Applications & Pathways

In order to improve the energy efficiency of the internal combustion engine and replace fossil fuel with alternative fuels a concept of the methanol-syngas engine was proposed and the prototype was developed. Gasoline and dissociated methanol gas (GDM) were used as dual fuels and the engine performance was investigated by simulation and experiments. Dissociated methanol gas is produced by recycling the exhaust heat. The performance and combustion process was studied and compared with the gasoline engine counterpart. There is 1.9% energy efficiency improvement and 5.5% fuel consumption reduction under 2000r/min 100 N · m working condition with methanol substitution ratio of 10%. In addition the engine efficiency further improves with an increase of dissociated methanol gas substitution ratio because of the increased heating value of the fuel and effects of hydrogen. The peak pressure in the cylinder and the peak heat release rate of the GDM engine are higher than that of the original gasoline engine with a phase closer to the top dead center (TDC). Therefore blending hydrogen-rich gas in the spark-ignition engine can recycle the exhaust heat and improve the thermal efficiency of the engine.

Missions targeting the extreme and rugged environments on the moon and Mars have rich potential for a high science return although several risks exist in performing these exploration missions. The current generation of robots is unable to access these high-priority targets. We propose using teams of small hopping and rolling robots called SphereX that are several kilograms in mass and can be carried by a large rover or lander and tactically deployed for exploring these extreme environments. Considering that the importance of minimizing the mass and volume of these robot platforms translates into significant mission-cost savings we focus on the optimization of an integrated power and propulsion system for SphereX. Hydrogen is used as fuel for its high energy and it is stored in the form of lithium hydride and oxygen in the form of lithium perchlorate. The system design undergoes optimization using Genetic Algorithms integrated with gradient-based search techniques to find optimal solutions for a mission. Our power and propulsion system as we show in this paper is enabling because the robots can travel long distances to perform science exploration by accessing targets not possible with conventional systems. Our work includes finding the optimal mass and volume of SphereX such that it can meet end-to-end mission requirements.

Facing the challenge that the single-motor electric drive powertrain cannot meet the continuous uphill requirements in the cold mountainous area of the 2022 Beijing Winter Olympics the manuscript adopted a dual-motor coupling technology. Then according to the operating characteristics and performance indicators of the fuel cell (FC)–traction battery hybrid power system the structure design and parameter matching of the vehicle power system architecture were carried out to improve the vehicle’s dynamic performance. Furthermore considering the extremely cold conditions in the Winter Olympics competition area and the poor low-temperature tolerance of core components of fuel cell electric vehicles (FCEV) under extremely cold conditions such as the reduced capacity and service life of traction batteries caused by the rapid deterioration of charging and discharging characteristics the manuscript proposed a fuzzy logic control-based energy management strategy (EMS) optimization method for the proton exchange membrane fuel cell (PEMFC) to reduce the power fluctuation hydrogen consumption and battery charging/discharging times and at the same time to ensure the hybrid power system meets the varying demand under different conditions. In addition the performance of the proposed approach was investigated and validated in an intercity coach in real-world driving conditions. The experimental results show that the proposed powertrain with an optimal control strategy successfully alleviated the fluctuation of vehicle power demand reduced the battery charging/discharging times of traction battery and improved the energy efficiency by 20.7%. The research results of this manuscript are of great significance for the future promotion and application of fuel cell electric coaches in all climate environments especially in an extremely cold mountain area.

Electrical energy storage technologies for stationary applications are reviewed. Particular attention is paid to pumped hydroelectric storage compressed air energy storage battery flow battery fuel cell solar fuel superconducting magnetic energy storage flywheel capacitor/supercapacitor and thermal energy storage. Comparison is made among these technologies in terms of technical characteristics applications and deployment status.

