Publications

Green hydrogen holds potential for decarbonizing the energy sector but high production costs are a major barrier. This study provides a comprehensive techno-economic-financial-environmental analysis of PV-based grid-connected hydrogen production plants targeting hard-to-abate industries having constant hydrogen demand across all Italy. Using real hourly data the Multi Energy System Simulator (MESS) an in-house developed rule-based tool was employed and integrated with Genetic Algorithm for optimal plant sizing. The aim is to minimize the Levelized Cost of Hydrogen (LCOH) while complying with regulatory frameworks for green hydrogen incentives access. Key findings show that hydrogen storage is more advantageous than battery storage for supply-side flexibility and the optimal PV-to-electrolyzer size ratio ranges from 1.8 in Southern Italy to 2.1 in Northern Italy with hydrogen tank designed for daily storage. Considering photovoltaic electrolyzer and battery aging models grid dependence increases by 60 % when comparing the first and worst year of operation and leads to a 7 % increase in LCOH. Transitioning from the strictest (hourly) to the least stringent (annual) temporal correlation increases certified green hydrogen by 22 % while LCOH decreases by only 3 % suggesting that the environmental benefits of stringent temporal requirements outweigh their moderate economic drawbacks. These findings underscore the need for additional national-level incentives to allow the deployment of this technology and achieving cost parity with grey hydrogen.

This paper explores the current scope and direction of the emerging global governance of hydrogen within the broader context of the energy transition where technological innovation and institutional change intersect. Hydrogen as a critical yet complex energy vector requires coordinated governance efforts to navigate its development effectively. To this end we critically engage with key challenges facing the hydrogen sector and examine how institutional frameworks are addressing these issues. Departing from the broader scholarship on global energy governance we conceptually leverage the socio-technical transition and innovation system liter ature to understand the complexities underpinning the development of the global hydrogen economy. We identify three overarching issue areas pertaining to the nature and role of hydrogen in the global energy system: end-use sector development infrastructure and trade and environmental and socio-economic sustainability. Each of these areas presents distinct challenges to hydrogen’s global governance from stimulating supply and demand to managing geo-economic challenges and establishing comprehensive certification and standards. Through mapping multilateral institutions at the global and regional levels and their main objectives we offer insights into the emerging institutional architecture related to hydrogen and identify potential gaps in current governance. Our findings suggest that while newer hydrogen-specific institutions complement the broader agenda of the main established international organizations the overall global hydrogen structure remains a patchwork of diverse actors and frameworks each addressing hydrogen-related challenges to varying degrees. Our research contributes to a nuanced understanding of global governance in the hydrogen sector and advances scholarly discussions on how institutional and actor dynamics shape the emergence and development of new technologies.

The lack of clarity and uncertainty about hydrogen’s role demand applications and economics has been a barrier to the development of the hydrogen economy. In this paper an optimisation model for the integrated planning and operation of hydrogen and electricity systems is presented to identify the role of hydrogen technologies and linepack in decarbonising energy systems improving system flexibility and enhancing energy system security and resilience against extreme weather events. The studies are conducted on Great Britain’s (GB) 2050 net-zero electricity and gas transmission systems to analyse the hydrogen transport and capacity requirements within the existing infrastructure under different scenarios. This includes sensitivities on the level of flexibility high gas prices hydrogen production mixes enabled reversibility of electrolysers electricity generation cost and hydrogen storage facilities. In all sensitivity scenarios efficient hydrogen transport within the existing infrastructure is enabled by the optimal allocation of green and blue hydrogen sources distributed storage facilities and the intra-day flexibility provided by linepack. The findings highlight that increased renewable deployment transfers intermittency to the hydrogen network requiring greater linepack flexibility compared to the current paradigm (up to 83%). Furthermore the necessity of synergy between different gas and electricity systems components in providing flexibility security and resilience is quantified.

