Publications

A new type of hydrogen produced in situ in petroleum reservoirs is proposed. This technology is based on ex situ catalytic gasification of biomass combining two thermal enhanced oil recovery techniques currently used in industrial fields: cyclic steam stimulation and in situ combustion. This hydrogen named “light-blue hydrogen” is produced in reservoirs like naturally occurring white hydrogen and from fossil fuels like blue hydrogen. The color light blue results from the blending of white and blue. This approach is particularly suitable for mature petroleum reservoirs which are in the final stages of production or no longer producing oil. This manuscript describes the method for producing light-blue hydrogen in situ its commercial application prospects and the challenges for developing and scaling up this technology.

Hydrogen-based steelmaking using green hydrogen can achieve above 95 % CO2 emission reductions. Low-cost renewable electricity is a prerequisite and research has found that access to renewable energy resources could pull energy-intensive industry to new locations the “renewables pull”-effect. However previous studies on hydrogen-based steel differ on key assumptions and analyse a wide range of energy costs (10–105 EUR/MWh) making conclusions hard to compare. In this paper we assess techno-economic and strategic drivers for and against such a pull-effect by calculating the levelized cost of green hydrogen-based steel across five archetypical new value chain configurations. We find that the strength of the pull-effect is sensitive to assumptions and that the cost of hydrogen-based steel vary across geographies and value chain configurations to a similar degree as conventional steel. Other geographically varying factors such as labour costs can be as important for relocation and introducing globally varying cost of capital moderates the effect. The renewables pull effect can enable faster access to low-cost renewables and export of green iron ore is an important option to consider. However it is not clear how strong a driver the pull-effect will actually be compared to other factors and polices implemented for strategic reasons. A modest “strategic push“ implemented through various subsidies such as lowering the cost of hydrogen or capital will reduce the pull-effect. In addition focusing on the renewables pull effect as enabling condition risk slowing innovation and upscaling by 2030 in line with climate goals which is currently initiated in higher cost regions.

As one of the most promising clean energy sources hydrogen power has gradually emerged as a viable alternative to traditional energy sources. However hydrogen safety remains a significant concern due to the potential for explosions and the associated risks. This review systematically examines hydrogen explosions with a focus on high-pressure and low-temperature storage transportation and usage processes mostly based on the published papers from 2020. The fundamental principles of hydrogen explosions classifications and analysis methods including experimental testing and numerical simulations are explored. Key factors influencing hydrogen explosions are also discussed. The safety issues of hydrogen power on railway applications are focused and finally recommendations are provided for the safe application of hydrogen power in railway transportation particularly for long-distance travel and heavy-duty freight trains with an emphasis on storage safety considerations.

Methane cracking (MC) is emerging as a low-carbon hydrogen production technology. This review conducts a comprehensive bibliometric analysis of 46 studies examining the sustainability of MC process. The review employs Life Cycle Assessment (LCA) Life Cycle Cost (LCC) Techno-Economic Analysis (TEA) and Social Life Cycle Assessment (SLCA) methodologies. The findings reveal that LCOH for MC technologies ranges from 0.9 to 6.6 $/kg H2 at the same time GHG emissions span 0.8–14.5 kg CO2eq/kg H2 depending on the specific reactor configurations plant geographical locations and carbon revenues. These results indicate that MC can be competitive with steam methane reforming with carbon capture and electrolysis under certain conditions. However the review identifies significant research gaps including limited comprehensive LCA studies a lack of social impact assessments insufficient environmental impact analysis of molten media catalysts and particulate matter formation in MC processes as well as insufficient analysis of the potential of biomethane cracking.

The large-scale utilization of hydrogen energy is currently hindered by challenges in lowcost production storage and transportation. This study focused on investigating the impact of the diaphragm cavity profile on the movement behavior and stress distribution of a dual-stage diaphragm compressor. Firstly an experimental platform was established to test the gas mass flowrate and fluid pressures under various preset conditions. Secondly a simulation path integrating the finite element method simulation theoretical stress model and movement model was developed and experimentally validated to analyze the diaphragm stress distribution and deformation characteristics. Finally comparative optimization analyses were conducted on different types of diaphragm cavity profiles. The results indicated that the driving pressure differences at the top dead center position reached 85.58 kPa for the first-stage diaphragm and 75.49 kPa for the second-stage diaphragm. Under experimental conditions of 1.6 MPa suction pressure 8 MPa second-stage discharge pressure and 200 rpm rotational speed the first-stage and second-stage diaphragms reached the maximum center deflections of 4.14 mm and 2.53 mm respectively at the bottom dead center position. Moreover the cavity profile optimization analysis indicated that the double-arc profile (DAP) achieved better cavity volume and diaphragm stress characteristics. The first-stage diaphragm within the optimized DAP-type cavity exhibited 173.95 MPa maximum principal stress with a swept volume of 0.001129 m3 whereas the second-stage optimized configuration reached 172.57 MPa stress with a swept volume of 0.0003835 m3 . This research offers valuable insights for enhancing the reliability and performance of diaphragm compressors.

