Italy
Hydrogen Blending in Natural Gas Grid: Energy, Environmental, and Economic Implications in the Residential Sector
Jul 2024
Publication
The forthcoming implementation of national policies towards hydrogen blending into the natural gas grid will affect the technical and economic parameters that must be taken into account in the design of building heating systems. This study evaluates the implications of using hydrogenenriched natural gas (H2NG) blends in condensing boilers and Gas Adsorption Heat Pumps (GAHPs) in a residential building in Rome Italy. The analysis considers several parameters including nonrenewable primary energy consumption CO2 emissions Levelized Cost of Heat (LCOH) and Carbon Abatement Cost (CAC). The results show that a 30% hydrogen blend achieves a primary energy consumption reduction of 12.05% and 11.19% in boilers and GAHPs respectively. The presence of hydrogen in the mixture exerts a more pronounced influence on the reduction in fossil primary energy and CO2 emissions in condensing boilers as it enhances combustion efficiency. The GAHP system turns out to be more cost-effective due to its higher efficiency. At current hydrogen costs the LCOH of both technologies increases as the volume fraction of hydrogen increases. The forthcoming cost reduction in hydrogen will reduce the LCOH and the decarbonization cost for both technologies. At low hydrogen prices the CAC for boilers is lower than for GAHPs; therefore replacing boilers with other gas technologies rather than electric heat pumps increases the risk of creating stranded assets. In conclusion blending hydrogen into the gas grid can be a useful policy to reduce emissions from the overall natural gas consumption during the process of end-use electrification while stimulating the development of a hydrogen economy.
Analysis of a Distributed Green Hydrogen Infrastructure Designed to Support the Sustainable Mobility of a Heavy-duty Fleet
Aug 2023
Publication
Clean hydrogen is a key pillar for the net zero economy which can be deployed by consistent utilization on heavy-duty transport. This study investigates a distributed green hydrogen infrastructure (DHI) for heavy-duty transportation consisting of on-site hydrogen production storage compression and refueling systems in Italy. Two options for energy supply are analyzed: grid connection using green energy via Power Purchasing Agreements (PPAs) and direct connection to the photovoltaic field respectively. Radiation data are representative of the three main Italian areas namely South (Catania) Center (Roma) and North (Milano). The sensitivity analysis varies the PPA value between 50 V/MWh and 200 V/MWh and the water electrolysis capacity factor between 20% and 100%. The study finds that the LCOH ranges from 7.4 V/kgH2 to 67.8 V/kgH2 for the first option and 5.5 V/kgH2 to 27.5 V/kgH2 for the second option with Southern Italy having the lowest LCOH due to higher solar irradiation. The research shows that a DHI can offer economic and technical benefits for heavy-duty mobility. However the performance is highly influenced by external conditions such as hydrogen demand and electricity prices. This study provides valuable insights into designing and operating a DHI for heavy-duty mobility promoting a carbon-free society.
Comparative Study of Electric and Hydrogen Mobility Infrastructures for Sustainable Public Transport: A PyPSA Optimization for a Remote Island Context
Jul 2024
Publication
Decarbonizing road transportation is vital for addressing climate change given that the sector currently contributes to 16% of global GHG emissions. This paper presents a comparative analysis of electric and hydrogen mobility infrastructures in a remote context i.e. an off-grid island. The assessment includes resource assessment and sizing of renewable energy power plants to facilitate on-site self-production. We introduce a comprehensive methodology for sizing the overall infrastructure and carry out a set of techno-economic simulations to optimize both energy performance and cost-effectiveness. The levelized cost of driving at the hydrogen refueling station is 0.40 e/km i.e. 20% lower than the electric charging station. However when considering the total annualized cost the battery-electric scenario (110 ke/year) is more favorable compared to the hydrogen scenario (170 ke/year). To facilitate informed decision-making we employ a multi-criteria decision-making analysis to navigate through the techno-economic findings. When considering a combination of economic and environmental criteria the hydrogen mobility infrastructure emerges as the preferred solution. However when energy efficiency is taken into account electric mobility proves to be more advantageous.
Toward Green Steel: Modelling and Environmental Economic Analysis of Iron Direct Reduction with Different Reducing Gases
Sep 2023
Publication
The objective of the paper is to simulate the whole steelmaking process cycle based on Direct Reduced Iron and Electric Arc Furnace technologies by modeling for the first time the reduction furnace based on kinetic approach to be used as a basis for the environmental and techno-economic plant analysis by adopting different reducing gases. In addition the impact of carbon capture section is discussed. A complete profitability analysis has been conducted for the first time adopting a Monte Carlo simulation approach.<br/>In detail the use of syngas from methane reforming syngas and hydrogen from gasification of municipal solid waste and green hydrogen from water electrolysis are analyzed. The results show that the Direct Reduced Iron process with methane can reduce CO2 emissions by more than half compared to the blast furnace based-cycle and with the adoption of carbon capture greenhouse gas emissions can be reduced by an additional 40%. The use of carbon capture by amine scrubbing has a limited economic disadvantage compared to the scenario without it becoming profitable once carbon tax is included in the analysis. However it is with the use of green hydrogen from electrolyzer that greenhouse gas emissions can be cut down almost completely. To have an environmental benefit compared with the methane-based Direct Reduced Iron process the green hydrogen plant must operate for at least 5136 h per year (64.2% of the plant's annual operating hours) on renewable energy.<br/>In addition the use of syngas and separated hydrogen from municipal solid waste gasification is evaluated demonstrating its possible use with no negative effects on the quality of produced steel. The results show that hydrogen use from waste gasification is more economic with respect to green hydrogen from electrolysis but from the environmental viewpoint the latter results the best alternative. Comparing the use of hydrogen and syngas from waste gasification it can be stated that the use of the former reducing gas results preferable from both the economic and environmental viewpoint.
