Publications

Hydrogen is considered as an attractive alternative to fossil fuels in the transportation sector. However the penetration of Fuel Cell Electric Vehicles (FCEV) is hindered by the lack of hydrogen refueling station infrastructures. In this study the feasibility of a hybrid PV/wind system for hydrogen refueling station is investigated. Refueling events data is collected in different locations including industrial residential highway and tourist areas. Station Occupancy Fractions (SOF) and Social-to-Solar Fraction (STSF) indicators are developed to assess the level of synchronization between the hydrogen demand and solar potential. Then a validated computer code is used to optimize the renewable system components for off/on-grid cases based on minimizing the Net Present Cost (NPC) and the Loss of Hydrogen Supply Probability (LHSP). For off grid cases the results show that STSF attains maximum value in the industrial area where 0.62 fraction of refueling events occur during the sunshine hours and minimum NPC is achieved. It is observed that when STSF attains lower values of 0.52 0.41 and 0.38 for residential highway and tourist areas NPC increases by 8 16 and 31% respectively. This is associated with lower level of coordination between the hydrogen demand and solar potential. The same conclusion can be stated for the on-grid cases. Therefore for green hydrogen production via solar energy utilization it is recommended that a tariff should be applied to encourage refueling hydrogen vehicles during the availability of solar radiation while reducing the environmental impact storage requirements and eventually the cost of hydrogen production.

This paper presents the development of a thermodynamic model for the hydrogen refuelling station (HRS) to simulate the process of refuelling which involves the transfer of hydrogen gas from a high-pressure storage tank to the onboard tank of a fuel cell electric vehicle (FCEV). This model encompasses the fundamental elements of an HRS which consists of a storage tank compressor piping system heat exchanger and an on-board vehicle tank. The model is implemented and validated using experimental data from SAE J2601. Various simulations are conducted to assess the impact of the Joule-Thomson effect and compression on the temperature of hydrogen flow specifically focusing on an average pressure rate of 18 MPa/min. Furthermore a comprehensive analysis is conducted to examine the impact of pressure variations in the storage tank (10–90 MPa) and the initial pressure within the vehicle tank (5–35 MPa) as well as variations in ambient temperature (0–40 °C). The study revealed that the energy consumption in the cooling system surpasses the average power consumption in the more advantageous scenario of 60 MPa by a range of 36% to over 220% when the pressure in the storage system drops below 30 MPa. Furthermore it was noted that the impact of ambient temperature is comparatively less significant when compared to the initial pressure of the vehicle's tank. The impact of an ambient temperature change of 10 °C on the final temperature of a hydrogen vehicle is found to be approximately 2 °C. Similarly a variation in the initial vehicle pressure of 10 MPa results in a modification of the final hydrogen vehicle temperature by approximately 8.5 °C.

The integration of hydrogen energy systems into nearly zero-emission buildings (nZEB) is emerging as a viable strategy to curtail greenhouse gas emissions associated with energy use in these buildings. However the indoor or outdoor placement of certain hydrogen system components or equipment necessitates stringent safety measures particularly in confined environments. This study aims to investigate the dynamics of hydrogen dispersion within an enclosure featuring forced ventilation analyzing the interplay between leakage flow rates and ventilation efficiency both experimentally and numerically. To simulate hydrogen's behavior helium gas which shares similar physical characteristics with hydrogen was utilized in experiments conducted at leakage flows of 4 8 and 10 L/min alongside a ventilation rate of 30 air changes per hour (ACH). The experiments revealed that irrespective of the leakage rate the oxygen concentration returned to its initial level approximately 11 min post-leakage at a ventilation rate of 30 ACH. This study also encompasses a numerical analysis to validate the experimental findings and assess the congruence between helium and hydrogen behaviors. Additionally the impact of varying ACH rates (30 45 60 75) on the concentrations of oxygen and hydrogen was quantified through numerical analysis for different hydrogen leakage rates (4 8 10 20 L/min). The insights derived from this research offer valuable guidance for building facility engineers on designing ventilation systems that ensure hydrogen and oxygen concentrations remain within safe limits in hydrogen-utilizing indoor environments.

