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A detailed thermodynamic analysis of the sorption enhanced chemical looping reforming of methane (SE-CL-SMR) using CaO and NiO as CO2 sorbent and oxygen transfer material (OTM) respectively was conducted. Conventional reforming (SMR) and sorption enhanced reforming (SE-SMR) were also investigated for comparison reasons. The results of the thermodynamic analysis show that there are significant advantages of both sorption enhanced processes compared to conventional reforming. The presence of CaO leads to higher methane conversion and hydrogen purity at low temperatures. Addition of the OTM in the SECL-SMR process concept minimizes the thermal requirements and results in superior performance compared to SE-SMR and SMR in a two-reactor concept with use of pure oxygen as oxidant/sweep gas.

This paper discusses the numerical modeling of an automobile fuel cell system using a two-stage turbo-compressor for air supply. The numerical model incorporates essential input parameters for air and hydrogen flow. The model also performed mass and energy balances across different components such as pump fan heat-exchanger air compressor and keeps in consideration the pressure losses across flow pipes and various mechanical parts. The compressor design process initiates with numerical analysis of the preliminary design of a highly efficient two-stage turbo compressor with an expander as a single-stage compressor has several limitations in terms of efficiency and pressure ratio. The compressor’s design parameters were carefully studied and analyzed with respect to the highly efficient fuel cell stack (FCS) used in modern hydrogen vehicles. The model is solved to evaluate the overall performance of PEM FCS. The final compressor has a total pressure and temperature of 4.2 bar and 149.3°C whereas the required power is 20.08kW with 3.18kW power losses and having a combined efficiency of 70.8%. According to the FC model with and without expander the net-power outputs are 98.15kW and 88.27kW respectively and the maximum efficiencies are 65.1% and 59.1% respectively. Therefore it can be concluded that a two-stage turbo compressor with a turbo-expander can have significant effects on overall system power and efficiency. The model can be used to predict and optimize system performance for PEM FCS at different operating conditions.

Dry reforming of hydrocarbons alcohols and biological compounds is one of the most promising and effective avenues to increase hydrogen (H2 ) production. Catalytic dry reforming is used to facilitate the reforming process. The most popular catalysts for dry reforming are Ni-based catalysts. Due to their inactivation at high temperatures these catalysts need to use metal supports which have received special attention from researchers in recent years. Due to the existence of a wide range of metal supports and the need for accurate detection of higher H2 production in this study a systematic review and meta-analysis using ANNs were conducted to assess the hydrogen production by various catalysts in the dry reforming process. The Scopus Embase and Web of Science databases were investigated to retrieve the related articles from 1 January 2000 until 20 January 2021. Forty-seven articles containing 100 studies were included. To determine optimal models for three target factors (hydrocarbon conversion hydrogen yield and stability test time) artificial neural networks (ANNs) combined with differential evolution (DE) were applied. The best models obtained had an average relative error for the testing data of 0.52% for conversion 3.36% for stability and 0.03% for yield. These small differences between experimental results and predictions indicate a good generalization capability.

Hydrogen (H2) has attained significant benefits as an energy carrier due to its gross calorific value (GCV) and inherently clean operation. Thus hydrogen as a fuel can lead to global sustainability. Conventional H2 production is predominantly through fossil fuels and electrolysis is now identified to be most promising for H2 generation. This review describes the recent state of the art and challenges on ultra-pure H2 production through methanol electrolysis that incorporate polymer electrolyte membrane (PEM). It also discusses about the methanol electrochemical reforming catalysts as well as the impact of this process via PEM. The efficiency of H2 production depends on the different components of the PEM fuel cells which are bipolar plates current collector and membrane electrode assembly. The efficiency also changes with the nature and type of the fuel fuel/oxygen ratio pressure temperature humidity cell potential and interfacial electronic level interaction between the redox levels of electrolyte and band gap edges of the semiconductor membranes. Diverse operating conditions such as concentration of methanol cell temperature catalyst loading membrane thickness and cell voltage that affect the performance are critically addressed. Comparison of various methanol electrolyzer systems are performed to validate the significance of methanol economy to match the future sustainable energy demands.

The transition to cleaner energy sources including renewables introduces the need for versatile and transportable energy carriers such as hydrogen. This paper aims to quantify the hydrogen export competitiveness of all countries using a newly developed comprehensive index. The developed competitiveness index includes 21 indicators under four main categories: resource availability and potential economic and financial potential political and regulatory status and industrial knowledge. Expert interviews and surveys are conducted to properly identify choose and modify the categories and indicators and to calculate the appropriate weight for each. Top-ranking countries include the United States Australia Canada United Kingdom China Norway India Russia Netherlands and Germany and they are poised to be significant players in the hydrogen market. Policy recommendations for growing the hydrogen production and export sector are given based on each category.