Feasibility Assessment of Alternative Clean Power Systems onboard Passenger Short-Distance Ferry
Sep 2023
Publication
In order to promote low-carbon fuels such as hydrogen to decarbonize the maritime sector it is crucial to promote clean fuels and zero-emission propulsion systems in demonstrative projects and to showcase innovative technologies such as fuel cells in vessels operating in local public transport that could increase general audience acceptability thanks to their showcase potential. In this study a short sea journey ferry used in the port of Genova as a public transport vehicle is analyzed to evaluate a ”zero emission propulsion” retrofitting process. In the paper different types of solutions (batteries proton exchange membrane fuel cell (PEMFC) solid oxide fuel cell (SOFC)) and fuels (hydrogen ammonia natural gas and methanol) are investigated to identify the most feasible technology to be implemented onboard according to different aspects: ferry daily journey and scheduling available volumes and spaces propulsion power needs energy storage/fuel tank capacity needed economics etc. The paper presents a multi-aspect analysis that resulted in the identification of the hydrogen-powered PEMFC as the best clean power system to guarantee for this specific case study a suitable retrofitting of the vessel that could guarantee a zero-emission journey
Risk Management in a Containerized Metal Hydride Storage System
Sep 2023
Publication
HyCARE project supported by the Clean Hydrogen Partnership of the European Union deals with a prototype of hydrogen storage tank using a solid-state hydrogen carrier. Up to 40 kilograms of hydrogen are stored in twelve tanks at less than 50 barg and less than 100 °C. The innovative design is based on a standard twenty-foot container including twelve TiFe-based metal hydride (MH) hydrogen storage tanks coupled with a thermal energy storage in phase change materials (PCM). This article aims at showing the main risks related to hydrogen storage in a MH system and the safety barriers considered based on HyCARE’s specific risk analysis.<br/>Regarding the TiFe MH material used to store hydrogen experimental tests showed that the exposure of the MH to air or water did not cause spontaneous ignition. Furthermore an explosion within the solid MH cannot propagate due to internal pore size. Additionally in case of leakage the speed of hydrogen desorption from the MH is self-limited which is an important safety characteristic since it reduces the potential consequences from the hydrogen release scenario.<br/>Regarding the integrated system the critical scenarios identified during the risk analysis were: explosion due to release of hydrogen inside or outside the container internal explosion inside MH tanks due to accidental mix of hydrogen and air and asphyxiation due to inert gas accumulation in the container. This identification phase of the risk analysis allowed to pinpoint the most relevant safety barriers already in place and recommend additional ones if needed to further reduce the risk that were later implemented.<br/>The main safety barriers identified were: material and component selection (including the MH selected) safety interlocks safety valves ventilation gas detection and safety distances.<br/>The risk management process based on risk identification and assessment contributed to coherently integrate inherently safe design features and safety barriers.
Assessing Techno-economic Feasibility of Cogeneration and Power to Hydrogen Plants: A Novel Dynamic Simulation Model
Aug 2023
Publication
Green hydrogen technologies are crucial for decarbonization purposes while cogeneration offers efficient heat and power generation. Integrating green hydrogen and cogeneration brings numerous benefits optimizing energy utilization reducing emissions and supporting the transition to a sustainable future. While there are numerous studies examining the integration of combined heat and power with Power to Gas certain aspects still requires a more detailed analysis especially for internal combustion engines fuelled by natural gas due to their widespread adoption as one of the primary technologies in use. Therefore this paper presents a comprehensive numerical 0-D dynamic simulation model implemented within the TRNSYS environment considering internal combustion engines fuelled by natural gas. Specifically the study focuses on capturing CO2 from exhaust gases and producing green hydrogen from electrolysis. Based on these considerations two configurations are proposed: the first involves the methanation reaction while the second entails the production of a hydromethane mixture. The aim is to evaluate the technical and economic feasibility of these configurations and compare their performance within the Power to Gas framework. Self-sufficiency from the national electricity grid has been almost achieved for the two configurations considering an industrial case. The production of hydromethane allows smaller photovoltaic plant (81 kWp) compared to the production of synthetic methane (670 kWp) where a high quantity of hydrogen is required especially if all the carbon dioxide captured is used in the methanation process. Encouraging economic results with payback times below ten years have been obtained with the use of hydromethane. Moreover hydromethane shows potential residential applications with small required photovoltaic sizes.
The Economic Impact and Carbon Footprint Dependence of Energy Management Strategies in Hydrogen-Based Microgrids
Sep 2023
Publication
This paper presents an economic impact analysis and carbon footprint study of a hydrogenbased microgrid. The economic impact is evaluated with respect to investment costs operation and maintenance (O&M) costs as well as savings taking into account two different energy management strategies (EMSs): a hydrogen-based priority strategy and a battery-based priority strategy. The research was carried out in a real microgrid located at the University of Huelva in southwestern Spain. The results (which can be extrapolated to microgrids with a similar architecture) show that although both strategies have the same initial investment costs (EUR 52339.78) at the end of the microgrid lifespan the hydrogen-based strategy requires higher replacement costs (EUR 74177.4 vs. 17537.88) and operation and maintenance costs (EUR 35254.03 vs. 34877.08) however it provides better annual savings (EUR 36753.05 vs. 36282.58) and a lower carbon footprint (98.15% vs. 95.73% CO2 savings) than the battery-based strategy. Furthermore in a scenario where CO2 emission prices are increasing the hydrogen-based strategy will bring even higher annual cost savings in the coming years.
Energy and Greenhouse Gases Life Cycle Assessment of Electric and Hydrogen Buses: A Real-world Case Study in Bolzano Italy
May 2023
Publication
The transportation sector plays an important role in the current effort towards the control of global warming. Against this backdrop electrification is currently attracting attention as the life cycle environmental performance of different powertrain technologies is critically assessed. In this study a life cycle analysis of the public transportation buses was performed. The scope of the analysis is to compare the energy and global warming performances of the different powertrain technologies in the city fleet: diesel full electric and hydrogen buses. Real world monitored data were used in the analysis for the energy consumptions of the buses and to produce hydrogen in Bolzano. Compared to the traditional diesel buses the electric vehicles showed a 43% reduction of the non-renewable primary energy demand and a 33% of the global warming potential even in the worst consequential scenario considered. The switch to hydrogen buses leads to very different environmental figures: from very positive if it contributes to a further penetration of renewable electricity to hardly any difference if hydrogen from steam-methane reforming is used to clearly negative ones (approximately doubling the impacts) if a predominantly fossil electricity mix is used in the electrolysis.
The Use of Hydrogen as Alternative Fuel for Ship Propulsion: A Case Study of Full and Partial Retrofitting of Roll-on/Roll-off Vessels for Short Distance Routes
Oct 2023
Publication
Roll-on/Roll-Off (Ro-Ro) vessels including those without and with passenger accommodation Roll-on/roll-off passenger (Ro-Pax) can be totally or partially retrofitted to reduce the greenhouse gas (GHG) emissions in maritime transport not only during hoteling operation at the dock but also during service. This study is based on data of the vessel routes connecting the Port of Piombino to the Elba Island in Italy. Three retrofitting scenarios have been considered: replacement of the main and auxiliary engines with fuel cells (FC) (full retrofitting) replacement of the auxiliary engines with FCs (partial retrofitting) and replacement of the auxiliary engines with FCs and hoteling only with auxiliary engines for one specific vessel. The amount of hydrogen the filling time and the energy needed for production compression and pre-cooling of hydrogen have been calculated for the different scenarios.
