Applications & Pathways
Fuel Cells in Road Vehicles
Nov 2022
Publication
Issues related to the reduction of the environmental impact of means of road transport by the use of electric motors powered by Proton Exchange Membrane (PEM) fuel cells are presented in this article. The overall functional characteristics of electric vehicles are presented as well as the essence of the operation of a fuel cell. On the basis of analyzing the energy conversion process significant advantages of electric drive are demonstrated especially in vehicles for urban and suburban applications. Moreover the analyzed literature indicated problems of controlling and maintaining fuel cell power caused by its highest dynamic and possible efficiency. This control was related to the variable load conditions of the fuel cell vehicle (FCV) engine. The relationship with the conventional dependencies in the field of vehicle dynamics is demonstrated. The final part of the study is related to the historical outline and examples of already operating fuel cell systems using hydrogen as an energy source for energy conversion to power propulsion vehicle’s engines. In conclusion the necessity to conduct research in the field of methods for controlling the power of fuel cells that enable their effective adaptation to the temporary load resulting from the conditions of vehicle motion is indicated.
Hydrogen Fuel Cell Electric Trains: Technologies, Current Status, and Future
Feb 2024
Publication
Trains have been a crucial part of modern transport and their high energy efficiency and low greenhouse gas emissions make them ideal candidates for the future transport system. Transitioning from diesel trains to hydrogen fuel cell electric trains is a promising way to decarbonize rail transport. That’s because the fuel cell electric trains have several advantages over other electric trains such as lower life-cycle emissions and shorter refueling time than battery ones and less requirements for wayside infrastructure than the ones with overhead electric wires. However hydrogen fuel technology still needs to be advanced in areas including hydrogen production storage refueling and on-board energy management. Currently there are several pilot projects of hydrogen fuel cell electric trains across the globe especially in developed countries including one commercialized and permanent route in Germany. The experiences from the pilot projects will promote the technological and economic feasibility of hydrogen fuel in rail transport.
Evaluation of Significant Greenhouse Gas Emissions Reduction Using Hydrogen Fuel in a LFG/Diesel RCCI Engine
Jan 2024
Publication
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.
Towards Defossilised Steel: Supply Chain Options for a Green European Steel Industry
Mar 2023
Publication
As the European Union intensifies its response to the climate emergency increased focus has been placed on the hard-to-abate energy-intensive industries. Primary among these is the steel industry a cornerstone of the European economy and industry. With the emergence of new hydrogen-based steelmaking options particularly through hydrogen direct reduction the structure of global steel production and supply chains will transition from being based on low-cost coal resources to that based on low-cost electricity and therefore hydrogen production. This study examines the techno-economic options for three European countries of Germany Spain and Finland under five different steel supply chain configurations compared to local production. Results suggest that the high costs of hydrogen transportation make a European steelmaking supply chain cost competitive to steel produced with imported hydrogen with local production costs ranging from 465-545 €/t of crude steel (CS) and 380-494 €/tCS for 2030 and 2040 respectively. Conversely imports of hot briquetted iron and crude steel from Morocco become economically competitive with European supply chains. Given the capital and energy intensive nature of the steel industry critical investment decisions are required in this decade and this research serves to provide a deeper understanding of supply chain options for Europe.
A New Path towards Sustainable Energy Transition: Techno-Economic Feasibility of a Complete Hybrid Small Modular Reactor/Hydrogen (SMR/H2) Energy System
Oct 2023
Publication
Small modular reactors (SMRs) are nuclear reactors with a smaller capacity than traditional large-scale nuclear reactors offering advantages such as increased safety flexibility and cost-effectiveness. By producing zero carbon emissions SMRs represent an interesting alternative for the decarbonization of power grids. Additionally they present a promising solution for the production of hydrogen by providing large amounts of energy for the electrolysis of water (pink hydrogen). The above hint at the attractiveness of coupling SMRs with hydrogen production and consumption centers in order to form clusters of applications which use hydrogen as a fuel. This work showcases the techno-economic feasibility of the potential installation of an SMR system coupled with hydrogen production the case study being the island of Crete. The overall aim of this approach is the determination of the optimal technical characteristics of such a system as well as the estimation of the potential environmental benefits in terms of reduction of CO2 emissions. The aforementioned system which is also connected to the grid is designed to serve a portion of the electric load of the island while producing enough hydrogen to satisfy the needs of the nearby industries and hotels. The results of this work could provide an alternative sustainable approach on how a hydrogen economy which would interconnect and decarbonize several industrial sectors could be established on the island of Crete. The proposed systems achieve an LCOE between EUR 0.046/kWh and EUR 0.052/kWh while reducing carbon emissions by more than 5 million tons per year in certain cases.
The Status of On-Board Hydrogen Storage in Fuel Cell Electric Vehicles
Aug 2023
Publication
Hydrogen as an energy carrier could help decarbonize industrial building and transportation sectors and be used in fuel cells to generate electricity power or heat. One of the numerous ways to solve the climate crisis is to make the vehicles on our roads as clean as possible. Fuel cell electric vehicles (FCEVs) have demonstrated a high potential in storing and converting chemical energy into electricity with zero carbon dioxide emissions. This review paper comprehensively assesses hydrogen’s potential as an innovative alternative for reducing greenhouse gas (GHG) emissions in transportation particularly for on-board applications. To evaluate the industry’s current status and future challenges the work analyses the technology behind FCEVs and hydrogen storage approaches for on-board applications followed by a market review. It has been found that to achieve long-range autonomy (over 500 km) FCEVs must be capable of storing 5–10 kg of hydrogen in compressed vessels at 700 bar with Type IV vessels being the primary option in use. Carbon fiber is the most expensive component in vessel manufacturing contributing to over 50% of the total cost. However the cost of FCEV storage systems has considerably decreased with current estimates around 15.7 $/kWh and is predicted to drop to 8 $/kWh by 2030. In 2021 Toyota Hyundai Mercedes-Benz and Honda were the major car brands offering FCEV technology globally. Although physical and chemical storage technologies are expected to be valuable to the hydrogen economy compressed hydrogen storage remains the most advanced technology for on-board applications.
Assessment of Selected Alternative Fuels for Spanish Navy Ships According to Multi-Criteria Decision Analysis
Dec 2023
Publication
Climate change and environmental degradation are growing concerns in today’s society which has led to greater awareness and responsibility regarding the need to adopt sustainable practices. The European Union has established the goal of achieving climate neutrality by 2050 which implies a significant reduction in greenhouse gas emissions in all sectors. To achieve this goal renewable energies the circular economy and energy efficiency are being promoted. A major source of emissions is the use of fossil fuels in different types of ships (from transport ships to those used by national navies). Among these it highlights the growing interest of the defense sector in trying to reduce these emissions. The Spanish Ministry of Defense is also involved in this effort and is taking steps to reduce the carbon footprint in military operations and improve sustainability in equipment acquisition and maintenance. The objective of this study is to identify the most promising alternative fuel among those under development for possible implementation on Spanish Navy ships in order to reduce greenhouse gas emissions and improve its capabilities. To achieve this a multi-criteria decision-making method will be used to determine the most viable fuel option. The data provided by the officers of the Spanish Navy is of great importance thanks to their long careers in front of the ships. The analysis revealed that hydrogen was the most suitable fuel with the highest priority ahead of LNG and scored the highest in most of the sections of the officials’ ratings. These fuels are less polluting and would allow a significant reduction in emissions during the navigation of ships. However a further study would also have to be carried out on the costs of adapting to their use and the safety of their use.