Demand response (DR) is a crucial element in the optimization of integrated energy systems (IESs) that incor porate distributed generation (DG). However its inherent uncertainty poses significant challenges to the eco nomic viability of IESs. This research presents a novel economic dispatch model for IESs utilizing information gap decision theory (IGDT). The model integrates various components to improve IES performance and dispatch efficiency. With a focus on hydrogen energy the model considers users’ energy consumption patterns thereby improving system flexibility. By applying IGDT the model effectively addresses the uncertainty associated with DR and DG overcoming the limitations of traditional methods. The research findings indicate that in relation to the baseline method the proposed model has the potential to reduce operating costs by 6.3 % and carbon emissions by 4.2 %. The integration of a stepwise carbon trading mechanism helps boost both economic and environmental advantages achieving a 100 % wind power consumption rate in the optimized plan. In addition the daily operating costs are minimized to 23758.99 ¥ while carbon emissions are significantly reduced to 34192 kg. These findings provide quantitative decision support for IES dispatch planners to help them develop effective dispatch strategies that are consistent with low-carbon economic initiatives.

The global issue of climate change caused by humans and its inextricable linkage to our present and future energy demand presents the biggest challenge facing our globe. Hydrogen has been introduced as a new renewable energy resource. It is envisaged to be a crucial vector in the vast low-carbon transition to mitigate climate change minimize oil reliance reinforce energy security solve the intermittency of renewable energy resources and ameliorate energy performance in the transportation sector by using it in energy storage energy generation and transport sectors. Many technologies have been developed to generate hydrogen. The current paper presents a review of the current and developing technologies to produce hydrogen from fossil fuels and alternative resources like water and biomass. The results showed that reformation and gasification are the most mature and used technologies. However the weaknesses of these technologies include high energy consumption and high carbon emissions. Thermochemical water splitting biohydrogen and photo-electrolysis are long-term and clean technologies but they require more technical development and cost reduction to implement reformation technologies efficiently and on a large scale. A combination of water electrolysis with renewable energy resources is an ecofriendly method. Since hydrogen is viewed as a considerable game-changer for future fuels this paper also highlights the challenges facing hydrogen generation. Moreover an economic analysis of the technologies used to generate hydrogen is carried out in this study.

The global push for sustainable energy has heightened the demand for green hydrogen which is crucial for decarbonizing heavy industry. However current electrolysis plant capacities are insufficient. This research addresses the challenge through optimizing large-scale electrolysis construction via standardization modularization process optimization and automation. This paper introduces H2Giga a project for mass-producing electrolyzers and HyPLANT100 investigating largescale electrolysis plant structure and construction processes. Modularizing electrolyzers enhances production efficiency and scalability. The integration of AutomationML facilitates seamless information exchange. A digital twin concept enables simulations optimizations and error identification before assembly. While construction site automation provides advantages tasks like connection technologies and handling cables tubes and hoses require pre-assembly. This study identifies key tasks suitable for automation and estimating required components. The Enapter Multicore electrolyzer serves as a case study showcasing robotic technology for tube fittings. In conclusion this research underscores the significance of standardization modularization and automation in boosting the electrolysis production capacity for green hydrogen contributing to ongoing efforts in decarbonizing the industrial sector and advancing the global energy transition.

Natural ventilation is a well-known passive mitigation method to limit hydrogen build-up in confined spaces in case of accidental release [1-3]. In most cases a basic design of H2 infrastructure is adopted and vents installed for natural ventilation are adjusted according to safety targets and constraints of the considered structure. With the growing H2 mobility market the demand for H2 refueling infrastructure in our urban environment is on the rise. In order to meet both safety requirements and societal acceptance the design of such infrastructure is becoming more important. In this study a novel design concept is proposed for the hydrogen refueling station (HRS) by modifying physical structure while keeping safety consideration as the top priority of the concept. In this collaborative project between Air Liquide and the University of Delaware an extensive evaluation was performed on new structures of the processing container and dispenser of HRS by integrating safety protocols via passive means. Through a SWOT analysis combined with the most relevant approaches including analytical engineering models numerical simulations [4] and dedicated experimental trials an optimized design was obtained and its safety enhancement was fully evaluated. A small-scale processing container and an almost full-scale dispenser were built and tested to validate the design concepts by simulating accidental H2 release scenarios and assessing the associated consequences in terms of accumulation and potential flammable volumes formation. A conical dispenser and a V-shaped roof-top processing container which were easy to build and implement were designed and tested for this proof-of-concept study. This unique methodology from conception fundamental analysis investigation and validation through experimental design execution and evaluation is fully described in this study.