QRA of Hydrogen Vehicles in a Road Tunnel
Sep 2023
Publication
Hydrogen energy is recognized by many European governments as an important part of the development to achieve a more sustainable energy infrastructure. Great efforts are spent to build up a hydrogen supply chain to support the increasing number of hydrogen-powered vehicles. Naturally these vehicles will use the common traffic infrastructure. Thus it has to be ensured these infrastructures are capable to withstand the hazards and associated risks that may arise from these new technologies. In order to have an appropriate assessment tool for hydrogen vehicles transport through tunnels a new QRA methodology is developed and presented here. In Europe the PIARC is a very common approach. It is therefore chosen as a starting point for the new methodology. It provides data on traffic statistics accident frequencies tunnel geometries including certain prevention and protection measures. This approach is enhanced by allowing better identification of hazards and their respective sources for hydrogen vehicles. A detailed analysis of the accident scenarios that are unique for hydrogen vehicles hereunder the initiating events severity of collision types that may result in a release of hydrogen gas in a tunnel and the location of such an accident are included. QRA enables the assessment and evaluation of scenarios involving external fires or vehicles that burst into fire because of an accident or other fire sources. Event Tree Analysis is the technique used to estimate the event frequencies. The consequence analysis includes the hazards from blast waves hydrogen jet fires DDT.
Hydrogen and ICEs: Validation of a 3D-CFD Approach for In-cylinder Combustion Simulations of Ultra-lean Mixture with a focus on the combustion regime
Sep 2025
Publication
This paper proposes a numerical setup for 3D-CFD in-cylinder simulations of H2-fuelled internal combustion engines. The flamelet G-equation model based on Verhelst and Damkohler-like ¨ correlations for laminar and turbulent flame speeds respectively is used to reproduce the flame propagation. The validation against experimental data from a homogeneous-mixture port-injection engine enables a focus on combustion simulation by minimising stratification uncertainties. Accurate flame propagation modelling is identified as the main challenge. The results on different operating conditions confirm the predictive capabilities of the framework thanks to the agreement with the experimental pressure traces combustion indicators and flame imaging. Notably combustion rate predictions remain accurate even without considering the flame thermo-diffusive instability as the turbulence effect dominates at the investigated conditions. The combustion regime is analysed by a modified Borghi-Peters diagram and it ranges from flamelet to thin reaction zones. This highlights the numerical setup flexibility which accurately simulates combustion across different regimes.
Towards the Validation of Ultrasonic Flowmeters Operating in Hydrogen-enriched Natural Gas Mixtures though Speed of Sound Measurements Obtained by a Clamp-on Meter
Jan 2025
Publication
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.
An Experimentally Validated Curve-fit Model of a Hydrogen-fueled Internal Combustion Engine for Use in Techno-economic Analyses
Oct 2025
Publication
The growing share of renewables in power grids increases the need for backup generators able to compensate production profiles whenever needed. Hydrogen internal combustion engines (H2 ICEs) offer a promising solution in terms of flexibility reduced capital cost and looser requirements on hydrogen purity. These systems are however still not well characterized. This study introduces a zero-dimensional (0D) model for a 100 % hydrogen engine calibrated using experimental data under varying loads and air-fuel ratios. Unlike existing models it proposes validated electrical efficiency data across multiple operating points. Efficiency curves are provided in quadratic and linear forms allowing integration into diverse energy system simulations including linear programming. The model performance is evaluated in a peak-shaving case study using real data from a remote site with limited grid supply. Three engine-generators are used to match single-minute resolution load demand. Compared to typical models that lack validation and ignore part-load efficiency losses the proposed model highlights differences in hydrogen consumption estimation up to 13.4 % thus offering improved accuracy for techno-economic analyses of hydrogen-based systems.
Operating Principles, Performance and Technology Readiness Level of Reversible Solid Oxide Cells
Apr 2021
Publication
The continuous increase of energy demand with the subsequent huge fossil fuel consumption is provoking dramatic environmental consequences. The main challenge of this century is to develop and promote alternative more eco-friendly energy production routes. In this framework Solid Oxide Cells (SOCs) are a quite attractive technology which could satisfy the users’ energy request working in reversible operation. Two operating modes are alternated: from “Gas to Power” when SOCs work as fuel cells fed with hydrogen-rich mixture to provide both electricity and heat to “Power to Gas” when SOCs work as electrolysers and energy is supplied to produce hydrogen. If solid oxide fuel cells are an already mature technology with several stationary and mobile applications the use of solid oxide electrolyser cells and even more reversible cells are still under investigation due to their insufficient lifetime. Aiming at providing a better understanding of this new technological approach the study presents a detailed description of cell operation in terms of electrochemical behaviour and possible degradation highlighting which are the most commonly used performance indicators. A thermodynamic analysis of system efficiency is proposed followed by a comparison with other available electrochemical devices in order to underline specific solid oxide cell advantages and limitations.
Hydrogen Supply Design for the Decarbonization of Energy-intensive Industries Addressing Cost, Inherent Safety and Environmental Performance
Sep 2025
Publication
Through mathematical modeling this paper integrates economic safety and environmental assessments to evaluate alternative hydrogen supply options (on-site production and external supply) and various hydrogenbased system configurations for decarbonizing energy-intensive industries. The model is applied to a case study in the glass sector. While reliance on natural gas remains the most cost-effective and safest solution it does not align with decarbonization objectives. Assuming a complete hydrogen transition on-site production reduces emissions by 85 % compared to current levels and improves safety performance over external supply. External supply of grey hydrogen becomes counterproductive increasing emissions by 68 % compared to natural gas operations. Nevertheless hydrogen cost rises from 3.6 €/kg with external supply to 4.2 €/kg with on-site production doubling the fuel cost relative to natural gas. To address the trade-offs the paper explores how specific constraints influence system design. A sensitivity analysis on key factors affecting hydrogen-related decisions provides additional support for strategic decision-making.
Performance Analysis of Silica Fluidized Bed Membrane Reactor for Hydrogen Production as a Green Process Using CFD Modelling
Aug 2025
Publication
The main aim of this study deals with the potential evaluation of a fluidized bed membrane reactor (FBMR) for hydrogen production as a clean fuel carrier via methanol steam reforming reaction comparing its performance with other reactors including packed bed membrane reactors (PBMR) fluidized bed reactors (FBR) and packed bed reactors (PBR). For this purpose a two-dimensional axisymmetric numerical model was developed using computational fluid dynamics (CFD) to simulate the reactor performances. Model accuracy was validated by comparing the simulation results for PBMR and PB with experimental data showing an accurate agreement within them. The model was then employed to examine the effects of key operating parameters including reaction temperature pressure steam-to-methanol molar ratio and gas volumetric space velocity on reactor performance in terms of methanol conversion hydrogen yield hydrogen recovery and selectivity. At 573 K 1 bar a feed molar ratio of 3/1 and a space velocity of 9000 h−1 the PBMR reached the best results in terms of methanol conversion hydrogen yield hydrogen recovery and hydrogen selectivity such as 67.6% 69.5% 14.9% and 97.1% respectively. On the other hand the FBMR demonstrated superior performance with respect to the latter reaching a methanol conversion of 98.3% hydrogen yield of 95.8% hydrogen recovery of 74.5% and hydrogen selectivity of 97.4%. These findings indicate that the FBMR offers significantly better performance than the other reactor types studied in this work making it a highly efficient method for hydrogen production through methanol steam reforming and a promising pathway for clean energy generation.