Previously suggested options to achieve carbon neutrality involve the use of fossil fuels with carbon capture or exploiting biomass as sources of energy. Industrial high-temperature heating could possibly exploit electrical heating or combustion using hydrogen. However it is difficult to replace all the current coal or natural gas furnaces with these options for chemical industry. In this work a method that integrates solid oxide electrolysis cells (SOEC) and H2–O2 combustion is proposed and the related parameters are modelled to analyze their impacts. There is no waste heat and waste emissions in the proposed option and all substances are recycled. Unlike previous research the heat required for SOEC operation is generated from H2 combustion. The best working condition is under thermoneutral voltage and the highest electricity-to-thermal efficiency that can be achieved is 86.88% under a current density of 12000 A/m2 and operating temperature of 750 ◦C. Ohmic overpotential has the greatest effect on electricity consumption and the anode activation overpotential is the second most important option. Increasing combustion product temperature cannot significantly improve thermal efficiency but can raise the available maximum thermal energy.

The European Green Deal aims to transform the EU into a modern resource-efficient and competitive economy. The REPowerEU plan launched in May 2022 as part of the Green Deal reveals the willingness of several countries to become energy independent and tackle the climate crisis. Therefore the decarbonization of different sectors such as maritime shipping is crucial and may be achieved through sustainable energy. Hydrogen is potentially clean and renewable and might be chosen as fuel to power ships and boats. Hydrogen technologies (e.g. fuel cells for propulsion) have already been implemented on board ships in the last 20 years mainly during demonstration projects. Pressurized tanks filled with gaseous hydrogen were installed on most of these vessels. However this type of storage would require enormous volumes for large long-range ships with high energy demands. One of the best options is to store this fuel in the cryogenic liquid phase. This paper initially introduces the hydrogen color codes and the carbon footprints of the different production techniques to effectively estimate the environmental impact when employing hydrogen technologies in any application. Afterward a review of the implementation of liquid hydrogen (LH2 ) in the transportation sector including aerospace and aviation industries automotive and railways is provided. Then the focus is placed on the maritime sector. The aim is to highlight the challenges for the adoption of LH2 technologies on board ships. Different aspects were investigated in this study from LH2 bunkering onboard utilization regulations codes and standards and safety. Finally this study offers a broad overview of the bottlenecks that might hamper the adoption of LH2 technologies in the maritime sector and discusses potential solutions.

In order to decarbonize the rail industry the development of innovative locomotives with the ability to use multiple energy sources constituting hybrid powertrains plays a central role in transitioning from conventional diesel trains. In this paper four configurations based on suitable combinations of fuel cells and/or batteries are designed to replace or supplement a diesel/overhead line powertrain on a real passenger train (the Hitachi Blues) tested on an existing regional track the Catanzaro Lido–Reggio Calabria line (Italy) managed by Trenitalia SpA. (Italy). The configurations (namely battery–electrified line full-battery fuel cell–battery–electrified line and fuel cell–battery) are first sized with the intention of completing a round trip then integrated on board with diesel engine replacement in mind and finally occupy a portion of the passenger area within two locomotives. The achieved performance is thoroughly examined in terms of fuel cell efficiency (greater than 47%) hydrogen consumption (less than 72 kg) braking energy recovery (approximately 300 kWh) and battery interval SOC.

The remaining useful life (RUL) prediction for hydrogen fuel cells is an important part of its prognostics and health management (PHM). Artificial neural networks (ANNs) are proven to be very effective in RUL prediction as they do not need to understand the failure mechanisms behind hydrogen fuel cells. A novel RUL prediction method for hydrogen fuel cells based on the gated recurrent unit ANN is proposed in this paper. Firstly the data were preprocessed to remove outliers and noises. Secondly the performance of different neural networks is compared including the back propagation neural network (BPNN) the long short-term memory (LSTM) network and the gated recurrent unit (GRU) network. According to our proposed method based on GRU the root mean square error was 0.0026 the mean absolute percentage error was 0.0038 and the coefficient of determination was 0.9891 for the data from the challenge datasets provided by FCLAB Research Federation when the prediction starting point was 650 h. Compared with the other RUL prediction methods based on the BPNN and the LSTM our prediction method is better in both prediction accuracy and convergence rate.

This review critically evaluates the latest trends in fuel cell development for portable and stationary fuel cell applications and their integration into the automotive industry. Fast start-up high efficiency no toxic emissions into the atmosphere and good modularity are the key advantages of fuel cell applications. Despite the merits associated with fuel cells the high cost of the technology remains a key factor impeding its widespread commercialization. Therefore this review presents detailed information into the best operating conditions that yield maximum fuel cell performance. The paper recommends future research geared towards robust fuel cell geometry designs as this determines the cell losses and material characterization of the various cell components. When this is done properly it will support a total reduction in the cost of the cell which in effect will reduce the total cost of the system. Despite the strides made by the fuel cell research community there is a need for public sensitization as some people have reservations regarding the safety of the technology. This hurdle can be overcome if there is a well-documented risk assessment which also needs to be considered in future research activities.