Introduction: Several cities in Malaysia have established plans to reduce their CO2 emissions in addition to Malaysia submitting a Nationally Determined Contribution to reduce its carbon intensity (against GDP) by 45% in 2030 compared to 2005. Meeting these emissions reduction goals will require ajoint effort between governments industries and corporations at different scales and across sectors.<br/>Methods: In collaboration with national and sub-national stakeholders we developed and used a global integrated assessment model to explore emissions mitigation pathways in Malaysia and Kuala Lumpur. Guided by current climate action plans we created a suite of scenarios to reflect uncertainties in policy ambition level of adoption and implementation for reaching carbon neutrality. Through iterative engagement with all parties we refined the scenarios and focus of the analysis to best meet the stakeholders’ needs.<br/>Results: We found that Malaysia can reduce its carbon intensity and reach carbon neutrality by 2050 and that action in Kuala Lumpur can play a significant role. Decarbonization of the power sector paired with extensive electrification energy efficiency improvements in buildings transportation and industry and the use of advanced technologies such as hydrogen and carbon capture and storage will be Major drivers to mitigate emissions with carbon dioxide removal strategies being key to eliminate residual emissions.<br/>Discussion: Our results suggest a hopeful future for Malaysia’s ability to meet its climate goals recognizing that there may be technological social and financial challenges along the way. This study highlights the participatory process in which stakeholders contributed to the development of the model and guided the analysis as well as insights into Malaysia’s decarbonization potential and the role of multilevel governance.

Hydrogen has attracted growing research interest due to its exceptionally high energy per mass content and being a clean energy carrier unlike the widely used hydrocarbon fuels. With the possibility of long-term energy storage and re-electrification hydrogen promises to promote the effective utilization of renewable and sustainable energy resources. Clean hydrogen can be produced through a renewable-powered water electrolysis process. Although alkaline water electrolysis is currently the mature and commercially available electrolysis technology for hydrogen production it has several shortcomings that hinder its integration with intermittent and fluctuating renewable energy sources. The proton exchange membrane water electrolysis (PEMWE) technology has been developed to offer high voltage efficiencies at high current densities. Besides PEMWE cells are characterized by a fast system response to fluctuating renewable power enabling operations at broader partial power load ranges while consistently delivering high-purity hydrogen with low ohmic losses. Recently much effort has been devoted to improving the efficiency performance durability and economy of PEMWE cells. The research activities in this context include investigations of different cell component materials protective coatings and material characterizations as well as the synthesis and analysis of new electrocatalysts for enhanced electrochemical activity and stability with minimized use of noble metals. Further many modeling studies have been reported to analyze cell performance considering cell electrochemistry overvoltage and thermodynamics. Thus it is imperative to review and compile recent research studies covering multiple aspects of PEMWE cells in one literature to present advancements and limitations of this field. This article offers a comprehensive review of the state-of-the-art of PEMWE cells. It compiles recent research on each PEMWE cell component and discusses how the characteristics of these components affect the overall cell performance. In addition the electrochemical activity and stability of various catalyst materials are reviewed. Further the thermodynamics and electrochemistry of electrolytic water splitting are described and inherent cell overvoltage are elucidated. The available literature on PEMWE cell modeling aimed at analyzing the performance of PEMWE cells is compiled. Overall this article provides the advancements in cell components materials electrocatalysts and modeling research for PEMWE to promote the effective utilization of renewable but intermittent and fluctuating energy in the pursuit of a seamless transition to clean energy.

This report is an output of the Clean Energy Technology Observatory (CETO). CETO's objective is to provide an evidence-based analysis feeding the policy making process and hence increasing the effectiveness of R&I policies for clean energy technologies and solutions. It monitors EU research and innovation activities on clean energy technologies needed for the delivery of the European Green Deal; and assesses the competitiveness of the EU clean energy sector and its positioning in the global energy market. CETO is being implemented by the Joint Research Centre for DG Research and Innovation in coordination with DG Energy.