From LNG to LH2 in Maritime Transport: A Review of Technology, Materials, and Safety Challenges
Sep 2025
Publication
The adoption of low-carbon fuels in maritime propulsion requires operational autonomy material suitability and compliance with safety standards making liquid fuels like LNG and LH2 the most viable options. LNG is widely used for reducing GHG NOx and SOx emissions while LH2 though new to the maritime sector leverages aerospace experience. This paper explores the operational requirements and challenges of LH2 cryogenic handling systems using LNG practices as a reference. Key comparisons are made between LNG and LH2 supply systems focusing on cryogenic materials hydrogen embrittlement and structural integrity under maritime conditions. Most maritime-approved materials are suitable for cryogenic use and hydrogen embrittlement is less critical at cryogenic temperatures due to reduced atomic mobility. Risk assessments suggest LH2’s safety record stems from limited operational data rather than superior inherent safety. The paper also addresses crucial safety and regulatory considerations for both fuels underscoring the need for strict adherence to standards to ensure the safe and compliant integration of LH2 in the maritime industry.
Optimization of Baseload Electricity and Hydrogen Services by Renewables for a Nuclear-sized District in South Italy
Nov 2024
Publication
We present an optimization model of an energy district in South Italy that supplies baseload electricity and hydrogen services. The district is sized such that a nuclear reactor could provide these services. We define scenarios for 2050 to explore the system effects of discount rate sensitivity vetoes on technologies and cost uncertainties. We address the following issues relevant to decarbonization in South Italy: land-based wind and solar vs. exclusive solar rooftop extra cost of a veto on nuclear conservative assumptions on future storage technology and the role of pumped hydro storage lack of low-cost geological storage of hydrogen and the industrial competitiveness of this carrier and the methanation synergy with the agroforestry sector. Our results quantify the high system cost of vetoes on land-based wind and solar. Nuclear may enter the optimal mix only with a veto against onshore wind and a hypothesis of equal project risk hence an equal discount rate with renewables. Scenarios with land-based wind and solar obtain low-cost hydrogen and thus allow industrial uses for this carrier. The methanation synergy with the agroforestry sector does not offer a system cost advantage but improves the district’s configuration. The extra cost of full decarbonization relative to unregulated fossil gas is small with land-based wind and solar and significant with vetoes to these technologies.
How the Boundaries of the Supply Chain Affect Climate Profile: The Case of Renewable Electricity and Green Hydrogen for Italy and the UK
Feb 2025
Publication
Green hydrogen obtained from renewable electricity can play an essential role in the decarbonization of different sectors. The reliability of the data used to model the entire supply chain is a crucial parameter in Life Cycle Assessment. In this study the authors show how photovoltaic and wind electricity supply chains influence the carbon footprint of green H2. While most published studies rely on default datasets from commercial libraries the current work exploits the actual supply chain of the PV panels and builds an updated average European wind turbine supply chain. The updated values for PV-based H2 experiencing a 40–60% reduction are 2.7 and 1.8 kg CO2 eq./kg H2 for the UK and Italy. The carbon footprint of UK offshore wind-based H2 can be reduced up to 24% and get close to 0.6 kg CO2 eq./kg H2. The findings emphasize the sensitivity of the final climate profile generated by the processes upstream of the electrolysis system.
A Model for Assessing the Risk of Liquid Hydrogen Transport through Road Tunnels
Sep 2023
Publication
Among the new energy carriers aimed at reducing greenhouse gas emissions the use of hydrogen is expected to grow significantly in various applications and sectors (i.e. industrial commercial transportation etc.) due to its high energy content by weight and zero carbon emissions. The increasingly widespread use of hydrogen will require massive distribution from production sites to final consumers and the delivery by means of liquid hydrogen road tankers may be a suitable cost-effective option for market penetration in the short-medium term. Liquid hydrogen (LH2) presents different hazards compared to gaseous hydrogen and an accidental release in confined spaces such as road tunnels might lead to the formation of a flammable hydrogen cloud that might deflagrate or even detonate. Nevertheless the potential negative effects on users in the event of accidental leakage of liquid hydrogen from a tanker in road tunnels so far have not been sufficiently investigated. Therefore a 3D Computational Fluid Dynamics model for the release of LH2 and its dispersion within a road tunnel was developed in this study. The proposed model was validated by a comparison with certain experimental and numerical studies found in the literature. Such modeling is demanding for long tunnels. Therefore the results of the simulations (e.g. the amount of hydrogen contained within the cloud) were combined with established simplified consequence methods to estimate the overpressures generated from a potential hydrogen deflagration. This was then used to evaluate the effects on users while evacuating from the tunnel. The findings showed that the worst scenario is when the release is in the middle of the tunnel length and the ignition occurs 90 s after the leakage.
Numerical Analysis of Dual Fuel Combustion in a Medium Speed Marine Engine Supplied with Methane/Hydrogen Blends
Sep 2023
Publication
Compression ignition engines will still be predominant in the naval sector: their high efficiency high torque and heavy weight perfectly suit the demands and architecture of ships. Nevertheless recent emission legislations impose limitations to the pollutant emissions levels in this sector as well. In addition to post-treatment systems it is necessary to reduce some pollutant species and therefore the study of combustion strategies and new fuels can represent valid paths for limiting environmental harmful emissions such as CO2 . The use of methane in dual fuel mode has already been implemented on existent vessels but the progressive decarbonization will lead to the utilization of carbon-neutral or carbon-free fuels such as in the last case hydrogen. Thanks to its high reactivity nature it can be helpful in the reduction of exhaust CH4 . On the contrary together with the high temperatures achieved by its oxidation hydrogen could cause uncontrolled ignition of the premixed charge and high emissions of NOx. As a matter of fact a source of ignition is still necessary to have better control on the whole combustion development. To this end an optimal and specific injection strategy can help to overcome all the before-mentioned issues. In this study three-dimensional numerical simulations have been performed with the ANSYS Forte® software (version 19.2) in an 8.8 L dual fuel engine cylinder supplied with methane hydrogen or hydrogen–methane blends with reference to experimental tests from the literature. A new kinetic mechanism has been used for the description of diesel fuel surrogate oxidation with a set of reactions specifically addressed for the low temperatures together with the GRIMECH 3.0 for CH4 and H2 . This kinetics scheme allowed for the adequate reproduction of the ignition timing for the various mixtures used. Preliminary calculations with a one-dimensional commercial code were performed to retrieve the initial conditions of CFD calculations in the cylinder. The used approach demonstrated to be quite a reliable tool to predict the performance of a marine engine working under dual fuel mode with hydrogen-based blends at medium load. As a result the system modelling shows that using hydrogen as fuel in the engine can achieve the same performance as diesel/natural gas but when hydrogen totally replaces methane CO2 is decreased up to 54% at the expense of the increase of about 76% of NOx emissions.
