Publications

As Europe transitions away from natural gas dependency and accelerates its adoption of renewable energy 12 green hydrogen has emerged as a key energy carrier for industrial and automotive applications. Similarly plans 13 to export hydrogen and ammonia from resource-rich regions like Australia and the Middle East to major importers 14 such as Japan and South Korea underline the global commitment to decarbonization. Central to these efforts is 15 the advancement of efficient hydrogen compression technologies which are essential for establishing a 16 sustainable hydrogen supply chain. This study provides a comparative analysis of two key hydrogen compression 17 technologies categorized under positive displacement and non-mechanical systems. The evaluation emphasizes 18 the technical characteristics energy efficiency and potential applications of these systems in the emerging 19 hydrogen economy. Special focus is placed on electric motor-driven compressors which integrate advanced 20 materials and optimized designs to enhance efficiency and minimize energy consumption. By addressing the gap 21 in comparative evaluations this paper offers insights into the performance and sustainability of these technologies 22 contributing to the development of cost-effective and reliable hydrogen supply systems.

The FuelEU Maritime Regulation part of the European Union’s (EU’s) Fit for 55 initiative aims to achieve significant reductions in greenhouse gas (GHG) emissions within the maritime sector. This study assesses the feasibility of alternative fuels for the Estonian pilot fleet using a Well-to-Wake (WtW) life cycle assessment (LCA) methodology. Operational data from 18 vessels sourced from the Estonian State Fleet’s records were analyzed including technical specifications fuel consumption patterns and operational scenarios. The study focused on marine diesel oil (MDO) biomethane hydrogen biodiesel ammonia and hydrotreated vegetable oil (HVO) each presenting distinct trade-offs. Biomethane achieved a 59% GHG emissions reduction but required a volumetric storage capacity up to 353% higher compared to MDO. Biodiesel reduced GHG emissions by 41.2% offering moderate compatibility with existing systems while requiring up to 23% larger storage volumes. HVO demonstrated a 43.6% emissions reduction with seamless integration into existing marine engines. Ammonia showed strong potential for long-term decarbonization but its adoption is hindered by low energy density and complex storage requirements. This research underscores the importance of a holistic evaluation of alternative fuels taking into account technical economic and environmental factors specific to regional and operational contexts. The findings offer a quantitative basis for policymakers and maritime stakeholders to develop effective decarbonization strategies for the Baltic Sea region.

This study explores the potential of renewable seafood shell waste for sustainable energy conversion and longterm storage particularly for isolated communities. Despite its rich chitin and protein composition seafood shell waste is often neglected. The research evaluates and compares three advanced gasification technologies: biomass gasification plasma gasification and chemical looping to convert seafood shell waste into syngas and H2. The study uses validated Aspen Plus models to optimize feedstock blending ratios and operational parameters. Results show that feedstocks high in lobster and shrimp shells yield higher H2 outputs and improved syngas quality compared to clam-dominated blends. For instance biomass gasification at 1200 ◦C yielded approximately 500 kg/h of H2 from pure lobster or shrimp feeds while plasma gasification at 4500 ◦C achieved yields near 730 kg/ h. Plasma gasification when integrated with fuel cell conversion and heat recovery systems can generate over 10000 kWh during a 6-hour peak period enough to power over 1100 single-detached homes. Its levelized cost of hydrogen (LCOH) varies from $5.72-$8.37/kg H2 making it less expensive than chemical looping and biomass gasification. Plasma gasification also has the lowest global warming potential (GWP) at 6 kg CO2e/kg H2. Combining plasma gasification with carbon capture and storage may reduce GWP to 0.3 kg CO2e/kg H2 and can be further explored. These findings underscore the technical and economic viability of converting seafood shell renewable waste into H2 advancing sustainable energy transitions and supporting net-zero goals.