Solar H2 production is considered as a potentially promising way to utilizesolar energy and tackle climate change stemming from the combustion of fossil fuels.Photocatalytic photoelectrochemical photovoltaic−electrochemical solar thermochem-ical photothermal catalytic and photobiological technologies are the most intensivelystudied routes for solar H2 production. In this Focus Review we provide a comprehensivereview of these technologies. After a brief introduction of the principles and mechanisms ofthese technologies the recent achievements in solar H2 production are summarized with aparticular focus on the high solar-to-H 2 (STH) conversion efficiency achieved by eachroute. We then comparatively analyze and evaluate these technologies based on the metricsof STH efficiency durability economic viability and environmental sustainability aimingto assess the commercial feasibility of these solar technologies compared with currentindustrial H 2 production processes. Finally the challenges and prospects of future researchon solar H2 production technologies are presented.

The present study comprehensively examines the application of hydro wave tidal undersea current and geothermal energy sources of Canada for green hydrogen fuel production. The estimated potential capacity of each province is derived from official data and acceptable assumptions and is subject to discussion and evaluation in the context of a viable hydrogen economy. According to the findings the potential for green hydrogen generation in Canada is projected to be 48.86 megatons. The economic value of the produced green hydrogen results in an equivalent of 21.30 billion US$. The top three provinces with the highest green hydrogen production potential using hydro resources including hydro wave tidal undersea current and geothermal are Alberta Quebec and British Columbia with 26.13 Mt 7.34 Mt and 4.39 Mt respectively. Quebec is ranked first by only considering the marine sources including 4.14 Mt with hydro 1.46 Mt with wave 0.27 Mt underwater current and 1.45 Mt with tidal respectively. Alberta is listed as the province with the highest capacity for hydrogen production from geothermal energy amounting up to 26.09 Mt. The primary objective is to provide comprehensive hydrogen maps for each province in Canada which will be based on the identified renewable energy potential and the utilization of electrolysers. This may further be examined within the framework of the prevailing policies implemented by local communities and officials in order to develop a sustainable energy plan for the nation.

One of the emerging and environmentally friendly technologies is the photoelectrochemical generation of green hydrogen; however the cheap cost of production and the need for customizing photoelectrode properties are thought to be the main obstacles to the widespread adoption of this technology. The primary players in hydrogen production by photoelectrochemical (PEC) water splitting which is becoming more common on a worldwide basis are solar renewable energy and widely available metal oxide based PEC electrodes. This study attempts to prepare nanoparticulate and nanorod-arrayed films to better understand how nanomorphology can impact structural optical and PEC hydrogen production efficiency as well as electrode stability. Chemical bath deposition (CBD) and spray pyrolysis are used to create ZnO nanostructured photoelectrodes. Various characterization methods are used to investigate morphologies structures elemental analysis and optical characteristics. The crystallite size of the wurtzite hexagonal nanorod arrayed film was 100.8 nm for the (002) orientation while the crystallite size of nanoparticulate ZnO was 42.1 nm for the favored (101) orientation. The lowest dislocation values for (101) nanoparticulate orientation and (002) nanorod orientation are 5.6 × 10−4 and 1.0 × 10−4 dislocation/nm2 respectively. By changing the surface morphology from nanoparticulate to hexagonal nanorod arrangement the band gap is decreased to 2.99 eV. Under white and monochromatic light irradiation the PEC generation of H2 is investigated using the proposed photoelectrodes. The solar-to-hydrogen conversion rate of ZnO nanorod-arrayed electrodes was 3.72% and 3.12% respectively under 390 and 405 nm monochromatic light which is higher than previously reported values for other ZnO nanostructures. The output H2 generation rates for white light and 390 nm monochromatic illuminations were 28.43 and 26.11 mmol.h−1 cm−2 respectively. The nanorod-arrayed photoelectrode retains 96.6% of its original photocurrent after 10 reusability cycles compared to 87.4% for the nanoparticulate ZnO photoelectrode. The computation of conversion efficiencies H2 output rates Tafel slope and corrosion current as well as the application of low-cost design methods for the photoelectrodes show how the nanorod-arrayed morphology offers low-cost high-quality PEC performance and durability.