Review on Ammonia as a Potential Fuel: From Synthesis to Economics
Feb 2021
Publication
Ammonia a molecule that is gaining more interest as a fueling vector has been considered as a candidate to power transport produce energy and support heating applications for decades. However the particular characteristics of the molecule always made it a chemical with low if any benefit once compared to conventional fossil fuels. Still the current need to decarbonize our economy makes the search of new methods crucial to use chemicals such as ammonia that can be produced and employed without incurring in the emission of carbon oxides. Therefore current efforts in this field are leading scientists industries and governments to seriously invest efforts in the development of holistic solutions capable of making ammonia a viable fuel for the transition toward a clean future. On that basis this review has approached the subject gathering inputs from scientists actively working on the topic. The review starts from the importance of ammonia as an energy vector moving through all of the steps in the production distribution utilization safety legal considerations and economic aspects of the use of such a molecule to support the future energy mix. Fundamentals of combustion and practical cases for the recovery of energy of ammonia are also addressed thus providing a complete view of what potentially could become a vector of crucial importance to the mitigation of carbon emissions. Different from other works this review seeks to provide a holistic perspective of ammonia as a chemical that presents benefits and constraints for storing energy from sustainable sources. State-of-the-art knowledge provided by academics actively engaged with the topic at various fronts also enables a clear vision of the progress in each of the branches of ammonia as an energy carrier. Further the fundamental boundaries of the use of the molecule are expanded to real technical issues for all potential technologies capable of using it for energy purposes legal barriers that will be faced to achieve its deployment safety and environmental considerations that impose a critical aspect for acceptance and wellbeing and economic implications for the use of ammonia across all aspects approached for the production and implementation of this chemical as a fueling source. Herein this work sets the principles research practicalities and future views of a transition toward a future where ammonia will be a major energy player.
Toward Sustainability: An Overview of the Use of Green Hydrogen in the Agriculture and Livestock Sector
Aug 2023
Publication
The agro-livestock sector produces about one third of global greenhouse gas (GHG) emissions. Since more energy is needed to meet the growing demand for food and the industrial revolution in agriculture renewable energy sources could improve access to energy resources and energy security reduce dependence on fossil fuels and reduce GHG emissions. Hydrogen production is a promising energy technology but its deployment in the global energy system is lagging. Here we analyzed the theoretical and practical application of green hydrogen generated by electrolysis of water powered by renewable energy sources in the agro-livestock sector. Green hydrogen is at an early stage of development in most applications and barriers to its large-scale deployment remain. Appropriate policies and financial incentives could make it a profitable technology for the future.
Life Cycle Assessment Comparison of Orchard Tractors Powered by Diesel and Hydrogen Fuel Cell
Sep 2024
Publication
To reduce the impact of the agricultural sector on the environment human health and resource depletion several steps should be taken to develop innovative powertrain systems. The agricultural sector must be involved in this innovation since diesel-powered tractors are an important source in terms of pollution. In this context fuel-cell systems have gained importance making them one of the possible substitutes due to their characteristics featuring almost zero local emissions low refueling time and high efficiency. However to effectively assess the sustainability of a fuel-cell tractor a cradle-to-grave life cycle assessment comprising production use phase and end of life must be performed. This article presents a comparative analysis according to different impact categories of the life cycle impacts of a traditional diesel-powered tractor and a fuel-cell hybrid tractor designed considering operative requirements and functional constraints. The study was conducted according to the LCA technique (defined by ISO 14040 and ISO 14044 standards) combining secondary data mainly derived from studies and reports available in the literature with the use of the Ecoinvent 3.0 database. The results are presented according to ten different impact categories defined by ReCiPe 2016 v 1.03 at the midpoint level. The findings obtained showed that the fuel-cell tractor allows for a relevant reduction in all the considered categories. The highest-impact reduction more than 92% was obtained in the human toxicity non-carcinogenic category while the lowest reduction around 4.55% was observed for the fossil fuel scarcity category mainly due to the adoption of gray hydrogen which is produced from fossil fuels. As for the climate change category the fuel-cell tractor showed a reduction of more than 34% in the life cycle impact. Finally the authors also considered the case of green hydrogen produced using solar energy. In this case further reductions in the impact on climate change and fossil fuel resource depletion were obtained. However for the other impact categories the results were worse compared to using gray hydrogen.
A Comprehensive Literature Review on Hydrogen Tanks: Storage, Safety, and Structural Integrity
Oct 2024
Publication
In recent years there has been a significant increase in research on hydrogen due to the urgent need to move away from carbon-intensive energy sources. This transition highlights the critical role of hydrogen storage technology where hydrogen tanks are crucial for achieving cleaner energy solutions. This paper aims to provide a general overview of hydrogen treatment from a mechanical viewpoint and to create a comprehensive review that integrates the concepts of hydrogen safety and storage. This study explores the potential of hydrogen applications as a clean energy alternative and their role in various sectors including industry automotive aerospace and marine fields. The review also discusses design technologies safety measures material improvements social impacts and the regulatory landscape of hydrogen storage tanks and safety technology. This work provides a historical literature review up to 2014 and a systematic literature review from 2014 to the present to fill the gap between hydrogen storage and safety. In particular a fundamental feature of this work is leveraging systematic procedural techniques for performing an unbiased review study to offer a detailed analysis of contemporary advancements. This innovative approach differs significantly from conventional review methods since it involves a replicable scientific and transparent process which culminates in minimizing bias and allows for highlighting the fundamental issues about the topics of interest and the main conclusions of the experts in the field of reference. The systematic approach employed in the paper was used to analyze 55 scientific articles resulting in the identification of six primary categories. The key findings of this review work underline the need for improved materials enhanced safety protocols and robust infrastructure to support hydrogen adoption. More importantly one of the fundamental results of the present review analysis is pinpointing the central role that composite materials will play during the transition toward hydrogen applications based on thin-walled industrial vessels. Future research directions are also proposed in the paper thereby emphasizing the importance of interdisciplinary collaboration to overcome existing challenges and facilitate the safe and efficient use of hydrogen.
Hydrogen Carriers: Scientific Limits and Challenges for the Supply Chain, and Key Factors for Techno-Economic Analysis
Aug 2023
Publication
Hydrogen carriers are one of the keys to the success of using hydrogen as an energy vector. Indeed sustainable hydrogen production exploits the excess of renewable energy sources after which temporary storage is required. The conventional approaches to hydrogen storage and transport are compressed hydrogen (CH2 ) and liquefied hydrogen (LH2 ) which require severe operating conditions related to pressure (300–700 bar) and temperature (T < −252 ◦C) respectively. To overcome these issues which have hindered market penetration several alternatives have been proposed in the last few decades. In this review the most promising hydrogen carriers (ammonia methanol liquid organic hydrogen carriers and metal hydrides) have been considered and the main stages of their supply chain (production storage transportation H2 release and their recyclability) have been described and critically analyzed focusing on the latest results available in the literature the highlighting of which is our current concern. The last section reviews recent techno-economic analyses to drive the selection of hydrogen carrier systems and the main constraints that must be considered. The analyzed results show how the selection of H2 carriers is a multiparametric function and it depends on technological factors as well as international policies and regulations.