Assessment of the Co-combustion Process of Ammonia with Hydrogen in a Research VCR Piston Engine
Oct 2022
Publication
The presented work concerns experimental research of a spark-ignition engine with variable compression ratio (VCR) adapted to dual-fuel operation in which co-combustion of ammonia with hydrogen was conducted and the energy share of hydrogen varied from 0% to 70%. The research was aimed at assessing the impact of the energy share of hydrogen co-combusted with ammonia on the performance stability and emissions of an engine operating at a compression ratio of 8 (CR 8) and 10 (CR 10). The operation of the engine powered by ammonia alone for both CR 8 and CR 10 is associated with either a complete lack of ignition in a significant number of cycles or with significantly delayed ignition and the related low value of the maximum pressure pmax. Increasing the energy share of hydrogen in the fuel to 12% allows to completely eliminate the instability of the ignition process in the combustible mixture which is confirmed by a decrease in the IMEP uniqueness and a much lower pmax dispersion. For 12% of the energy share of hydrogen co-combusted with ammonia the most favorable course of the combustion process was obtained the highest engine efficiency and the highest IMEP value were recorded. The conducted research shows that increasing the H2 share causes an increase in NO emissions for both analyzed compression ratios
Numerical Analysis of Dual Fuel Combustion in a Medium Speed Marine Engine Supplied with Methane/Hydrogen Blends
Sep 2023
Publication
Compression ignition engines will still be predominant in the naval sector: their high efficiency high torque and heavy weight perfectly suit the demands and architecture of ships. Nevertheless recent emission legislations impose limitations to the pollutant emissions levels in this sector as well. In addition to post-treatment systems it is necessary to reduce some pollutant species and therefore the study of combustion strategies and new fuels can represent valid paths for limiting environmental harmful emissions such as CO2 . The use of methane in dual fuel mode has already been implemented on existent vessels but the progressive decarbonization will lead to the utilization of carbon-neutral or carbon-free fuels such as in the last case hydrogen. Thanks to its high reactivity nature it can be helpful in the reduction of exhaust CH4 . On the contrary together with the high temperatures achieved by its oxidation hydrogen could cause uncontrolled ignition of the premixed charge and high emissions of NOx. As a matter of fact a source of ignition is still necessary to have better control on the whole combustion development. To this end an optimal and specific injection strategy can help to overcome all the before-mentioned issues. In this study three-dimensional numerical simulations have been performed with the ANSYS Forte® software (version 19.2) in an 8.8 L dual fuel engine cylinder supplied with methane hydrogen or hydrogen–methane blends with reference to experimental tests from the literature. A new kinetic mechanism has been used for the description of diesel fuel surrogate oxidation with a set of reactions specifically addressed for the low temperatures together with the GRIMECH 3.0 for CH4 and H2 . This kinetics scheme allowed for the adequate reproduction of the ignition timing for the various mixtures used. Preliminary calculations with a one-dimensional commercial code were performed to retrieve the initial conditions of CFD calculations in the cylinder. The used approach demonstrated to be quite a reliable tool to predict the performance of a marine engine working under dual fuel mode with hydrogen-based blends at medium load. As a result the system modelling shows that using hydrogen as fuel in the engine can achieve the same performance as diesel/natural gas but when hydrogen totally replaces methane CO2 is decreased up to 54% at the expense of the increase of about 76% of NOx emissions.
Optimal Scheduling of Power Systems with High Proportions of Renewable Energy Accounting for Operational Flexibility
Jul 2023
Publication
Yi Lin,
Wei Lin,
Wei Wu and
Zhenshan Zhu
The volatility and uncertainty of high-penetration renewable energy pose significant challenges to the stability of the power system. Current research often fails to consider the insufficient system flexibility during real-time scheduling. To address this issue this paper proposes a flexibility scheduling method for high-penetration renewable energy power systems that considers flexibility index constraints. Firstly a quantification method for flexibility resources and demands is introduced. Then considering the constraint of the flexibility margin index optimization scheduling strategies for different time scales including day-ahead scheduling and intra-day scheduling are developed with the objective of minimizing total operational costs. The intra-day optimization is divided into 15 min and 1 min time scales to meet the flexibility requirements of different time scales in the power system. Finally through simulation studies the proposed strategy is validated to enhance the system’s flexibility and economic performance. The daily operating costs are reduced by 3.1% and the wind curtailment rate is reduced by 4.7%. The proposed strategy not only considers the economic efficiency of day-ahead scheduling but also ensures a sufficient margin to cope with the uncertainty of intra-day renewable energy fluctuations.
Capacity Configuration Optimization for Green Hydrogen Generation by Solar-wind Hybrid Power Based on Comprehensive Performance Criteria
Aug 2023
Publication
Green hydrogen generation driven by solar-wind hybrid power is a key strategy for obtaining the low-carbon energy while by considering the fluctuation natures of solar-wind energy resource the system capacity configuration of power generation hydrogen production and essential storage devices need to be comprehensively optimized. In this work a solar-wind hybrid green hydrogen production system is developed by combining the hydrogen storage equipment with the power grid the coordinated operation strategy of solar-wind hybrid hydrogen production is proposed furthermore the NSGA-III algorithm is used to optimize the system capacity configuration with the comprehensive performance criteria of economy environment and energy efficiency. Through the implemented case study with the hydrogen production capacity of 20000 tons/year the abandoned energy power rate will be reduced to 3.32% with the electrolytic cell average load factor of 64.77% and the system achieves the remarkable carbon emission reduction. In addition with the advantage of connect to the power grid the generated surplus solar/wind power can be readily transmitted with addition income when the sale price of produced hydrogen is suggested to 27.80 CNY/kgH2 the internal rate of return of the system reaches to 8% which present the reasonable economic potential. The research provides technical and methodological suggestions and guidance for the development of solar-wind hybrid hydrogen production schemes with favorable comprehensive performance.
Performance Evaluation of a Fuel Cell mCHP System under Different Configurations of Hydrogen Origin and Heat Recovery
Sep 2023
Publication
Motivated by the growing importance of fuel cell systems as the basis for distributed energy generation systems this work considers a micro-combined heat and power (mCHP) generation system based on a fuel cell integrated to satisfy the (power and thermal) energy demands of a residential application. The main objective of this work is to compare the performance of several CHP configurations with a conventional alternative in terms of primary energy consumption greenhouse gas (GHG) emissions and economic viability. For that a simulation tool has been developed to easily estimate the electrical and thermal energy generated by a hydrogen fuel cell and all associated results related to the hydrogen production alternatives: excess or shortfall of electrical and thermal energy CO2 emission factor overall performance operating costs payback period etc. A feasibility study of different configuration possibilities of the micro-CHP generation system has been carried out considering different heat-to-power ratios (HPRs) in the possible demands and analyzing primary energy savings CO2 emissions savings and operating costs. An extensive parametric study has been performed to analyze the effect of the fuel cell’s electric power and number of annual operation hours as parameters. Finally a study of the influence of the configuration parameters on the final results has been carried out. Results show that in general configurations using hydrogen produced from natural gas save more primary energy than configurations with hydrogen production from electricity. Furthermore it is concluded that the best operating points are those in which the generation system and the demand have similar HPR. It has also been estimated that a reduction in renewable hydrogen price is necessary to make these systems profitable. Finally it has been determined that the most influential parameters on the results are the fuel cell electrical efficiencies hydrogen production efficiency and hydrogen cost.