The defossilization of industry has far-reaching implications regarding the future demand for hydrogen and other forms of energy. This paper presents and applies a fundamental bottom-up model that relies on techno-economic data of industrial production processes. Its aim is to identify across a range of scenarios the most cost-effective low-carbon options considering a variety of production systems. Subsequently it derives the hydrogen and electricity demand that would result from the implementation of these least-cost low-carbon options in process industries in Germany. Aligning with the German government's target year for achieving climate neutrality this study’s reference year is 2045. The primary contribution lies in analyzing which hydrogen-based and direct electrification solutions would be cost-effective for a range of energy price levels under climate-neutral industrial production and what the resulting hydrogen and electricity demand would be. To this end the methodology of this paper comprises the following steps: selection of the relevant industries (I) definition of conventional reference production systems and their low-carbon options (II) investigation and processing of the techno-economic data of the standardized production systems (III) establishment of a scenario framework (IV) determination of the least-cost low-carbon solution of a conventional reference production system under the scenario assumptions made (V) and estimation of the resulting hydrogen and electricity demand (VI). According to the results the expected industrial hydrogen consumption in 2045 ranges from 255 TWh for higher hydrogen prices in or above the range of onshore wind-based green hydrogen supply costs to up to 542 TWh for very low hydrogen prices corresponding to typical blue hydrogen production costs. Meanwhile the direct electricity consumption of the process industries in the results ranges from 122 TWh for these rather low hydrogen prices to 368 TWh for the higher hydrogen prices in the region of or above the hydrogen supply costs from the electrolysis of energy from an onshore wind farm. Most of the break-even hydrogen prices that are relevant to the choice of low-carbon options are in the range of the benchmark purchase costs for blue hydrogen and green hydrogen produced from offshore wind power which span between €40 per MWh and €97 per MWh.

Morocco despite its heavy reliance on imported fossil fuels which made up 68% of electricity generation in 2020 has recognised its significant renewable energy potential. The Nationally Determined Contribution (NDC) commitment is to reduce emissions by 45.5% from baseline levels with international assistance and abstain from constructing new coal plants. Moreover the Green Hydrogen Roadmap aims to export 10 TWh of green hydrogen by 2030 as well as use it for local electricity storage. This paper critically analyses this Roadmap and Morocco’s readiness to reach its ambitious targets focusing specifically on an energy trilemma perspective and using OSeMOSYS (Open-Source energy Modelling System) for energy modelling. The results reveal that the NDC scenario is only marginally more expensive than the least-cost scenario at around 1.3% (approximately USD 375 million) and facilitates a 23.32% emission reduction by 2050. An important note is the continued reliance on existing coal power plants across all scenarios which challenges both energy security and emissions. The assessment of the Green Hydrogen Scenarios highlights that it could be too costly for the Moroccan government to fund the Green Hydrogen Roadmap at this scale which leads to increased imports of polluting fossil fuels for cost reduction. In fact the emission levels are 39% higher in the green hydrogen exports scenario than in the least-cost scenario. Given these findings it is recommended that the Green Hydrogen Roadmap be re-evaluated with a suggestion for a postponement and reduction in scope.

Oceanic energy sources notably offshore wind and wave power present a significant opportunity to generate green hydrogen through water electrolysis. This approach allows for offshore hydrogen production which can be efficiently transported through existing pipelines and stored in various forms offering a versatile solution to tackle the intermittency of renewable energy sources and potentially revolutionize the entire electrical grid infrastructure. This research focusses on assessing the technical and economic feasibility of this method in six strategic coastal regions in Morocco: Laayoune Agadir Essaouira Eljadida Casablanca and Larache. Our proposed system integrates offshore wind turbines oscillating water column wave energy converters and PEM electrolyzers to meet energy demands while aligning with global sustainability objectives. Significant electricity production estimates are observed across these regions ranging from 14 MW to 20 MW. Additionally encouraging annual estimates of hydrogen production varying between 20 and 40 tonnes for specific locations showcase the potential of this approach. The system’s performance demonstrates promising efficiency rates ranging from 13% to 18% while maintaining competitive production costs. These findings underscore the ability of oceanic energy-driven green hydrogen to diversify Morocco’s energy portfolio bolster water resilience and foster sustainable development. Ultimately this research lays the groundwork for comprehensive energy policies and substantial infrastructure investments positioning Morocco on a trajectory towards a decarbonized future powered by innovative and clean technologies.

