Saudi Arabia

This study investigates hydrogen-diesel dual-fuelling specifically for a modern 4.4L 4-cylinder heavy-duty diesel engine using extensive one-dimensional combustion modelling in Ricardo WAVE. Parametric analyses from 900 to 2200 rpm speeds and 0 to 17.5% hydrogen fractions introduced via port injection are undertaken to assess the effect of exhaust gas recirculation (EGR) for controlling NOx. Moreover impacts on key indicators like brake power torque thermal efficiency and emissions are also evaluated. Results revealed that the benefits of hydrogen enrichment are highly dependent on operating conditions. At speeds above 1700 rpm and hydrogen mass fraction of 17.5% remarkable gains were attained increasing brake power and torque by up to 17% and 16.5% respectively. Brake-specific diesel consumption (BSDC) improves by 29% at higher speeds due to hy drogen’s larger energy content. NOx emissions display a trade-off decreasing substantially by 96% at lower speeds but increasing by 43% at 2200 rpm with 17.5% hydrogen.

There is a growing interest in green hydrogen with researchers institutions and countries focusing on its development efficiency improvement and cost reduction. This paper explores the concept of green hydrogen and its production process using renewable energy sources in several leading countries including Australia the European Union India Canada China Russia the United States South Korea South Africa Japan and other nations in North Africa. These regions possess significant potential for “green” hydrogen production supporting the transition from fossil fuels to clean energy and promoting environmental sustainability through the electrolysis process a common method of production. The paper also examines the benefits of green hydrogen as a future alternative to fossil fuels highlighting its superior environmental properties with zero net greenhouse gas emissions. Moreover it explores the potential advantages of green hydrogen utilization across various industrial commercial and transportation sectors. The research suggests that green hydrogen can be the fuel of the future when applied correctly in suitable applications with improvements in production and storage techniques as well as enhanced efficiency across multiple domains. Optimization strategies can be employed to maximize efficiency minimize costs and reduce environmental impact in the design and operation of green hydrogen production systems. International cooperation and collaborative efforts are crucial for the development of this technology and the realization of its full benefits.

Green hydrogen is becoming increasingly popular with academics institutions and governments concentrating on its development efficiency improvement and cost reduction. The objective of the Ministry of Petroleum Mines and Energy is to achieve a 35% proportion of renewable energy in the overall energy composition by the year 2030 followed by a 50% commitment by 2050. This goal will be achieved through the implementation of feed-in tariffs and the integration of independent power generators. The present study focused on the economic feasibility of green hydrogen and its production process utilizing renewable energy resources on the northern coast of Mauritania. The current investigation also explored the wind potential along the northern coast of Mauritania spanning over 600 km between Nouakchott and Nouadhibou. Wind data from masts Lidar stations and satellites at 10 and 80 m heights from 2022 to 2023 were used to assess wind characteristics and evaluate five turbine types for local conditions. A comprehensive techno-economic analysis was carried out at five specific sites encompassing the measures of levelized cost of electricity (LCOE) and levelized cost of green hydrogen (LCOGH) as well as sensitivity analysis and economic performance indicators. The results showed an annual average wind speed of 7.6 m/s in Nouakchott to 9.8 m/s in Nouadhibou at 80 m. The GOLDWIND 3.0 MW model showed the highest capacity factor of 50.81% due to its low cut-in speed of 2.5 m/s and its rated wind speed of 10.5 to 11 m/s. The NORDEX 4 MW model forecasted an annual production of 21.97 GWh in Nouadhibou and 19.23 GWh in Boulanoir with the LCOE ranging from USD 5.69 to 6.51 cents/kWh below the local electricity tariff and an LCOGH of USD 1.85 to 2.11 US/kg H2 . Multiple economic indicators confirmed the feasibility of wind energy and green hydrogen projects in assessed sites. These results boosted the confidence of the techno-economic model highlighting the resilience of future investments in these sustainable energy infrastructures. Mauritania’s north coast has potential for wind energy aiding green hydrogen production for energy goals.

