources. It also underscores the current regulatory gap regarding reject water treatment stressing the need for clear environmental guidelines to ensure project sustainability.

Hydrogen has attracted growing research interest due to its exceptionally high energy per mass content and being a clean energy carrier unlike the widely used hydrocarbon fuels. With the possibility of long-term energy storage and re-electrification hydrogen promises to promote the effective utilization of renewable and sustainable energy resources. Clean hydrogen can be produced through a renewable-powered water electrolysis process. Although alkaline water electrolysis is currently the mature and commercially available electrolysis technology for hydrogen production it has several shortcomings that hinder its integration with intermittent and fluctuating renewable energy sources. The proton exchange membrane water electrolysis (PEMWE) technology has been developed to offer high voltage efficiencies at high current densities. Besides PEMWE cells are characterized by a fast system response to fluctuating renewable power enabling operations at broader partial power load ranges while consistently delivering high-purity hydrogen with low ohmic losses. Recently much effort has been devoted to improving the efficiency performance durability and economy of PEMWE cells. The research activities in this context include investigations of different cell component materials protective coatings and material characterizations as well as the synthesis and analysis of new electrocatalysts for enhanced electrochemical activity and stability with minimized use of noble metals. Further many modeling studies have been reported to analyze cell performance considering cell electrochemistry overvoltage and thermodynamics. Thus it is imperative to review and compile recent research studies covering multiple aspects of PEMWE cells in one literature to present advancements and limitations of this field. This article offers a comprehensive review of the state-of-the-art of PEMWE cells. It compiles recent research on each PEMWE cell component and discusses how the characteristics of these components affect the overall cell performance. In addition the electrochemical activity and stability of various catalyst materials are reviewed. Further the thermodynamics and electrochemistry of electrolytic water splitting are described and inherent cell overvoltage are elucidated. The available literature on PEMWE cell modeling aimed at analyzing the performance of PEMWE cells is compiled. Overall this article provides the advancements in cell components materials electrocatalysts and modeling research for PEMWE to promote the effective utilization of renewable but intermittent and fluctuating energy in the pursuit of a seamless transition to clean energy.

The paper discusses some of the requirements drivers and resulting technological paths for manufacturers to develop hydrogen combustion engines for use in two types of market application – onroad heavy- and light-duty. One of the main requirements is legislative certainty and this has now been afforded – at least in the major market of Europe – by the European Union’s recent adoption into law of tailpipe emissions limits specifically designed to encourage the uptake of hydrogen engines in heavy-duty vehicles giving manufacturers the confidence they need to invest in productionized solutions to offer to customers. It then discusses combustion systems and boosting systems for the two market types emphasizing that heavy-duty vehicles need best efficiency throughout their operating map while light-duty ones since they are rarely operated at full load will mainly primarily need efficiency in the part-load region. This difference will likely cause a divergence in solutions with heavy-duty engines running very lean everywhere and light-duty ones likely operating at the stoichiometric air-fuel ratio at least for most of the map. The impacts of the strategies on engine systems and vehicle integration are discussed. It is postulated that due to reasons of preignition avoidance and efficiency hydrogen engines will rapidly adopt direct injection and that the long-term heavy-duty types will migrate towards the typical current spark-ignition-type cylinder head architecture where tumble rather than swirl will ultimately be needed for air motion in the cylinder for these reasons. They may also adopt active pre-chamber technology to ignite extremely lean mixtures for maximum efficiency and minimum emissions of oxides of nitrogen. It is suggested that light-duty engines will evolve less from their current gasoline architectural norm since they already contain all of the necessary fundamentals for hydrogen combustion. However since partload efficiency will be important some new strategies may become desirable. Developing dual-fuel light-duty engines could accelerate their uptake as the heavy-duty market simultaneously accelerates the creation of the fuel supply infrastructure. The likely technological evolution suggests that variable valve trains and specifically cam profile switching technology would be extremely useful for all types of hydrogen engine especially since they are readily available in different gasoline engines now. New operating strategies afforded by variable valve trains would benefit both heavy- and light-duty engines and these strategies will become more sophisticated. There will therefore likely be a convergence of technologies for the two markets albeit with some key differences maintained due to their vehicle applications and their differing operation in the field.

Public perceptions might determine the ease of the transition from a fossil-based to a green hydrogen-based production pathway in the industrial sector. The primary objective of this paper is to empirically identify the antecedents of the acceptance of two relevant industrial applications of green hydrogen: green methanol and green steel. The analysis relying on linear regression models utilises survey data from samples of residents near a chemical park and a steel plant (509 and 502 participants respectively) contrasting them with a representative sample of 1502 individuals in Germany. The findings suggest that acceptance of the transitions to green methanol and green steel is high both locally and nationally. In all surveys >59 % of the participants are in favour while the share of those who are opposed to the respective transitions is below 9 %. Key antecedents of acceptance which are conducive in all models relate to individuals’ attitudes towards green hydrogen and perceptions of the legitimacy of the industry actors involved with varying results across legitimacy types. In general the findings were similar across industrial applications and across levels of observation but varied across regions. This study highlights the importance of civil society perceptions and suggests that relationship management efforts aimed at maintaining positive perceptions of industrial hydrogen applications should consider their broader physical and social contexts.

This paper provides a systematic visualization of the development current status and challenges of salt cavern hydrogen storage technology based on the relevant literature from the past five years in the Web of Science Core Collection database. Using VOSviewer (version 1.6.20) and CiteSpace software (advanced version 6.3.R3) this study analyzes the field from a knowledge mapping perspective. The findings reveal that global research hotspots are primarily focused on multi-energy collaboration integration of renewable energy systems and exploration of commercialization highlighting the essential role of salt cavern hydrogen storage in driving the energy transition and promoting sustainable development. In China research mainly concentrates on theoretical innovations and technological optimizations to address complex geological conditions. Despite the rapid growth in the number of Chinese publications unresolved challenges remain such as the complexity of layered salt rock and thermodynamic coupling effects during highfrequency injection and extraction as well as issues concerning permeability and microbial activity. Moving forward China’s salt cavern hydrogen storage technology should focus on strengthening engineering practices suited to local geological conditions and enhancing the application of intelligent technologies thereby facilitating the translation of theoretical research into practical applications.

Hybrid hydrogen-battery powertrains represent a promising solution for sustainable transport. In these systems a fuel cell converts hydrogen into electricity to power the motors and charge a battery which in turn manages power fluctuations and enables regenerative braking. This study investigates degradation in hybrid powertrain components for the railway sector focusing on optimizing their operation to enhance durability. The analysis applied to a real case study on a non-electrified railway line in northern Italy evaluates different operating strategies by constraining the fuel cell current ramp. The results show that operating the fuel cell with minimal power fluctuations – while relying on the battery to handle power peaks – offers a clear advantage. Specifically reducing the maximum fuel cell current ramp from 1500 A/s (load-following operation) to 1 A/s (near-constant operation) extends fuel cell lifetime by 50.5 % though at the expense of a 25.1 % reduction in battery lifetime.