The transport sector heavily relies on the use of fossil fuels which are causing major environmental concerns. Solutions relying on the direct or indirect use of electricity through efuel production are emerging to power the transport sector. To ensure environmental benefits are achieved over this transition an accurate estimation of the impact of the use of electricity is needed. This requires a high temporal resolution to capture the high variability of electricity. This paper presents a previously unseen temporal analysis of the carbon intensity of e-fuels using grid electricity in countries that are members of the European Network of Transmission System Operators (ENTSO-E). It also provides an estimation of the potential load factor for producing low-carbon e-fuels according to the European Union legislative framework. This was achieved by building on top of the existing EcoDynElec tool to develop EcoDynElec_xr a python tool enabling—with an hourly time resolution—the calculation visualisation and analysis of the historical time-series of electricity mixing from the ENTSO-E. The results highlight that in 2023 very few European countries were reaching low carbon intensity for electricity that enables the use of grid electricity for the production of green electrolytic hydrogen. The methodological assumptions consider the consumption of the electricity mix instead of the production mix and the considered time step is of paramount importance and drastically impacts the potential load factor of green hydrogen production. The developed tools are released under an open-source license to ensure transparency result reproducibility and reuse regarding newer data for other territories or for other purposes.

Today the hydrogen is considered an essential element in speeding up the energy transition and generate important environmental benefits. Not all hydrogen is the same though. The “green hydrogen” which is produced using renewable energy and electrolysis to split water is really and completely sustainable for stationary and mobile applications. This paper is focused on the techno-economic analysis of an on-site hydrogen refueling station (HRS) in which the green hydrogen production is assured by a PV plant that supplies electricity to an alkaline electrolyzer. The hydrogen is stored in low pressure tanks (200 bar) and then is compressed at 900 bar for refueling FCHVs by using the innovative technology of the ionic compressor. From technical point of view the components of the HRS have been sized for assuring a maximum capacity of 450 kg/day. In particular the PV plant (installed in the south of Italy) has a size of 8MWp and supplies an alkaline electrolyzer of 2.1 MW. A Li-ion battery system (size 3.5 MWh) is used to store the electricity surplus and the grid-connection of the PV plant allows to export the electricity excess that cannot be stored in the battery system. The economic analysis has been performed by estimating the levelized cost of hydrogen (LCOH) that is an important economic indicator based on the evaluation of investment operational & maintenance and replacement costs. Results highlighted that the proposed on-site configuration in which the green hydrogen production is assured is characterized by a LCOH of 10.71 €/kg.

A holistic approach to decision-making in modern energy systems is vital due to their increase in complexity and interconnectedness. However decision makers often rely on narrowlyfocused strategies such as economic assessments for energy system strategy selection. The approach in this paper helps considers various factors such as economic viability technological feasibility environmental impact and social acceptance. By integrating these diverse elements decision makers can identify more economically feasible sustainable and resilient energy strategies. While existing focused approaches are valuable since they provide clear metrics of a potential solution (e.g. an economic measure of profitability) they do not offer the much needed system-as-a-whole understanding. This lack of understanding often leads to selecting suboptimal or unfeasible solutions which is often discovered much later in the process when a change may not be possible. This paper presents a novel evaluation framework to support holistic decision-making in energy systems. The framework is based on a systems thinking approach applied through systems engineering principles and model-based systems engineering tools coupled with a multicriteria decision analysis approach. The systems engineering approach guides the development of feasible solutions for novel energy systems and the multicriteria decision analysis is used for a systematic evaluation of available strategies and objective selection of the best solution. The proposed framework enables holistic multidisciplinary and objective evaluations of solutions and strategies for energy systems clearly demonstrates the pros and cons of available options and supports knowledge collection and retention to be used for a different scenario or context. The framework is demonstrated in case study evaluation solutions for a novel energy system of clean hydrogen generation.