The global need for energy has risen sharply recently. A global shift to clean energy is urgently needed to avoid catastrophic climate impacts. Hydrogen (H2) has emerged as a potential alternative energy source with near-net-zero emissions. In the African continent for sustainable access to clean energy and the transition away from fossil fuels this paper presents a new approach through which waste energy can produce green hydrogen from biomass. Bio-based hydrogen employing organic waste and biomass is recommended using biological (anaerobic digestion and fermentation) processes for scalable cheaper and low-carbon hydrogen. By reviewing all methods for producing green hydrogen dark fermentation can be applied in developed and developing countries without putting pressure on natural resources such as freshwater and rare metals the primary feedstocks used in producing green hydrogen by electrolysis. It can be expanded to produce medium- and long-term green hydrogen without relying heavily on energy sources or building expensive infrastructure. Implementing the dark fermentation process can support poor communities in producing green hydrogen as an energy source regardless of political and tribal conflicts unlike other methods that require political stability. In addition this approach does not require the approval of new legislation. Such processes can ensure the minimization of waste and greenhouse gases. To achieve cost reduction in hydrogen production by 2030 governments should develop a strategy to expand the use of dark fermentation reactors and utilize hot water from various industrial processes (waste energy recovery from hot wastewater).

This review article provides a comprehensive overview of the pivotal role that nanomaterials particularly graphene and its derivatives play in advancing hydrogen energy technologies with a focus on storage production and transport. As the quest for sustainable energy solutions intensifies the use of nanoscale materials to store hydrogen in solid form emerges as a promising strategy toward mitigate challenges related to traditional storage methods. We begin by summarizing standard methods for producing modified graphene derivatives at the nanoscale and their impact on structural characteristics and properties. The article highlights recent advancements in hydrogen storage capacities achieved through innovative nanocomposite architectures for example multi-level porous graphene structures containing embedded nickel particles at nanoscale dimensions. The discussion covers the distinctive characteristics of these nanomaterials particularly their expansive surface area and the hydrogen spillover effect which enhance their effectiveness in energy storage applications including supercapacitors and batteries. In addition to storage capabilities this review explores the role of nanomaterials as efficient catalysts in the hydrogen evolution reaction (HER) emphasizing the potential of metal oxides and other composites to boost hydrogen production. The integration of nanomaterials in hydrogen transport systems is also examined showcasing innovations that enhance safety and efficiency. As we move toward a hydrogen economy the review underscores the urgent need for continued research aimed at optimizing existing materials and developing novel nanostructured systems. Addressing the primary challenges and potential future directions this article aims to serve as a roadmap to enable scientists and industry experts to maximize the capabilities of nanomaterials for transforming hydrogen-based energy systems thus contributing significantly to global sustainability efforts.

Green hydrogen generated from water through renewable energies like solar and wind is a key player in sus tainable energy. It only produces water when used making it a clean energy source. However the inconsistent nature of solar and wind energy highlights the need for storage solutions where green hydrogen is promising. This study uniquely combines green hydrogen (GH) and renewable energy (RE) domains using a comprehensive bibliometric approach covering 2018–2022. It identifies emerging trends collaboration networks and key contributors that shape the global landscape of GH research. Our findings show a significant yearly growth in this research field averaging 93.56 %. The study also identifies China Germany India and Italy as leaders among 76 countries involved in this area. Research trends have shifted from technical details to social and economic factors. Given the increasing global commitment to achieving carbon neutrality understanding the evolution and integration of GH within RE systems is essential for guiding future research policy-making and technology development. The analysis categorizes the research into seven main themes focusing on green hydrogen’s role in energy transition and storage. Other vital topics include improving hydrogen production methods assessing its climate impact examining its environmental benefits and exploring various production techniques like water electrolysis and photocatalysis. Our analysis reveals a 93.56 % annual growth rate in GH research highlighting key challenges in storage integration and policy development and offering a roadmap for future studies. The study highlights areas needing more exploration such as better storage methods integration with existing energy infrastructures risk management and policy development. The advancement of green hydrogen as a sustainable energy solution depends on innovative research international collaboration and supportive policy frameworks.