Assessing the Potential of Hybrid Systems with Batteries, Fuel Cells and E-Fuels for Onboard Generation and Propulsion in Pleasure Vessels
Dec 2024
Publication
Electro-fuels (E-fuels) represent a potential solution for decarbonizing the maritime sector including pleasure vessels. Due to their large energy requirements direct electrification is not currently feasible. E-fuels such as synthetic diesel methanol ammonia methane and hydrogen can be used in existing internal combustion engines or fuel cells in hybrid configurations with lithium batteries to provide propulsion and onboard electricity. This study confirms that there is no clear winner in terms of efficiency (the power-to-power efficiency of all simulated cases ranges from 10% to 30%) and the choice will likely be driven by other factors such as fuel cost onboard volume/mass requirements and distribution infrastructure. Pure hydrogen is not a practical option due to its large storage necessity while methanol requires double the storage volume compared to current fossil fuel solutions. Synthetic diesel is the most straightforward option as it can directly replace fossil diesel and should be compared with biofuels. CO2 emissions from E-fuels strongly depend on the electricity source used for their synthesis. With Italy’s current electricity mix E-fuels would have higher impacts than fossil diesel with potential increases between +30% and +100% in net total CO2 emissions. However as the penetration of renewable energy increases in electricity generation associated E-fuel emissions will decrease: a turning point is around 150 gCO2/kWhel.
Greenhouse Gas Emissions of a Hydrogen Engine for Automotive Application through Life-Cycle Assessment
May 2024
Publication
Hydrogen combustion engine vehicles have the potential to rapidly enter the market and reduce greenhouse gas emissions (GHG) compared to conventional engines. The ability to provide a rapid market deployment is linked to the fact that the industry would take advantage of the existing internal combustion engine production chain. The aim of this paper is twofold. First it aims to develop a methodology for applying life-cycle assessment (LCA) to internal combustion engines to estimate their life-cycle GHG emissions. Also it aims to investigate the decarbonization potential of hydrogen engines produced by exploiting existing diesel engine technology and assuming diverse hydrogen production routes. The boundary of the LCA is cradle-to-grave and the assessment is entirely based on primary data. The products under study are two monofuel engines: a hydrogen engine and a diesel engine. The hydrogen engine has been redesigned using the diesel engine as a base. The engines being studied are versatile and can be used for a wide range of uses such as automotive cogeneration maritime off-road and railway; however this study focuses on their application in pickup trucks. As part of the redesign process certain subsystems (e.g. combustion injection ignition exhaust gas recirculation and exhaust gas aftertreatment) have been modified to make the engine run on hydrogen. Results revealed that employing a hydrogen engine using green hydrogen (i.e. generated from water electrolysis using wind-based electricity) might reduce GHG emission by over 90% compared to the diesel engine This study showed that the benefits of the new hydrogen engine solution outweigh the increase of emissions related to the redesign process making it a potentially beneficial solution also for reconditioning current and used internal combustion engines.
Routes for Hydrogen Introduction in the Industrial Hard-to-Abate Sectors for Promoting Energy Transition
Aug 2023
Publication
This paper offers a set of comprehensive guidelines aimed at facilitating the widespread adoption of hydrogen in the industrial hard-to-abate sectors. The authors begin by conducting a detailed analysis of these sectors providing an overview of their unique characteristics and challenges. This paper delves into specific elements related to hydrogen technologies shedding light on their potential applications and discussing feasible implementation strategies. By exploring the strengths and limitations of each technology this paper offers valuable insights into its suitability for specific applications. Finally through a specific analysis focused on the steel sector the authors provide in-depth information on the potential benefits and challenges associated with hydrogen adoption in this context. By emphasizing the steel sector as a focal point the authors contribute to a more nuanced understanding of hydrogen’s role in decarbonizing industrial processes and inspire further exploration of its applications in other challenging sectors.
Multi-objective Optimization of a Hydrogen Supply Chain Network: Wind and Solid Biomass as Primary Energy Sources for the Public Transport in Sicily
Jun 2024
Publication
Europe’s heavy reliance on diesel power for nearly half of its railway lines for both goods and passengers has significant implications for carbon emissions. To address this challenge the European Union advocates for a shift towards hydrogen-based mobility necessitating the development of robust and cost-effective hydrogen supply chains at regional and national levels. Leveraging renewable energy sources such as wind farms and solid biomass could foster the transition to sustainable hydrogen-based transportation. In this study a mixed-integer linear programming approach integrated with an external heavy-duty refueling station analysis model is employed to address the optimal design of a new hydrogen supply chain. Through multi-objective optimization this study aimed to minimize the overall daily costs and emissions of the supply chain. By applying the model to a case study in Sicily different scenarios with varying supply chain configurations and wind curtailment factors were explored. The findings revealed that increasing the wind curtailment factor from 1% to 2% led to reductions of 12% and 15% in the total daily emission costs and network costs respectively. Additionally centralized biomass-based plants dominated hydrogen production accounting for 96% and 94% of the total production under 1% and 2% wind curtailment factors respectively. Furthermore transporting gaseous hydrogen via tube trailers proved more cost effective than using tanker trucks for liquid hydrogen when compressed gaseous hydrogen is required at the dispenser of forecourt refueling stations. Finally the breakdown of the levelized cost for the hydrogen refuelling station strongly depends on the form of hydrogen received at the gate namely liquid or gaseous. Specifically for the former the dispenser accounts for 60% of the total cost whereas for the latter the compressor is responsible for 58% of the total cost. This study highlights the importance of preliminary and quantitative analyses of new hydrogen supply chains through model-based optimization.
3D CFD Simulation of a Gaseous Fuel Injection in a Hydrogen-fueled Internal Combustion Engine
Oct 2021
Publication
Nowadays one of the hottest topic in the automotive engineering community is the reduction of fossil fuels. Hydrogen is an alternative energy source that is already providing clean renewable and efficient power being used in fuel cells. Despite being developed since a few decades fuel cells are affected by several hurdles the most impacting one being their cost per unit power. While waiting for their cost reduction and mass-market penetration hydrogen-fueled internal combustion engines (H2ICEs) can be a rapidly applicable solution to reduce pollution caused by the combustion of fossil fuels. Such engines benefit from the advanced technology of modern internal combustion engines (ICEs) and the advantages related to hydrogen combustion although some modifications are needed for conventional liquid-fueled engines to run on hydrogen. The gaseous injection of hydrogen directly into the combustion chamber is a challenge both for the designers and for the injection system suppliers. To reduce uncertainties time and development cost computational fluid dynamics (CFD) tools appear extremely useful since they can accurately predict mixture formation and combustion before the expensive production/testing phase. The high-pressure gaseous injection which takes place in Direct-Injected H2ICEs promotes a super-sonic flow with very high gradients in the zone between the bulk of the injected hydrogen and the flow already inside the combustion chamber. To develop a methodology for an accurate simulation of these phenomena the SoPHy Engine of the Engine Combustion Network group (ECN) is used and presented. This engine is fed through a single nozzle H2-injector; planar laser-induced fluorescence (PLIF) data are available for comparison with the CFD outcomes.
