Publications

New flow metering challenges are presented by the energy transition program since the available and new infrastructures might be used to transport energy using energy vectors such as hydrogen-enriched natural gas mixtures including blends never adopted before in current distribution lines. In this framework it is necessary to have the possibility to verify the performance of flowmeters which are currently calibrated using natural gas and nitrogen as reference fluids even when operating with fluids that are not yet in use. For this reason a commercial clamp-on ultrasonic flowmeter was used to measure the speed of sound in a mixture of hydrogen and iso-butane after being calibrated using helium as reference fluid. Helium is actually much more expensive than nitrogen but in our case it is advantageous because in the temperature and pressure ranges considered in this work the speeds of sound of helium are more comparable with those of the binary mixture of hydrogen and isobutane than the speeds of sound of nitrogen under the same thermodynamic conditions. A specifically developed control apparatus was designed to adjust the temperature and the pressure of the gas filling a DN50-PN100 spool where the ultrasonic meter was mounted on. The instrument was calibrated for temperatures between (270 and 320) K and for pressures up to 3 MPa by using the prediction of the reference equation of state for helium of Ortiz-Vega et al. The measurements of the speed of sound were obtained in a binary mixture containing mainly hydrogen with a small content of iso-butane since for these compounds new results are necessary to validate and improve the predictions of thermodynamic models installed in flowmeters and in flow computers. The expanded relative uncertainty was evaluated to be of 0.09% ( = 2) that was estimated by considering the contributions of the main influence quantities repeatability and reproducibility of the measurements. The obtained results were compared with the AGA-8-92DC and GERG-2008 equations of state and found to be consistent with the values predicted by both models demonstrating the feasibility of using a clamp-on ultrasonic flowmeter to determine the speed of sound and possibility to verify the performance of flowmeter installed on the gas networks using the speed of sound as transfer quantity.

Rural mini-grids in Ghana often experience substantial midday solar PV generation surpluses due to mismatches between peak production and local demand with excess energy (redundant energy) frequently curtailed once batteries are fully charged. This underutilisation limits the socio-economic benefits of renewable electrification and highlights the need for alternative long-duration storage solutions. This study investigated the technoeconomic feasibility of converting excess PV energy from a 54 kWp mini-grid in Aglakope Ghana into hydrogen via electrolysis storing it and reconverting it to electricity using fuel cells. Redundant energy generation was quantified using measured PV output and load consumption and validated using statistical error metrics (R2 = 0.955). Hydrogen production and recovery potential were modelled for different electrolyser technologies and system performance was evaluated using round-trip efficiency (RTE) levelized cost of hydrogen (LCOH) and levelized cost of storage (LCOS) with comparative analysis against additional battery capacity. The results yielded an average monthly excess energy of about 2250 kWh convertible into 43–53 kg per month of hydrogen depending on electrolyser type. The proposed hydrogen-fuel cell pathway yielded a RTE of 44.4 % LCOH of $4.97/kg and LCOS of $0.249/kWh which is about 13 % higher than lithium-ion storage benchmarks. The study findings demonstrate that hydrogen storage can complement batteries offer seasonal and multi-day storage capability and reduce renewable curtailment. Therefore wider adoption could be supported by cost reductions efficiency improvements and enabling policies positioning hydrogen-based storage as a viable pathway for resilient low-carbon rural electrification in off-grid contexts.

Proton exchange membrane water electrolysis is a core technology for green hydrogen production but its widespread adoption is hindered by a prohibitively high and uncertain life cycle cost. To address the dynamic complexity and multi-source uncertainties inherent in cost assessment this paper proposes an integrated modeling framework that combines system dynamics with an intuitionistic fuzzy bayesian network. The system dynamics model captures the macro-level feedback loops driving long-term cost evolution such as technological innovation economy-of-scale effects and other critical factors. To model and infer causal dependencies among uncertain variables that are challenging to specify precisely within the system dynamics model the intuitionistic fuzzy bayesian network is incorporated enabling quantification of relationships under conditions of incomplete data and cognitive fuzziness. Through comprehensive simulations the framework forecasts the cost evolution trajectories. Results indicate a potential 77 % reduction in the unit power cost of a 1 MW system by 2060. Uncertainty analysis revealed that the initial prediction variance for the catalyst layer was approximately 20 % significantly higher than the 6.5 % for the bipolar plate highlighting a key investment risk. A comparative analysis demonstrates that the proposed framework achieves a superior forecast accuracy with a mean absolute percentage error of 4.8 %. The proposed method provides a more accurate and robust decision support tool for long-term investment planning and policy formulation for hydrogen production through proton exchange membrane water electrolysis technology.