Low carbon hydrogen can be an excellent source of clean energy which can combat global climate change and poor air quality. Hydrogen based economy can be a great opportunity for a country like Qatar to decarbonize its multiple sectors including transportation shipping global energy markets and industrial sectors. However there are still some barriers to the realization of a hydrogen-based economy which includes large scale hydrogen production cost infrastructure investments bulk storage transport & distribution safety consideration and matching supply-demand uncertainties. This paper highlights how the aforementioned challenges can be handled strategically through a multi-sector industrial-urban symbiosis for the hydrogen supply chain implementation. Such symbiosis can enhance the mutual relationship between diverse industries and urban planning by exploring varied scopes of multi-purpose hydrogen usage (i.e. clean energy source as a safer carrier industrial feedstock and intermittent products vehicle and shipping fuel and international energy trading etc.) both in local and international markets. It enables individual entities and businesses to participate in the physical exchange of materials by-products energy and water with strategic advantages for all participants. Besides waste/by-product exchanges several different kinds of synergies are also possible such as the sharing of resources and shared facilities. The diversified economic base regional proximity and the facilitation of rules strategies and policies may be the key drivers that support the creation of a multi-sector hydrogen supply chain in Qatar.

The water-gas shift reaction (WGSR) is an intermediate reaction in hydrocarbon reforming processes considered one of the most important reactions for hydrogen production. Here water and carbon monoxide molecules react to generate hydrogen and carbon dioxide. From the thermodynamics aspect pressure does not have an impact whereas low-temperature conditions are suitable for high hydrogen selectivity because of the exothermic nature of the WGSR reaction. The performance of this reaction can be greatly enhanced in the presence of suitable catalysts. The WGSR has been widely studied due do the industrial significance resulting in a good volume of open literature on reactor design and catalyst development. A number of review articles are also available on the fundamental aspects of the reaction including thermodynamic analysis reaction condition optimization catalyst design and deactivation studies. Over the past few decades there has been an exceptional development of the catalyst characterization techniques such as near-ambient x-ray photoelectron spectroscopy (NA-XPS) and in situ transmission electron microscopy (in situ TEM) providing atomic level information in presence of gases at elevated temperatures. These tools have been crucial in providing nanoscale structural details and the dynamic changes during reaction conditions which were not available before. The present review is an attempt to gather the recent progress particularly in the past decade on the catalysts for low-temperature WGSR and their structural properties leading to new insights that can be used in the future for effective catalyst design. For the ease of reading the article is divided into subsections based on metals (noble and transition metal) oxide supports and carbon-based supports. It also aims at providing a brief overview of the reaction conditions by including a table of catalysts with synthesis methods reaction conditions and key observations for a quick reference. Based on our study of literature on noble metal catalysts atomic Pt substituted Mn3O4 shows almost full CO conversion at 260 °C itself with zero methane formation. In the case of transition metals group the inclusion of Cu in catalytic system seems to influence the CO conversion significantly and in some cases with CO conversion improvement by 65% at 280 °C. Moreover mesoporous ceria as a catalyst support shows great potential with reports of full CO conversion at a low temperature of 175 °C.

The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based) step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar) step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH) is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle) and solar-to-fuel energy conversion efficiency (ηsolar´to´fuel) attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar´to´fuel both increase with decreasing TH due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance in the case where TH = 2280 K ηcycle = 24.4% and ηsolar´to´fuel = 29.5% (without heat recuperation) while ηcycle = 31.3% and ηsolar´to´fuel = 37.8% (with 40% heat recuperation).

Natural gas is the most growing fossil fuel due to its environmental advantages. For the economical transportation of natural gas to distant markets physical (i.e. liquefaction and compression) or chemical (i.e. direct and indirect) monetisation options must be considered to reduce volume and meet the demand of different markets. Planning natural gas supply chains is a complex problem in today’s turbulent markets especially considering the uncertainties associated with final market demand and competition with emerging renewable and hydrogen energies. This review study evaluates the latest research on mathematical programming (i.e. MILP and MINLP) as a decisionmaking tool for designing and planning natural gas supply chains under different planning horizons. The first part of this study assesses the status of existing natural gas infrastructures by addressing readily available natural monetisation options quantitative tools for selecting monetisation options and single-state and multistate natural gas supply chain optimisation models. The second part investigates hydrogen as a potential energy carrier for integration with natural gas supply chains carbon capture utilisation and storage technologies. This integration is foreseen to decarbonise systems diversify the product portfolio and fill the gap between current supply chains and the future market need of cleaner energy commodities. Since natural gas markets are turbulent and hydrogen energy has the potential to replace fossil fuels in the future addressing stochastic conditions and demand uncertainty is vital to hedge against risks through designing a responsive supply chain in the project’s early design stages. Hence hydrogen supply chain optimisation studies and the latest works on hydrogen–natural gas supply chain optimisation were reviewed under deterministic and stochastic conditions. Only quantitative mathematical models for supply chain optimisation including linear and nonlinear programming models were considered in this study to evaluate the effectiveness of each proposed approach.

