Publications

Hydrogen-diesel dual direct-injection (H2DDI) engines present a promising pathway towards cleaner and more efficient transportation. In this study hydrogen split injection strategies were explored in an automotive-size single-cylinder compression ignition (CI) engine with a focus on varying the injection timings and energy fractions. The engine was operated at an intermediate load with fixed combustion phasing through adjustments of pilot diesel injection timing. An energy substitution principle guided the variation in energy fraction between the two hydrogen injections and then diesel injection while keeping the total energy input constant. The findings demonstrate that early first hydrogen injection timings lead to characteristics indicative of premixed combustion reflecting a high homogeneity of the hydrogen-air mixture. In contrast hydrogen stratification levels were predominantly influenced by later second injection timings with mixing-controlled combustion behaviour apparent for very late injections near top dead centre or when the second hydrogen injection held high energy fractions which led to decreased nitrogen oxides (NOx: NO and NO2) emissions. The carbon dioxide (CO2) emissions did not show high sensitivity to the hydrogen split injection strategies exhibiting about 77 % reduction compared to the diesel baseline due primarily to increased hydrogen energy fraction of up to 90 %

Pursuing net-zero emission operations in the shipping industry are quintessential for this sector to mitigate the environmental impact caused by hydrocarbon fuel combustion. Significant contributions to this are expected from the substitution of conventional marine fuels by alternative emission-free fuels with lower emission footprints. This study aims to conduct a comprehensive literature review for delineating the main characteristics of the considered alternative fuels specifically focusing on hydrogen methanol and ammonia which have recently attracted attention from both industry and academia. This study comparatively assesses the potential of using these fuels in marine engines and their subsequent performance characteristics as well as the associated environmental benefits. In addition the required storage conditions space as well as the associated costs are reviewed. Special attention is given to the safety characteristics and requirements for each alternative fuel. The results of this study demonstrate that the environmental benefits gained from alternative fuel use are pronounced only when renewable energy is considerably exploited for their production whereas the feasibility of each fuel depends on the vessel type used and pertinent storage constraints. Hydrogen ammonia and methanol are considered best-fit solutions for small scale shipping requiring minimal on-board storage. In addition the need for comparative assessments between diesel and alternative fuels is highlighted and sheds light on marine engines’ operational characteristics. Moreover using combinations of alternative and diesel fuels is identified as a direction towards decarbonisation of the maritime sector; intensifying the need for optimisation studies on marine engine design and operation. This study concludes with recommendations for future research directions thus contributing to fuel research concepts that can facilitate the shipboard use of alternative fuels.

Liquid hydrogen (LH2) aircraft have the potential to achieve carbon neutrality. However if the hydrogen is produced using electricity grids that utilise fossil fuel they have a non-zero carbon dioxide (CO2) emission associated with their well-to-wing pathway. To assess the potential of LH2 in aviation decarbonisation an energy systems comparison of large commercial LH2 liquified natural gas (LNG) conventional Jet-A and LH2 dual-fuel aircraft is presented. The performance of each aircraft is compared towards 2050 over which three system changes occur: (1) LH2 aircraft technology develops; (2) both world average and region-specific grid electricity which is used to produce the hydrogen decarbonises; and (3) the International Air Transportation Association (IATA) emissions targets which are used to restrict the passenger-range performance of each aircraft tighten. In 2050 the emissions of all aircraft are thus constrained to 0.063 kg-CO2/p-km relative to 0.110 kg-CO2/p-km for the unconstrained Jet A fuelled Boeing 787-8. It is estimated that in this year an LH2 aircraft powered by fuel cells and sourcing world average electricity can travel 6000 km 20% further than the conventional Jet A aircraft that is also constrained to meet the IATA targets but not as far as the LNG aircraft. At its maximum range the LH2 aircraft carries 84% of the Jet A passenger demand. Analysis using region-specific hydrogen indicates that LH2 aircraft can travel further than LNG aircraft in North America only accounting for 17% of the global demand. 1.59 times the current aviation energy consumption is required if all conventional aircraft are replaced with LH2 designs. Under stricter emissions constraints than those outlined by the IATA LH2 outperforms LNG in Europe and the Americas accounting for 41% of the global demand. Also in these regions the range energy consumption and passenger capacity of LH2 aircraft can be improved upon by combining the advantages of LH2 with LNG in dual-fuel aircraft concepts. The use of LH2 is therefore advantageous within several prominent niches of a future decarbonising aviation system.