Can Hydrogen Storage in Metal Hydrides be Economically Competitive with Compressed and Liquid Hydrogen Storage? A Techno-economical Perspective for the Maritime Sector
Aug 2023
Publication
The aim of this work is to evaluate if metal hydride hydrogen storage tanks are a competitive alternative for onboard hydrogen storage in the maritime sector when compared to compressed gas and liquid hydrogen storage. This is done by modelling different hydrogen supply and onboard storage scenarios and evaluating their levelized cost of hydrogen variables. The levelized cost of hydrogen for each case is calculated considering the main components that are required for the refueling infrastructure and adding up the costs of hydrogen production compression transport onshore storage dispensing and the cost of the onboard tanks when known. The results show that the simpler refueling needs of metal hydride-based onboard tanks result in a significant cost reduction of the hydrogen handling equipment. This provides a substantial leeway for the investment costs of metal hydride-based storage which depending on the scenario can be between 3400 - 7300 EUR/kgH2 while remaining competitive with compressed hydrogen storage.
Application and Limitations of Batteries and Hydrogen in Heavy Haul Rail using Australian Case Studies
Oct 2022
Publication
Decarbonisation of heavy haul rail is an essential contributor to a zero-emissions future. However the transition from diesel to battery locomotives is not always practical given the unique characteristics of each haul. This paper demonstrates the limitations of state-of-the-art batteries using real-world data from multiple locomotives operating in Australian rail freight. An energy model was developed to assess each route’s required energy and potential regenerated energy. The tractive and regenerative battery energy mass and cost were determined using data from the energy model coupled with battery specifications. The feasibility of implementing lithium iron phosphate (LFP) nickel manganese cobalt (NMC) and lithium titanium oxide (LTO) chemistries was explored based on cost energy density cycle lifespan and locomotive data. LFP was identified as the most suitable current battery solution based on current chemistries. Further examination of the energy demands and associated mass/volume constraints concluded that three platforms are required for heavy haul rail decarbonisation i) a battery electric locomotive for low-energy demands which can be coupled with either ii) a battery electric tender for medium energy demands or iii) a hydrogen fuel cell electric tender for higher energy demands. A future-looking techno-economic assessment of battery and hydrogen fuel cell platforms concludes that the lowest cost solution for low-energy hauls is a battery-only system and for high-energy hauls a battery-hydrogen system.
Green Fleet: A Prototype Biogas and Hydrogen Refueling Management System for Private Fleet Stations
Aug 2023
Publication
Biogas and hydrogen (H2 ) are breaking through as alternative energy sources in road transport specifically for heavy-duty vehicles. Until a public network of service stations is deployed for such vehicles the owners of large fleets will need to build and manage their own refueling facilities. Fleet refueling management and remote monitoring at these sites will become key business needs. This article describes the construction of a prototype system capable of solving those needs. During the design and development process of the prototype the standard industry protocols involved in these installations have been considered and the latest expertise in information technology systems has been applied. This prototype has been essential to determine the Strengths Challenges Opportunities and Risks (SCOR) of such a system which is the first step of a more ambitious project. A second stage will involve setting up a pilot study and developing a commercial system that can be widely installed to provide a real solution for the industry.
An Overview of Application-orientated Multifunctional Large-scale Stationary Battery and Hydrogen Hybrid Energy Storage System
Dec 2023
Publication
The imperative to address traditional energy crises and environmental concerns has accelerated the need for energy structure transformation. However the variable nature of renewable energy poses challenges in meeting complex practical energy requirements. To address this issue the construction of a multifunctional large-scale stationary energy storage system is considered an effective solution. This paper critically examines the battery and hydrogen hybrid energy storage systems. Both technologies face limitations hindering them from fully meeting future energy storage needs such as large storage capacity in limited space frequent storage with rapid response and continuous storage without loss. Batteries with their rapid response (90%) excel in frequent short-duration energy storage. However limitations such as a selfdischarge rate (>1%) and capacity loss (~20%) restrict their use for long-duration energy storage. Hydrogen as a potential energy carrier is suitable for large-scale long-duration energy storage due to its high energy density steady state and low loss. Nevertheless it is less efficient for frequent energy storage due to its low storage efficiency (~50%). Ongoing research suggests that a battery and hydrogen hybrid energy storage system could combine the strengths of both technologies to meet the growing demand for large-scale long-duration energy storage. To assess their applied potentials this paper provides a detailed analysis of the research status of both energy storage technologies using proposed key performance indices. Additionally application-oriented future directions and challenges of the battery and hydrogen hybrid energy storage system are outlined from multiple perspectives offering guidance for the development of advanced energy storage systems.
A Review on Production and Implementation of Hydrogen as a Green Fuel in Internal Combustion Engines
Nov 2022
Publication
Huge and continuously growing non-renewable energy consumption due to human daily activities is accountable for the fossil fuel source crisis in recent decades. The growing concern about the emissions from internal combustion engines also impels the development of new energy sources to replace or reduce conventional non-renewable energy usage. In this context hydrogen is found to be a promising solution in internal combustion engines to address these issues. The novelty of this review is to provide an overview of the use of hydrogen as internal combustion fuel covering the operations in both spark-ignition (SI) and compression-ignition (CI) engines. Majority of the studies had shown that hydrogen enrichment fuels marked incredible engine performance in terms of thermal efficiency fuel consumption and energy consumption. In addition reductions in exhaust emissions such as smoke soot HC CO CO2 and NOx can be achieved in both SI and CI engines with proper operating conditions. Moreover outstanding combustion behaviours were observed in both internal combustion engines with the application of hydrogen fuel. These enhancements were mainly attributed to the physico-chemical properties of hydrogen which exhibits higher calorific value and rapid flaming speed as discussed in this paper. To summarize hydrogen utilisation in the IC and SI engines aided improvements in engine performance exhaust emissions and combustion behaviours under appropriate operating conditions and minor engine modifications such as ignition system and iridium spark plug for SI engines.
Lab-Scale Investigation of the Integrated Backup/Storage System for Wind Turbines Using Alkaline Electrolyzer
Apr 2023
Publication
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.
Enhancing Safety through Optimal Placement of Components in Hydrogen Tractor: Rollover Angle Analysis
Feb 2024
Publication
Hydrogen tractors are being developed necessitating consideration of the variation in the center of gravity depending on the arrangement of components such as power packs and cooling modules that replace traditional engines. This study analyzes the effects of component arrangement on stability and rollover angle in hydrogen tractors through simulations and proposes an optimal configuration. Stability is evaluated by analyzing rollover angles in various directions with rotations around the tractor’s midpoint. Based on the analysis of rollover angles for Type 1 Type 2 and Type 3 hydrogen tractors Type 2 demonstrates superior stability compared to the other types. Specifically when comparing lateral rollover angles at 0◦ rotation Type 2 exhibits a 2% increase over Type 3. Upon rotations at 90◦ and 180◦ Type 2 consistently displays the highest rollover angles with differences ranging from approximately 6% to 12% compared to the other types. These results indicate that Type 2 with its specific component arrangement offers the most stable configuration among the three types of tractors. It is confirmed that the rollover angle changes based on component arrangement with a lower center of gravity resulting in greater stability. These findings serve as a crucial foundation for enhancing stability in the future design and manufacturing phases of hydrogen tractors.