Fuel cell hybrid electric vehicles have attracted a large amount of attention in recent years owing to their advantages of zero emissions high efficiency and low noise. To improve the fuel economy and system durability of vehicles this paper proposes an energy management strategy optimization method for fuel cell hybrid electric vehicles based on dynamic programming. Rule-based and dynamic-programming-based strategies are developed based on building a fuel cell/battery hybrid system model. The rule-based strategy is improved with a power distribution scheme of dynamic programming strategy to improve the fuel economy of the vehicle. Furthermore a limit on the rate of change of the output power of the fuel cell system is added to the rule-based strategy to avoid large load changes to improve the durability of the fuel cell. The simulation results show that the equivalent 100 km hydrogen consumption of the strategy based on the dynamic programming optimization rules is reduced by 6.46% compared with that before the improvement and by limiting the rate of change of the output power of the fuel cell system the times of large load changes are reduced. Therefore the strategy based on the dynamic programming optimization rules effectively improves the fuel economy and system durability of vehicles.

The year 2014 marked hydrogen fuel cell electric vehicles (FCEVs) first becoming commercially available in California where significant investments are being made to promote the adoption of alternative transportation fuels. A refueling infrastructure network that guarantees adequate coverage and expands in line with vehicle sales is required for FCEVs to be successfully adopted by private customers. In this paper we provide an overview of modelling methodologies used to project hydrogen refueling infrastructure requirements to support FCEV adoption and we describe in detail the National Renewable Energy Laboratory’s scenario evaluation and regionalization analysis (SERA) model. As an example we use SERA to explore two alternative scenarios of FCEV adoption: one in which FCEV deployment is limited to California and several major cities in the United States; and one in which FCEVs reach widespread adoption becoming a major option as passenger vehicles across the entire country. Such scenarios can provide guidance and insights for efforts required to deploy the infrastructure supporting transition toward different levels of hydrogen use as a transportation fuel for passenger vehicles in the United States.

A proton exchange membrane fuel cell (PEMFC) is known as one of the most promising energy sources for electric vehicles. A hydrogen system is required to provide hydrogen to the stack in time to meet the flow and pressure requirements according to the power requirements. In this study a 1-D model of a hydrogen system including the fuel cell stack was established. Two modes one with and one without a proportion integration differentiation (PID) control strategy were applied to analyze the pressure characteristics and performance of the PEMFC. The results showed that the established model could be well verified with experimental data. The anode pressure fluctuation with a PID control strategy was more stable which reduced the damage to the fuel cell stack caused by sudden changes of anode pressure. In addition the performance of the stack with the PID control mode was slightly improved. There was an inflection point for hydrogen utilization; the hydrogen utilization rate was higher under the mode without PID control when the current density was greater than 0.4 A/cm2 . What is more a hierarchical control strategy was proposed which made the pressure difference between the anode and cathode meet the stack working requirements and more importantly maintained the high hydrogen utilization of the hydrogen system.

The authors have proposed a new combustion process called the Plume Ignition Combustion Concept (PCC) in which with an optimal combination of hydrogen injection timing and controlled jet geometry the plume of the hydrogen jet is spark-ignited to accomplish combustion of a rich mixture. This combustion process markedly improves thermal efficiency by reducing cooling loss which is essential for increasing thermal efficiency in a hydrogen engine while maintaining high power. In order to improve thermal efficiency and reduce NOx formation further PCC was applied to a lean-burn regime to burn a leaner mixture globally. In this study the effect of supercharging which was applied to recover the reduced output power due to the leaner mixture on improving thermal efficiency was confirmed along with clarifying the cause.