Alkaline electrolysis is already a proven technology on land with a high maturity level and good economic performance. However at sea little is known about its economic performance toward hydrogen production. Alkaline electrolysis units operate with purified water to split its molecules into hydrogen and oxygen. Purified water and especially that sourced from the sea has a variable cost that ultimately depends on its quality. However the impurities present in that purified water have a deleterious effect on the electrolyte of alkaline electrolysis units that cause them to drop their energy efficiency. This in turn implies a source of economic losses resulting from the cost of electricity. In addition at sea there are various options regarding the electrolyte management of which the cost depends on various factors. All these factors ultimately impact on the levelized cost of the produced hydrogen. This article aims to shed some light on the economic performance of alkaline electrolysis units operating under sea conditions highlighting the knowledge gaps in the literature and initiating a debate in the field.

In view of the GHG reduction targets to be met Brazilian researchers are looking for cleaner alternatives to energy sources. These alternatives are primarily to be applied in the transport sector which presents high energy consumption as well as high CO2 emissions. In this sense this research developed an LCI study considering two bus alternatives for the city of Rio de Janeiro: diesel-powered internal combustion buses (ICEB) and a hydrogen-powered polymer fuel cell hybrid bus (FCHB). For the FCHB three hydrogen production methods were also included: water electrolysis (WE) ethanol steam reforming (ESR) and natural gas steam reforming (NGSR). The research was aimed at estimating energy consumption including the percentage of energy that is renewable as well as CO2 emissions. The results show diesel as the energy source with the highest emissions as well as the highest fossil energy consumption. Regarding the alternatives for hydrogen production water electrolysis stood out with the lowest emissions.

The member countries of the European Union (EU) have prioritized the incorporation of hydrogen as a key component of their energy objectives. As the world moves towards reducing its dependence on fossil fuels alternative sources of energy have gained prominence. With the growing development of Fuel Cell Electric Vehicles (FCEVs) the establishment of an infrastructure for hydrogen production and the creation of a network of service stations have become essential. This article’s purpose is to conduct a methodical review of literature regarding the use of green hydrogen for transportation and the planning of imperative infrastructure in the territory of the EU specifically Hydrogen Refueling Stations (HRS). In order to increase the acceptance of fuel cell vehicles a comprehensive network of hydrogen refueling stations (HRS) must be built that enable drivers to refuel their vehicles quickly and easily similar to gasoline or diesel vehicles. The literature review on this topic was conducted using the Web of Science database (WOS) with a variety of search terms proposed to cover all the key components of green hydrogen production and refueling infrastructure. The implementation of HRS powered by renewable energy sources is an important step in the adoption of fuel cell vehicles and overcoming the obstacles that come with their implementation will require cooperation and innovation from governments private businesses and other stakeholders.

Shifting from fossil fuels to clean alternative fuel options such as hydrogen is an essential step in decarbonising the road freight transport sector and facilitating an efficient transition towards zero-emissions goods distribution of the future. Designing an economically viable and competitive Hydrogen Supply Chain (HSC) to support and accelerate the widespread adoption of hydrogen powered Heavy Goods Vehicles (H2-HGVs) is however significantly hindered by the lack of the infrastructure required for producing storing transporting and distributing the required hydrogen. This paper focuses on a bespoke design of a hydrogen supply chain and distribution network for the long-haul road freight transportation in the UK and develops an improved end-to-end and spatially-explicit optimisation tool to perform scenario analysis and provide important first-hand managerial and policy making insights. The proposed methodology improves over existing grid-based methodologies by incorporating spatially-explicit locations of Hydrogen Refuelling Stations (HRSs) and allowing further flexibility and accuracy. Another distinctive feature of the method and the analyses carried out in the paper pertains to the inclusion of bulk geographically agnostic as well as geological underground hydrogen storage options and reporting on significant cost saving opportunities. Finally the curve for H2-HGVs penetration levels safety stock period decisions and the transport mode capacity against hydrogen levelized cost at pump have been generated as important policy making tools to provide decision support and insights into cost resilience and reliability of the HSC.