Knock Mitigation and Power Enhancement of Hydrogen Spark-Ignition Engine through Ammonia Blending
Jun 2023
Publication
Hydrogen and ammonia are primary carbon-free fuels that have massive production potential. In regard to their flame properties these two fuels largely represent the two extremes among all fuels. The extremely fast flame speed of hydrogen can lead to an easy deflagration-to-detonation transition and cause detonation-type engine knock that limits the global equivalence ratio and consequently the engine power. The very low flame speed and reactivity of ammonia can lead to a low heat release rate and cause difficulty in ignition and ammonia slip. Adding ammonia into hydrogen can effectively modulate flame speed and hence the heat release rate which in turn mitigates engine knock and retains the zero-carbon nature of the system. However a key issue that remains unclear is the blending ratio of NH3 that provides the desired heat release rate emission level and engine power. In the present work a 3D computational combustion study is conducted to search for the optimal hydrogen/ammonia mixture that is knock-free and meanwhile allows sufficient power in a typical spark-ignition engine configuration. Parametric studies with varying global equivalence ratios and hydrogen/ammonia blends are conducted. The results show that with added ammonia engine knock can be avoided even under stoichiometric operating conditions. Due to the increased global equivalence ratio and added ammonia the energy content of trapped charge as well as work output per cycle is increased. About 90% of the work output of a pure gasoline engine under the same conditions can be reached by hydrogen/ammonia blends. The work shows great potential of blended fuel or hydrogen/ammonia dual fuel in high-speed SI engines.
Low Carbon Optimal Operation of Integrated Energy Systems Considering Air Pollution Emissions
Apr 2023
Publication
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.
Ammonia as Green Fuel in Internal Combustion Engines: State-of-the-Art and Future Perspectives
Jul 2022
Publication
Ammonia (NH3) is among the largest-volume chemicals produced and distributed in the world and is mainly known for its use as a fertilizer in the agricultural sector. In recent years it has sparked interest in the possibility of working as a high-quality energy carrier and as a carbon-free fuel in internal combustion engines (ICEs). This review aimed to provide an overview of the research on the use of green ammonia as an alternative fuel for ICEs with a look to the future on possible applications and practical solutions to related problems. First of all the ammonia production process is discussed. Present ammonia production is not a “green” process; the synthesis occurs starting from gaseous hydrogen currently produced from hydrocarbons. Some ways to produce green ammonia are reviewed and discussed. Then the chemical and physical properties of ammonia as a fuel are described and explained in order to identify the main pros and cons of its use in combustion systems. Then the most viable solutions for fueling internal combustion engines with ammonia are discussed. When using pure ammonia high boost pressure and compression ratio are required to compensate for the low ammonia flame speed. In spark-ignition engines adding hydrogen to ammonia helps in speeding up the flame front propagation and stabilizing the combustion. In compression-ignition engines ammonia can be successfully used in dual-fuel mode with diesel. On the contrary an increase in NOx and the unburned NH3 at the exhaust require the installation of apposite aftertreatment systems. Therefore the use of ammonia seems to be more practicable for marine or stationary engine application where space constraints are not a problem. In conclusion this review points out that ammonia has excellent potential to play a significant role as a sustainable fuel for the future in both retrofitted and new engines. However significant further research and development activities are required before being able to consider large-scale industrial production of green ammonia. Moreover uncertainties remain about ammonia safe and effective use and some technical issues need to be addressed to overcome poor combustion properties for utilization as a direct substitute for standard fuels.
Thermal Design of a System for Mobile Powersupply
Sep 2023
Publication
Ever more stringent emission regulations for vehicles encourage increasing numbers of battery electric vehicles on the roads. A drawback of storing electric energy in a battery is the comparable low energy density low driving range and the higher propensity to deplete the energy storage before reaching the destination especially at low ambient temperatures. When the battery is depleted stranded vehicles can either be towed or recharged with a mobile recharging station. Several technologies of mobile recharging stations already exist however most of them use fossil fuels to recharge battery electric vehicles. The proposed novel zero emission solution for mobile charging is a combined high voltage battery and hydrogen fuel cell charging station. Due to the thermal characteristics of the fuel cell and high voltage battery (which allow only comparable low coolant temperatures) the thermal design for this specific application (available heat exchanger area zero vehicle speed air flow direction) becomes challenging and is addressed in this work. Experimental methods were used to obtain reliable thermal and electric power measurement data of a 30 kW fuel cell system which is used in the Mobile Hydrogen Powersupply. Subsequently simulation methods were applied for the thermal design and optimisation of the coolant circuits and heat exchangers. It is shown that an battery electric vehicle charging power of 22 kW requires a heat exchanger area of 1 m2 of which 60 % is used by the fuel cell heat exchanger and the remainder by the battery heat exchanger to achieve steady state operation at the highest possible ambient temperature of 436 °C. Furthermore the simulation showed that when the charging power of 22 kW is solely provided by the high voltage battery the highest possible ambient temperature is 42 °C. When the charging power is decreased operation up to the maximum ambient temperatures of 45 °C can be achieved. The results of maximum charging power and limiting ambient temperature give insights for further system improvements which are: sizing of fuel cell or battery trailer design and heat exchanger area operation strategy of the system (power split between high voltage battery and fuel cell) as well as possible dynamic operation scenarios.
Operating Characteristics Analysis and Capacity Configuration Optimization of Wind-Solar-Hydrogen Hybrid Multi-energy Complementary System
Dec 2023
Publication
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.
Optimized Scheduling of Integrated Energy Systems Accounting for Hydrogen Energy Multi-Utilization Models
Jan 2024
Publication
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.
Modelling Methodologies to Design and Control Renewables and Hydrogen-Based Telecom Towers Power Supply Systems
Aug 2023
Publication
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.
Numerical Modelling of Hydrogen Release and Dispersion in Under-deck Compressed Hydrogen Storage of Marine Ships
Feb 2024
Publication
There is growing interest in using hydrogen (H2) as a marine fuel. Fire and explosion risks depend on hydrogen release and dispersion characteristics. Based on a validated Computational Fluid Dynamics (CFD) model this study performed hydrogen release and dispersion analysis on an under-deck compressed H2 storage system for a Live-Fish Carrier. A realistic under-deck H2 storage room was modelled based on the ship’s main dimensions and operational profile. Det Norske Veritas (DNV) Rules and Regulations for natural gas storage as a marine fuel were employed as base design guidelines. Case studies were developed to study the effect of two ceiling types (flat and slanted) in terms of flammable cloud formation and dissipation. During the leak’s duration it was found that the recommended ventilation rate was insufficient to dilute the average H2 concentration below 25% of the flammable range as required by DNV (1.2% required against 1.3% slanted and 1.4% flat). However after 35 s of gas extraction the H2 concentration was reduced to 0.5% and 0.6% in the slanted and flat cases respectively. The proposed methodology remains valid to improve the ventilation system and assess mitigation alternatives or other leakage scenarios in confined or semi-confined spaces containing compressed hydrogen gas.
