Applications & Pathways

The growing concern about climate change and the contemporary increase in mobility requirements call for faster cheaper safer and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this direction. The goal of this investigation is a comparative analysis of the environmental impact of conventional and hydrogen-based propulsive systems. As a case study a hybrid electric configuration consisting of a fuel cell with a nominal power of about 30 kW a 6 kWh LFP battery and a pressurized hydrogen vessel is proposed to replace a piston prop configuration for an ultralight aerial vehicle. Both power systems are modeled with a backward approach that allows the efficiency of the main components to be evaluated based on the load and altitude at every moment of the flight with a time step of 1 s. A typical 90 min flight mission is considered for the comparative analysis which is performed in terms of direct and indirect emissions of carbon dioxide water and pollutant substances. For the hydrogen-based configuration two possible strategies are adopted for the use of the battery: charge sustaining and charge depleting. Moreover the effect of the altitude on the parasitic power of the fuel cell compressor and consequently on the net efficiency of the fuel cell system is taken into account. The results showed that even if the use of hydrogen confines the direct environmental impact to the emission of water (in a similar quantity to the fossil fuel case) the indirect emissions associated with the production transportation and delivery of hydrogen and electricity compromise the desired achievement of pollutant-free propulsion in terms of equivalent emissions of CO2 and VOCs if hydrogen is obtained from natural gas reforming. However in the case of green hydrogen from electrolysis with wind energy the total (direct and indirect) emissions of CO2 can be reduced up to 1/5 of the fossil fuel case. The proposed configuration has the additional advantage of eliminating the problem of lead which is used as an additive in the AVGAS 100LL.

Wind and solar energy are the important renewable energy sources while their inherent natures of random and intermittent also exert negative effect on the electrical grid connection. As one of multiple energy complementary route by adopting the electrolysis technology the wind-solar-hydrogen hybrid system contributes to improving green power utilization and reducing its fluctuation. Therefore the moving average method and the hybrid energy storage module are proposed which can smooth the wind-solar power generation and enhance the system energy management. Moreover the optimization of system capacity configuration and the sensitive analysis are implemented by the MATLAB program platform. The results indicate that the 10-min grid-connected volatility is reduced by 38.7% based on the smoothing strategy and the internal investment return rate can reach 13.67% when the electricity price is 0.04 $/kWh. In addition the annual coordinated power and cycle proportion of the hybrid energy storage module are 80.5% and 90% respectively. The developed hybrid energy storage module can well meet the annual coordination requirements and has lower levelized cost of electricity. This method provides reasonable reference for designing and optimizing the wind-solar-hydrogen complementary system.

The world’s economy heavily depends on the energy resources used by various countries. India is one of the promising developing nations with very low crude reserves actively looking for new renewable energy resources to power its economy. Higher energy consumption and environmental pollution are two big global challenges for our sustainable development. The world is currently facing a dual problem of an energy crisis as well as environmental degradation. So there is a strong need to reduce our dependency on fossil fuels and greenhouse gas emissions. This can be achieved to a great extent by universally adopting clean fuels for all daily life uses like ethanol or liquified natural gas (LNG) as these burn very clean and do not emit many pollutants. Nowadays green hydrogen has emerged as a new clean energy source which is abundantly available and does not pollute much. This article explores the various benefits of green hydrogen with respect to fossil fuels various techniques of producing it and its possible use in different sectors such as industry transport and aviation as well as in day-to-day life. Finally it explores the use of green hydrogen as fuel in automobile engines its blending with CNG gas and its benefits in reducing emissions compared to fossil fuels. On combustion green hydrogen produces only water vapours and is thus a highly clean fuel. Thus it can potentially help humanity preserve the environment due to its ultra-low emissions and can be a consistent and reliable source of energy for generations to come thereby ending the clean energy security debate forever.

Decarbonising and decontaminating remote regions in the world presents several challenges. Many of these regions feature isolation dispersed demand in large areas and a lack of economic resources that impede the development of robust and sustainable networks. Furthermore isolated systems in the developing world are mostly based on diesel generation for electricity and firewood and liquefied petroleum gas for heating as these options do not require a significant infrastructure cost. In this context we present a stochastic multi-energy multi-microgrid system planning model that integrates electricity heat and hydrogen networks in isolated systems. The model is stochastic to capture uncertainty in renewable generation outputs particularly hydro and wind and thus design a multi-energy system proved secured against such uncertainty. The model also features two distinct constraints to limit the emissions of CO2 (for decarbonisation) and particulate matter (for decontamination) and incorporates firewood as a heating source. Moreover given that the focus is on low-voltage networks we introduce a fully linear AC power flow equations set allowing the planning model to remain tractable. The model is applied to a real-world case study to design a multi-energy multi-microgrid system in an isolated region in Chilean Patagonia. In a case with a zero limit over direct CO2 emissions the total system’s cost increases by 34% with respect to an unconstrained case. In a case with a zero limit over particulate matter emissions the total system’s cost increases by 189%. Finally although an absolute zero limit over both particulate matter and direct CO2 emissions leads to a total system’s cost increase of 650% important benefits in terms of decarbonisation and decontamination can be achieved at marginal cost increments.

In view of the GHG reduction targets to be met Brazilian researchers are looking for cleaner alternatives to energy sources. These alternatives are primarily to be applied in the transport sector which presents high energy consumption as well as high CO2 emissions. In this sense this research developed an LCI study considering two bus alternatives for the city of Rio de Janeiro: diesel-powered internal combustion buses (ICEB) and a hydrogen-powered polymer fuel cell hybrid bus (FCHB). For the FCHB three hydrogen production methods were also included: water electrolysis (WE) ethanol steam reforming (ESR) and natural gas steam reforming (NGSR). The research was aimed at estimating energy consumption including the percentage of energy that is renewable as well as CO2 emissions. The results show diesel as the energy source with the highest emissions as well as the highest fossil energy consumption. Regarding the alternatives for hydrogen production water electrolysis stood out with the lowest emissions.

The member countries of the European Union (EU) have prioritized the incorporation of hydrogen as a key component of their energy objectives. As the world moves towards reducing its dependence on fossil fuels alternative sources of energy have gained prominence. With the growing development of Fuel Cell Electric Vehicles (FCEVs) the establishment of an infrastructure for hydrogen production and the creation of a network of service stations have become essential. This article’s purpose is to conduct a methodical review of literature regarding the use of green hydrogen for transportation and the planning of imperative infrastructure in the territory of the EU specifically Hydrogen Refueling Stations (HRS). In order to increase the acceptance of fuel cell vehicles a comprehensive network of hydrogen refueling stations (HRS) must be built that enable drivers to refuel their vehicles quickly and easily similar to gasoline or diesel vehicles. The literature review on this topic was conducted using the Web of Science database (WOS) with a variety of search terms proposed to cover all the key components of green hydrogen production and refueling infrastructure. The implementation of HRS powered by renewable energy sources is an important step in the adoption of fuel cell vehicles and overcoming the obstacles that come with their implementation will require cooperation and innovation from governments private businesses and other stakeholders.

