Liquid Hydrogen Fuels Research Articles

A Comprehensive Review on Material Compatibility and Safety Standards for Liquid Hydrogen Cargo and Fuel Containment Systems in Marine Applications

As the maritime industry’s emphasis on sustainable fuels has increased, liquid hydrogen (LH2) has emerged as a promising alternative due to its high energy density and zero-emission characteristics. While the experience of using natural gas in ships can serve as a basis for the introduction of hydrogen, the different risks associated with the two fuels must also be considered. This review article provides a methodology for selecting suitable metal materials for shipboard LH2 storage and piping systems based on operational requirements. The effects of both liquid and gaseous hydrogen environments on metal materials are first comprehensively reviewed. The minimum requirements for metal materials in liquefied natural gas (LNG) storage systems, as stipulated in the IGC and IGF codes, were used as a baseline to establish minimum requirements for liquid hydrogen. The applicability of austenitic stainless steel, a representative metal material for cryogenic use, to a liquid hydrogen environment according to nickel content was examined. In order to apply liquid hydrogen to the marine environment, the minimum requirements for liquid hydrogen were organized based on the minimum requirements for metal materials in the LNG storage system covered by the IGC and IGF codes. Finally, to expand the material selection criteria for low-temperature cargo and fuel storage facilities at sea, slow strain tensile testing, fatigue life, and fracture toughness considering the hydrogen environment and cryogenic temperature were derived as evaluation items.

Estimation of Liquid Hydrogen Fuels in Aviation

As the demand for alternative fuels to solve environmental problems increases worldwide due to the greenhouse gas problem, this study predicted the demand for liquid hydrogen fuel in aviation to achieve ‘zero-emission flight’. The liquid hydrogen fuel models of an aircraft and all aviation sectors were produced based on the prediction of aviation fleet growth through the classification of currently operated aircraft. Using these models, the required amount of liquid hydrogen fuel and the total cost of liquid hydrogen were also calculated when various environmental regulations were satisfied. As a result, it was found to be necessary to convert approximately 66% to 100% of all aircraft from existing aircraft to liquid hydrogen aircraft in 2050, according to regulations. The annual liquid hydrogen cost was 4.7–5.2 times higher in the beginning due to the high production cost, but after 2030, it will be maintained at almost the same price, and it was found that the cost was rather low compared to jet fuel.

Integrated Fischer-Tropsch synthesis process with hydrogen liquefaction cycle

The increasing need of humans for energy and the limited resources of fossil fuels require too much attention to replacing renewable energies with the energies from fossil fuels. Hydrogen is one of the most significant renewable energies. Liquefaction is used for storing and transferring this fuel to other areas. Waste heat can be used in other integrated structures at the time of liquefying hydrogen. In this study, an integrated structure was developed for the simultaneous production of liquid hydrogen (LH2) and liquid fuels (LF) using electrolyzer, hydrogen liquefaction cycle, Fischer-Tropsch synthesis, and carbon dioxide power cycle. The integrated structure produced 1.157 kg/s liquid hydrogen, 3.756 kg/s liquid fuels, and 359.8 kg/s hot water. The natural gas to liquid (GTL) process was developed by absorbing the steam generated from the waste thermal energy of the liquid hydrogen production cycle, the oxygen produced by the electrolyzer, and natural gas in the reforming reactors and the Fischer-Tropsch synthesis. The GTL process was highly exothermic and the released energy from the liquid fuel production was used for power production. The specific power consumption of the hydrogen liquefaction cycle was 6.642 kWh/kg LH2. The power to fuel and exergy efficiencies of the integrated structure were 83.75% and 62.54%. The exergy analysis of integrated structure indicated that electrolyzers with a share of 48.05% and reactors with a share of 15.16% had the maximum amount of exergy destruction. The results of the economic analysis of the system depict that the period of return and additive value were 3.581 years and 71.39 $/m3 LF.

Exploring cost-effective transitions to fossil independent transportation in the future energy system of Denmark

In this paper, in the light of national targets of a fossil independent future Danish energy system, cost-effective deep decarbonisation solutions in transportation have been explored under base-, alternative technical-, and policy scenarios in the TIMES modelling environment. The TIMES-DK model was further developed to concurrently represent all emerging transport technologies (ETTs) in road- and off-road transport applications, disaggregated transport technologies and service demands segmentation to capture consumers preferences and heterogeneity, and to endogenise fuel infrastructures. The model runs optimise the societal surplus in between 2010 and 2050. There is a particular focus on the role of gas in transport. The results reveal that in between 2020 and 2040, natural gas (NG) could cost-efficiently serve as a transition fuel. Decarbonisation pace and fuel infrastructure assumptions were found to have a large impact on the NG adoption levels. This study showed that the combined use of liquid biofuels (mainly biomethanol), upgraded biogas, electricity, and hydrogen fuels would deliver cost-effective deep decarbonisation by 2050; however, their various decarbonisation roles vary within and across transport segments. Depending on the decarbonisation pace, a marginal CO2 abatement cost of 419–549 €/ton (or 1–1.29 €/L gasoline) is required by 2050 in Denmark. The results also showed that 25% and 30% cost reductions of BEVs and hydrogen fuel cell vehicles (HFCVs), compared to our central cost assumptions, would increase their respective adoption by 36% and 66% towards 2050. They show high market shares particularly in the medium size segment than in the small and large segments. Competition for limited biomass resources coupled with higher fuel demand results in adoption of ETTs.