Hydrogen energy has a significant potential in mitigating the intermittency of renewable energy generation by converting the excess of renewable energy into hydrogen through many technologies. Also hydrogen is expected to be used as an energy carrier that contribute to the global decarbonization in transportation industrial and building sectors. Many technologies have been developed to store hydrogen energy. Hydrogen can be stored to be used when needed and thus synchronize generation and consumption. The current paper presents a review on the different technologies used to store hydrogen. The storage capacity advantages drawbacks and development stages of various hydrogen storage technologies were presented and compared.

To address climate change energy security and waste management new sustainable energy sources must be developed. This study uses Aspen Plus software to extract bio-H2 from food waste with the goal of efficiency and environmental sustainability. Anaerobic digestion optimised to operate at 20-25°C and keep ammonia at 3% greatly boosted biogas production. The solvent [Emim][FAP] which is based on imidazolium had excellent performance in purifying biogas. It achieved a high level of methane purity while consuming a minimal amount of energy with a solvent flow rate of 13.415 m³/h. Moreover the utilization of higher temperatures (600-700°C) during the bio-H2 generation phase significantly enhanced both the amount and quality of hydrogen produced. Parametric and sensitivity assessments were methodically performed at every stage. This integrated method was practicable and environmentally friendly according to the economic assessment. H2 generation using steam reforming results in a TCC of 1.92×106 USD. The CO2 separation step has higher costs (TCC of 2.15×107 USD) due to ionic liquid washing and CO2 liquefaction. Compressor electricity consumption significantly impacts total operating cost (TOC) totaling 4.73×108 USD. showing its ability to reduce greenhouse gas emissions optimize resource utilization and promote energy sustainability. This study presents a sustainable energy solution that addresses climate and waste challenges.

Underground hydrogen (H2) storage (UHS) and carbon dioxide (CO2) geo-storage (CGS) are prominent methods of meeting global energy needs and enabling a low-carbon global economy. The pore-scale distribution reservoir-scale storage capacity and containment security of H2 and CO2 are significantly influenced by interfacial properties including the equilibrium contact angle (θE) and solid-liquid and solid-gas interfacial tensions (γSL and γSG). However due to the technical constraints of experimentally determining these parameters they are often calculated based on advancing and receding contact angle values. There is a scarcity of θE γSL and γSG data particularly related to the hydrogen structural sealing potential of caprock which is unavailable in the literature. Young's equation and Neumann's equation of state were combined in this study to theoretically compute these three parameters (θE γSL and γSG) at reservoir conditions for the H2 and CO2 geo-storage potential. Pure mica organic-aged mica and alumina nano-aged mica substrates were investigated to explore the conditions for rock wetting phenomena and the sealing potential of caprock. The results reveal that θE increases while γSG decreases with increasing pressure organic acid concentration and alkyl chain length. However γSG decreases with increasing temperatures for H2 gas and vice versa for CO2. In addition θE and γSL decrease whereas γSG increases with increasing alumina nanofluid concentration from 0.05 to 0.25 wt%. Conversely θE and γSL increase whereas γSG decreases with increasing alumina nanofluid concentration from 0.25 to 0.75 wt%. The hydrogen wettability of mica (a proxy of caprock) was generally less than the CO2 wettability of mica at similar physio-thermal conditions. The interfacial data reported in this study are crucial for predicting caprock wettability alterations and the resulting structural sealing capacity for UHS and CGS.