Shifting from fossil fuels to clean alternative fuel options such as hydrogen is an essential step in decarbonising the road freight transport sector and facilitating an efficient transition towards zero-emissions goods distribution of the future. Designing an economically viable and competitive Hydrogen Supply Chain (HSC) to support and accelerate the widespread adoption of hydrogen powered Heavy Goods Vehicles (H2-HGVs) is however significantly hindered by the lack of the infrastructure required for producing storing transporting and distributing the required hydrogen. This paper focuses on a bespoke design of a hydrogen supply chain and distribution network for the long-haul road freight transportation in the UK and develops an improved end-to-end and spatially-explicit optimisation tool to perform scenario analysis and provide important first-hand managerial and policy making insights. The proposed methodology improves over existing grid-based methodologies by incorporating spatially-explicit locations of Hydrogen Refuelling Stations (HRSs) and allowing further flexibility and accuracy. Another distinctive feature of the method and the analyses carried out in the paper pertains to the inclusion of bulk geographically agnostic as well as geological underground hydrogen storage options and reporting on significant cost saving opportunities. Finally the curve for H2-HGVs penetration levels safety stock period decisions and the transport mode capacity against hydrogen levelized cost at pump have been generated as important policy making tools to provide decision support and insights into cost resilience and reliability of the HSC.

With the aggravation of global environmental pollution problems and the need for energy restructuring hydrogen energy as a highly clean resource has gradually become a hot spot for research in countries around the world. Facing the requirement of distributed hydrogen in refueling the original station for hydrogen transportation and other usage this paper proposes a comprehensive energy system planning model for hydrogen refueling stations to obtain the necessary devices construction the devices’ capacity decisions and the optimal operation behaviors of each device. Comparing to traditional single hydrogen producing technics in the traditional planning model the proposed model in this paper integrates both water-electrolysis-based and methanol-based manufacturing technics. A two-level optimization model is designed for this comprehensive system. The result of the numerical study shows that the proposed model can achieve a better optimal solution for distributed hydrogen production. Also it considers the single producing situation when price of one primary resource is sufficient higher than the other.

Airlines are faced with the challenge of reducing their environmental footprint in an effort to push for climate-neutral initiatives that comply with international regulations. In the past the aviation industry has followed the approach of incremental improvement of fuel efficiency while simultaneously experiencing significant growth in annual air traffic. With the increase in air traffic negating any reduction in Greenhouse Gas (GHG) emissions more disruptive technologies such as hydrogen-based onboard power generation are required to reduce the environmental impact of airline operations. However despite initial euphoria and first conceptual studies for hydrogen-powered aircraft several decades ago there still has been no mass adoption to this day. Besides the challenges of a suitable ground infrastructure this can partly be attributed to uncertainties with the associated maintenance requirements and the expected operating costs to demonstrate the economic viability of this technology. With this study we address this knowledge gap by estimating changes towards scheduled maintenance activities for an airborne hydrogen storage and distribution system. In particular we develop a detailed system design for a hydrogen-powered fuel-cell-based auxiliary power generation and perform a comparative analysis with an Airbus A320 legacy system. That analysis allows us to (a) identify changes for the expected maintenance effort to enhance subsequent techno-economic assessments (b) identify implications of specific design assumptions with corresponding maintenance activities while ensuring regulatory compliance and (c) describe the impact on the resulting task execution. The thoroughly examined interactions between system design and subsequent maintenance requirements of this study can support practitioners in the development of prospective hydrogen-powered aircraft. In particular it allows the inclusion of maintenance implications in early design stages of corresponding system architectures. Furthermore since the presented methodology is transferable to different design solutions it provides a blueprint for alternative operating concepts such as the complete substitution of kerosene by hydrogen to power the main engines.

This study proposes a predictive equivalent consumption minimization strategy (P-ECMS) that utilizes velocity prediction and considers various dynamic constraints to mitigate fuel cell degradation assessed using a dedicated sub-model. The objective is to reduce fuel consumption in real-world conditions without prior knowledge of the driving mission. The P-ECMS incorporates a velocity prediction layer into the Energy Management System. Comparative evaluations with a conventional adaptive-ECMS (A-ECMS) a standard ECMS with a well-tuned constant equivalence factor and a rule-based strategy (RBS) are conducted across two driving cycles and three fuel cell dynamic restrictions (|∕| ≤ 0.1 0.01 and 0.001 A∕cm2 ). The proposed strategy achieves H2 consumption reductions ranging from 1.4% to 3.0% compared to A-ECMS and fuel consumption reductions of up to 6.1% when compared to RBS. Increasing dynamic limitations lead to increased H2 consumption and durability by up to 200% for all tested strategies.

Especially the electrification of the industry sector is highly complex and challenging mainly due to process-specific requirements. In this context there are several industrial processes where the direct and indirect use of electricity is subject to technical restrictions. In order to achieve the national climate goals the fossil energy consumption remaining after the implementation of efficiency and sufficiency measures as well as direct electrification has to be substituted through hydrogen and synthetic gaseous liquid and solid hydrocarbons. As the main research object the role of synthetic fuels in industrial transformation paths is investigated and analyzed by combining individual greenhouse gas abatement measures within the Sector Model Industry. Sector Model Industry is an energy consumption model that performs discrete deterministic energy and emission dynamic calculations with a time horizon up to 2050 at macroeconomic level. The results indicate that the use of synthetic fuels can be expected with a high level of climate protection. The industrial CO2 target in the model makes it necessary to replace CO2 -intensive fossil with renewable fuels. The model uses a total of 163 TWh of synthetic fuels in the climate protection scenario and thus achieves an 88% decrease in CO2 emissions in 2050 compared to 1990. This means that the GHG abatement achieved in industry is within the range of the targeted CO2 mitigation of the overall system in Germany of between 80 and 95% in 2050 compared to 1990. Due to technical restrictions the model mainly uses synthetic methane instead of hydrogen (134 TWh). The results show that despite high costs synthetic fuels are crucial for defossilization as a fall back option in the industrial scenario considering high climate ambition. The scenario does not include hydrogen technologies for heat supply. Accordingly the climate protection scenario uses hydrogen only in the steel industry for the direct reduction of iron (21 TWh). 8 TWh of synthetic oil substitute the same amount of fossil oil in the climate protection scenario. A further analysis conducted on the basis of the model results shows that transformation in the energy system and the use of smart ideas concepts and technologies are a basic prerequisite for enabling the holistic defossilisation of industry. The findings in the research can contribute to the cost-efficient use of synthetic fuels in industry and thus serve as a basis for political decision making. Moreover the results may have a practical relevance not only serving as a solid comparison base for the outcome of other studies but also as input data for further simulation of energy system transformation paths.