The exploration of green energy is a demanding issue due to climate change and ecology. Green energy hydrogen is gaining importance in the area of alternative energy sources. Many methods are being explored for this but most of them are utilizing other sources of energy to produce hydrogen. Therefore these approaches are not economic and acceptable at the industrial level. Sunlight and nuclear radiation as free or low-cost energy sources to split water for hydrogen. These methods are gaining importance in recent times. Therefore attempts are made to explore the latest updates in direct radiation water-splitting methods of hydrogen production. This article discusses the advances made in green hydrogen production by water splitting using visible and UV radiations as these are freely available in the solar spectrum. Besides water splitting by gamma radiation (a low-cost energy source) is also reviewed. Eforts are also made to describe the water-splitting mechanism in photo- and gamma-mediated water splitting. In addition to these challenges and future perspectives have also been discussed to make this article useful for further advanced research.

Securing decarbonized economies for energy and commodities will requireabundant and widely available green H2. Ubiquitous wastewaters and nontraditional watersources could potentially feed water electrolyzers to produce this green hydrogen withoutcompeting with drinking water sources. Herein we show that the energy and costs of treatingnontraditional water sources such as municipal wastewater industrial and resource extractionwastewater and seawater are negligible with respect to those for water electrolysis. We alsoillustrate that the potential hydrogen energy that could be mined from these sources is vast.Based on these findings we evaluate the implications of small-scale distributed waterelectrolysis using disperse nontraditional water sources. Techno-economic analysis and lifecycle analysis reveal that the significant contribution of H2 transportation to costs and CO2emissions results in an optimal levelized cost of hydrogen at small- to moderate-scale waterelectrolyzer size. The implications of utilizing nontraditional water sources and decentralizedor stranded renewable energy for distributed water electrolysis are highlighted for severalhydrogen energy storage and chemical feedstock applications. Finally we discuss challengesand opportunities for mining H2 from nontraditional water sources to achieve resilient and sustainable economies for water andenergy.

The global economic growth the increase in thepopulation and advances in technology lead to an increment in theglobal primary energy demand. Considering that most of thisenergy is currently supplied by fossil fuels a considerable amountof greenhouse gases are emitted contributing to climate changewhich is the reason why the next European Union bindingagreement is focused on reducing carbon emissions usinghydrogen. This study reviews different technologies for hydrogenproduction using renewable and non-renewable resources.Furthermore a comparative analysis is performed on renewable-based technologies to evaluate which technologies are economically and energetically more promising. The results show howbiomass-based technologies allow for a similar hydrogen yield compared to those obtained with water-based technologies but withhigher energy efficiencies and lower operational costs. More specifically biomass gasification and steam reforming obtained a properbalance between the studied parameters with gasification being the technique that allows for higher hydrogen yields while steamreforming is more energy-efficient. Nevertheless the application of hydrogen as the energy vector of the future requires both the useof renewable feedstocks with a sustainable energy source. This combination would potentially produce green hydrogen whilereducing carbon dioxide emissions limiting global climate change and thus achieving the so-called hydrogen economy.

This paper presents a comprehensive safety assessment of hydrogen production using Alkaline Water Electrolysis (AWE). The study utilizes various risk assessment methodologies including Hazard Identification (HAZID) What-If analysis Fault Tree Analysis (FTA) Event Tree Analysis (ETA) and Bow Tie analysis to systematically identify and evaluate potential hazards associated with the AWE process. Key findings include the identification of critical hazards such as hydrogen leaks oxygen-related risks and maintenance challenges. The assessment emphasizes the importance of robust safety measures including preventive and mitigative strategies to manage these risks effectively. Consequence modeling highlights significant threat zones for thermal radiation and explosion risks underscoring the need for comprehensive safety protocols and emergency response plans. This work contributes valuable insights into hydrogen safety providing a framework for risk assessment and mitigation in hydrogen production facilities crucial for the safe and sustainable development of hydrogen infrastructure in the global energy transition.