Hydrogen is considered as an attractive alternative to fossil fuels in the transportation sector. However the penetration of Fuel Cell Electric Vehicles (FCEV) is hindered by the lack of hydrogen refueling station infrastructures. In this study the feasibility of a hybrid PV/wind system for hydrogen refueling station is investigated. Refueling events data is collected in different locations including industrial residential highway and tourist areas. Station Occupancy Fractions (SOF) and Social-to-Solar Fraction (STSF) indicators are developed to assess the level of synchronization between the hydrogen demand and solar potential. Then a validated computer code is used to optimize the renewable system components for off/on-grid cases based on minimizing the Net Present Cost (NPC) and the Loss of Hydrogen Supply Probability (LHSP). For off grid cases the results show that STSF attains maximum value in the industrial area where 0.62 fraction of refueling events occur during the sunshine hours and minimum NPC is achieved. It is observed that when STSF attains lower values of 0.52 0.41 and 0.38 for residential highway and tourist areas NPC increases by 8 16 and 31% respectively. This is associated with lower level of coordination between the hydrogen demand and solar potential. The same conclusion can be stated for the on-grid cases. Therefore for green hydrogen production via solar energy utilization it is recommended that a tariff should be applied to encourage refueling hydrogen vehicles during the availability of solar radiation while reducing the environmental impact storage requirements and eventually the cost of hydrogen production.

Hydrogen has the capability of being a potential energy carrier and providing a long-term solution for sustainable lower-carbon and ecologically benign fuel supply. Because lower-carbon hydrogen is widely used in chemical synthesis it is regarded as a fuel with no emissions for transportation. This review paper offers a novel technique for producing hydrogen using wastewater in a sustainable manner. The many techniques for producing hydrogen with reduced carbon emissions from wastewater are recognized and examined in detail taking into account the available prospects significant obstacles and potential future paths. A comparison of the assessment showed that water electrolysis and dark fermentation technologies are the most effective methods for hydrogen generation from wastewater with microbial electrolysis and photofermentation. Thus the incorporation of systems that are simultaneously producing lower-carbon hydrogen and meant for wastewater treatment is important for the minimization of emissions from greenhouse gases and recovering the energy utilized in the treatment of wastewater.

Endeavors have recently been concentrated on minimizing the dependency on fossil fuels in order to mitigate the ever-increasing problem of greenhouse gas (GHG) emissions. Hydrogen energy is regarded as an alternative to fossil fuels due to its cleaner emission attributes. Reforming of hydrocarbon fuels is amongst the most popular and widely used methods for hydrogen production. Hydrogen produced from reforming processes requires additional processes to separate from the reformed gases. In some cases further purification of hydrogen has to be carried out to use the hydrogen in power generation applications. Metallic membranes especially palladium (Pd)-based ones have demonstrated sustainable hydrogen separation potential with around 99.99% hydrogen purity. Comprehensive and critical research investigations must be performed to optimize membrane-assisted reforming as well as to maximize the production of hydrogen. The computational fluid dynamic (CFD) can be an excellent tool to analyze and visualize the flow/reaction/permeation mechanisms at a lower cost in contrast with the experiments. In order to provide the necessary background knowledge on membrane reactor modeling this study reviews summarizes and analyses the kinetics of different fuel reforming processes equations to determine hydrogen permeation and lastly various geometry and operating condition adopted in the literature associated with membrane-reactor modeling works. It is indicated that hydrogen permeation through Pd-membranes depends highly on the difference in hydrogen pressure. It is found that hydrogen permeation can be improved by employing different pressure configuration introducing sweep flow on the permeate side of the membrane reducing retentate side flow rate and increasing the temperature.