The sorption-enhanced steam gasification of biomass (SEBSG) is considered a prospective thermo-chemical technology for high-purity H2 production with in-situ CO2 capture. Fundamental concepts and operating conditions of SEBSG technology were summarized in this review. Considerable industrial demonstration units have been conducted on pilot scales for large-scale availability of the SEBSG process. The influence of process parameters such as reaction temperature Steam/Biomass (S/B) ratio feedstock characteristics cyclic CO2 capture capacity of CaO-based sorbents and catalysis were critically reviewed to provide theoretical recommendations for industrial operation. Bifunctional materials that have high catalytic activity and CO2 capture activity are crucial for ensuring high H2 production in the SEBSG. The application of density functional theory (DFT) and reactive force field molecular dynamic (ReaxFF MD) simulations on microcosmic reaction mechanisms in the SEBSG process such as pyrolysis WGS and reforming reactions and CO2 capture of CaO-based materials are comprehensively overviewed. Several research gaps like the exploitation of more efficient and low-cost bifunctional material integrated process economics and revelation of well-rounded mechanisms need to be filled for the following large-scale industrial applications.

Hydrogen refuelling is imperative for the emerging market of hydrogen vehicles. The pressure control valve (PCV) at the hydrogen refuelling station (HRS) plays a major role in ensuring that hydrogen delivery to the vehicle follows the prescribed refuelling protocols. A three-dimensional CFD model with a detailed resolution of PCV motion affecting heat and mass transfer is developed. The PCV motion controlling the mass flow rate is simulated using dynamic mesh. The CFD model captures refuelling from high-pressure tanks through entire HRS equipment to onboard tanks capturing pressure and temperature changes upstream and downstream of the PCV. The Joule-Thomson effect resulting in a hydrogen temperature increase at PCV is captured using the NIST real gas database. The model is validated against Test No.1 of NREL on refuelling through the entire equipment of HRS. The CFD model can be used to design HRS equipment parameters including PCV and develop efficient refuelling protocols.

The global energy transition necessitates the development of technologies enabling cost-effective and scalable conversion of renewable energies into storable and transportable forms. Green ammonia with its high hydrogen storage capacity emerges as a promising carbon-free hydrogen carrier. This article reviews recent progress in industrially relevant catalysts and technologies for ammonia cracking which is a pivotal step in utilizing ammonia as a hydrogen storage material. Catalysts based on Ru Ni Fe Co and Fe–Co are evaluated with Cobased catalysts showing exceptional potential for ammonia cracking. Different reactor technologies and their applications are briefly discussed. This review concludes with perspectives on overcoming existing challenges emphasizing the need for catalyst development effective reactor design and sustainable implementation in the context of the energy transition.

Many off-grid communities in Canada are dependent on diesel generators to fulfill their utility and transportation needs causing destructive environmental impact. This study aims to optimize and investigate the technoeconomic feasibility of a hybrid renewable energy system to satisfy the 1.6 MWh/day electricity 184.2 kWh/day thermal and 428.38 kg/year hydrogen demand simultaneously Trout Lake a remote community of Northern Alberta. A novel hybrid energy system consisting of solar PV wind turbine electrolyzer hydrogen tank battery fuel cell hydrogen boiler and thermal load controller has been proposed to generate electricity heat and hydrogen by renewables which reduce carbon emission utilizing the excess energy (EE). Five different scenarios were developed in HOMER Pro software and the results were compared to identify the best combination of hybrid renewable energy systems. The results indicate that the fifth scenario is the optimal renewable energy system that provides a lower cost of energy (COE) at $0.675/kWh and can reduce 99.99% carbon emission compared to the diesel-based system. Additionally the utilization of thermal load controller battery and fuel cell improved the system’s reliability increasing renewable fraction (RF) (93.5%) and reducing EE (58.3%) significantly. In comparison to the diesel-based systems it is also discovered that battery energy storage is the most affordable option while fuel cells are the more expensive choice for remote community. Sensitivity analyses are performed to measure the impact of different dominating factors on COE EE and RF.