To reduce carbon sulfur dioxide (SO2) and nitrogen oxide (NOX) emissions from the integrated energy system (IES) a low carbon optimization strategy for the IES is proposed taking into account carbon SO2 and NOX emissions. Firstly hydrogen production storage and use equipment such as methane reactor electrolysis tank hydrogen fuel cell and hydrogen energy storage are added to the traditional IES to build a multi-energy complementary system of electricity gas cooling thermal and hydrogen. Then this paper introduces a stepped carbon trading mechanism and the model of the emissions of SO2 and NOX. Finally to further reduce its pollutant emissions the model of combined heat and power units and hydrogen fuel cells with adjustable thermoelectric ratio is built. To compare and account for the impact of air pollutant emissions on the optimal low-carbon operation of IES this paper construsted three scenarios with the lowest cost of carbon trading the lowest penalty cost for SO2 and NOX emissions and total operation cost as objective functions respectively The results show that the strategy is effective in reducing air pollutant emissions from integrated energy systems and the outputs of CHP and HFC with adjustable thermoelectric ratios are more flexible and can effectively achieve carbon reduction and pollutant emission reduction.

This paper offers a comprehensive analysis of the historical evolution and the current state of the aviation industry with a particular emphasis on the critical need for this sector to decarbonize. It delves into emerging propulsion technologies such as battery electric and hydrogen-based systems assessing their potential impact on sustainability within the aviation sector. Special attention is devoted to the global regulatory framework notably carbon offsetting and emission reduction scheme for international aviation which encapsulates initiatives such as lower carbon aviation fuels and sustainable aviation fuels. Examining the environmental challenges facing aviation the paper underscores the necessity for a balanced and comprehensive strategy that integrates various approaches to achieve sustainable solutions. By addressing both the historical context and contemporary advances the paper aims to provide a nuanced understanding of the complexities surrounding aviation's decarbonization journey acknowledging the industry's strides while recognizing the ongoing challenges in the pursuit of sustainability.

Hydrogen is seen as a prime choice for complete replacement of gasoline so as to achieve zero-emissions energy and mobility. Combining the use of this alternative fuel with a circular economy approach for giving new life to the existing fleet of passenger cars ensures further benefits in terms of cost competitiveness. Transforming spark ignition (SI) engines to H2 power requires relatively minor changes and limited added components. Within this framework the conversion of a small-size passenger car to hydrogen fueling was evaluated based on 0D/1D simulation. One of the methods to improve efficiency is to apply exhaust gas recirculation (EGR) which also lowers NOx emissions. Therefore the previous version of the quasi-dimensional model was modified to include EGR and its effects on combustion. A dedicated laminar flame speed model was implemented for the specific properties of hydrogen and a purpose-built sub-routine was implemented to correctly model the effects of residual gas at the start of combustion. Simulations were performed in several operating points representative of urban and highway driving. One of the main conclusions was that highpressure recirculation was severely limited by the minimum flow requirements of the compressor. Low-pressure EGR ensured wider applicability and significant improvement of efficiency especially during partial-load operation specific to urban use. Another benefit of recirculation was that pressure rise rates were predicted to be more contained and closer to the values expected for gasoline fueling. This was possible due to the high tolerance of H2 to the presence of residual gas.

With the pressured timescale in determining effective and viable net zero solutions within the transport sector it is important to understand the extent of implementing a new refuelling infrastructure for alternative fuel such as hydrogen. The proposed ATHENA framework entails three components which encapsulates the demand data analysis an optimisation model in determining the minimal cost hydrogen refuelling infrastructure design and an agent-based model simulating the operational system. As a case study the ATHENA framework is applied to Northern England focusing on the design of a hydrogen refuelling infrastructure for heavy goods vehicles. Analysis is performed in calibrating parameters and investigating different scenarios within the optimisation and agent-based simulation models. For this case study the system optimality is limited by the feasible number of tube trailer deliveries per day which suggests an opportunity for alternative delivery methods.

Hydrogen fuel and electricity are energy carriers viewed as promising alternatives for the modernization and decarbonization of public bus transportation fleets. In order to choose development pathways that will lead transportation systems toward a sustainable future the authors developed an environmental model based on the Life Cycle Assessment approach. The model tested the impact of energy carrier consumption during driving as well as the electricity origin employed to power electric buses and produce hydrogen. Energy sources such as wind solar waste and grid electricity were investigated. The scope of the study included the life cycles of the energy carrier and the necessary infrastructure. The results were presented from two perspectives: the total environmental impact and global warming potential. In order to create a roadmap an original method for choosing sustainable development pathways was prepared. It was shown that the modernization of conventional bus fleets using hydrogen and electrical pathways can provide significant environmental benefits from both perspectives but especially in terms of global warming potential. It was emphasized that attention should be paid to the use of low- and zero-emission energy sources because their impact often strongly influenced the final environmental judgment. The energy carrier consumption also had a strong impact on the results obtained and that is why efforts should be made to reduce it. In addition it was confirmed that hydrogen and electricity production systems based on electricity generated by a waste-to-energy plant could be an environmentally reasonable dual solution for both sustainable waste management and meeting transport needs.

Amidst the growing imperative to address carbon emissions aiming to improve energy utilization efficiency optimize equipment operation flexibility and further reduce costs and carbon emissions of regional integrated energy systems (RIESs) this paper proposes a low-carbon economic operation strategy for RIESs. Firstly on the energy supply side energy conversion devices are utilized to enhance multi-energy complementary capabilities. Then an integrated demand response model is established on the demand side to smooth the load curve. Finally consideration is given to the RIES’s participation in the green certificate–carbon trading market to reduce system carbon emissions. With the objective of minimizing the sum of system operating costs and green certificate–carbon trading costs an integrated energy system optimization model that considers electricity gas heat and cold coupling is established and the CPLEX solver toolbox is used for model solving. The results show that the coordinated optimization of supply and demand sides of regional integrated energy systems while considering multi-energy coupling and complementarity effectively reduces carbon emissions while further enhancing the economic efficiency of system operations.

Proton exchange membrane fuel cell (PEMFCS) and electrolyser (PEMELS) systems together with a hydrogen storage tank (HST) are suitable to be integrated with renewable microgrids to cover intermittency and fully exploit the excess of electrical energy. Such an integration perfectly fits telecom tower power supply needs both in off-grid and grid-connected sites. In this framework a model-based tool enabling both optimal sizing and proper year-through energy management of both the above applications is proposed. Respectively the islanded optimisation is performed considering two economic indices i.e. simple payback (SPB) and levelised cost of energy (LCOE) together with two strategies of hydrogen tank management charge sustaining and depleting and also accounting for the impact of grid extension distance. On the other hand the grid connection is addressed through the dynamic programming method while downsizing PEMELS and HST sizes to improve techno-economic effectiveness thanks to grid contribution towards renewables curtailment issues mitigation. For both the above introduced HST management strategies a reduction of more than 70% of the nominal PEMELS power and 90% of the HST size which will in turn lead to SPB and LCOE being reduced by 80% and 60% in comparison to the islanded case respectively is achieved. Furthermore the charge depleting strategy relying on possible hydrogen purchase interestingly provides an SPB and LCOE of 9% and 7% lower than the charge sustaining one.