Due to the aviation energy sector's increasing contribution to climate change and the impact of climate change on the aviation sector determining key energy policy and economic research priorities for enabling an effective and equitable aviation climate action is becoming an increasingly important topic. In this perspective we address this research need using a four-pronged methodology. It includes (i) identifying topical matters highlighted in the media (news); (ii) formulating novel and feasible policy and economic research challenges that pertain to these contemporary issues; (iii) cross-referencing the proposed research challenges with academic literature to confirm their novelty and refining them as necessary; and (iv) validating the importance novelty and feasibility of these research challenges through consultation with a diverse group of aviation experts in fuel policy technology and infrastructure fields. Our results highlight twelve main themes. Among these the top emerging policy and economic research challenges as prioritized by expert input are – (i) frameworks for equitable responsibility allocation between developed and developing country airlines for future emissions; (ii) cost analysis of airlines' net-zero by 2050 commitments; (iii) effectiveness and opportunity cost of airlines investing in offsetting relative to reduction measures; (iv) EU aviation policies' historical and potential effects on airfares demand emissions EU air carriers' competitiveness passenger traffic through EU hubs regional economies and social climate funds' ability to mitigate distributional effects of EU aviation policies. These identified priorities can steer both industry and academic research toward creating practical recommendations for policymakers and industry participants. When it comes to future research the ever-changing nature of the challenges in achieving aviation climate action means that our findings might need regular updates.

For low-carbon hydrogen to become a viable decarbonization solution the creation of a robust and effective market is essential. This paper examines the applicability of market reforms from the renewable energy natural gas and liquefied natural gas (LNG) sectors with a focus on pricing mechanisms business models and infrastructure access to facilitate hydrogen market development. Applying the Structure-Conduct-PerformanceRegulation (SCP-R) framework and informed by stakeholder insights we identify critical enablers for advancing the hydrogen market formation. Our analysis highlights the importance of innovative pricing strategies and regulatory measures incentivizing investment and managing risks. Establishing a market reference price for low-carbon hydrogen — akin to benchmarks in the natural gas and LNG sectors—is critical for ensuring transparency predictability and regional adaptability in trade. Additionally customized business models are also needed to mitigate volume risks for producers. Government interventions such as offtake agreements and the development of hydrogen hubs are indispensable for fostering competition and driving decarbonization.

Addressing the critical need for sustainable high-density hydrogen (H2) carriers to decarbonize the global energy landscape this paper presents a comprehensive critical review of ammonia’s pivotal role in the energy transition with a specific focus on its application in the transportation sector. While H2 is recognized as a future fuel its storage and distribution challenges necessitate alternative vectors. Ammonia (NH3) with its compelling advantages including high volumetric H2 density established global infrastructure and potential for near-zero greenhouse gas emissions emerges as a leading candidate. This review uniquely synthesizes the evolving landscape of sustainable NH3 production pathways (e.g. green NH3 from renewable electricity) with a systematic analysis of technological advancements to investigate its direct utilization as a transportation fuel. The paper critically examines the multifaceted challenges and opportunities associated with NH3-fueled vehicles refueling infrastructure development and comprehensive safety considerations alongside their environmental and economic implications. By providing a consolidated forward-looking perspective on this complex energy vector this paper offers crucial insights for researchers policymakers and industry stakeholders highlighting NH3’s transformative potential to accelerate the decarbonization of hard-to-abate transportation sectors and contribute significantly to a sustainable energy future.

Steam methane reforming (SMR) is a leading technology for hydrogen production. However this technology is still carbon-intensive since in current SMR units the PSA tail gas containing H2 CO and CH4 is burned at the reformer with air and exits the stack at a CO2 purity of less than 5% which is not feasible to capture. In this paper we aim to either harness the energy content of this gas to generate power in a solid oxide fuel cell (SOFC) or burn it via chemical looping combustion (CLC) or oxy-combustion process to produce off-gas with high CO2 purity ready to storage. Therefore an industrial-scale PSA with 72000 Nm3/h feed capacity was modelled to obtain the tail gas flow rate and composition. Then CLC SOFC and oxy-combustion were modelled to use tail gas. Finally a techno-economic analysis was conducted to calculate each technology's levelised cost of hydrogen (LCOH). It was observed that CO2 purity for CLC meets the criteria for storage (>95%) without further purification. On the other hand from the economic point of view all three technologies show a promising performance with an LCOH of 1.9 €/kg.