Integration of polymer electrolyte membrane water electrolyzers (PEMWEs) for clean hydrogen generation requires a robust understanding of the impact cell designs and conditioning protocols have on operation and stability. Here catalyst-coated electrode and catalyst-coated membrane cells employing Pt/C cathode catalyst layer an IrO2 anode catalyst layer with a platinized titanium mesh or a carbon paper with a microporous layer as the porous transport layer were developed. The impact of cell conditioning above and below 0.25 A cm− 2 was investigated using advanced electrochemical impedance spectroscopy analyses and microscopic imaging with the electrochemical response related to physicochemical processes. Operation below 0.25 A cm− 2 prior to operation above 0.25 A cm− 2 resulted in anode corrosion and titanium cation contamination increasing the cell voltage at 1 A cm− 2 by 200 mV compared to uncontaminated cells. Conditioning above 0.25 A cm− 2 led to nonnegligible hydrogen transport resistances due to cathode flooding that resulted in a ca. 50 mV contribution at 1 A cm− 2 and convoluted with the anode impedance response. The presence of a microporous layer increased catalyst utilization but increased the cell voltage by 300 mV at 1 A cm− 2 due to increased anodic mass transport resistances. These results yield critical insights into the impact of PEMWE cell design and operation on corresponding cell performance and stability while highlighting the need for application dependent standardized operating protocols and operational windows.

Billions of litres of wastewater are produced daily from domestic and industrial areas and whilst wastewater is often perceived as a problem it has the potential to be viewed as a rich source for resources and energy. Wastewater contains between four and five times more energy than is required to treat it and is a potential source of bio-hydrogen—a clean energy vector a feedstock chemical and a fuel widely recognised to have a role in the decarbonisation of the future energy system. This paper investigates sustainable low-energy intensive routes for hydrogen production from wastewater critically analysing five technologies namely photo-fermentation dark fermentation photocatalysis microbial photo electrochemical processes and microbial electrolysis cells (MECs). The paper compares key parameters influencing H2 production yield such as pH temperature and reactor design summarises the state of the art in each area and highlights the scale-up technical challenges. In addition to H2 production these processes can be used for partial wastewater remediation providing at least 45% reduction in chemical oxygen demand (COD) and are suitable for integration into existing wastewater treatment plants. Key advancements in lab-based research are included highlighting the potential for each technology to contribute to the development of clean energy. Whilst there have been efforts to scale dark fermentation electro and photo chemical technologies are still at the early stages of development (Technology Readiness Levels below 4); therefore pilot plants and demonstrators sited at wastewater treatment facilities are needed to assess commercial viability. As such a multidisciplinary approach is needed to overcome the current barriers to implementation integrating expertise in engineering chemistry and microbiology with the commercial experience of both water and energy sectors. The review concludes by highlighting MECs as a promising technology due to excellent system modularity good hydrogen yield (3.6–7.9 L/L/d from synthetic wastewater) and the potential to remove up to 80% COD from influent streams.

Until recently electrified aircraft propulsion (EAP) technology development has been driven by the dual objectives of reducing greenhouse gas (GHG) emissions and addressing the depletion of fossil fuels. However the increasing severity of climate change posing a significant threat to all life forms has resulted in the global consensus of achieving net-zero GHG emissions by 2050. This major shift has alerted the aviation electrification industry to consider the following: What is the clear path forward for EAP technology development to support the net-zero GHG goals for large commercial transport aviation? The purpose of this paper is to answer this question. After identifying four types of GHG emissions that should be used as metrics to measure the effectiveness of each technology for GHG reduction the paper presents three significant categories of GHG reduction efforts regarding the engine evaluates the potential of EAP technologies within each category as well as combinations of technologies among the different categories using the identified metrics and thus determines the path forward to support the net-zero GHG objective. Specifically the paper underscores the need for the aviation electrification industry to adapt adjust and integrate its EAP technology development into the emerging new engine classes. These innovations and collaborations are crucial to accelerate net-zero GHG efforts effectively.

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.