Applications & Pathways

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.