This paper explores the potential for hydrogen energy to become a future trend in Saudi Arabia energy industry. With the emergence of hydrogen as a promising clean energy source there has been growing interest and investment in this area globally. This study investigated whether the country is likely to pursue this trend given its current energy mix and policies. A study was conducted to provide an overview of the global trends and best practices in hydrogen energy adoption and investment. The outcomes of the analysis show that the country current energy mix has the potential to produce green hydrogen energy. The evaluation of its readiness and potential obstacles for hydrogen energy adoption has been drowned and there are several challenges that need to be addressed. The study outcomes also conclude with policy implications and recommendations for the country energy industry.

Several challenges have emerged due to the increasing deterioration of urban mobility and its severe impacts on the environment and human health. Primary dependence on internal combustion engines that use petrol or diesel has led to poor air quality time losses noise traffic jams and further environmental pollution. Hence the transitions to using rail and or seaway-based public transportation cleaner fuels and electric vehicles are some of the ultimate goals of urban and national decision-makers. However battery natural gas hybrid and fuel cell vehicles require charging stations to be readily available with a sustainable energy supply within urban regions in different residential and business neighborhoods. This study aims to provide an updated and critical review of the concept and recent examples of urban mobility and transportation modes. It also highlights the adverse impacts of several air pollutants emitted from internal combustion engine vehicles. It also aims to shed light on several possible systems that integrate the electric vehicle stations with renewable energy sources. It was found that using certain components within the integrated system and connecting the charging stations with a grid can possibly provide an uninterrupted power supply to electric vehicles leading to less pollution which would encourage users to use more clean vehicles. In addition the environmental impact assessments as well as several implementation challenges are discussed. To this end the main implementation issues related to consumer incentives infrastructure and recommendations are also reported.

As a result of particular locations of large-scale energy producers and increases in energy demand transporting energy has become one of the key challenges of energy supply. For a long-distance ocean transportation transfer of energy carriers via ocean tankers is considered as a decent solution compared to pipelines. Due to cryogenic temperatures of energy carriers heat leaks into storage tanks of these carriers causes a problem called boil-off gas (BOG). BOG losses reduce the quantity of energy carriers which affects their economic value. Therefore this study proposes to examine the effects of BOG economically in production and transportation phases of potential energy carriers produced from natural gas namely; liquefied natural gas (LNG) dimethyl-ether (DME) methanol liquid ammonia (NH3) and liquid hydrogen (H2). Mathematical approach is used to calculate production and transportation costs of these energy carriers and to account for BOG as a unit cost within the total cost. The results of this study show that transportation costs of LNG liquid ammonia methanol DME and liquid hydrogen from natural gas accounting for BOG are 0.74 $/GJ 1.09 $/GJ 0.68 $/GJ 0.53 $/GJ and 3.24 $/GJ respectively. DME and methanol can be more economic compared to LNG to transport the energy of natural gas for the same ship capacity. Including social cost of carbon (SCC) within the total cost of transporting the energy of natural gas the transportation cost of liquid ammonia is 1.11 $/GJ whereas LNG transportation cost rises significantly to 1.68 $/GJ at SCC of 137 $/t CO2 eq. Consequently liquid ammonia becomes economically favored compared to LNG. Transportation cost of methanol (0.70 $/GJ) and DME (0.55 $/GJ) are also lower than LNG however liquid hydrogen transportation cost (3.24 $/GJ) is still the highest even though the increment of the cost is about 0.1% as SCC included within the transportation cost.

