Applications & Pathways

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.

Aviation is of crucial importance for the transportation sector and fundamental for the economy as it facilitates trade and private travel. Nonetheless this sector is responsible for a great amount of global carbon dioxide emissions exceeding 920 million tonnes annually. Alternative energy fuels (AEFs) can be considered as a promising solution to tackle this issue with the potential to lower greenhouse gas emissions and reduce reliance on fossil fuels in the aviation industry. A life cycle analysis is performed considering an aircraft running on conventional jet fuel and various alternative fuels (biojet methanol and DME) including hydrogen and ammonia. The comparative assessment investigates different fuel production pathways including the following: JETA-1 and biojet fuels via hydrotreated esters and fatty acids (HEFAs) as well as hydrogen and ammonia employing water electrolysis using wind and solar photovoltaic collectors. The outputs of the assessment are quantified in terms of carbon dioxide equivalent emissions acidification eutrophication eco-toxicity human toxicity and carcinogens. The life cycle phases included the following: (i) the construction maintenance and disposal of airports; (ii) the operation and maintenance of aircrafts; and (iii) the production transportation and utilisation of aviation fuel in aircrafts. The results suggest that hydrogen is a more environmentally benign alternative compared to JETA-1 biojet fuel methanol DME and ammonia.

Integrated hydrogen energy systems (IHESs) have attracted extensive attention in miti-gating climate problems. As a kind of large-scale hydrogen storage device undergroundhydrogen storage (UHS) can be introduced into IHES to balance the seasonal energy mis-match while bringing challenges to optimal operation of IHES due to the complex geolog-ical structure and uncertain hydrodynamics. To address this problem a deep deterministicpolicy gradient (DDPG)-based optimal scheduling method for underground space basedIHES is proposed. The energy management problem is formulated as a Markov decisionprocess to characterize the interaction between environmental states and policy. Based onDDPG theory the actor-critic structure is applied to approximate deterministic policy andactor-value function. Through policy iteration and actor-critic network training the oper-ation of UHS and other energy conversion devices can be adaptively optimised which isdriven by real-time response data instead of accurate system models. Finally the effective-ness of the proposed optimal scheduling method and the benefits of underground spaceare verified through time-domain simulations.

The recent targets by different countries to stop the sales or registrations of internal combustion engines (ICE) have led to the further development of battery and fuel cell technologies to provide power for different applications. The main aim of this study is to evaluate the possibility of using an integrated Lithium-Ion battery and proton exchange membrane fuel cell (PEMFC) as the prime mover for a case study of a 800 kW ferry with a total length of 50.8 m to transport 780 passengers for a distance of 24 km in 70 min. Accounting for five types of Lithium-Ion batteries and different numbers of PEMFCs twenty-five scenarios are suggested based on a quasi-static model. To perform the optimization the Performance Criterion of the Fuel cell–Battery integrated systems (PCFB) is introduced to include the effects of the sizes weights costs hydrogen consumption efficiency and power in addition to the number of fuel cells and the battery capacity. Results indicate that the maximum PCFB value of 10.755 (1/kg2m3 $) can be obtained once the overall size weight efficiency hydrogen consumption and cost of the system are 18 m3 11160 kg 49.25% 33.6 kg and 119.58 k$ respectively using the Lithium Titanite Oxide (LTO) Lithium-Ion battery with nine PEMFCs.

In this study the Bald Eagle Search Algorithm performed hydrogen consumption and battery cycle optimization of a fuel cell electric vehicle. To save time and cost the digital vehicle model created in Matlab/Simulink and validated with real-world driving data is the main platform of the optimization study. The digital vehicle model was run with the minimum and maximum battery charge states determined by the Bald Eagle Search Algorithm and hydrogen consumption and battery cycle values were obtained. By using the algorithm and digital vehicle model together hydrogen consumption was minimized and range was increased. It was aimed to extend the life of the parts by considering the battery cycle. At the same time the number of battery packs was included in the optimization and its effect on consumption was investigated. According to the study results the total hydrogen consumption of the fuel cell electric vehicle decreased by 57.8% in the hybrid driving condition 23.3% with two battery packs and 36.27% with three battery packs in the constant speed driving condition.

The hydrogen internal combustion engine (H2-ICE) is proposed as a robust and viable solution to decarbonise the heavy-duty on- and off-road as well as the light-duty automotive sectors of the transportation markets and is therefore the subject of rapidly growing research interest. With the potential for engine performance improvement by controlling the internal mixture formation and avoiding combustion anomalies hydrogen direct injection (H2DI) is a promising combustion mode. Furthermore the H2-ICE poses an attractive proposition for original equipment manufacturers (OEMs) and their suppliers since the fundamental base engine design components and manufacturing processes are largely unchanged. Nevertheless to deliver the highest thermal efficiency and zero-harm levels of tailpipe emissions moderate adaptations are needed to the engine control air path fuel injection and ignition systems. Therefore in this article critical design features fuel-air mixing combustion regimes and exhaust after-treatment systems (EATS) for H2DI engines are carefully assessed.