Development of Electric Power Generator by Using Hydrogen
Nov 2023
Publication
In this research we developed a hydrogen (H2 ) electric generator in an H2 generation system based on chemical reactions. In the experiment we tested the performance of the H2 electric generator and measured the amount of H2 generated. The maximum output was 700 W and the thermal efficiency was 18.2%. The theoretical value and measured value were almost the same and the maximum error was 4%.
Utilization of Hydrogen in Gas Turbines: A Comprehensive Review
Feb 2022
Publication
The concerns regarding the consumption of traditional fuels such as oil and coal have driven the proposals for several cleaner alternatives in recent years. Hydrogen energy is one of the most attractive alternatives for the currently used fossil fuels with several superiorities such as zero-emission and high energy content. Hydrogen has numerous advantages compared to conventional fuels and as such has been employed in gas turbines (GTs) in recent years. The main benefit of using hydrogen in power generation with the GT is the considerably lower emission of greenhouse gases. The performance of the GTs using hydrogen as a fuel is influenced by several factors including the performance of the components the operating condition ambient condition etc. These factors have been investigated by several scholars and scientists in this field. In this article studies on hydrogen-fired GTs are reviewed and their results are discussed. Furthermore some recommendations are proposed for the upcoming works in this field.
Batteries or Hydrogen or Both for Grid Electricity Storage Upon Full Electrification of 145 Countries with Wind-Water-Solar?
Jan 2024
Publication
Grids require electricity storage. Two emerging storage technologies are battery storage (BS) and green hydrogen storage (GHS) (hydrogen produced and compressed with clean-renewable electricity stored then returned to electricity with a fuel cell). An important question is whether GHS alone decreases system cost versus BS alone or BS+GHS. Here energy costs are modeled in 145 countries grouped into 24 regions. Existing conventional hydropower (CH) storage is used along with new BS and/or GHS. A method is developed to treat CH for both baseload and peaking power. In four regions only CH is needed. In five CH+BS is lowest cost. Otherwise CH+BS+GHS is lowest cost. CH+GHS is never lowest cost. A metric helps estimate whether combining GHS with BS reduces cost. In most regions merging (versus separating) grid and non-grid hydrogen infrastructure reduces cost. In sum worldwide grid stability may be possible with CH+BS or CH+BS+GHS. Results are subject to uncertainties.
Prospects and Impediments for Hydrogen Fuel Cell Buses
Jun 2021
Publication
The number of demonstration projects with fuel cell buses has been increasing worldwide. The goal of this paper is to analyse prospects and barriers for fuel cell buses focusing on their economic- technical- and environmental performance. Our results show that the prices of fuel cell buses although decreasing over time are still about 40% higher than those of diesel buses. With the looming ban of diesel vehicles and current limitations of battery electric vehicles fuel cell buses could become a viable alternative in the mid-to long-term. With the requirements for a better integration of renewable energy sources in the transport system interest in hydrogen is rising. Hydrogen produced from renewables used in fuel cell buses has the potential to save about 93% of CO2 emissions in comparison to diesel buses. Yet from environmental point-of-view it has to be ensured that hydrogen is produced from renewables. Currently the major barrier for a faster penetration of fuel cell buses are their high purchase prices which could be significantly reduced with the increasing number of buses through technological learning. The final conclusion is that a tougher transport policy framework is needed which fully reflects the environmental impact of different buses used.
Performance, Emissions, and Combustion Characteristics of a Hydrogen-Fueled Spark-Ignited Engine at Different Compression Ratios: Experimental and Numerical Investigation
Jul 2023
Publication
This paper investigates the performance of hydrogen-fueled spark-ignited single-cylinder Cooperative Fuel Research using experimental and numerical approaches. This study examines the effect of the air–fuel ratio on engine performance emissions and knock behaviour across different compression ratios. The results indicate that λ significantly affects both engine performance and emissions with a λ value of 2 yielding the highest efficiency and lowest emissions for all the tested compression ratios. Combustion analysis reveals normal combustion at λ ≥ 2 while knocking combustion occurs at λ < 2 irrespective of the tested compression ratios. The Livenwood–Wu integral approach was evaluated to assess the likelihood of end-gas autoignition based on fuel reactivity demonstrating that both normal and knocking combustion possibilities are consistent with experimental investigations. Combustion analysis at the ignition timing for maximum brake torque conditions demonstrates knock-free stable combustion up to λ = 3 with increased end-gas autoignition at lower λ values. To achieve knock-free combustion at those low λs the spark timings are significantly retarded to after top dead center crank angle position. Engine-out NOx emissions consistently increase in trend with a decrease in the air–fuel ratio of up to λ = 3 after which a distinct variation in NOx is observed with an increase in the compression ratio.
Experimental Comparison of Hydrogen Refueling with Directly Pressurized vs. Cascade Method
Aug 2023
Publication
This paper presents a comparative analysis of two hydrogen station configurations during the refueling process: the conventional “directly pressurized refueling process” and the innovative “cascade refueling process.” The objective of the cascade process is to refuel vehicles without the need for booster compressors. The experiments were conducted at the Hydrogen Research and Fueling Facility located at California State University Los Angeles. In the cascade refueling process the facility buffer tanks were utilized as high-pressure storage enabling the refueling operation. Three different scenarios were tested: one involving the cascade refueling process and two involving compressor-driven refueling processes. On average each refueling event delivered 1.6 kg of hydrogen. Although the cascade refueling process using the high-pressure buffer tanks did not achieve the pressure target it resulted in a notable improvement in the nozzle outlet temperature trend reducing it by approximately 8 ◦C. Moreover the overall hydrogen chiller load for the two directly pressurized refuelings was 66 Wh/kg and 62 Wh/kg respectively whereas the cascading process only required 55 Wh/kg. This represents a 20% and 12% reduction in energy consumption compared to the scenarios involving booster compressors during fueling. The observed refueling range of 150–350 bar showed that the cascade process consistently required 12–20% less energy for hydrogen chilling. Additionally the nozzle outlet temperature demonstrated an approximate 8 ◦C improvement within this pressure range. These findings indicate that further improvements can be expected in the high-pressure region specifically above 350 bar. This research suggests the potential for significant improvements in the high-pressure range emphasizing the viability of the cascade refueling process as a promising alternative to the direct compression approach.
Technoeconomic, Environmental and Multi-criteria Decision Making Investigations for Optimisation of Off-grid Hybrid Renewable Energy System with Green Hydrogen Production
Jan 2024
Publication
The current study presents a comprehensive investigation of different energy system configurations for a remote village community in India with entirely renewable electricity. Excess electricity generated by the systems has been stored using two types of energy storage options: lithium-ion batteries and green hydrogen production through the electrolysers. The hybrid renewable energy system (HRES) configurations have been sized by minimising the levelised cost of energy (LCOE). In order to identify the best-performing HRES configuration economic and environmental performance indicators has been analysed using the multi-criteria decision-making method (MCDM) TOPSIS. Among the evaluated system configurations system-1 with a photovoltaic panel (PV) size of 310.24 kW a wind turbine (WT) size of 690 kW a biogas generator (BG) size of 100 kW a battery (BAT) size of 174 kWh an electrolyser (ELEC) size of 150 kW a hydrogen tank (HT) size of 120 kg and a converter (CONV) size of 106.24 kW has been found to be the best-performing system since it provides the highest relative closeness (RC) value (∼0.817) and also has the lowest fuel consumption rate of 2.31 kg/kWh. However system-6 shows the highest amount of CO2 (143.97 kg/year) among all the studied system configurations. Furthermore a detailed technical economic and environmental analysis has been conducted on the optimal HRES configuration. The minimum net present cost (NPC) LCOE and cost of hydrogen (COH) for system 1 has been estimated to be $1960584 $0.44/kWh and $22.3/kg respectively.