Hydrogen is regarded as a viable alternative energy carrier because of its superior energy density and low emissions with great potential for decarbonizing multiple sectors and improving energy sustainability by integrating into the existing energy systems and renewable energy source within the utility. This paper provides a bibliometric assessment through an extensive review of highly cited articles on hydrogen storage integrated microgrid. The study utilized the Web of Science (WoS) database to look for specific keywords related to hydrogen storage integrated microgrid and associated research. The findings reveal that optimization highly positioned and connected to many other keywords is demonstrating its importance in the research area. Notable insights highlight the dominance of simulation-based studies a significant number of publications in toptier journals and the rise of innovative research fields including the creation of sustainable electrodes and improvements in system reliability and efficiency. The evaluation of the articles that are highly cited sheds light on diverse elements such as approach and system challenges and research spaces. This analysis shows ways to improve the performance of operation energy efficiency environmental sustainability cost-effectiveness stable supply of power on-location energy generation and flexibility thereby advancing technological innovation and fostering the development of hydrogen storage-integrated microgrids.

The exploration of green energy is a demanding issue due to climate change and ecology. Green energy hydrogen is gaining importance in the area of alternative energy sources. Many methods are being explored for this but most of them are utilizing other sources of energy to produce hydrogen. Therefore these approaches are not economic and acceptable at the industrial level. Sunlight and nuclear radiation as free or low-cost energy sources to split water for hydrogen. These methods are gaining importance in recent times. Therefore attempts are made to explore the latest updates in direct radiation water-splitting methods of hydrogen production. This article discusses the advances made in green hydrogen production by water splitting using visible and UV radiations as these are freely available in the solar spectrum. Besides water splitting by gamma radiation (a low-cost energy source) is also reviewed. Eforts are also made to describe the water-splitting mechanism in photo- and gamma-mediated water splitting. In addition to these challenges and future perspectives have also been discussed to make this article useful for further advanced research.

Developing new injection systems and combustion chambers for hydrogen is a central topic for the new generation of engines. In this effort simulations take a central role but methods developed for conventional hydrocarbons (methane kerosene) must be revisited for hydrogen. Validation then becomes an essential part and clean well documented experiments are needed to guaranty that computational fluid dynamics solvers are as predictive and accurate as expected. In this framework the HYLON case is a swirled hydrogen/air burner used by multiple groups worldwide to validate simulation methods for hydrogen combustion in configurations close to gas turbine burners with experimental data available through the TNF web site. The present study compares recent Raman spectroscopy and Particle Image Velocimetry measurements and Large Eddy Simulations (LES). The LES results are evaluated against a dataset comprising mean and RMS measurements of H2 N2 O2 H2O molar fractions temperature and velocity fields offering new insights into flame stabilization mechanisms. The simulations incorporate conjugate heat transfer to predict the combustor wall temperatures and are conducted for two atmospheric-pressure operating conditions each representing distinct combustion regimes diffusion and partially premixed. Novelty and significance statement Data on confined hydrogen flames in burner similar as industrial ones are limited. This work aims to fill this gap by performing multiple and simultaneous diagnostics on the swirled hydrogen-air flame called HYLON. For the first time in such a swirled configuration mean and RMS fields of temperature main species and velocities are compared to LES allowing new insight into the potential and limits of the models as well as the physics of these flames. These experimental results will be made available on TNF as over 30 research groups worldwide have expressed interest in using them.