Design of a Helium Vapor Shroud for Liquid Hydrogen Fueling of an Unmanned Aerial Vehicle (UAV)

Filling a vehicular liquid hydrogen fuel tank presents the potential for flammable mixtures due to oxygen concentration from liquid air condensation. Current liquid hydrogen tank designs utilize insulating paradigms such as aerogel/fiberglass materials, vacuum jackets, or inert gas purge systems to keep the outer surface from reaching the condensation temperature of air. This work examines the heat transfer at the refuelling connection of the tank to identify potential areas of condensation, as well as the surface temperature gradient. A shrouded inert gas purge was designed to minimize vehicle weight and refuelling time. The design of a shrouded inert gas purge system is presented to displace air preventing air condensation. The design investigates 3D printed materials for an inert gas shroud, as well as low-temperature sealing designs. Shroud designs and temperature profiles were measured and tested by running liquid nitrogen through the filling manifold. Materials for the inert gas shroud are discussed and experimental results are compared to analytical model predictions. Suggestions for future design improvements are made.

An assessment of the potential of alternative fuels for “greening” commercial air transportation

This paper deals with an assessment of the potential of conventional (oil-kerosene) Jet-A1/8 and alternative synthetic & biomass-derived SPK (Synthetic Paraffinic Kerosene) and LH2 (Liquid Hydrogen) fuels for “greening” commercial air transportation through reducing its fuel consumption and related direct emissions of GHG (Green House Gases) in the medium- and long-term period of time. For such a purpose, the convenient analytical models for estimating this fuel consumption and corresponding direct emissions of GHG have been developed and applied according to “what-if” scenario approach. The results have shown that: i) Introducing the alternative SPK (F-T&HRJ) fuels fully (i.e., 100% replacement of Jet-A1/8 fuel) would bring only a marginal reduction of the cumulative direct emissions of CO2. Such reduction would not substantially contribute to achieving the globally agreed targets on reducing GHG emissions; and ii) Introducing the alternative LH2 fuel would almost immediately bring rather substantive reduction of the cumulative emissions of CO2. If such introduction started earlier, it would contribute to achieving the globally agreed targets on reducing emissions of GHG during given period.

Benefits and challenges of liquid hydrogen fuels in commercial aviation

Benefits and challenges of liquid hydrogen fuels in commercial aviation

Benefits and challenges of liquid hydrogen fuels in commercial aviation

This paper aims to highlight the opportunities and challenges associated with the adoption of hydrogen fuels in aviation. An overview of the environmental and economic benefits and technological challenges is presented. A simplified model is subsequently introduced to estimate the benefits of liquid hydrogen fuels in aircraft of conventional configurations, encompassing changes in volume, weights and environmental impacts. This paper concludes that hydrogen in cryogenic liquid form demonstrates great potential to become a highly sustainable commercial aviation fuel with lower emissions and less fuel mass for a given range, resulting in better economies. The presented numerical case study highlights that despite the worsened aerodynamic and structural characteristics, a take-off weight saving of more than 11% (small regional jet) and up to 25% (large wide-body aircraft) can be achieved when considering a liquid hydrogen retrofit of current generation jetliners. Unfortunately, the volume required by integral tanks prevents the translation of this weight saving in additional payload, but remarkable economic savings can be obtained. However, the implementation of this technology comes with many technical challenges, including the development of sustainable production, storage and delivery systems that shall not dilute the environmental benefits as well as widespread uptake to ensure financial sustainability.

Feasibility of Hydrogen Cooled Superconducting Magnets

It looks feasible to realize hydrogen cooled superconducting magnets with High Tc Superconductors (HTS) and newly discovered magnesium di-boride (MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). As is well known, liquid and slush hydrogen between 15~20 K, could be not only an excellent refrigerant for HTS and MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , but also a clean energy transporter without exhaust of carbon di-oxide. HTS cooled by liquid hydrogen at 22 K can carry as large as several times current at 77 K cooled by liquid nitrogen. These are reasons why liquid hydrogen is preferable for SMES refrigerant to liquid nitrogen. One of such possibilities, an emergent power supply composed with SMES, Liquid Hydrogen Storage, Fuel Cell and Lithium Battery is designed and proposed. As a practical example, the conceptual design of 200 MW, 10 hour emergency power supply is described

Energy generation from volcanic ground states. Application to cold He 22+

The lifetime of the ν=0 vibrational level of the volcanic He 2 2+ 1Σ g + state, which autodissociates to He + + He + fragments, has been calculated to be extremely long: 220 min. This finding, together with the high energy content of He 2 2+ and its small mass, offers the possibility of new physical and chemical reactions for the release of propulsive energies in the range 230-1000 kcal/mol, with specific impulses much larger than that of existing liquid hydrogen plus oxygen fuels. The observation of He 2 2+ via charge-stripping mass spectroscopy has been reported in the literature. Based on computed data, we propose alternative methods for its production involving collisional and radiative processes.