Design of a Hydrogen Aircraft for Zero Persistent Contrails
Jul 2023
Publication
Contrails are responsible for a significant proportion of aviation’s climate impact. This paper uses data from the European Centre for Medium-Range Weather Forecasts to identify the altitudes and latitudes where formed contrails will not persist. This reveals that long-lived contrails may be prevented by flying lower in equatorial regions and higher in non-equatorial regions. Subsequently it is found that the lighter fuel and reduced seating capacity of hydrogen-powered aircraft lead to a reduced aircraft weight which increases the optimal operating altitude by about 2 km. In non-equatorial regions this would lift the aircraft’s cruise point into the region where long-lived contrails do not persist unlocking hydrogen-powered low-contrails operation. The baseline aircraft considered is an A320 retrofitted with in-fuselage hydrogen tanks. The impacts of the higher-altitude cruise on fuel burn and the benefits unlocked by optimizing the wing geometry for this altitude are estimated using a drag model based on theory proposed by Cavcar Lock and Mason and verified against existing aircraft. The weight penalty associated with optimizing wing geometry for this altitude is estimated using Torenbeek’s correlation. It is found that thinner wings with higher aspect ratios are particularly suited to this high-altitude operation and are enabled by the relaxation of the requirement to store fuel in the wings. An example aircraft design for the non-equatorial region is provided which cruises at a 14 km altitude at Mach 0.75 with a less than 1% average probability of generating long-lived contrails when operating at latitudes more than 35◦ from the equator. Compared to the A320 this concept design is estimated to have a 20% greater cruise lift–drag ratio due to the 33% thinner wings with a 50% larger aspect ratio enabling just 5% more energy use per passenger-km despite fitting 40% fewer seats.
Factors Driving the Decarbonisation of Industrial Clusters: A Rapid Evidence Assessment of International Experience
Sep 2023
Publication
Reducing industrial emissions to achieve net-zero targets by the middle of the century will require profound and sustained changes to how energy intensive industries operate. Preliminary activity is now underway with governments of several developed economies starting to implement policy and providing funding to support the deployment of low carbon infrastructure into high emitting industrial clusters. While clusters appear to offer the economies of scale and institutional capacity needed to kick-start the industrial transition to date there has been little systematic assessment of the factors that may influence the success of these initiatives. Drawing from academic and grey literature this paper presents a rapid evidence assessment of the approaches being used to drive the development of low carbon industrial clusters internationally. Many projects are still at the scoping stage but it is apparent that current initiatives focus on the deployment of carbon capture technologies alongside hydrogen as a future secondary revenue stream. This model of decarbonisation funnels investment into large coastal clusters with access to low carbon electricity and tends to obscure questions about the integration of these technologies with other decarbonisation interventions such as material efficiency and electrification. The technology focus also omits the importance that a favourable location and shared history and culture appears to have played in helping progress the most advanced initiatives; factors that cannot be easily replicated elsewhere. If clusters are to kick-start the low-carbon industrial transition then greater attention is needed to the social and political dimensions of this process and to a broader range of decarbonisation interventions and cluster types than represented by current projects.
Toward Green Steel: Modelling and Environmental Economic Analysis of Iron Direct Reduction with Different Reducing Gases
Sep 2023
Publication
The objective of the paper is to simulate the whole steelmaking process cycle based on Direct Reduced Iron and Electric Arc Furnace technologies by modeling for the first time the reduction furnace based on kinetic approach to be used as a basis for the environmental and techno-economic plant analysis by adopting different reducing gases. In addition the impact of carbon capture section is discussed. A complete profitability analysis has been conducted for the first time adopting a Monte Carlo simulation approach.<br/>In detail the use of syngas from methane reforming syngas and hydrogen from gasification of municipal solid waste and green hydrogen from water electrolysis are analyzed. The results show that the Direct Reduced Iron process with methane can reduce CO2 emissions by more than half compared to the blast furnace based-cycle and with the adoption of carbon capture greenhouse gas emissions can be reduced by an additional 40%. The use of carbon capture by amine scrubbing has a limited economic disadvantage compared to the scenario without it becoming profitable once carbon tax is included in the analysis. However it is with the use of green hydrogen from electrolyzer that greenhouse gas emissions can be cut down almost completely. To have an environmental benefit compared with the methane-based Direct Reduced Iron process the green hydrogen plant must operate for at least 5136 h per year (64.2% of the plant's annual operating hours) on renewable energy.<br/>In addition the use of syngas and separated hydrogen from municipal solid waste gasification is evaluated demonstrating its possible use with no negative effects on the quality of produced steel. The results show that hydrogen use from waste gasification is more economic with respect to green hydrogen from electrolysis but from the environmental viewpoint the latter results the best alternative. Comparing the use of hydrogen and syngas from waste gasification it can be stated that the use of the former reducing gas results preferable from both the economic and environmental viewpoint.
Identification of Hydrogen-Energy-Related Emerging Technologies Based on Text Mining
Dec 2023
Publication
As a versatile energy carrier hydrogen possesses tremendous potential to reduce greenhouse emissions and promote energy transition. Global interest in producing hydrogen from renewable energy sources and transporting storing and utilizing hydrogen is rising rapidly. However the high costs of producing clean hydrogen and the uncertain application scenarios for hydrogen energy result in its relatively limited utilization worldwide. It is necessary to find new promising technological paths to drive the development of hydrogen energy. As part of technological innovation emerging technologies have vital features such as prominent impact novelty relatively fast growth etc. Identifying emerging hydrogen-energy-related technologies is important for discovering innovation opportunities during the energy transition. Existing research lacks analysis of the characteristics of emerging technologies. Thus this paper proposes a method combining the latent Dirichlet allocation topic model and hydrogen-energy expert group decision-making. This is used to identify emerging hydrogen-related technology regarding two features of emerging technologies novelty and prominent impact. After data processing topic modeling and analysis the patent dataset was divided into twenty topics. Six emerging topics possess novelty and prominent impact among twenty topics. The results show that the current hotspots aim to promote the application of hydrogen energy by improving the performance of production catalysts overcoming the wide power fluctuations and large-scale instability of renewable energy power generation and developing advanced hydrogen safety technologies. This method efficiently identifies emerging technologies from patents and studies their development trends. It fills a gap in the research on emerging technologies in hydrogen-related energy. Research achievements could support the selection of technology pathways during the low-carbon energy transition.