Dark fermentation (DF) has gained increasing interest over the past two decades as a sustainable route for biohydrogen production; however understanding how reproducible the process can be both from macro- and microbiological perspectives remains limited. This study assessed the reproducibility of a parallel continuous DF system using fruit-vegetable waste as a substrate under strictly controlled operational conditions. Three stirred-tank reactors were operated in parallel for 90 days monitoring key process performance indicators. In addition to baseline operation different process enhancement strategies were tested including bioaugmentation supplementation with nutrients and/or additional fermentable carbohydrates and modification of key operational parameters such as pH and hydraulic retention time all widely used in the field to improve DF performance. Microbial community structure was also analyzed to evaluate its reproducibility and potential relationship with process performance and metabolic patterns. Under these conditions key performance indicators and core microbial features were reproducible to a large extent yet full consistency across reactors was not achieved. During operation unforeseen operational issues such as feed line clogging pH control failures and mixing interruptions were encountered. Despite these disturbances the system maintained an average hydrogen productivity of 3.2 NL H2/L-d with peak values exceeding 6 NL H2/L-d under optimal conditions. The dominant microbial core included Bacteroides Lactobacillus Veillonella Enterococcus Eubacterium and Clostridium though their relative abundances varied notably over time and between reactors. An inverse correlation was observed between lactate concentration in the fermentation broth and the amount of hydrogen produced suggesting it can serve as a precursor for hydrogen. Overall the findings presented here demonstrate that DF processes can be resilient and broadly reproducible. However they also emphasize the sensitivity of these processes to operational disturbances and microbial shifts. This underscores the necessity for refined control strategies and further systematic research to translate these insights into stable high-performance real-world systems.

The growing interest in hydrogen as an alternative fuel has stimulated research into methods that enable the global shift to sustainable green energy. One promising pathway is the production of green hydrogen via electrolysis particularly when coupled with renewable energy sources like solar power. Integrating a proton exchange membrane (PEM) electrolyzer with solar energy can aid this transition. Using treated sewage effluent instead of deionized water can make the process more economical and sustainable. Thus the objective of this research is to demonstrate that an integrated electrolysis-water treatmentsolar energy system can be a viable candidate for producing green hydrogen in a sustainable manner. This study assesses different combinations of water pretreatment (RO and UF) and solar energy input (PV ST and PTC) evaluating their techno-economic feasibility efficiencies environmental impact and sustainability. The study shows that CSP scenarios have the highest CAPEX roughly fourfold that of PV cases and sevenfold that of national grid cases. Using solar energy sources like PV ST and PTC results in high material efficiency (94.87%) and environmental efficiency (98.34%) while also reducing CO2 emissions by approximately 88% compared to the national grid. The process’s economic sustainability averages 57% but it could reach 90% if hydrogen production costs fall to $2.08-$2.27 per kg. The outcome of this study is to provide a green hydrogen production pathway that is technically feasible environmentally sustainable and economically viable.

Efficient hydrogen storage is critical for advancing hydrogen-based technologies. This study investigates the effects of pressure and surface area on hydrogen storage in three carbon-based materials: graphite graphene oxide and reduced graphene oxide. Hydrogen adsorption–desorption experiments under pressures ranging from 1 to 9 bar revealed nonlinear storage capacity responses with optimal performance at around 5 bar. The specific surface area plays a pivotal role with reduced graphene oxide and exhibiting a surface area of 70.31 m2/g outperforming graphene oxide (33.75 m2/g) and graphite (7.27 m2/g). Reduced graphene oxide achieved the highest hydrogen storage capacity with 768 sccm and a 3 wt.% increase over the other materials. In assessing proton-exchange fuel cell performance this study found that increased hydrogen storage correlates with enhanced power density with reduced graphene oxide reaching a maximum of 0.082 W/cm2 compared to 0.071 W/cm2 for graphite and 0.017 W/cm2 for graphene oxide. However desorption rates impose temporal constraints on fuel cell operation. These findings enhance our understanding of pressure–surface interactions and underscore the balance between hydrogen storage capacity surface area and practical performance in carbon-based materials offering valuable insights for hydrogen storage and fuel cell applications.