Thoroughly assessing future energy systems requires examining both their end states and the paths leading to them. Employing dynamic investment or multi-stage optimization models is crucial for this analysis. However solving these optimization problems becomes increasingly challenging due to their long time horizons – often spanning several decades – and their dynamic nature. While simplifications like aggregations are often used to expedite solving procedures they introduce higher uncertainty into the results and might lead to suboptimal solutions compared to non-simplified models. Against this background this paper presents a rigorous optimization method tailored for multi-stage optimization problems in long-term energy system planning. By dividing the solution algorithm into a design and operational optimization step the proposed method efficiently finds feasible solutions for the non-simplified optimization problem with simultaneous quality proof. Applied to a real-life energy system of a waste treatment plant in Germany the method significantly outperforms a benchmark solver by reducing the computational time to find the first feasible solution from more than two weeks to less than one hour. Furthermore it exhibits greater robustness compared to a conventional long-term optimization approach and yields solutions closer to the optimum. Overall this method offers decision-makers computationally efficient and reliable information for planning investment decisions in energy systems.

The growing awareness about climate change and environmental pollution is pushing the industrial and academic world to investigate more sustainable solutions to reduce the impact of anthropic activities. As a consequence a process of electrification is involving all kind of vehicles with a view to gradually substitute traditional powertrains that emit several pollutants in the exhaust due to the combustion process. In this context fuel cell powertrains are a more promising strategy with respect to battery electric alternatives where productivity and endurance are crucial. It is important to replace internal combustion engines in those vehicles such as the those in the sector of NonRoad Mobile Machinery. In the present paper a preliminary analysis of a fuel cell powertrain for a telehandler is proposed. The analysis focused on performance fuel economy durability applicability and environmental impact of the vehicle. Numerical models were built in MATLAB/Simulink and a simple power follower strategy was developed with the aim of reducing components degradation and to guarantee a charge sustaining operation. Simulations were carried out regarding both peak power conditions and a typical real work scenario. The simulations’ results showed that the fuel cell powertrain was able to achieve almost the same performances without excessive stress on its components. Indeed a degradation analysis was conducted showing that the fuel cell system can achieve satisfactory durability. Moreover a Well-to-Wheel approach was adopted to evaluate the benefits in terms of greenhouse gases of adopting the fuel cell system. The results of the analysis demonstrated that even if considering grey hydrogen to feed the fuel cell system the proposed powertrain can reduce the equivalent CO2 emissions of 69%. This reduction can be further enhanced using hydrogen from cleaner production processes. The proposed preliminary analysis demonstrated that fuel cell powertrains can be a feasible solution to substitute traditional systems on off-road vehicles even if a higher investment cost might be required.

Hydrogen refueling stations rely on pressure vessels capable of withstanding pressures up to 90 MPa while mitigating concerns related to hydrogen embrittlement. However a gap exists in understanding the long-term fatigue behavior of these vessels under real operational conditions. This study focuses on evaluating the safety of SA372 pressure vessels using operational data from a hydrogen refueling station in Pyeongtaek South Korea. A predictive reinspection methodology is proposed based on this evaluation. Parameters including hydrogen-induced stress intensity factor (KIH) initial crack size (a0 c0) and pressure vessel specifications are considered to assess critical crack depth (ac) critical usage cycles (Nc) and allowable usage cycles (Nallowed). Leveraging operational data collected between August and November 2023 fatigue analysis and Rainflow counting inform reinspection schedules. Results indicate a need for mid-bank vessel reinspection within the second year high-bank vessel reinspection every 20 years and low-bank vessel reinspection every 143 years in accordance with safety regulations. Additionally a revised refueling logic is proposed to optimize vehicle charging methods and pressure ranges enhancing operational safety. This study serves as a preliminary investigation highlighting the need for broader data collection and analysis to generalize findings across multiple stations.

The Integrated Energy System (IES) that coordinates multiple energy sources can effectively improve energy utilization and is of great significance to achieving energy conservation and emission reduction goals. In this context a low-carbon and economic dispatch model for IES is proposed. Firstly a hydrogen energy-based IES (H2-IES) is constructed to refine the utilization process of hydrogen energy. Secondly the carbon emissions of different energy chains throughout their life cycle are analyzed using the life cycle assessment method (LCA) and the carbon emissions of the entire energy supply and demand chain are considered. Finally a staged carbon trading mechanism is adopted to promote energy conservation and emission reduction. Based on this an IES low-carbon and economic dispatch model is constructed with the optimization goal of minimizing the sum of carbon trading costs energy procurement costs and hydrogen sales revenue while considering network constraints and constraints on key equipment. By analyzing the model under different scenarios the introduction of life cycle assessment staged carbon trading and hydrogen energy utilization is shown to promote low-carbon and economic development of the comprehensive energy system.

Sustainable aviation fuel (SAF) production is one of the strategies to guarantee an environmental-friendly development of the aviation sector. This work evaluates the technical economic and environmental feasibility of obtaining SAFs by hydrogenation of vegetable oils thanks to in-situ hydrogen production via aqueous phase reforming (APR) of glycerol by-product. The novel implementation of APR would avoid the environmental burden of conventional fossil-derived hydrogen production as well as intermittency and storage issues related to the use of RES-based (renewable energy sources) electrolysers. The conceptual design of a conventional and advanced (APR-aided) biorefinery was performed considering a standard plant capacity equal to 180 ktonne/y of palm oil. For the advanced scenario the feed underwent hydrolysis into glycerol and fatty acids; hence the former was subjected to APR to provide hydrogen which was further used in the hydrotreatment reactor where the fatty acids were deoxygenated. The techno-economic results showed that APR implementation led to a slight increase of the fixed capital investment by 6.6% compared to the conventional one while direct manufacturing costs decreased by 22%. In order to get a 10% internal rate of return the minimum fuel selling price was found equal to 1.84 $/kg which is 17% lower than the one derived from conventional configurations (2.20 $/kg). The life-cycle GHG emission assessment showed that the carbon footprint of the advanced scenario was equal to ca. 12 g CO2/MJSAF i.e. 54% lower than the conventional one (considering an energy-based allocation). The sensitivity analysis pointed out that the cost of the feedstock SAF yield and the chosen plant size are keys parameters for the marketability of this biorefinery while the energy price has a negligible impact; moreover the source of hydrogen has significant consequences on the environmental footprint of the plant. Finally possible uncertainties for both scenarios were undertaken via Monte Carlo simulations.

In the framework of the ongoing EMPIR JRP 16ENG01 ‘‘Metrology for Hydrogen Vehicles’’ a main task is to investigate the influence of pressure on the measurement accuracy of Coriolis Mass Flow Meters (CFM) used at Hydrogen Refueling Stations (HRS). At a HRS hydrogen is transferred at very high and changing pressures with simultaneously varying flow rates and temperatures. It is clearly very difficult for CFMs to achieve the current legal requirements with respect to mass flow measurement accuracy at these measurement conditions. As a result of the very dynamic filling process it was observed that the accuracy of mass flow measurement at different pressure ranges is not sufficient. At higher pressures it was found that particularly short refueling times cause significant measurement deviations. On this background it may be concluded that pressure has a great impact on the accuracy of mass flow measurement. To gain a deeper understanding of this matter RISE has built a unique high-pressure test facility. With the aid of this newly developed test rig it is possible to calibrate CFMs over a wide pressure and flow range with water or base oils as test medium. The test rig allows calibration measurements under the conditions prevailing at a 70 MPa HRS regarding mass flows (up to 3.6 kg min−1) and pressures (up to 87.5 MPa).