Purpose: The policy module of the FCHO presents an overview of EU and national policies across various hydrogen and fuel cell related sectors. It provides a snapshot of the current state of hydrogen legislation and policy. https://www.fchobservatory.eu/observatory/policy-and-rcs/eu-policies https://www.fchobservatory.eu/index.php/observatory/policy-and-rcs/nationalpolicies Scope: While FCHO covers 38 entities around the world due to the unavailability of some data at the time of writing this report covers 34 entities. The report reflects data collected January 2021 – May 2021. Key Findings: Hydrogen policies are relatively commonplace among European countries but with large differences between Member States. EU hydrogen leaders do not lag behind global outliers such as South Korea or Japan.

Purpose: The standards module of the FCHO presents a large number of standards relevant for the deployment of hydrogen and fuel cells. The standards are categorized per application enhancing ease of access and findability. The development of sector-relevant standards facilitate and enhance economies of scale interoperability comparability safety and many other issues. https://www.fchobservatory.eu/observatory/Policy-and-RCS/Standards Scope: This report presents the developments in European and international standards for the year 2020.Standards from the following standards developing organizations are included: CEN CENELEC ISO IEC OIML. Key Findings: The development of sector relevant standards on an international level continued to grow in 2020; on a European level many standards are still in the process of being drafted. In 2020 12 new standards have been published mainly on the subject of fuel cell technologies. The recently established committee CEN-CLC JTC 6 (Hydrogen in energy systems) has not published standards yet but is working on drafting standards on for example Guarantees of Origin. Previous Reports The first report was published in September 2020. This report is the 2nd Annual report.

This paper provides a comprehensive overview of the physical properties and applications of natural gas (NG) and hydrogen as fuels in internal combustion (IC) engines. The paper also meticulously examines the use of both NG and hydrogen as a fuel in vehicles their production physical characteristics and combustion properties. It reviews the current experimental studies in the literature and investigates the results of using both fuels. It further covers the challenges associated with injectors needle valves lubrication spark plugs and safety requirements for both fuels. Finally the challenges related to the storage production and safety of both fuels are also discussed. The literature review reveals that NG in spark ignition (SI) engines has a clear and direct positive impact on fuel economy and certain emissions notably reducing CO2 and non-methane hydrocarbons. However its effect on other emissions such as unburnt hydrocarbons (UHC) nitrogen oxides (NOx) and carbon monoxide (CO) is less clear. NG which is primarily methane has a lower carbon-to-hydrogen ratio than diesel fuel resulting in lower CO2 emissions per unit of energy released. In contrast hydrogen is particularly well-suited for use in gasoline engines due to its high self-ignition temperature. While increasing the hydrogen content of NG engines reduces torque and power output higher hydrogen input results in reduced fuel consumption and the mitigation of toxic exhaust emissions. Due to its high ignition temperature hydrogen is not inherently suitable for direct use in diesel engines necessitating the exploration of alternative methods for hydrogen introduction into the cylinder. The literature review suggests that hydrogen in diesel engines has shown a reduction in specific exhaust emissions and fuel consumption and an increase in NOx emissions. Overall the paper provides a valuable and informative overview of the challenges and opportunities associated with using hydrogen and NG as fuels in IC engines. It highlights the need for further research and development to address the remaining challenges such as the development of more efficient combustion chambers and the reduction of NOx emissions.