Simultaneous and interactive combustion of three fuels with differing reactivities is investigated by numerical simulations. In the present study conventional dual-fuel (DF) ignition phenomena relevant to DF compression ignition (CI) engines are extended and explored in tri-fuel (TF) context. In the present TF setup a low reactivity fuel (LRF) methane or methanol is perfectly mixed with hydrogen and air to form the primary fuel blend at the lean equivalence ratio of 0.5. Further such primary fuel blends are ignited by a high-reactivity fuel (HRF) here n-dodecane under conditions similar to HRF spray assisted ignition. Here ignition is relevant to the HRF containing parts of the tri-fuel mixtures while flame propagation is assumed to occur in the premixed LRF/ containing end gas regions. The role of hydrogen as TF mixture reactivity modulator is explored. Mixing is characterized by n-dodecane mixture fraction ξ and molar ratio . When x < 0.6 minor changes are observed for the first- and second-stage ignition delay time (IDT) of tri-fuel compared to dual-fuel blends (x = 0). For methane when x > 0.6 first- and second-stage IDT increase by factor 1.4–2. For methanol a respective decrease by factor 1.2–2 is reported. Such contrasting trends for the two LRFs are explained by reaction sensitivity analysis indicating the importance of OH radical production/consumption in the ignition process. Observations on LRF/ end gas laminar flame speed () indicate that  increases with x due to the highly diffusive features of . For methane  increase with x is more significant than for methanol.

Alternative and especially renewable marine fuels are needed to reduce the environmental and climate impacts of the shipping sector. This paper investigates the business case for hydrogen as an alternative fuel in a new-built vessel utilizing fuel cells and liquefied hydrogen. A real option approach is used to model the optimal time and costs for investment as well as the value of deferring an investment as a result of uncertainty. This model is then used to assess the impact of a carbon tax on a ship owner’s investment decision. A low carbon tax results in ship owners deferring investments which then slows the uptake of the technology. We recommend that policymakers set a high carbon tax at an early stage in order to help hydrogen compete with fossil fuels. A clear and timely policy design promotes further investments and accelerates the uptake of new technologies that can fulfill decarbonization targets.

Current standard practice at wastewater treatment plants (WWTPs) involves the recycling of digestate liquor produced from the anaerobic digestion of sludge back into the treatment process. However a significant amount of energy is required to enable biological breakdown of ammonia present in the liquor. This biological processing also results in the emission of damaging quantities of greenhouse gases making diversion of liquor and recovery of ammonia a noteworthy option for improving the sustainability of wastewater treatment. This study presents a novel process which combines ammonia recovery from diverted digestate liquor for use (alongside biomethane) in a solid oxide fuel cell (SOFC) system for implementation at WWTPs. Aspen Plus V.8.8 and numerical steady state models have been developed using data from a WWTP in West Yorkshire (UK) as a reference facility (750000p.e.). Aspen Plus simulations demonstrate an ability to recover 82% of ammoniacal nitrogen present in digestate liquor produced at the WWTP. The recovery process uses a series of stripping absorption and flash separation units where water is recovered alongside ammonia. This facilitates effective internal steam methane as a case of study has the potential to make significant impacts energetically and environmentally; findings suggest the treatment facility could transform from a net consumer of electricity to a net producer. The SOFC has been demonstrated to run at an electrical efficiency of 48% with NH3 contributing 4.6% of its power output. It has also been demonstrated that 3.5 kg CO2e per person served by the WWTP could be mitigated a year due to a combination of emissions savings by diversion of ammonia from biological processing and lifecycle emissions associated with the lack of reliance on grid electricity.

As a countermeasure to the greenhouse gas problem the world is focusing on alternative fuel vehicles (AFVs). The most prominent alternatives are battery electric vehicles (BEV) and fuel cell electric vehicles (FCEVs). This study examines FCEVs especially considering hydrogen refueling stations to fill the gap in the research. Many studies suggest the important impact that infrastructure has on the diffusion of AFVs but they do not provide quantitative preferences for the design of hydrogen refueling stations. This study analyzes and presents a consumer preference structure for hydrogen refueling stations considering the production method distance probability of failure to refuel number of dispensers and fuel costs as core attributes. For the analysis stated preference data are applied to choice experiments and mixed logit is used for the estimation. Results indicate that the supply stability of hydrogen refueling stations is the second most important attribute following fuel price. Consumers are willing to pay more for green hydrogen compared to gray hydrogen which is hydrogen produced by fossil fuels. Driver fuel type and perception of hydrogen energy influence structure preference. Our results suggest a specific design for hydrogen refueling stations based on the characteristics of user groups.

