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The concept of the “hydrogen economy” was first coined by Prof. John Bockris during a talk he gave in 1970 at the General Motors Technical Center. Bockris’s talk introduced the vision of a world economy in which energy was carried in the form of hydrogen resulting in zero emissions at its point of use—be that as a chemical feedstock or as a fuel for industrial or domestic heating for power generation in a gas turbine or in a fuel cell “engine” for transport applications. Despite several waves of significant interest and investment however due to the relative costs and technological immaturity of hydrogen technologies the hydrogen economy was never delivered at scale nor was there sufficient motivation to create the technology needed to overcome these hurdles.<br/>But today as the world seeks to transition to a truly net-zero carbon economy hydrogen has returned to the fore as a key energy carrier—not as a hydrogen economy but as “hydrogen in the economy” synergistically working alongside low- to zero-carbon electricity to decarbonize those parts of the economy that are too expensive or too difficult to be directly decarbonized with electricity. These include:<br/>♦ Transport applications in which large amounts of energy are needed on the vehicle such as planes trains shipping long-distance trucks and heavy-duty vehicles;<br/>♦ Industrial applications such as steelmaking and cement manufacturing;<br/>♦ Long-term energy storage for days to weeks at a time;<br/>♦ The production of green chemicals such as green ammonia and green methanol;<br/>♦ Industrial (and potentially residential) heating.

In the latest OIES podcast from the Hydrogen Programme James Henderson talks to Abdurahman Alsulaiman about his latest paper entitled “Navigating Turbulence: Hydrogen’s Role in the Decarbonisation of the Aviation Sector.” In the podcast we discuss the current balance of fuels in the aviation sector the importance of increasing efficiency of aero-engines and the impact of increasing passenger miles travelled. The podcast then considers different decarbonisation options for the sector focussing on a change of engine technology to allow the use of alternative fuels such as hydrogen or electricity but also looking at the potential for hydrogen to play an important role in the development of Sustainable Aviation Fuels (SAFs) for use with current engine technology. We also look at Low Carbon Aviation Fuels which are essentially existing fuels derived from a significantly decarbonised supply chain and assess whether they have an important role to play as the aviation sector targets a net zero outcome.

The podcast can be found on their website.

As climate change intensifies determining a developing region’s role in achieving net-zero emissions worldwide is crucial. However regional efforts considering historical emissions remain underexplored. Here we assess energy system changes technology adoption and investments needed for developing regions including five major- and minor-emitting nations. Our analysis using an integrated assessment model shows a large gap in regional efforts toward global net-zero emissions stemming from the necessary shift of energy systems to low-carbon resources. The use of new technologies like electric vehicles hydrogen and carbon capture varies by region with the highest adoption required between 2020 and 2030. Financing this shift needs an average gross domestic product (GDP) investment rise of 0.464% in minor-emitting regions and up to 2.1% in major-emitting regions by 2085. Our results could guide policies and support setting quantifiable targets for developing nations. The findings are key to facilitating strategic technology use and finance mobilization to achieve a carbon-neutral future.

This article presents a comprehensive review of the current landscape and prospects of large-scale hydrogen storage technologies with a focus on both onshore and offshore applications and flexibility. Highlighting the evolving technological advancements it explores storage and compression techniques identifying potential research directions and avenues for innovation. Underwater hydrogen storage and hybrid metal hydride com pressed gas tanks have been identified for offshore buffer storage as well as exploration of using metal hydride slurries to transport hydrogen to/from offshore wind farms coupled with low pressure high flexibility elec trolyser banks. Additionally it explores the role of metal hydride hydrogen compressors and the integration of oxyfuel processes to enhance roundtrip efficiency. With insights into cost-effectiveness environmental and technology considerations and geographical factors this review offers insights for policymakers researchers and industry stakeholders aiming to advance the deployment of large-scale hydrogen storage systems in the transition towards sustainable energy.