The most practical way of storing hydrogen gas for fuel cell vehicles is to use a composite overwrapped pressure vessel. Depending on the driving distance range and power requirement of the vehicles there can be various operational pressure and volume capacity of the tanks ranging from passenger vehicles to heavy-duty trucks. The current commercial hydrogen storage method for vehicles involves storing compressed hydrogen gas in high-pressure tanks at pressures of 700 bar for passenger vehicles and 350 bar to 700 bar for heavy-duty trucks. In particular hydrogen is stored in rapidly refillable onboard tanks meeting the driving range needs of heavy-duty applications such as regional and line-haul trucking. One of the most important factors for fuel cell vehicles to be successful is their cost-effectiveness. So in this review the cost analysis including the process analysis raw materials and manufacturing processes is reviewed. It aims to contribute to the optimization of both the cost and performance of compressed hydrogen storage tanks for various applications.

Aviation is a major contributor to transportation carbon emissions but aims to reduce its carbon footprint. Sustainable and environmentally friendly green hydrogen fuel is essential for decarbonization of this industry. Using the extremely low temperature of liquid hydrogen in aviation sector unlocks the opportunity for cryoelectric aircraft concept which exploits the advantageous properties of superconductors onboard. A significant barrier for green hydrogen adoption relates to its high cost and the immediate need for large-scale production which Proton Exchange Membrane Water Electrolyzers (PEMWE) can address through optimal dynamic performance high lifetimes good efficiencies and importantly scalability. In PEMWE the cell is a crucial component that facilitates the electrolysis process and consists of a polymer membrane and electrodes. To control the required production rate of hydrogen the output power of cell should be monitored which usually is done by measuring the cell’s potential and current density. In this paper five different machine learning (ML) models based on different algorithms have been developed to predict this parameter. Findings of the work highlight that the model based on Cascade-Forward Neural Network (CFNN) is investigated to accurately predict the cell potential of PEMWE under different anodic material and working conditions with an accuracy of 99.998 % and 0.001884 in terms of R2 and root mean square error respectively. It can predict the cell potential with a relative error of less than 0.65 % and an absolute error of below 0.01 V. The Standard deviation of 0.000061 for 50 iterations of stability analysis indicated that this model has less sensitivity to the random selection of training data. By accurately estimating different cell’s output with one model and considering its ultra-fast response CFNN model has the potential to be used for both monitoring and the designing purposes of green hydrogen production.

The type IV hydrogen storage tank with a polymer liner is a promising storage solution for fuel cell electric vehicles (FCEVs). The polymer liner reduces the weight and improves the storage density of tanks. However hydrogen commonly permeates through the liner especially at high pressure. If there is rapid decompression damage may occur due to the internal hydrogen concentration as the concentration inside creates the pressure difference. Thus a comprehensive understanding of the decompression damage is significant for the development of a suitable liner material and the commercialization of the type IV hydrogen storage tank. This study discusses the decompression damage mechanism of the polymer liner which includes damage characterizations and evaluations influential factors and damage prediction. Finally some future research directions are proposed to further investigate and optimize tanks.

CO2 emission reduction of sectors such as aviation maritime shipping road haulage and chemical production is challenging but necessary. Although these sectors will most likely continue to rely on carbonaceous energy carriers they are expected to gradually shift away from fossil fuels. In order to do so the prominent option is to utilize alternative carbon sources—like biomass and CO2 originating from carbon capture—for the production of non-fossil carbonaceous vectors (biofuels and e-fuels). However the limited availability of biomass and the varying nature of other carbon sources necessitate a comprehensive evaluation of trade-offs between potential carbon uses and existing sources. Then it is primordial to understand the origin of carbon used in sustainable aviation fuel (SAF) to understand the implications of defossilizing aviation for the energy system. Moreover the production of SAF implies deep changes to the energy system that are quantified in this work. This study utilizes the linear programming cost optimization tool EnergyScope TD to analyze the holistic French energy system encompassing transport industry electricity and heat sectors while ensuring net greenhouse gas neutrality. A novel method to model and quantify carbon flows within the system is introduced enabling a comprehensive assessment of greenhouse gas neutrality. This study highlights the significance of fulfilling clean energy requirements and implementing carbon dioxide removal measures as crucial steps toward achieving climate neutrality. Indeed to reach climate neutrality a production of 1046 TWh of electricity by non-fossil sources is needed. Furthermore the findings underscore the critical role of efficient carbon and energy valorization from biomass providing evidence that producing fuels by combining biomass and hydrogen is optimal. The study also offers valuable insights into the future cost and impact of SAF production for air travel originating from France. That is the European law ReFuelEU would increase the price of plane tickets by +33% and would require 126 TWh of hydrogen and 50 TWh of biomass to produce the necessary 91 TWh of jet fuel. Finally the implications of the assumption behind the production of SAF are discussed.