The hydrogen fuel cell (HFC) vehicle is an important clean energy vehicle which has prospects for development. The behavior of the hydrogen fuel cell (HFC) vehicle power system and in particular the proton-exchange membrane fuel cell has been extensively studied as of recent. The development of the dynamic system modeling technology is of paramount importance for HFC vehicle studies; however it is hampered by the separation of the electrochemical properties and dynamic properties. In addition the established model matching the follow-up control method lacks applicability. In attempts to counter these obstructions we proposed an improved fuzzy (Proportional Integral Derivative) PID control method considering HFC voltage-output characteristics. By developing both the electrochemical and dynamic model for HFC vehicle we can realize the coordinated control of HFC and power cell. The simulation results are in good agreement with the experimental results in the two models. The proposed control algorithm has a good control effect in all stages of HFC vehicle operation.

Electromobility is a growing technology for land transport constituting an important element of the concept of sustainable economic development. The article presents selected research results concerning one of the segments of this market-vehicles powered by hydrogen fuel cells. The subject of the research was to gain extensive knowledge on the economic factors influencing the future purchasing decisions of the demand side in relation to this category of vehicles. The research was based on a numerical experiment. For this purpose a comparative analysis of purchase prices in relation to the TCO of the vehicle after 3–5 years of use was performed. The research included selected models that are powered by both conventional and alternative fuels. The use of this method will allow to assess the real costs associated with the hydrogen vehicle. The authors emphasize the important role of economic factors in the form of the TCO index for the development of this market. The experimental approach may be helpful in understanding the essence of economic relations that affect the development of the electro-mobility market and the market demand for hydrogen fuel cell-powered vehicles in Poland.

This article provides an overview of modern technologies and implemented projects in the field of renewable energy systems for the electrification of railway transport. In the first part the relevance of the use of renewable energy on the railways is discussed. Various types of power-generating systems in railway stations and platforms along the track as well as in separate areas are considered. The focus is on wind and solar energy conversion systems. The second part is devoted to the analysis of various types of energy storage devices used in projects for the electrification of railway transport since the energy storage system is one of the key elements in a hybrid renewable energy system. Systems with kinetic storage electrochemical storage batteries supercapacitors hydrogen energy storage are considered. Particular attention is paid to technologies for accumulating and converting hydrogen into electrical energy as well as hybrid systems that combine several types of storage devices with different ranges of charge/discharge rates. A comparative analysis of various hybrid electric power plant configurations depending on the functions they perform in the electrification systems of railway transport has been carried out.

Breakthrough discoveries in high-throughput formulation of abundant materials and advanced engineering approaches are both in utter need as prerequisites for developing novel large-scale energy conversion technologies required to address our planet's rising energy demands. Nowadays the rapid deployment of Internet of Things (IoT) associated with a distributed network of power-demanding smart devices concurrently urges for miniaturized systems powered by ambient energy harvesting. Graphene and other related two-dimensional materials (GRM) consist a perfect fit to drive this innovation owing to their extraordinary optoelectronic physical and chemical properties that emerge at the limit of two-dimensions. In this review after a critical analysis of GRM's emerging properties that are beneficial for power generation novel approaches are presented for developing ambient energy conversion devices covering a wide range of scales. Notable examples vary from GRM-enabled large-scale photovoltaic panels and fuel cells smart hydrovoltaics and blue energy conversion routes to miniaturized radio frequency piezoelectric triboelectric and thermoelectric energy harvesters. The insights from this review demonstrate that GRM-enabled energy harvesters apart from enabling the self-powered operation of individual IoT devices have also the potential to revolutionize the way that grid-electricity is provided in the cities of the future. This approach is materialized by two complementary paradigms: cross-coupled integration of GRM into firstly a network consisted of a vast number of miniaturized in-series-connected harvesters and secondly into up-scaled multi-energy hybrid harvesters both approaches having the potential for on-grid energy generation under all-ambient-conditions. At the end of the discussion perspectives on the trends limitations and commercialisation potential of these emerging up-scalable energy conversion technologies are provided. This review aims to highlight the importance of building a network of GRM-based cross-scaled energy conversion systems and their potential to become the guideline for the energy sustainable cities of the future.