In this work the design and modeling of a fuel cell vehicle using low-loading platinum catalysts were investigated. Data from single fuel cells with low Pt-loading cathode catalysts were scaled up to fuel cell stacks and systems implemented in a vehicle and then compared to a commercial fuel cell vehicle. The low-loading Pt systems have shown lower efficiency at high loads compared to the commercial systems suggesting less stable materials. However the analysis showed that the vehicle comprising low-loading Pt catalysts achieves similar or higher efficiency compared to the commercial fuel cell vehicle when being scaled up for the same number of cells. When the systems were scaled up for the same maximum power as the commercial fuel cell vehicle all the low-loading Pt fuel cell systems showed higher efficiencies. In this case more cells are needed but still the amount of Pt is significantly reduced compared to the commercial one. The high-efficiency results can be associated with the vehicle’s power range operation that meets the region where the low-loading Pt fuel cells have high performance. The results suggested a positive direction towards the reduction of Pt in commercial fuel cell vehicles supporting a cost-competitive clean energy transition based on hydrogen.

Recently major problems related to fuel consumption and greenhouse gas (GHG) emissions have arisen in the transportation sector. Therefore developing transportation modes powered by alternative fuels has become one of the main targets for car manufacturers and governments around the world. This study aimed to investigate the economic prospects of using hydrogen fuel cell technology in taxi fleets in Westbank. For this purpose a model that could predict the number of taxis was developed and the expected economic implications of using hydrogen fuel cell technology in taxi fleets were determined based on the expected future fuel consumption and future fuel cost. After analysis of the results it was concluded that a slight annual increase in the number of taxis in Palestine is expected in the future due to the government restrictions on issuing new taxi permits in order to get this sector organized. Furthermore using hydrogen fuel cells in taxi fleets is expected to become more and more feasible over time due to the expected future increase in oil price and the expected significant reduction in hydrogen cost as a result of the new technologies that are expected to be used in the production and handling of hydrogen.

Blending hydrogen to existing fuel mix represents a major opportunity for decarbonisation. One important consideration for this application is the chemical interaction between hydrogen and hydrocarbon fuels arising from their different combustion chemistries and varying considerably with combustion processes. This paper conducted an exploratory study of hydrogen’s impact on autoignition in several combustion processes where hydrogen is used as a blending component or the main fuel. Case studies are presented for spark ignition engines (H2/natural gas) compression ignition engines (H2/diesel) moderate or intense low-oxygen dilution (MILD) combustors (H2/natural gas) and rotational detonation engines (H2/natural gas). Autoignition reactivity as a function of the hydrogen blending level is investigated numerically using the ignition delay iso-contours and state-of-the-art kinetic models at time scales representative of each application. The results revealed drastically different impact of hydrogen blending on autoignition due to different reaction temperature pressure and time scale involved in these applications leaving hydrocarbon interacting with hydrogen at different ignition branches where the negative pressure/temperature dependency of oxidation kinetics could take place. The resulted non-linear and at times non-monotonic behaviours indicate a rich topic for combustion chemistry and also demonstrates ignition delay iso-contour as a useful tool to scope autoignition reactivity for a wide range of applications.

Distributed waste-to-hydrogen (WtH) systems are a potential solution to tackle the dual challenges of sustainable waste management and zero emission transport. Here we propose a concept of distributed WtH systems based on gasification and fermentation to support hydrogen fuel cell buses in Glasgow. A variety of WtH scenarios were configured based on biomass waste feedstock hydrogen production reactors and upstream and downstream system components. A cost-benefit analysis (CBA) was conducted to compare the economic feasibility of the different WtH systems with that of the conventional steam methane reforming-based method. This required the curation of a database that included inter alia direct cost data on construction maintenance operations infrastructure and storage along with indirect cost data comprising environmental impacts and externalities cost of pollution carbon taxes and subsidies. The levelized cost of hydrogen (LCoH) was calculated to be 2.22 GB P/kg for municipal solid waste gasification and 2.02 GB P/kg for waste wood gasification. The LCoHs for dark fermentation and combined dark and photo fermentation systems were calculated to be 2.15 GB P/kg and 2.29 GB P/kg. Sensitivity analysis was conducted to identify the most significant influential factors of distributed WtH systems. It was indicated that hydrogen production rates and CAPEX had the largest impact for the biochemical and thermochemical technologies respectively. Limitations including high capital expenditure will require cost reduction through technical advancements and carbon tax on conventional hydrogen production methods to improve the outlook for WtH development.

This paper aims to optimize dual-fuel facilitated off-/on-grid multi-energy systems (MESs) for different renewable energy zones (REZs) in Australia. The main objective is to develop a novel MES with the main feature of green hydrogen production and blended natural gas utilization for remote households. The proposed optimal system produces green hydrogen of 5343 kg/yr via proton exchange membrane (PEM) electrolyzer and blends it with natural gas. It involves 20 % hydrogen and 80 % natural gas in the overall volume of the blending process. This study contributes by performing optimal sizing of the components economic-energy-environmental and performance analyses to examine the most feasible solution for each REZ. The results indicate that the optimal system in North Queensland REZ has the lowest levelized cost of energy (LCE) of 1.28 A$/kWh and 0.1003 A $/kWh and the net present cost (NPC) of A$0.311 million and A$0.219 million for off-grid and on-grid configurations. The optimal on-grid system has 95.27 % less carbon emissions than the natural gas-fueled combustion energy system.

The depletion of fossil fuel sources has encouraged the authorities to use renewable resources such as wind energy to generate electricity. A backup/storage system can improve the performance of wind turbines due to fluctuations in power demand. The novelty of this study is to utilize a hybrid system for a wind farm using the excess electricity generated by the wind turbines to produce hydrogen in an alkaline electrolyzer (AEL). The hydrogen storage tank stores the produced hydrogen and provides hydrogen to the proton-exchange membrane fuel cell (PEMFC) to generate electricity once the power demand is higher than the electricity generated by the wind turbines. The goal of this study is to use the wind profile of a region in Iran namely the Cohen region to analyze the performance of the suggested integrated system on a micro scale. The output results of this study can be used as a case study for construction in the future based on the exact specification of NTK300 wind turbines. The results indicate that with the minimum power supply of 30 kW from the wind turbines on a lab scale the generated power by the PEMFC will be 1008 W while the maximum generated hydrogen will be 304 mL/h.

A promising method of energy storage is the combination of hydrogen and compressed-air energy storage (CAES) systems. CAES systems are divided into diabatic adiabatic and isothermal cycles. In the diabatic cycle thermal energy after air compression is discharged into the environment and the scheme implies the use of organic fuel. Taking into account the prospects of the decarbonization of the energy industry it is advisable to replace natural gas in the diabatic CAES scheme with hydrogen obtained by electrolysis using power-to-gas technology. In this article the SENECA-1A project is considered as a high-power hybrid unit using hydrogen instead of natural gas. The results show that while keeping the 214 MW turbines powered the transition to hydrogen reduces carbon dioxide emissions from 8.8 to 0.0 kg/s while the formation of water vapor will increase from 17.6 to 27.4 kg/s. It is shown that the adiabatic CAES SENECA-1A mode compared to the diabatic has 0.0 carbon dioxide and water vapor emission with relatively higher efficiency (71.5 vs. 62.1%). At the same time the main advantage of the diabatic CAES is the possibility to produce more power in the turbine block (214 vs. 131.6 MW) having fewer capital costs. Thus choosing the technology is a subject of complex technical economic and ecological study.