Water electrolyzers play a crucial role in green hydrogen production. However their efficiency and scalability are often compromised by bubble dynamics across various scales from nanoscale to macroscale components. This review explores multi-scale modeling as a tool to visualize multi-phase flow and improve mass transport in water electrolyzers. At the nanoscale molecular dynamics (MD) simulations reveal how electrode surface features and wettability influence nanobubble nucleation and stability. Moving to the mesoscale models such as volume of fluid (VOF) and lattice Boltzmann method (LBM) shed light on bubble transport in porous transport layers (PTLs). These insights inform innovative designs including gradient porosity and hydrophilic-hydrophobic patterning aimed at minimizing gas saturation. At the macroscale VOF simulations elucidate two-phase flow regimes within channels showing how flow field geometry and wettability affect bubble discharging. Moreover artificial intelligence (AI)-driven surrogate models expedite the optimization process allowing for rapid exploration of structural parameters in channel-rib flow fields and porous flow field designs. By integrating these approaches we can bridge theoretical insights with experimental validation ultimately enhancing water electrolyzer performance reducing costs and advancing affordable highefficiency hydrogen production.

The global shipping industry is transitioning toward decarbonization with hydrogen-powered vessels emerging as a key solution to meet international emission reduction targets particularly the IMO’s goal of reducing emissions by 50% by 2050. As a zero-emission fuel hydrogen aligns with international regulations such as the IMO’s greenhouse gas reduction strategy the MARPOL Convention and regional policies like the EU’s Emissions Trading System. Despite regulatory support and advancements in hydrogen fuel cell technology challenges remain in hydrogen storage fuel cell integration and operational safety. Currently high-pressure gaseous hydrogen storage is the most viable option but its spatial and safety limitations must be addressed. Alternative storage methods including cryogenic liquid hydrogen organic liquid hydrogen carriers and metal hydride storage hold potential for application but still face technical and integration barriers. Overcoming these challenges requires continued innovation in vessel design fuel cell technology and storage systems supported by comprehensive safety standards and regulations. The successful commercialization of hydrogen-powered vessels will be instrumental in decarbonizing global shipping and achieving climate goals.

The UK has set an ambitious target of delivering clean power by 2030. Low carbon dispatchable power generation using hydrogen will play a key role in a clean power system by providing flexibility and other services for system operability and also by providing supply adequacy during extended periods of low renewable output decarbonising the role currently performed by an aging portfolio of unabated natural gas power generation. While some 100% hydrogen to power (H2P) commercial projects are already being deployed globally using multi megawatt fuel cells alongside blending hydrogen into existing gas turbines and new hydrogen ready turbines industrial scale 100% H2P projects face additional challenges of deploying new technology into a nascent system one which requires significant volumes of hydrogen storage with long lead times. To achieve the 2030 clean power system ambition and lay the foundations for a clean resilient and secure power system beyond 2030 it is critical that the new government takes resolute actions now to support H2P at scale. A clear strategic plan should be developed within the first 12 months of the new administration with clarity being given on policy business models and deployment rates for hydrogen to power (H2P) and its enabling infrastructure. This report produced by Hydrogen UK’s Power Generation Working Group explores the role that H2P will play in the decarbonised power system of the future the barriers to deployment and recommendations for overcoming them.

This paper can be found on their website.

Hydrogen as a clean energy source has gradually become an important choice for the energy transformation in the world. Utilizing existing natural gas pipelines for hydrogen-blended transportation is one of the most economical and effective ways to achieve large-scale hydrogen transportation. However hydrogen can easily penetrate into the pipe material during the hydrogen-blended transportation process causing damage to the properties of the pipe. The heat-affected zone (HAZ) of the weld being the weakest part of the pipeline is highly sensitive to hydrogen embrittlement. The microstructure and properties of the grains in the heat-affected zone undergoes changes during the welding process. Therefore this paper divides the HAZ of X80 welded pipes into three sub-HAZ namely the coarse-grained HAZ fine-grained HAZ and intercritical HAZ to study the hydrogen behavior. The results show that the degree of hydrogen damage in each sub-HAZ varies significantly at different strain rates. The coarse-grained HAZ has the highest hydrogen embrittlement sensitivity at low strain rates while the intercritical HAZ experiences the greatest hydrogen damage at high strain rates. By combining the microstructural differences within each sub-HAZ the plastic damage mechanism of hydrogen in each sub-HAZ is analyzed with the aim of providing a scientific basis for the feasibility of using X80 welded pipes in hydrogen-blended transportation.