Hydrogen is used as a fuel in various fields such as aviation space and automobiles due to its high specific energy. Hydrogen can be stored as a compressed gas at high pressure and as a liquid at cryogenic temperatures. In order to keep liquid hydrogen at a cryogenic temperature the tanks for storing liquid hydrogen are required to have insulation to prevent heat leakage. When liquid hydrogen is vaporized by heat inflow a large pressure is generated inside the tank. Therefore a technology capable of predicting the tank pressure is required for cryogenic liquid hydrogen tanks. In this study a thermodynamic model was developed to predict the maximum internal pressure and pressure behavior of cryogenic liquid hydrogen fuel tanks. The developed model considers the heat inflow of the tank due to heat transfer the phase change from liquid to gas hydrogen and the fuel consumption rate. To verify the accuracy of the proposed model it was compared with the analyses and experimental results in the referenced literature and the model presented good results. A cryogenic liquid hydrogen fuel tank was simulated using the proposed model and it was confirmed that the storage time along with conditions such as the fuel filling ratio of liquid hydrogen and the fuel consumption rate should be considered when designing the fuel tanks. Finally it was confirmed that the proposed thermodynamic model can be used to sufficiently predict the internal pressure and the pressure behavior of cryogenic liquid hydrogen fuel tanks.

The use of hydrogen-blended natural gas presents an efficacious pathway toward the rapid large-scale implementation of hydrogen energy with pipeline transportation being the principal method of conveyance. However pipeline materials are susceptible to hydrogen embrittlement in high-pressure hydrogen environments. Natural gas contains various impurity gases that can either exacerbate or mitigate sensitivity to hydrogen embrittlement. In this study we analyzed the mechanisms through which multiple impurity gases could affect the hydrogen embrittlement behavior of pipeline steel. We examined the effects of O2 and CO2 on the hydrogen embrittlement behavior of L360 pipeline steel through a series of fatigue crack growth tests conducted in various environments. We analyzed the fracture surfaces and assessed the fracture mechanisms involved. We discovered that CO2 promoted the hydrogen embrittlement of the material whereas O2 inhibited it. O2 mitigated the enhancing effect of CO2 when both gases were mixed with hydrogen. As the fatigue crack growth rate increased the influence of impurity gases on the hydrogen embrittlement of the material diminished.

The goal of achieving a zero-emission energy system by 2050 requires accurate energy planning to minimise the overall cost of the energy transition. Long-term energy models based on cost-optimal solutions are extremely dependent on the cost forecasts of different technologies. However such forecasts are inherently uncertain. The aim of the present work is to identify a cost-optimal pathway for the Italian energy system decarbonisation and assess how renewable cost scenarios can affect the optimal solution. The analysis has been carried out with the H2RES model a single-objective optimisation algorithm based on Linear Programming. Different cost scenarios for photovoltaics on-shore and off-shore wind power and lithium-ion batteries are simulated. Results indicate that a 100% renewable energy system in Italy is technically feasible. Power-to-X technologies are crucial for balancing purposes enabling a share of non-dispatchable generation higher than 90%. Renewable cost scenarios affect the energy mix however both on-shore and off-shore wind saturate the maximum capacity potential in almost all scenarios. Cost forecasts for lithium-ion batteries have a significant impact on their optimal capacity and the role of hydrogen. Indeed as battery costs rise fuel cells emerge as the main solution for balancing services. This study emphasises the importance of conducting cost sensitivity analyses in long-term energy planning. Such analyses can help to determine how changes in cost forecasts may affect the optimal strategies for decarbonising national energy systems.