A regional integrated energy system (RIES) synergizing multiple energy forms is pivotal for enhancing renewable energy use and mitigating the greenhouse effect. Considering that the equipment of the current regional comprehensive energy system is relatively simple there is a coupling relationship linking power generation refrigeration and heating in the cogeneration system which is complex and cannot directly meet various load demands. This article proposes a RIES optimization model for bottom-source heat pumps and hydrogen storage systems in the context of comprehensive demand response. First P2G electric hydrogen production technology was introduced into RIES to give full play to the high efficiency advantages of hydrogen energy storage system and the adjustable thermoelectric ratio of the HFC was considered. The HFC could adjust its own thermoelectric ratio according to the system load and unit output. Second through the groundsource heat pump’s cleaning efficiency function further separation and cooling could be achieved. The heat and electrical output of RIES improved the operating efficiency of the system. Thirdly a comprehensive demand response model for heating cooling and electricity was established to enable users to reasonably adjust their own energy use strategies to promote the rational distribution of energy in the system. The model integrates power-to-gas (P2G) technology leveraging the tunable thermoelectric ratio of a hydrogen fuel cell (HFC) to optimize the generation of electricity and heat while maximizing the efficiency of the hydrogen storage system. Empirical analysis substantiated the proposed RIES model’s effectiveness and economic benefits when integrating ground-source HP and electric hydrogen production with IDR. Compared with the original model the daily operating cost of the proposed model was reduced by RMB 1884.16.

One of the key factors of the current energy transition is the use of hydrogen (H2 ) as fuel in energy transformation technologies. This fuel has the advantage of being produced from the most primary forms of energy and has the potential to reduce carbon dioxide (CO2 ) emissions. In recent years hydrogen or hydrogen-rich mixtures in internal combustion engines (ICEs) have gained popularity with numerous reports documenting their use in spark ignition (SI) and compression ignition (CI) engines. Homogeneous charge compression ignition (HCCI) engines have the potential for substantial reductions in nitrogen oxides (NOx) and particulate matter (PM) emissions and the use of hydrogen along with this kind of combustion could substantially reduce CO2 emissions. However there have been few reports using hydrogen in HCCI engines with most studies limited to evaluating technical feasibility combustion characteristics engine performance and emissions in laboratory settings at sea level. This paper presents a study of HCCI combustion using hydrogen in a stationary air-cooled Lombardini 25 LD 425-2 modified diesel engine located at 1495 m above sea level. An experimental phase was conducted to determine the intake temperature requirements and equivalence ratios for stable HCCI combustion. These results were compared with previous research carried out at sea level. To the best knowledge of the authors this is the first report on the combustion and operational limits for an HCCI engine fueled with hydrogen under the mentioned specific conditions. Equivalence ratios between 0.21 and 0.28 and intake temperatures between 188 ◦C and 235 ◦C effectively achieved the HCCI combustion. These temperature values were on average 100 ◦C higher than those reported in previous studies. The maximum value for the indicated mean effective pressure (IMEPn) was 1.75 bar and the maximum thermal efficiency (ITEn) was 34.5%. The achieved results are important for the design and implementation of HCCI engines running solely on hydrogen in developing countries located at high altitudes above sea level.

To cope with the growing penetration rate of renewable energy and to enhance the absorption capacity of wind power this paper investigates the applications of an Integrated Energy System (IES) Hydrogen Compressed Natural Gas (HCNG) and power-to-hydrogen (P2H) devices within the IES. It employs power-to-gas and gas blending with hydrogen to construct an efficient electricity–gas–electricity energy flow loop establishing a Natural Gas–Electricity Coupling System (NGECS) model. On this basis a coordinated scheduling method for gas–electric coupling systems using gas blended with hydrogen is proposed. A carbon trading mechanism is introduced to constrain carbon emissions further reducing the system’s carbon footprint. Multiple scenarios are set up for a comparative analysis in order to validate the effectiveness of the proposed model. This study also analyzes the impact of different hydrogen blending ratios and methods on the low-carbon and economic performance of IES.

Among the different hydrogen premixed combustion concepts direct injection (DI) is one of the most promising for internal combustion engine (ICE) applications. However to fully exploit the benefits of this solution the optimization of the mixture preparation process is a crucial factor. In the present work a study of the hydrogenair mixture formation process in a DI H2-ICE for off-road applications was performed through 3D-CFD simulations. First a sensitivity analysis on the injection timing was carried out to select the optimal injection operating window capable of maximizing mixture homogeneity without a significant volumetric efficiency reduction. Then different spray injector guiding caps were tested to assess their effect on in-cylinder dynamics and mixture characteristics consequently. Finally the impact of swirl intensity on hydrogen distribution has been assessed. The optimization of the combustion chamber geometry has allowed the achievement of significant improvements in terms of mixture homogeneity.

Developing an effective energy transition roadmap is crucial in the face of global commitments to achieve net zero emissions. While renewable power generation systems are expanding challenges such as curtailments and grid constraints can lead to energy loss. To address this surplus electricity can be converted into green hydrogen serving as a key component in the energy transition. This research explores the use of renewable solar energy for powering a proton exchange membrane electrolyser to produce green hydrogen while a downdraft gasifier fed by municipal solid waste generates hydrogen-enriched syngas. The blended fuel is then used to feed a Solid Oxide Fuel Cell (SOFC) system. The study investigates the impact of hydrogen content on the performance of the fuel cell-based power plant from thermodynamics and exergoeconomic perspectives. Multiobjective optimisation using a genetic algorithm identifies optimal operating conditions for the system. Results show that blending hydrogen with syngas increases combined heat and power efficiency by up to 3% but also raises remarkably the unit product cost and reduces carbon dioxide emissions. Therefore the optimal values for hydrogen content current density temperatures and other parameters are determined. These findings contribute to the design and operation of an efficient and sustainable energy generation system.

The production of solid waste in human societies and the related environmental and global warming concerns are increasing. Extensive use of existing conventional diesel and dual-fuel engines also causes the production of high levels of greenhouse gases and aggravating the aforementioned concerns. Therefore the aim of this study is to reduce the greenhouse emissions in existing natural gas/diesel dual-fuel heavy-duty diesel engine. For this purpose changing the type of combustion to reactivity-controlled compression-ignition combustion and using landfill gas instead of natural gas in a dual-fuel engine were simultaneously implemented. Moreover a traditional method was used to evaluate the effect of variations in three important parameters on the engine's performance in order to determine the appropriate engine operating ranges. The simulation results indicate that although the consumption of 102000 cubic meters per year of natural gas in each cylinder is reduced only by replacing landfill gas the level of engine greenhouse gas emissions is too high compared to the relevant levels of emissions standards. Hence by keeping the total energy content of the fuels constant landfill gas enrichment with hydrogen was considered to reduce the engine emissions. The simulation results show that by increasing the hydrogen energy share up to 37% the engine load has the potential to be improved up to 7% without any exposure to diesel knock. However the downfall is the reduction in the gross indicated efficiency up to 3%. Meanwhile not only the fifth level of the European emission standard for nitrogen oxides and the sixth level of this standard for carbon monoxide can be achieved but it is also possible to overcome the high level of unburned methane as a drastic greenhouse gas and formaldehyde as a related carcinogenic species.