This study aimed to compare hydrogen ammonia methanol and waste-derived biofuels as shipping fuels using life cycle assessment to establish what potential they have to contribute to the shipping industry’s 100% greenhouse gas emission reduction target. A novel approach was taken where the greenhouse gas emissions associated with one year of global shipping fleet operations was used as a common unit for comparison therefore allowing the potential life cycle greenhouse gas emission reduction from each fuel option to be compared relative to Paris Agreement compliant targets for international shipping. The analysis uses life cycle assessment from resource extraction to use within ships with all GHGs evaluated for a 100-year time horizon (GWP100). Green hydrogen waste-derived biodiesel and bio-methanol are found to have the best decarbonisation po tential with potential emission reductions of 74–81% 87% and 85–94% compared to heavy fuel oil; however some barriers to shipping’s decarbonisation progress are identified. None of the alternative fuels considered are currently produced at a large enough scale to meet shipping’s current energy demand and uptake of alternative fuel vessels is too slow considering the scale of the challenge at hand. The decarbonisation potential from alternative fuels alone is also found to be insufficient as no fuel option can offer the 100% emission reduction required by the sector by 2050. The study also uncovers several sensitives within the life cycles of the fuel options analysed that have received limited attention in previous life cycle investigations into alternative shipping fuels. First the choice of allocation method can potentially double the life cycle greenhouse gas emissions of e-methanol due to the carbon ac counting challenges of using waste carbon dioxide streams during fuel production. This leads to concerns related to the true impact of using carbon dioxide captured from fossil-fuelled processes to produce a combustible product due to the resultant high downstream emissions. Second nitrous oxide emissions from ammonia combustion are found to be highly sensitive due to high greenhouse gas potency potentially offsetting any greenhouse reduction potential compared to heavy fuel oil. Further uncertainties are highlighted due to limited available data on the rate of nitrous oxide production from ammonia engines. The study therefore highlights an urgent need for the shipping sector to consider these factors when investing in new ammonia and methanol engines; failing to do so risks jeopardizing the sector’s progress towards decarbonisation. Finally whilst alternative fuels can offer good decarbonisation potential (particularly waste derived biomethanol and bio-diesel and green hydrogen) this cannot be achieved without accelerated investment in new and retrofit vessels and new fuel supply chains: the research concludes that existing pipeline of vessel orders and fuel production facilities is insufficient. Furthermore there is a need to integrate alternative fuel uptake with other decarbonisation strategies such as slow steaming and wind propulsion.

In recent years the intensification of human activities has led to an increase in waste production and energy demand. The treatment of pollutants contained in wastewater coupled to energy recovery is an attractive solution to simultaneously reduce environmental pollution and provide alternative energy sources. Hydrogen represents a clean energy carrier for the transition to a decarbonized society. Hydrogen can be generated by photosynthetic water splitting where oxygen and hydrogen are produced and the process is driven by the light energy absorbed by the photocatalyst. Alternatively hydrogen may be generated from hydrogenated pollutants in water through photocatalysis and the overall reaction is thermodynamically more favourable than water splitting for hydrogen. This review is focused on recent developments in research surrounding photocatalytic and photoelectrochemical hydrogen production from pollutants that may be found in wastewater. The fundamentals of photocatalysis and photoelectrochemical cells are discussed along with materials and efficiency determination. Then the review focuses on hydrogen production linked to the oxidation of compounds found in wastewater. Some research has investigated hydrogen production from wastewater mixtures such as olive mill wastewater juice production wastewater and waste activated sludge. This is an exciting area for research in photocatalysis and semiconductor photoelectrochemistry with real potential for scale up in niche applications.