Thermal Design and Heat Transfer Optimisation of a Liquid Organic Hydrogen Carrier Batch Reactor for Hydrogen Storage
Aug 2023
Publication
Liquid organic hydrogen carriers (LOHCs) are considered a promising hydrogen storage technology. Heat must be exchanged with an external medium such as a heat transfer fluid for the required chemical reactions to occur. Batch reactors are simple but useful solutions for small-scale storage applications which can be modelled with a lumped parameter approach adequately reproducing their dynamic performance. For such reactors power is consumed to circulate the external heat transfer fluid and stir the organic liquid inside the reactor and heat transfer performance and power consumption are two key parameters in reactor optimisation. Therefore with reference to the hydrogen release phase this paper describes a procedure to optimise the reactor thermal design based on a lumped-parameter model in terms of heat transfer performance and minimum power consumption. Two batch reactors are analysed: a conventional jacketed reactor with agitation nozzles and a half-pipe coil reactor. Heat transfer performance is evaluated by introducing a newly defined dimensionless parameter the Heat Transfer Ratio (HTR) whose value directly correlates to the heat rate required by the carrier's dehydrogenation reaction. The resulting model is a valid tool for adequately reproducing the hydrogen storage behaviour within dynamic models of complex and detailed energy systems.
Suitability and Energy Sustainability of Atmospheric Water Generation Technology for Green Hydrogen Production
Sep 2023
Publication
This research investigated the suitability of air-to-water generator (AWG) technology to address one of the main concerns in green hydrogen production namely water supply. This study specifically addresses water quality and energy sustainability issues which are crucial research questions when AWG technology is intended for electrolysis. To this scope a reasoned summary of the main findings related to atmospheric water quality has been provided. Moreover several experimental chemical analyses specifically focused on meeting electrolysis process requirements on water produced using a real integrated AWG system equipped with certified materials for food contact were discussed. To assess the energy sustainability of AWGs in green hydrogen production a case study was presented regarding an electrolyzer plant intended to serve as energy storage for a 2 MW photovoltaic field on Iriomote Island. The integrated AWG used for the water quality analyses was studied in order to determine its performance in the specific island climate conditions. The production exceeded the needs of the electrolyzer; thus the overproduction was considered for the panels cleaning due to the high purity of the water. Due to such an operation the efficiency recovery was more than enough to cover the AWG energy consumption. This paper on the basis of the quantity results provides the first answers to the said research questions concerning water quality and energy consumption establishing the potential of AWG as a viable solution for addressing water scarcity and enhancing the sustainability of electrolysis processes in green hydrogen production.
Experimental Study of Cycle-by-cycle Variations in a Spark Ignition Internal Combustion Engine Fueled with Hydrogen
Feb 2024
Publication
High fluctuations in the combustion process from one cycle to another referred to as cycle-by-cycle variations can have adverse effects on internal combustion engine performances particularly in spark ignition (SI) engines. These effects encompass incomplete combustion the potential for misfires and adverse impacts on fuel economy. Furthermore the cycle-by-cycle variations can also affect a vehicle’s drivability and overall comfort especially when operating under lean-burn conditions. Although many cycle-by-cycle analyses have been investigated extensively in the past there is limited in-depth knowledge available regarding the causes of cycle-by-cycle (CbC) variations in hydrogen lean-burn SI engines. Trying to contribute to this topic the current study presents a comprehensive analysis of the CbC variations based on the cylinder pressure data. The study was carried out employing a hydrogen single-cylinder research SI engine. The experiments were performed by varying more than fifty operating conditions including the variations in lambda spark advance boost pressure and exhaust gas recirculation however the load and speed were kept constant throughout the experimental campaign. The results indicate that pressure exhibits significant variations during the combustion process and minor variations during non-combustion processes. In the period from the inlet valve close till the start of combustion pressure exhibits the least variations. The coefficient of variation of pressure (COVP) curve depicts three important points in H2-ICE as well: global minima global maxima and second local minima. The magnitude of the COVP curve changes across all the operating conditions however the shape of the COVP curve remains unchanged across all the operating conditions indicating its independence from the operating condition in an H2-ICE. This study presents an alternative approach for a quick combustion analysis of hydrogen engines. Without the need for more complex methodologies like heat release rate analysis the presented cylinder pressure cycle-by-cycle analysis enables a quick and precise identification of primary combustion features (start of combustion center of combustion end of combustion and operation condition stability). Additionally the engine control unit could implement these procedures to automatically adjust cycle-by-cycle variations therefore increasing engine efficiency.
Techno-economic Analysis of Territorial Case Studies for the Integration of Biorefineries and Green Hydrogen
Nov 2024
Publication
To achieve sustainable development the transition from a fossil-based economy to a circular economy is essential. The use of renewable energy sources to make the overall carbon foot print more favorable is an important pre-requisite. In this context it is crucial to valorize all renewable resources through an optimized local integration. One opportunity arises through the synergy between bioresources and green hydrogen. Through techno-economic assessments this work analyzes four local case studies that integrate bio-based processes with green hydrogen produced via electrolysis using renewable energy sources. An analysis of the use of webGIS tools (i.e. Atlas of Biorefineries of IEA Bioenergy) to identify existing biorefineries that require hydrogen in relation to territories with a potential availability of green hydrogen has never been conducted before. This paper provides an evaluation of the production costs of the target products as a function of the local green hydrogen supply costs. The results revealed that the impact of green hydrogen costs could vary widely ranging from 1% to 95% of the total production costs depending on the bio-based target product evaluated. Additionally hydrogen demand in the target area could require an installed variable renewable energy capacity of 20 MW and 500 MW. On the whole the local integration of biorefineries and green hydrogen could represent an optimal opportunity to make hydrogenated bio-based products 100% renewable.
Analysis and Comparison of Hydrogen Generators Safety Measures According to International Regulations, Codes and Standards (RCS)
Sep 2023
Publication
Climate change has prompted the international community to invest heavily in renewable energy sources in order to gradually replace fossil fuels. Whilst energy systems will be increasingly based on non-programmable renewable sources hydrogen is the main player when it comes to the role of energy reserve. This change has triggered a fast development of hydrogen production technologies with increasing use and installation of hydrogen generators (electrolyzers) in both the civil and industrial sector. The implementation of such investments requires the need for accurate design and verification of hydrogen systems with particular attention on fire safety. Due to its chemical-physical characteristics hydrogen is highly flammable and is often stored at very high-pressure levels. ISO 22734 and NFPA 2 are the main international standards which are currently available for the design of hydrogen generators and systems both of which include fire safety requirements. This paper analyses the main existing Regulations Codes and Standards (RCS) for hydrogen generators with the purpose of evaluating and comparing fire safety measures with focus on both active protection (detection systems extinguishing systems) and passive protection (safety distances separation walls). The scope of the paper is to identify safety measures which can be considered generally applicable and provide a reference for further fire safety regulations. The analysis carried out identifies potential gaps in RCS and suggests areas for potential future research.