The use of alternative fuels remains an important factor in solving the problem of reducing harmful substances caused by vehicles and decarbonising transport. It is also important to ensure the energy efficiency of vehicle power plants when using different fuels at a sufficient level. The article presents the results of theoretical and experimental studies of the conversion of diesel engine to alternative fuels with hydrogen admixtures. Methanol is considered as an alternative fuel which is a cheaper alternative to commercial diesel fuel. The chemical essence of improving the calorific value of alternative methanol fuel was investigated. Studies showed that the energy effect of burning an alternative mixture with hydrogen additives exceeds the effect of burning the same amount of methanol fuel. The increase in combustion energy and engine power is achieved as a result of heat from efficient use of the engine exhaust gases and chemical conversion of methanol. An experimental installation was created to study the work of a converted diesel engine on hydrogen–methanol mixtures and thermochemical regeneration processes. Experimental studies of the energy and environmental parameters of diesel engine converted to work on an alternative fuel with hydrogen admixtures have shown that engine power increases by 10–14% and emissions of harmful substances decrease.

This paper studies fast fueling of gaseous hydrogen into large hydrogen (H2) tanks suitable for maritime applications. Three modeling methods have been developed and evaluated: (1) Two-dimensional computational fluid dynamic (CFD) modeling (2) One-dimensional wall discretized modeling and (3) Zero-dimensional modeling. A detailed 2D CFD simulation of a small H2-tank was performed and validated with data from literature and then used to simulate a large H2-tank. Results from the 2D-model show non-uniform temperature distribution inside the large tank but not in the small H2-tank. The 1D-model can predict the mean temperature in small H2-tanks but not the inhomogeneous temperature field in large H2-tanks. The 0D-model is suitable as a screening tool to obtain rough estimates. Results from the modeling of the large H2-tank show that the heat transfer to the wall during fast filling is inhibited by heat conduction in the wall which leads to an unacceptably high mean hydrogen temperature.

Carbon dioxide (CO2 ) and hydrogen (H2 ) are essential energy vectors in the green energy transition. H2 is a fuel produced by electrolysis and is applied in heavy transportation where electrification is not feasible yet. The pollutant substance CO2 is starting to be captured and stored in different European locations. In Denmark the energy vision aims to use this CO2 to be reacted with H2 producing green methanol. Typically the production units are not co-located with consumers and thus the required transportation infrastructure is essential for meeting supply and demand. This work presents a novel scheme to allocate the transportation costs of CO2 and H2 in pipeline networks which can be applied to any network topology and with any allocation method. During the tariff formation process coordinated adjustments are made by the novel scheme on the original tariffs produced by the allocation method employed considering the location of each customer connected to pipeline network. Locational tariffs are provided as result and the total revenue recovery is guaranteed to the network owner. Considering active customers the novel scheme will lead to a decrease of distant pipeline flows thereby contributing to the prevention of bottlenecks in the transportation network. Thus structural reinforcements can be avoided reducing the total transportation cost paid by all customers in the long-term.

Currently the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore for gas turbine power systems including hybrid power plants with fuel cells it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion an increase in the temperature of the walls of the flame tubes and an increase in the emission of nitrogen oxides in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley” when operating on pure hydrogen the formation of flame flashback zones does not occur.

This work presents simulation results from a system where offshore wind power is used to produce hydrogen via electrolysis. Real-world data from a 2.3 MW floating offshore wind turbine and electricity price data from Nord Pool were used as input to a novel electrolyzer model. Data from five 31-day periods were combined with six system designs and hydrogen production system efficiency and production cost were estimated. A comparison of the overall system performance shows that the hydrogen production and cost can vary by up to a factor of three between the cases. This illustrates the uncertainty related to the hydrogen production and profitability of these systems. The highest hydrogen production achieved in a 31-day period was 17 242 kg using a 1.852 MW electrolyzer (i.e. utilization factor of approximately 68%) the lowest hydrogen production cost was 4.53 $/kg H2 and the system efficiency was in the range 56.1e56.9% in all cases.

Currently there is a growing interest in increasing the power range of air-cooled fuel cells (ACFCs) as they are cheaper easier to use and maintain than water-cooled fuel cells (WCFCs). However air-cooled stacks are only available up to medium power (<10 kW). Therefore a good solution may be the development of ACFCs consisting of several stacks until the required power output is reached. This is the concept of air-cooled multi-stack fuel cell (AC-MSFC). The objective of this work is to develop a turnkey solution for the integration of AC-MSFCs in renewable microgrids specifically those with high-voltage DC (HVDC) bus. This is challenging because the AC-MSFCs must operate in the microgrid as a single ACFC with adjustable power depending on the number of stacks in operation. To achieve this the necessary power converter (ACFCs operate at low voltages so high conversion rates are required) and control loops must be developed. Unlike most designs in the literature the proposed solution is compact forming a system (AC-MSFCS) with a single input (hydrogen) and a single output (high voltage regulated power or voltage) that can be easily integrated into any microgrid and easily scalable depending on the power required. The developed AC-MSFCS integrates stacks balance of plant data acquisition and instrumentation power converters and local controllers. In addition a virtual instrument (VI)has been developed which connected to the energy management system (EMS) of the microgrid allows monitoring of the entire AC-MSFCS (operating temperature purging cell voltage monitoring for degradation evaluation stacks operating point control and alarm and event management) as well as serving as a user interface. This allows the EMS to know the degradation of each stack and to carry out energy distribution strategies or specific maintenance actions which improves efficiency lifespan and of course saves costs. The experimental results have been excellent in terms of the correct operation of the developed AC-MSFCS. Likewise the accumulated degradation of the stacks was quantified showing cells with a degradation of >80%. The excellent electrical and thermal performance of the developed power converter was also validated which allowed the correct and efficient supply of regulated power (average efficiency above 90%) to the HVDC bus according to the power setpoint defined by the EMS of the microgrid.

A 3.5 tonne forklift containing proton exchange membrane fuel cells (PEMFCs) and lithium-ion batteries was manufactured and tested in a real factory. The work efficiency and economic applicability of the PEMFC forklift were compared with that of a lithium-ion battery-powered forklift. The results showed that the back-pressure of air was closely related to the power density of the stack whose stability could be improved by a reasonable control strategy and membrane electrode assemblies (MEAs) with high consistency. The PEMFC powered forklift displayed 40.6% higher work efficiency than the lithium-ion battery-powered forklift. Its lower use-cost compared to internal engine-powered forklifts is beneficial to the commercialization of this product.