The integration of renewable energy into industrial processes is crucial for reducing the carbon footprint of conventional hydrogen production. This work presents detailed design optical–thermal simulation and performance analysis of a solar parabolic dish (SPD) system for supplying high-temperature steam to a Steam Methane Reforming (SMR) plant. A 5 m diameter dish with a focal length of 3 m was designed and optimized using COMSOL Multiphysics (version 6.2) and MATLAB (version R2023a). Optical ray tracing confirmed a geometric concentration ratio of 896× effectively focusing solar irradiation onto a helical cavity receiver. Thermal–fluid simulations demonstrated the system’s capability to superheat steam to 551 ◦C at a mass flow rate of 0.0051 kg/s effectively meeting the stringent thermal requirements for SMR. The optimized SPD system with a 5 m dish diameter and 3 m focal length was designed to supply 10% of the total process heat (≈180 GJ/day). This contribution reduces natural gas consumption and leads to annual fuel savings of approximately 141000 SAR (Saudi Riyal) along with a substantial reduction in CO2 emissions. These quantitative results confirm the SPD as both a technically reliable and economically attractive solution for sustainable blue hydrogen production.

The transition to a sustainable energy future hinges on the development of reliable large-scale hydrogen storage solutions to balance the intermittency of renewable energy and decarbonize hard-to-abate industries. Underground hydrogen storage (UHS) in salt caverns emerged as a technically and economically viable strategy leveraging the unique geomechanical properties of salt formations—including low permeability self-healing capabilities and chemical inertness—to ensure safe and high-purity hydrogen storage under cyclic loading conditions. This review provides a comprehensive analysis of the advantages of salt cavern hydrogen storage such as rapid injection and extraction capabilities cost-effectiveness compared to other storage methods (e.g. hydrogen storage in depleted oil and gas reservoirs aquifers and aboveground tanks) and minimal environmental impact. It also addresses critical challenges including hydrogen embrittlement microbial activity and regulatory fragmentation. Through global case studies best operational practices for risk mitigation in real-world applications are highlighted such as adaptive solution mining techniques and microbial monitoring. Focusing on China’s regional potential this study evaluates the hydrogen storage feasibility of stratified salt areas such as Jiangsu Jintan Hubei Yunying and Henan Pingdingshan. By integrating technological innovation policy coordination and cross-sector collaboration salt cavern hydrogen storage is poised to play a pivotal role in realizing a resilient hydrogen economy bridging the gap between renewable energy production and industrial decarbonization.

Renewable energy systems are at the core of global efforts to reduce greenhouse gas (GHG) emissions and to combat climate change. Focusing on the role of energy storage in enhancing dependability and efficiency this paper investigates the design and optimization of a completely sustainable hybrid energy system. Furthermore hybrid storage systems have been used to evaluate their viability and cost-benefits. Examined under a 100% renewable energy microgrid framework three setup configurations are as follows: (1) photovoltaic (PV) and Battery Storage System (BSS) (2) Hybrid PV/Wind Turbine (WT)/BSS and (3) Integrated PV/WT/BSS/Electrolyzer/ Hydrogen Tank/Fuel Cell (FC). Using its geographical solar irradiance and wind speed data this paper inspires on an industrial community in Neom Saudi Arabia. HOMER software evaluates technical and economic aspects net present cost (NPC) levelized cost of energy (COE) and operating costs. The results indicate that the PV/ BSS configuration offers the most sustainable solution with a net present cost (NPC) of $2.42M and a levelized cost of electricity (LCOE) of $0.112/kWh achieving zero emissions. However it has lower reliability as validated by the provided LPSP. In contrast the PV/WT/BSS/Elec/FC system with a higher NPC of $2.30M and LCOE of $0.106/kWh provides improved energy dependability. The PV/WT/BSS system with an NPC of $2.11M and LCOE of $0.0968/kWh offers a slightly lower cost but does not provide the same level of reliability. The surplus energy has been implemented for hydrogen production. A sensitivity analysis was performed to evaluate the impact of uncertainties in renewable resource availability and economic parameters. The results demonstrate significant variability in system performance across different scenarios