Ammonia has been proposed as a potential energy storage medium in the transition towards a low-carbon economy. This paper details experimental results and numerical calculations obtained to progress towards optimisation of fuel injection and fluidic stabilisation in swirl burners with ammonia as the primary fuel. A generic tangential swirl burner has been employed to determine flame stability and emissions produced at different equivalence ratios using ammonia–methane blends. Experiments were performed under atmospheric and medium pressurised conditions using gas analysis and chemiluminescence to quantify emission concentrations and OH production zones respectively. Numerical calculations using GASEQ and CHEMKIN-PRO were performed to complement compare with and extend experimental findings hence improving understanding concerning the evolution of species when fuelling on ammonia blends. It is concluded that a fully premixed injection strategy is not appropriate for optimised ammonia combustion and that high flame instabilities can be produced at medium swirl numbers hence necessitating lower swirl and a different injection strategy for optimised power generation utilising ammonia fuel blends.

Two non-electrified railway lines one in Norway and the other in the USA are analysed for their potential to be electrified with overhead line equipment batteries hydrogen or hydrogen-battery hybrid powertrains. The energy requirements are established with single-train simulations including the altitude profiles of the lines air and rolling resistances and locomotive tractive-effort curves. The composition of the freight trains in terms of the number of locomotives battery wagons hydrogen wagons etc. is also calculated by the same model. The different technologies are compared by the criteria of equivalent annual costs benefit–cost ratio payback period and up-front investment based on the estimated techno-economic parameters for years 2020 2030 and 2050. The results indicate the potential of batteries and fuel cells to replace diesel on rail lines with low traffic volumes.

A process where power and biomass are converted to Fischer-Tropsch liquid fuels (PBtL) is compared to a conventional Biomass-to-Liquid (BtL) process concept. Based on detailed process models it is demonstrated that the carbon efficiency of a conventional Biomass to Liquid process can be increased from 38 to more than 90% by adding hydrogen from renewable energy sources. This means that the amount of fuel can be increased by a factor of 2.4 with the same amount of biomass. Electrical power is applied to split water/steam at high temperature over solid oxide electrolysis cells (SOEC). This technology is selected because part of the required energy can be replaced by available heat. The required electrical power for the extra production is estimated to be 11.6 kWh per liter syncrude (C ) 5+ . By operating the SOEC iso-thermally close to 850 °C the electric energy may be reduced to 9.5 kWh per liter which is close to the energy density of jet fuel. A techno-economic analysis is performed where the total investments and operating costs are compared for the BtL and PBtL. With an electrical power price of 0.05 $/kWh and with SOEC investment cost of the 1000 $/kW(el) the levelized cost of producing advanced biofuel with the PBtL concept is 1.7 $/liter which is approximately 30% lower than for the conventional BtL. Converting excess renewable electric power to advanced biofuel in a PBtL plant is a sensible way of storing energy as a fuel with a relatively high energy density.

The effects of climate change and global warming are arising a new awareness on the impact of our daily life. Power generation for transportation and mobility as well as in industry is the main responsible for the greenhouse gas emissions. Indeed currently 80% of the energy is still produced by combustion of fossil fuels; thus great efforts need to be spent to make combustion greener and safer than in the past. For this reason a review of the most recent gas turbines combustion strategy with a focus on fuels combustion techniques and burners is presented here. A new generation of fuels for gas turbines are currently under investigation by the academic community with a specific concern about production and storage. Among them biofuels represent a trustworthy and valuable solution in the next decades during the transition to zero carbon fuels (e.g. hydrogen and ammonia). Promising combustion techniques explored in the past and then abandoned due to their technological complexity are now receiving renewed attention (e.g. MILD PVC) thanks to their effectiveness in improving the efficiency and reducing emissions of standard gas turbine cycles. Finally many advances are illustrated in terms of new burners developed for both aviation and power generation. This overview points out promising solutions for the next generation combustion and opens the way to a fast transition toward zero emissions power generation.