A Comprehensive Review on Condition Monitoring and Fault Diagnosis in Fuel Cell Systems: Challenges and Issues
Jan 2024
Publication
The complexity of Fuel Cell (FC) systems demands a profound and sustained understanding of the various phenomena occurring inside of it. Thus far FCs especially Proton Exchange Membrane Fuel Cells (PEMFCs) have been recognized as being among the most promising technologies for reducing Green House Gas (GHG) emissions because they can convert the chemical energy bonded to hydrogen and oxygen into electricity and heat. However their efficiency remains limited. To enhance their efficiency two distinct factors are suggested. First the quality of materials plays a significant role in the development of more robust and efficient FCs. Second the ability to identify mitigate and reduce the occurrence of faults through the use of robust control algorithms is crucial. Therefore more focused on the second point this paper compiles distinguishes and analyzes several publications from the past 25 years related to faults and their diagnostic techniques in FCs. Furthermore the paper presents various schemes outlining different symptoms their causes and corresponding fault algorithms.
A Complete Assessment of the Emission Performance of an SI Engine Fueled with Methanol, Methane and Hydrogen
Feb 2024
Publication
This study explores the potentiality of low/zero carbon fuels such as methanol methane and hydrogen for motor applications to pursue the goal of energy security and environmental sustainability. An experimental investigation was performed on a spark ignition engine equipped with both a port fuel and a direct injection system. Liquid fuels were injected into the intake manifold to benefit from a homogeneous charge formation. Gaseous fuels were injected in direct mode to enhance the efficiency and prevent abnormal combustion. Tests were realized at a fixed indicated mean effective pressure and at three different engine speeds. The experimental results highlighted the reduction of CO and CO2 emissions for the alternative fuels to an extent depending on their properties. Methanol exhibited high THC and low NOx emissions compared to gasoline. Methane and even more so hydrogen allowed for a reduction in THC emissions. With regard to the impact of gaseous fuels on the NOx emissions this was strongly related to the operating conditions. A surprising result concerns the particle emissions that were affected not only by the fuel characteristics and the engine test point but also by the lubricating oil. The oil contribution was particularly evident for hydrogen fuel which showed high particle emissions although they did not contain carbon atoms.
Role of a Unitized Regenerative Fuel Cell in Remote Area Power Supply: A Review
Aug 2023
Publication
This manuscript presents a thorough review of unitized regenerative fuel cells (URFCs) and their importance in Remote Area Power Supply (RAPS). In RAPS systems that utilize solar and hydrogen power which typically include photovoltaic modules a proton exchange membrane (PEM) electrolyzer hydrogen gas storage and PEM fuel cells the cost of these systems is currently higher compared to conventional RAPS systems that employ diesel generators or batteries. URFCs offer a potential solution to reduce the expenses of solar hydrogen renewable energy systems in RAPS by combining the functionalities of the electrolyzer and fuel cell into a single unit thereby eliminating the need to purchase separate and costly electrolyzer and fuel cell units. URFCs are particularly well-suited for RAPS applications because the electrolyzer and fuel cell do not need to operate simultaneously. In electrolyzer mode URFCs function similarly to stand-alone electrolyzers. However in fuel cell mode the performance of URFCs is inferior to that of stand-alone fuel cells. The presented review summarizes the past present and future of URFCs with details on the operating modes of URFCs limitations and technical challenges and applications. Solar hydrogen renewable energy applications in RAPS and challenges facing solar hydrogen renewable energy in the RAPS is discussed in detail.
A New Generation of Hydrogen-Fueled Hybrid Propulsion Systems for the Urban Mobility of the Future
Dec 2023
Publication
The H2-ICE project aims at developing through numerical simulation a new generation of hybrid powertrains featuring a hydrogen-fueled Internal Combustion Engine (ICE) suitable for 12 m urban buses in order to provide a reliable and cost-effective solution for the abatement of both CO2 and criteria pollutant emissions. The full exploitation of the potential of such a traction system requires a substantial enhancement of the state of the art since several issues have to be addressed. In particular the choice of a more suitable fuel injection system and the control of the combustion process are extremely challenging. Firstly a high-fidelity 3D-CFD model will be exploited to analyze the in-cylinder H2 fuel injection through supersonic flows. Then after the optimization of the injection and combustion process a 1D model of the whole engine system will be built and calibrated allowing the identification of a “sweet spot” in the ultra-lean combustion region characterized by extremely low NOx emissions and at the same time high combustion efficiencies. Moreover to further enhance the engine efficiency well above 40% different Waste Heat Recovery (WHR) systems will be carefully scrutinized including both Organic Rankine Cycle (ORC)-based recovery units as well as electric turbo-compounding. A Selective Catalytic Reduction (SCR) aftertreatment system will be developed to further reduce NOx emissions to near-zero levels. Finally a dedicated torque-based control strategy for the ICE coupled with the Energy Management Systems (EMSs) of the hybrid powertrain both optimized by exploiting Vehicle-To-Everything (V2X) connection allows targeting H2 consumption of 0.1 kg/km. Technologies developed in the H2-ICE project will enhance the know-how necessary to design and build engines and aftertreatment systems for the efficient exploitation of H2 as a fuel as well as for their integration into hybrid powertrains.
The Role of Hydrogen Storage in an Electricity System with Large Hydropower Resources
Feb 2024
Publication
Hydrogen is considered one of the key pillars of an effective decarbonization strategy of the energy sector; however the potential of hydrogen as an electricity storage medium is debated. This paper investigates the role of hydrogen as an electricity storage medium in an electricity system with large hydropower resources focusing on the Swiss electricity sector. Several techno-economic and climate scenarios are considered. Findings suggest that hydrogen storage plays no major role under most conditions because of the large hydropower resources. More specifically no hydrogen storage is installed in Switzerland if today’s values of net-transfer capacities and low load-shedding costs are assumed. This applies even to hydrogen-favorable climate scenarios (dry years with low precipitation and dam inflows) and economic assumptions (high learning rates for hydrogen technologies). In contrast hydrogen storage is installed when net-transfer capacities between countries are reduced below 30% of current values and load-shedding costs are above 1000 EUR/MWh. When installed hydrogen is deployed in a few large-scale installations near the national borders.
Optimal Scheduling of an Electric-Hydrogen-Integrated Energy System Considering Virtual Energy Storage
Jan 2024
Publication
In this paper a two-layer optimization approach is proposed to facilitate the multi-energy complementarity and coupling and optimize the system configuration in an electric-hydrogen-integrated energy system (EH-IES). Firstly an EH-IES with virtual energy storage is proposed to reduce the cost of physical energy storage equipment. Secondly a two-layer optimal allocation method is proposed under a multi-timescale strategy to examine the comprehensive evaluation index of environmental protection and economy. The upper layer utilizes the NSGA-II multi-objective optimization method for system capacity allocation while the lower layer performs economic dispatch at the lowest cost. Ultimately the output includes the results of the equipment capacity allocation of the EH-IES that satisfies the reliability constraint interval and the daily scheduling results of the equipment. The results demonstrate that the electric-hydrogen-integrated energy system with the coupling of multiple energy equipment not only enhances the utilization of renewable energy sources but also reduces the usage of fossil energy and improves the system’s reliability.