With the massive use of traditional fossil fuels greenhouse gas emissions are increasing and environmental pollution is becoming an increasingly serious problem which led to an imminent energy transition. Therefore the development and application of renewable energy are particularly important. This paper reviews a wide range of issues associated with hybrid renewable energy systems (HRESs). The issues concerning system configurations energy storage options simulation and optimization with artificial intelligence are discussed in detail. Storage technology options are introduced for stand-alone (off-grid) and grid-connected (on-grid) HRESs. Different optimization methodologies including classical techniques intelligent techniques hybrid techniques and software tools for sizing system components are presented. Besides the artificial intelligence methods for optimizing the solar/wind HRESs are discussed in detail.

Renewable energy solutions play a crucial role in addressing the growing energy demands while mitigating environmental concerns. This study examines the techno-economic viability and sensitivity of utilizing solar photovoltaic/polymer electrolyte membrane (PEM) fuel cells (FCs) to meet specific power demands in NEOM Saudi Arabia. The novelty of this study lies in its innovative approach to analyzing and optimizing PV/PEMFC systems aiming to highlight their economic feasibility and promote sustainable development in the region. The analysis focuses on determining the optimal size of the PV/PEMFC system based on two critical criteria: minimum cost of energy (COE) and minimum net present cost (NPC). The study considers PEMFCs with power ratings of 30 kW 40 kW and 50 kW along with four PV panel options: Jinko Solar Powerwave Tindo Karra and Trina Solar. The outcomes show that the 30 kW PEMFC and the 201 kW Trina Solar TSM-430NEG9R.28 are the most favorable choices for the case study. Under these optimal conditions the study reveals the lowest values for NPC at USD 703194 and COE at USD 0.498 per kilowatt-hour. The levelized cost of hydrogen falls within the range of USD 15.9 to 23.4 per kilogram. Furthermore replacing the 30 kW Trina solar panel with a 50 kW Tindo PV module results in a cost reduction of 32%. The findings emphasize the criticality of choosing optimal system configurations to attain favorable economic outcomes thereby facilitating the adoption and utilization of renewable energy sources in the region. In conclusion this study stands out for its pioneering and thorough analysis and optimization of PV/PEMFC systems providing valuable insights for sustainable energy planning in NEOM Saudi Arabia.

A transition towards zero-emission fuels is required in the mobility sector in order to reach the climate goals. Here (green) renewable hydrogen for use in fuel cells will play an important role especially for heavy duty applications such as trucks. However there are still challenges to overcome regarding efficient storage infrastructure integration and optimization of the refuelling process. A key aspect is to reduce the refuelling duration as much as possible while staying below the maximum allowed temperature of 85 C. Experimental tests for the refuelling of a 320 l type III tank were conducted at different operating conditions and the tank gas temperature measured at the front and back ends. The results indicate a strongly inhomogeneous temperature field where measuring and verifying the actual maximum temperatures proves difficult. Furthermore a simulation approach is provided to calculate the average tank gas temperature at the end of the refuelling process.

The power and transport sectors are responsible for significant emissions of greenhouse gases. Therefore it is imperative that substantial efforts are directed towards the decarbonisation of these industries. This study establishes a combined-solar-wind system's economic and technical practicality for producing hydrogen for an onsite hydrogen refuelling station (HRS) and electricity to meet peak demand. To minimise the levelised cost of electricity and maximise the system's reliability at different commercial locations in South Africa the dual-objective optimisation sizing is carried out using Mixed Integer Quadratic Constrained Programming (MICQP) model and was executed with an Advanced Multi-dimensional Modelling System (AIMMS) [61] [62]. The levelised costs of electricity and hydrogen at Johannesburg Pretoria and Cape Town for 2 MW grid export benchmark are 74.2 $/MWh/5.85 $/kg 76.3 $/MWh/5.97 $/kg and 50 $/MWh/4.45 $/kg respectively. The CO₂ equivalent emissions (tonnes) are 54000 55800 59000 and the corresponding carbon taxes ($) avoided for the locations are 432100 446200 and 472000 for Johannesburg Pretoria and Cape Town respectively. The results of the framework show that it can be adopted as a viable and fossil-free replacement for conventional peaking generators.

Due to the emissions reduction commitments that Mexico compromised in the Paris Agreement several clean fuel and renewable energy technologies need to penetrate the market to accomplish the environmental goals. Therefore there is a need to develop achievable and realistic policies for such technologies to ease the decision-making on national energy strategies. Several countries are starting to develop large-scale green hydrogen production projects to reduce the carbon footprint of the multiple sectors within the country. The conversion sectors namely power and refinery are fundamental sectors to decarbonise due to their energy supply role. Nowadays the highest energy consumables of the country are hydrocarbons (more than 90%) causing a particular challenge for deep decarbonisation. The purpose of this study is to use a multi-regional energy system model of Mexico to analyse a decarbonisation scenario in line with the latest National Energy System Development Program. Results show that if the country wants to succeed in reducing 22% of its GHG emissions and 51% of its short-lived climate pollutants emissions green hydrogen could play a role in power generation in regions with higher energy demand growth rates. These results show regarding the power sector that H2 could represent 13.8 GW or 5.1% of the total installed capacity by 2050 while for the refinery sector H2 could reach a capacity of 157 PJ/y which is around 31.8% of the total share and it is mainly driven by the increasing demands of the transport industry and power sectors. Nevertheless as oil would still represent the largest energy commodity CCS technologies would have to be deployed for new and retrofitted refinery facilities.

In Sub-Saharan Africa (SSA) the capacity to generate energy faces significant hurdles. Despite efforts to integrate renewable energy sources and natural gas power plants into the energy portfolio the desired reduction in environmental impact and alleviation of energy poverty remain elusive. Hence exploring a spectrum of hybrid technologies encompassing storage and hydrogen-based solutions is imperative to optimize energy production while mitigating harmful emissions. To exemplify this necessity the 216 MW Kribi gas power plant in Cameroon is the case study. The primary aim is to investigate cutting-edge emissions and energy schemes within the SSA. This paper assessed the minimum complaint load technique and four power-to-fuel options from technical financial and environmental perspectives to assess the viability of a natural gas fuel system powered with hydrogen in a hybrid mode. The system generates hydrogen by using water electrolysis with photovoltaic electricity and gas power plant. This research also assesses process efficiency storage capacity annual costs carbon avoided costs and production prices for various fuels. Results showed that the LCOE from a photovoltaic solar plant is 0.19$/kWh with the Power-to-Hydrogen process (76.2% efficiency) being the most efficient followed by the ammonia and urea processes. The study gives a detailed examination of the hybrid hydrogen natural gas fuel system. According to the annual cost breakdown the primary costs are associated with the acquisition of electrical energy and electrolyser CAPEX and OPEX which account for 95% of total costs. Urea is the cheapest mass fuel. However it costs more in terms of energy. Hydrogen is the most cost-effective source of energy. In terms of energy storage and energy density by volume the methane resulted as the most suitable solution while the ammonia resulted as the best H2 storage medium in terms of kg of H2 per m3 of storage (108 kgH2/m3 ). By substituting the fuel system with 15% H2 the environmental effects are reduced by 1622 tons per year while carbon capture technology gathered 16664 tons of CO2 for methanation and urea operations yielding a total carbon averted cost of 21 $/ton.