Presently there is no single clear route for the near-term production of the huge volumes of CO2-free hydrogen necessary for the global transition to any type of hydrogen economy. All conventional routes to produce hydrogen from hydrocarbon fossil fuels (notably natural gas) involve the production—and hence the emission—of CO2 most notably in the steam methane reforming (SMR) process. Our recent studies have highlighted another route; namely the critical role played by the microwave-initiated catalytic pyrolysis decomposition or deconstruction of fossil hydrocarbon fuels to produce hydrogen with low to near-zero CO2 emissions together with high-value solid nanoscale carbonaceous materials. These innovations have been applied firstly to wax then methane crude oil diesel then biomass and most recently Saudi Arabian light crude oil as well as plastics waste. Microwave catalysis has therefore now emerged as a highly effective route for the rapid and effective production of hydrogen and high-value carbon nanomaterials co-products in many cases accompanied by low to near-zero CO2 emissions. Underpinning all of these advances has been the important concept from solid state physics of the so-called Size-Induced-Metal-Insulator Transition (SIMIT) in mesoscale or mesoscopic particles of catalysts. The mesoscale refers to a range of physical scale in-between the micro- and the macro-scale of matter (Huang W Li J and Edwards PP 2018 Mesoscience: exploring the common principle at mesoscale Natl. Sci. Rev. 5 321-326 (doi:10.1093/nsr/nwx083)). We highlight here that the actual physical size of the mesoscopic catalyst particles located close to the SIMIT is the primary cause of their enhanced microwave absorption and rapid heating of particles to initiate the catalytic—and highly selective—breaking of carbon–hydrogen bonds in fossil hydrocarbons and plastics to produce clean hydrogen and nanoscale carbonaceous materials. Importantly also since the surrounding ‘bath’ of hydrocarbons is cooler than the microwave-heated catalytic particles themselves the produced neutral hydrogen molecule can quickly diffuse from the active sites. This important feature of microwave heating thereby minimizes undesirable side reactions a common feature of conventional thermal heating in heterogeneous catalysis. The low to near-zero CO2 production of hydrogen via microwave-initiated decomposition or cracking of abundant hydrocarbon fossil fuels may be an interim viable alternative to the conventional widely-used SMR that a highly efficient process but unfortunately associated with the emission of vast quantities of CO2. Microwave-initiated catalytic decomposition also opens up the intriguing possibility of using distributed methane in the current natural gas structure to produce hydrogen and high-value solid carbon at either central or distributed sites. That approach will lessen many of the safety and environmental concerns associated with transporting hydrogen using the existing natural gas infrastructure. When completely optimized microwave-initiated catalytic decomposition of methane (and indeed all hydrocarbon sources) will produce no aerial carbon (CO2) and only solid carbon as a co-product. Furthermore reaction conditions can surely be optimized to target the production of high-quality synthetic graphite as the major carbon-product; that material of considerable importance as the anode material for lithium-ion batteries. Even without aiming for such products derived from the solid carbon co-product it is of course far easier to capture solid carbon rather than capturing gaseous CO2 at either the central or distributed sites. Through microwave-initiated catalytic pyrolysis this decarbonization of fossil fuels can now become the potent source of sustainable hydrogen and high-value carbon nanomaterials.

The reliability and sustainability of multi-energy networks are increasingly critical in addressing modern energy demands and environmental concerns. Hydrogen-based hybrid energy systems can mitigate the challenges of renewable energy utilization such as intermittency grid stability and energy storage by integrating hydrogen generation and electricity storage from renewable sources such as solar and wind. Therefore this review offers a comprehensive evaluation of the environmental economic and technological aspects of green hydrogen-based hybrid energy systems particularly highlighting improvements in terms of the economics of fuel cell and electrolysis procedures. It also highlights new approaches such as hybrid energy management strategies and power-to-gas (PtG) conversion to enhance the system’s dependability and resilience. Analyzing the role of green hydrogen-based hybrid energy systems in supporting global climate goals and improving energy security underscores their high potential to make a significant contribution to carbon-neutral energy networks and provide policymakers with useful recommendations for developing guidelines. In addition the social aspect of hydrogen systems like energy equity and community engagement towards a hydrogen-based society provides reasons for the continued development of next-generation energy systems.