Hydrogen is poised to play a pivotal role in achieving net-zero targets and advancing green economies. However a range of complex operational challenges hinders its planning production delivery and adoption. At the same time numerous drivers within the hydrogen value chain present significant opportunities. This paper investigates the intricate relationships between these drivers and barriers associated with hydrogen supply chain (HSC). Utilising expert judgment in combination Grey-DEMATEL technique we propose a framework to assess the interplay of HSC drivers and barriers. Gaining insight into these relationships not only improves access to hydrogen but also foster innovation in its development as a low-carbon resource. The use of prominence scores and net influence rankings for each driver and barrier in the framework provides a comprehensive understanding of their relative significance and impact. Our findings demonstrate that by identifying and accurately mapping these attributes clear cause-and-effect relationships can be established contributing to a more nuanced understanding of the HSC. These insights have broad implications across operational policy scholarly and social domains. For instance this framework can aid stakeholders in recognizing the range of opportunities available by addressing key barriers to hydrogen adoption.

Hydrogen spark-ignition direct-injection engines result in no carbon emissions at use but NOX remains a challenge. This study demonstrates that with lean combustion (ϕ < 0.38) in-cylinder NOX can be reduced to a quarter of the current maritime regulatory limit. An original contribution of this work is the use of speciesresolved emissions formation across multiple engine load conditions. A novel chemically detailed combustion modelling framework was developed in CHEMKIN-Pro incorporating the evolution of the CRECK C1–C3 NOX mechanism for improved high-pressure accuracy. The framework was extensively validated using crank-angleresolved data across 9–18 bar loads. The model accurately reproduced pressure traces heat release angles and NOX. Mechanistic analysis revealed a shift from thermal Zeldovich NOX to intermediate-species (notably N2Odriven) as equivalence ratio and pressure varied. The findings highlighted the use of a high-fidelity chemical kinetic modelling framework not only to match experimental results but to gain physically grounded insight into actionable near-zero emission strategies.

The research focuses on enhancing hydrogen production using a blend of municipal solid waste (MSW) with Biomass and mixed plastic waste (MPW) under the Bioenergy with Carbon Capture Utilisation and Storage (BECCUS) concept. The key challenges include optimising the feedstock blends and gasification process parameters to maximise hydrogen yield and carbon dioxide capture. This study introduces a novel approach that employs sorption-enhanced gasification and a high-temperature regenerator reactor. Using this method syngas streams with high hydrogen contents of up to 93 mol% and 66 mol% were produced respectively. Thermodynamic simulations with Aspen Plus® validated the integrated system for achieving high-purity hydrogen (99.99 mol%) and effective carbon dioxide isolation. The system produced 70.33 molH2 /kgfeed when using steam as a gasifying agent while 37.95 molH2 /kgfeed was produced under air gasification conditions. Case I employed a mixture of MSW and wood residue at a ratio of 1:1.25 with steam and calcium oxide added at 2:1 and 0.92:1 respectively resulting in 68.80 molH2 /kgfeed and a CO2 capture efficiency of 92 %. Case II utilised MSW and MPW at a 1:1 ratio with steam and calcium oxide at 2:1 and 0.4:1 respectively producing 100.17 molH2 /kgfeed and achieving a 90.09 % CO2 capture efficiency. The optimised parameters significantly improve hydrogen yield and carbon capture offering valuable insights for BECCUS applications.

Green hydrogen is likely to play a major role in decarbonising the aviation industry. It is crucial to understand the effects of microstructure on hydrogen redistribution which may be implicated in the embrittlement of candidate fuel system metals. We have developed a multiscale finite element modelling framework that integrates micromechanical and hydrogen transport models such that the dominant microstructural effects can be efficiently accounted for at millimetre length scales. Our results show that microstructure has a significant effect on hydrogen localisation in elastically anisotropic materials which exhibit an interesting interplay between microstructure and millimetre-scale hydrogen redistribution at various loading rates. Considering 316L stainless steel and nickel a direct comparison of model predictions against experimental hydrogen embrittlement data reveals that the reported sensitivity to loading rate may be strongly linked with rate-dependent grain scale diffusion. These findings highlight the need to incorporate microstructural characteristics in hydrogen embrittlement models.