Rail transit as a high-energy consumption field urgently requires the adoption of clean energy innovations to reduce energy consumption and accelerate the transition to new energy applications. As an energy-saving fluid machinery the ejector exhibits significant application potential and academic value within this field. This paper reviewed the recent advances technical challenges research hotspots and future development directions of ejector applications in rail transit aiming to address gaps in existing reviews. (1) In waste heat recovery exhaust heat is utilized for propulsion in vehicle ejector refrigeration air conditioning systems resulting in energy consumption being reduced by 12~17%. (2) In vehicle pneumatic pressure reduction systems the throttle valve is replaced with an ejector leading to an output power increase of more than 13% and providing support for zero-emission new energy vehicle applications. (3) In hydrogen supply systems hydrogen recirculation efficiency exceeding 68.5% is achieved in fuel cells using multi-nozzle ejector technology. (4) Ejector-based active flow control enables precise ± 20 N dynamic pantograph lift adjustment at 300 km/h. However current research still faces challenges including the tendency toward subcritical mode in fixed geometry ejectors under variable operating conditions scarcity of application data for global warming potential refrigerants insufficient stability of hydrogen recycling under wide power output ranges and thermodynamic irreversibility causing turbulence loss. To address these issues future efforts should focus on developing dynamic intelligent control technology based on machine learning designing adjustable nozzles and other structural innovations optimizing multi-system efficiency through hybrid architectures and investigating global warming potential refrigerants. These strategies will facilitate the evolution of ejector technology toward greater intelligence and efficiency thereby supporting the green transformation and energy conservation objectives of rail transit.

Lead–acid batteries are widely used in modern battery-powered ships. During the charging process of lead–acid batteries hydrogen gas is released which poses a potential hazard to ship safety. To address this this paper first establishes a turbulent flow model for hydrogen deflagration. Then using FDS6.7.9 software simulations of hydrogen deflagration are conducted and a simulation model of the ship’s cabin is constructed. The changes in temperature and pressure during the hydrogen deflagration process in the ship’s cabin are analyzed and the evolution process of hydrogen deflagration in the ship’s cabin is derived. Hydrogen deflagration poses a significant threat to the fire safety of battery-powered ships. Additionally a comparative analysis of hydrogen deflagration under different hydrogen concentrations is performed. It is concluded that battery-powered ships using lead–acid batteries should pay attention to controlling the hydrogen concentration below 4%.

Hydrogen is an abundant element and a flexible energy carrier offering substantial potential as an environmentally friendly energy source to tackle global energy issues. When used as a fuel hydrogen generates only water vapor upon combustion or in fuel cells presenting a means to reduce carbon emissions in various sectors including transportation industry and power generation. Nevertheless conventional hydrogen production methods often depend on fossil fuels leading to carbon emissions unless integrated with carbon capture and storage solutions. Conversely green hydrogen is generated through electrolysis powered by renewable energy sources like solar and wind energy. This production method guarantees zero carbon emissions throughout the hydrogen’s lifecycle positioning it as a critical component of global sustainable energy transitions. In Africa where there are extensive renewable energy resources such as solar and wind power green hydrogen is emerging as a viable solution to sustainably address the increasing energy demands. This research explores the influence of policy frameworks technological innovations and market forces in promoting green hydrogen adoption across Africa. Despite growing investments and favorable policies challenges such as high production costs and inadequate infrastructure significantly hinder widespread adoption. To overcome these challenges and speed up the shift towards a sustainable hydrogen economy in Africa strategic investments and collaborative efforts are essential. By harnessing its renewable energy potential and establishing strong policy frameworks Africa can not only fulfill its energy requirements but also support global initiatives to mitigate climate change and achieve sustainable development objectives.

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.

Climate policy will inevitably lead to the stranding of fossil energy assets such as production and transport assets for coal oil and natural gas. Resourcerich developing countries are particularly aected as they have a higher risk of asset stranding due to strong fossil dependencies and wider societal consequences beyond revenue disruption. However there is only little academic and political awareness of the challenge to manage the asset stranding in these countries as research on transition risk like asset stranding is still in its infancy. We provide a research framework to identify wider societal consequences of fossil asset stranding. We apply it to a case study of Nigeria. Analyzing dierent policy measures we argue that compensation payments come with implementation challenges. Instead of one policy alone to address asset stranding a problem-oriented mix of policies is needed. Renewable hydrogen and just energy transition partnerships can be a contribution to economic development and SDGs. However they can only unfold their potential if fair benefit sharing and an improvement to the typical institutional problems in resource-rich countries such as the lack of rule of law are achieved. We conclude with presenting a future research agenda for the global community and acade