Applying a 2 kW Polymer Membrane Fuel-Cell Stack to Building Hybrid Power Sources for Unmanned Ground Vehicles
Nov 2023
Publication
The novel constructions of hybrid energy sources using polymer electrolyte fuel cells (PEMFCs) and supercapacitors are developed. Studies on the energy demand and peak electrical power of unmanned ground vehicles (UGVs) weighing up to 100 kg were conducted under various conditions. It was found that the average electrical power required does not exceed ~2 kW under all conditions studied. However under the dynamic electrical load of the electric drive of mobile robots the short peak power exceeded 2 kW and the highest current load was in the range of 80–90 A. The electrical performance of a family of PEMFC stacks built in open-cathode mode was determined. A hydrogen-usage control strategy for power generation cleaning processes and humidification was analysed. The integration of a PEMFC stack with a bank of supercapacitors makes it possible to mitigate the voltage dips. These occur periodically at short time intervals as a result of short-circuit operation. In the second construction the recovery of electrical energy dissipated by a short-circuit unit (SCU) was also demonstrated in the integrated PEMFC stack and supercapacitor bank system. The concept of an energy-efficient mobile and environmentally friendly hydrogen charging unit has been proposed. It comprises (i) a hydrogen anion exchange membrane electrolyser (ii) a photovoltaic installation (iii) a battery storage (iv) a hydrogen buffer storage in a buffer tank (v) a hydrogen compression unit and (vi) composite tanks.
Eco-Sustainable Energy Production in Healthcare: Trends and Challenges in Renewable Energy Systems
Oct 2023
Publication
The shift from fossil fuels to renewable energy systems represents a pivotal step toward the realization of a sustainable society. This study aims to analyze representative scientific literature on eco-sustainable energy production in the healthcare sector particularly in hospitals. Given hospitals’ substantial electricity consumption the adoption of renewable energy offers a reliable low-CO2 emission solution. The COVID-19 pandemic has underscored the urgency for energyefficient and environmentally-responsible approaches. This brief review analyzes the development of experimental simulation and optimization projects for sustainable energy production in healthcare facilities. The analysis reveals trends and challenges in renewable energy systems offering valuable insights into the potential of eco-sustainable solutions in the healthcare sector. The findings indicate that hydrogen storage systems are consistently coupled with photovoltaic panels or solar collectors but only 14% of the analyzed studies explore this potential within hospital settings. Hybrid renewable energy systems (HRES) could be used to meet the energy demands of healthcare centers and hospitals. However the integration of HRES in hospitals and medical buildings is understudied.
Current Status and Economic Analysis of Green Hydrogen Energy Industry Chain
Feb 2024
Publication
Under the background of the power system profoundly reforming hydrogen energy from renewable energy as an important carrier for constructing a clean low-carbon safe and efficient energy system is a necessary way to realize the objectives of carbon peaking and carbon neutrality. As a strategic energy source hydrogen plays a significant role in accelerating the clean energy transition and promoting renewable energy. However the cost and technology are the two main constraints to green hydrogen energy development. Herein the technological development status and economy of the whole industrial chain for green hydrogen energy “production-storage-transportation-use” are discussed and reviewed. After analysis the electricity price and equipment cost are key factors to limiting the development of alkaline and proton exchange membrane hydrogen production technology; the quantity scale and distance of transportation are key to controlling the costs of hydrogen storage and transportation. The application of hydrogen energy is mainly concentrated in the traditional industries. With the gradual upgrading and progress of the top-level design and technology the application of hydrogen energy mainly including traffic transportation industrial engineering energy storage power to gas and microgrid will show a diversified development trend. And the bottleneck problems and development trends of the hydrogen energy industry chain are also summarized and viewed.
Techno-economic Analysis and Predictive Operation of a Power-to-hydrogen for Renewable Microgrids
Oct 2023
Publication
To enhance renewable energy (RE) generation and maintain power balance energy storage systems are of utmost importance. This research introduces a cutting-edge Power-to-Hydrogen (PtH) framework that harnesses hydrogen as a clean and versatile energy storage medium. The primary focus of this study lies in optimizing power flow within a microgrid (G) equipped with RE and energy storage systems considering various factors such as RE generation power demand battery charge cycles and operational costs. To achieve the optimal balance between power generation and consumption a sophisticated mathematical solution is devised. This solution governs the charging and discharging patterns for both battery and electrolyzer ensuring a harmonious power equilibrium. The use of short-term forecasting further refines the optimization process adapting the parameters based on anticipated RE sources and load requirements. To fine-tune the power management solution for day-to-day operations an artificial neural fuzzy inference system (ANFIS)-based shortterm prediction model is employed. The predictive analysis provides confidence intervals for crucial aspects including power generation demand battery charging cycles and hydrogen generation. This facilitates precise cost estimation across various hydrogen and heat price ranges. the proposed PtH optimization framework offers an efficient approach to balance power generation and consumption in Gs driven by RE sources and energy storage. To validate the proposed approach numerical simulations are performed based on data from wind and solar farms load requirements and cost of energy. The results show that the proposed energy management strategy significantly reduces operational costs and optimizes PtH generation while maintaining power balance within the microgrid (G). The predictive approach helps fine-tune the optimization process improving efficiency and cost-effectiveness. The research convincingly demonstrate the economic advantages of adopting hydrogen as an energy storage medium paving the way for a cleaner and more sustainable energy future.
Three-Stage Modeling Framework for Analyzing Islanding Capabilities of Decarbonized Energy Communities
May 2023
Publication
Contrary to microgrids (MGs) for which grid code or legislative support are lacking in the majority of cases energy communities (ECs) are one of the cornerstones of the energy transition backed up by the EU’s regulatory framework. The main difference is that unlike MGs ECs grow and develop organically through citizen involvement and investments in the existing low-voltage (LV) distribution networks. They are not planned and built from scratch as closed distribution systems that are independent of distribution system operator plans as assumed in the existing literature. An additional benefit of ECs could be the ability to transition into island mode contributing to the resilience of power networks. To this end this paper proposes a three-stage framework for analyzing the islanding capabilities of ECs. The framework is utilized to comprehensively assess and compare the islanding capabilities of ECs whose organic development is based upon three potential energy vectors: electricity gas and hydrogen. Detailed dynamic simulations clearly show that only fully electrified ECs inherently have adequate islanding capabilities without the need for curtailment or additional investments.
On the Green Transformation of the Iron and Steel Industry: Market and Competition Aspects of Hydrogen Biomass Options
Feb 2024
Publication
The iron and steel industry is a major emitter of carbon dioxide globally. To reduce their carbon footprint the iron and steel industry pursue different decarbonization strategies including deploying bio-based materials and energy carriers for reduction carburisation and/or energy purposes along their value-chains. In this study two potential roles for biomass were analysed: (a) substituting for fossil fuels in iron-ore pellets induration and (b) carburisation of DRI (direct reduced iron) produced via fully hydrogen-based reduction. The purpose of the study was to analyse the regional demand-driven price and allocative effects of biomass assortments under different biomass demand scenarios for the Swedish iron and steel industry. Economic modelling was used in combination with spatial biomass supply assessments to predict the changes on relevant biomass markets. The results showed that the estimated demand increases for forest biomass will have significant regional price effects. Depending on scenario the biomass demand will increase up to 25 percent causing regional prices to more than doubling. In general the magnitude of the price effects was driven by the volumes and types of biomasses needed in the different scenarios with larger price effects for harvesting residues and industrial by-products compared to those of roundwood. A small price effect of roundwood means that the incentives for forest-owners to increase their harvests and thus also the availability of harvest residues are small. Flexibility in the feedstock sourcing (both regarding quality and geographic origin) will thus be important if forest biomass is to satisfy demands in iron and steel industry.
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