Co-optimizing energy and water resources in a microgrid can increase efficiency and improve economic performance. Energy-water storage (EWS) devices are crucial components of a high-efficient energy-water microgrid (EWMG). The state of charge (SoC) at the end of the first day of operation is one of the most significant variables in EWS devices since it is used as a parameter to indicate the starting SoC for the second day which influences the operating cost for the second day. Hence this paper examines the benefits and applicability of a lookahead optimization strategy for an EWMG integrated with multi-type energy conversion technologies and multienergy demand response to supply various energy-water demands related to electric/hydrogen vehicles and commercial/residential buildings with the lowest cost for two consecutive days. In addition a hybrid info-gap/robust optimization technique is applied to cover uncertainties in photovoltaic power and electricity prices as a tri-level optimization framework without generating scenarios and using the probability distribution functions. Duality theory is also used to convert the problem into a single-level MILP so that it can be solved by CPLEX. According to the findings the implemented energy-water storage systems and look-ahead strategy accounted for respectively 4.03% and 0.43% reduction in the total cost.

This work presents a feasibility study on the provision of electricity and hydrogen with renewable grid connected and off-the-grid systems for Bandar Abbas City in the south of Iran. The software HOMER Pro® has been used to perform the analysis. A techno-enviro-economic study comparing a hybrid system consisting of the grid/wind turbine and solar cell is done. The wind turbine is analyzed using four types of commercially available vertical axis wind turbines (VAWTs). According to the literature review no similar study has been performed so far on the feasibility of using VAWTs and also no work exists on the use of a hybrid system in the studied area. The results indicated that the lowest price of providing the required hydrogen was $0.496 which was achieved using the main grid. Also the lowest price of the electricity generated was $1.55 which was obtained through using EOLO VAWT in the main grid/wind turbine/solar cell scenario. Also the results suggested that the highest rate of preventing CO2 emission which was also the lowest rate of using the national grid with 3484 kg/year was associated with EOLO wind turbines where only 4% of the required electricity was generated by the national grid.

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.

Logistics is becoming more cost competitive while customers and regulatory bodies pressure businesses to disclose their carbon footprints creating interest in alternative fuels as a decarbonization strategy. This paper provides a thematic review of the role of alternative fuels in sustainable air land and sea logistics their challenges and potential mitigations. Through an extensive literature survey we determined that biofuels synthetic kerosene natural gas ammonia alcohols hydrogen and electricity are the primary alternative fuels of interest in terms of environmental sustainability and techno-economic feasibility. In air logistics synthetic kerosene from hydrogenated esters and fatty acids is the most promising route due to its high technical maturity although it is limited by biomass sourcing. Electrical vehicles are favorable in road logistics due to cheaper green power and efficient vehicle designs although they are constrained by recharging infrastructure deployment. In sea logistics liquified natural gas is advantageous owing to its supply chain maturity but it is limited by methane slip control and storage requirements. Overall our examination indicates that alternative fuels will play a pivotal role in the logistics networks of the future.

During the last two decades Gulf Cooperation Council (GCC) countries have seen their population economies and energy production growing steeply with a substantial increase in Gross Domestic Product. As a result of this growth GCC consumption-based carbon dioxide (CO2) emissions increased from 540.79 Metric tons of CO2 equivalent (MtCO2) in 2003 to 1090.93 MtCO2 in 2020. The assumptions and strategies that have driven energy production in the past are now being recast to achieve a more sustainable economic development. The aim of this study is to review and analyze ongoing energy transition strategies that characterize this change to identify challenges and opportunities for bolstering the effectiveness of current strategic orientations. The ensuing analysis shows that since COP26 GCC countries have been pursuing a transition away from carbon-based energy policies largely characterized by the adoption of solar PV with other emerging technologies including energy storage carbon capture and hydrogen generation and storage. While as of 2022 renewable energy adoption in the GCC only represented 0.15 % of global installed capacity GCC countries are making strong efforts to achieve their declared 2030 energy targets that average about 26 % with peaks of 50 % in Saudi Arabia and 30 % in the UAE and Oman. With reference to solar energy plans are afoot to add 42.1 GW of solar photovoltaics and concentrated solar power which will increase 8-fold the current installed renewable capacity (5.1 GW). At the same time oil and gas production rates remain stable and fossil fuel subsidies have grown in the last few years. Also there is a marked preference for the deployment of CCUS and utility-scale solar energy technology vs. distributed solar energy energy efficiency and nature-based solutions. The pursuit of energy transition in the GCC will require increased efforts in the latter and other overlooked strategic endeavors to achieve a more balanced portfolio of sustainable energy solutions with stronger emphasis on energy efficiency (as long as rebound effects are mitigated) and nature-based solutions. Increased efforts are also needed in promoting governance practices aimed to institutionalize regulatory frameworks incentives and cooperation activities that promote the reduction of fossil fuel subsidies and the transition away from fossil fuels.