Green hydrogen (H2) produced from renewable energy sources (RES) through electrolysis offers a promising solution to decarbonize hard-to-abate sectors paving the way for H2 hubs. The agility of electrolyzers especially proton-exchange membrane (PEM) technology can be leveraged to provide flexibility to future integrated electricity and H2 systems. More flexibility can be unlocked by optimizing the designs of H2 hubs which generally consist of electrolyzers H2 storage tanks H2 liquefiers and battery energy storage systems (BESSs). This paper introduces a generic optimization framework for finding the least-cost designs of H2 hubs that also minimizes system operating costs under arbitrary H2 demand profiles. The proposed electrolyzer model incorporates a variable efficiency to avoid overestimating the power consumption and the true size of electrolyzers. In RES-rich countries like Australia envisaged H2 export demand may constitute a significant source of demand flexibility. The proposed framework is therefore demonstrated on a case study involving the Australian National Electricity Market (NEM) under a future large-scale green H2 export scenario assessing the impact of three different H2 export profile assumptions on H2 hub investment costs system operating costs and system flexibility. These profiles include: (a) a realistic one based on historical liquefied natural gas (LNG) ship schedules and a pilot H2 export project (b) an inflexible constant demand across the year and (c) a flexible monthly target without intraday and interday restrictions. Numerical analysis demonstrates that the optimal H2 hub designs obtained under the more realistic H2 export profile assumptions enjoy the lowest system operating costs and the highest flexibility the latter of which is evidenced by a substantial increase in availability of reserves.

‘Green’ hydrogen produced by the electrolysis of water using renewable energy sources is expected to become a versatile energy carrier in the future. This study examined the techno-economic performance of combined offshore wind-solar energy systems for hydrogen production in Choshi Chiba Prefecture Japan a region with high average wind speeds. Hourly wind speed and solar radiation data were used to simulate hydrogen production under two system configurations: unlimited power cuts without batteries and no power cuts with battery storage. In the no-power-cut case battery integration increased the nominal hydrogen cost by 43.8 % 17.7 % and 19.8 % in 2025 2030 and 2050 respectively. However sensitivity analysis considering higher electrolyzer OPEX due to degradation revealed that the unlimited power-cut system can become more expensive making battery-supported systems economically favorable over the long term. These findings highlight the importance of integrating battery storage to enhance technical reliability and economical pathways for offshore wind–solar hydrogen production systems.

On the path towards decarbonisation of the steel industry the use of H2 /NG blends in furnaces where high temperatures are needed is one of the alternatives that needs to be carefully studied. The present paper shows the CFD study carried out for a full-scale reheating furnace burner case. The real operating conditions as well as experimental measurements provided by the furnace operator were used to validate the results and reduce simulation uncertainties. The burner under consideration (2.5 MW) works in flameless mode with natural gas and preheated air (813 K). Starting from this point another three fuel blends with volumetric percentages of 23% (also known as G222) 50% and 75% of H2 in natural gas were considered. For this purpose the open source CFD code OpenFOAM was used where the novel NE-EDC turbulence-chemistry interaction model was implemented which has already been successfully validated specifically for flameless combustion in a furnace. The implementation incorporated an enhanced approach for calculating the chemical time-scale coupled with a specific post-processing solver to predict NO emissions. The study analyses the relative impact of the considered fuel blends on NO formation and flameless regime. The modelling results demonstrated the burner’s capability to operate efficiently with high concentrations of hydrogen maintaining flameless regime in all cases. This condition ensured uniform temperature distributions and low levels of NO emissions reaching a maximum value of 86 mg/m3 . These results indicated the proper functionality of the existing natural gas-based burner with H2 /NG blends which was the primary requirement for the conversion process.