Power-to-gas and Power-to-liquid Systems in Emerging Hydrogen Valleys: Techno-economic Assessment of Alternative Fuels
Feb 2025
Publication
This study presents a techno-economic assessment of power-to-gas and power-to-liquid pathways within the Hydrogen Valley concept to support the decarbonization of local energy systems. Using the EnergyPLAN software both business-as-usual and Hydrogen Valley scenarios were analyzed by varying renewable energy electrolyzer capacity and hydrogen storage. The levelized costs of green hydrogen electrofuels and synthetic natural gas were estimated for both scenarios. A sensitivity analysis was conducted to assess the impact of cost parameters on the levelized costs of hydrogen and alternative fuel production. The findings indicate that the Hydrogen Valley scenario results in a 5.9% increase in total annual costs but achieves a 29.5% reduction in CO2 emissions compared to the business-as-usual scenario. Additionally utilizing excess energy for power-to-gas and power-to-liquid conversion in the Hydrogen Valley scenario lowers the levelized cost of electrofuels from 0.28 €·kWh−1 to 0.21 €·kWh−1 . Similarly the levelized cost of synthetic natural gas decreases from 0.33 €·kWh−1 to 0.25 €·kWh−1 when transitioning from the businessas-usual scenario to the Hydrogen Valley scenario. The results highlight that Hydrogen Valleys enable low-emission energy systems with cost-effective alternative fuels underscoring the tradeoffs between deep decarbonization and cost optimization in the transition to clean energy systems.
Simulation of DDT in Obstructed Channels: Wavy Channels vs. Fence-type Obstacles
Sep 2023
Publication
The capabilities of an OpenFOAM solver to reproduce the transition of stoichiometric H2-air mixtures to detonation in obstructed 2-D channels were tested. The process is challenging numerically as it involves the ignition of a flame kernel its subsequent propagation and acceleration interaction with obstacles formation of shock waves ahead and detonation onset (DO). Two different obstacle configurations were considered in 10-mm high × 1-m long channels: (i) wavy walls (WW) that mimic the behavior of fencetype obstacles but prevent abrupt area changes. In this case flame acceleration (FA) is strongly affected by shock-flame interactions and DO often results from the compression of the gas present between the accelerating flame front and a converging section of the channel. (ii) Fence-type (FT) obstacles. In this case FA is driven by the increase in flame surface area as a result of the interaction of the flame front with the unburned gas flow field ahead particularly downstream of obstacles; shock-flame interactions play a role at the later stages of FA and DO takes place upon reflection of precursor shocks from obstacles. The effect of initial pressure p0 = 25 50 and 100 kPa at constant blockage ratio (BR = 0.6) was investigated and compared for both configurations. Results show that for the same initial pressure (p0 = 50 kPa) the obstacle configurations could lead to different final propagation regimes: a quasi-detonation for WW and a choked-flame for FT due to the increased losses for the latter. At p0 = 25 kPa however while both configurations result in choked flames WW seem to exhibit larger velocity deficits than FT due to longer flame-precursor shock distances during quasi-steady propagation and to the increased presence of unburnt mixture downstream of the tip of the flame that homogeneously explodes providing additional support to the propagation of the flame.
Artificial Neural Networks as a Tool for High-Accuracy Prediction of In-Cylinder Pressure and Equivalent Flame Radius in Hydrogen-Fueled Internal Combustion Engines
Jan 2025
Publication
The automotive industry is under increasing pressure to develop cleaner and more efficient technologies in response to stringent emission regulations. Hydrogenpowered internal combustion engines represent a promising alternative offering the potential to reduce carbon-based emissions while improving efficiency. However the accurate estimation of in-cylinder pressure is crucial for optimizing the performance and emissions of these engines. While traditional simulation tools such as GT-POWER are widely utilized for these purposes recent advancements in artificial intelligence provide new opportunities for achieving faster and more accurate predictions. This study presents a comparative evaluation of the predictive capabilities of GT-POWER and an artificial neural network model in estimating in-cylinder pressure with a particular focus on improvements in computational efficiency. Additionally the artificial neural network is employed to predict the equivalent flame radius thereby obviating the need for repeated tests using dedicated high-speed cameras in optical access research engines due to the resource-intensive nature of data acquisition and post-processing. Experiments were conducted on a single-cylinder research engine operating at low-speed and low-load conditions across three distinct relative air–fuel ratio values with a range of ignition timing settings applied for each air excess coefficient. The findings demonstrate that the artificial neural network model surpasses GT-POWER in predicting in-cylinder pressure with higher accuracy achieving an RMSE consistently below 0.44% across various conditions. In comparison GT-POWER exhibits an RMSE ranging from 0.92% to 1.57%. Additionally the neural network effectively estimates the equivalent flame radius maintaining an RMSE of less than 3% ranging from 2.21% to 2.90%. This underscores the potential of artificial neural network-based approaches to not only significantly reduce computational time but also enhance predictive precision. Furthermore this methodology could subsequently be applied to conventional road engines exhibiting characteristics and performance similar to those of a specific optical engine used as the basis for the machine learning analysis offering a practical advantage in real-time diagnostics.
A Comprehensive Review on Liquid Hydrogen Transfer Operations and Safety Considerations for Mobile Applications
Dec 2024
Publication
The adoption of liquid hydrogen (LH2) as an energy carrier presents significant opportunities for distributing large quantities of hydrogen efficiently. However ensuring safety of LH2 transfer operations requires the evo lution of suitable technologies and regulatory framework. This study offers an extensive overview of technical considerations and safety aspects pertaining to liquid hydrogen installations and mobile applications. A signif icant lack of regulations specifically tailored for LH2 transfer operations is highlighted. Additionally experi mental findings and outcomes of the modelling activities carried out in previous research are presented shedding light on the combustion and ignition behaviour of liquid hydrogen during accident scenarios. The identification of research gaps and ongoing research projects underscores the importance of continued investigation and development of this critical area.
Clean Hydrogen and Ammonia Synthesis in Paraguay from the Itaipu 14 GW Hydroelectric Plant
Nov 2019
Publication
This paper aims at investigating clean hydrogen production from the large size (14 GW) hydroelectric power plant of Itaipu located on the border between Paraguay and Brazil the two countries that own and manage the plant. The hydrogen produced by a water electrolysis process is converted into ammonia through the well-known Haber-Bosch process. Hydraulic energy is employed to produce H2 and N2 respectively from a large-scale electrolysis system and an air separation unit. An economic feasibility analysis is performed considering the low electrical energy price in this specific scenario and that Paraguay has strong excess of renewable electrical energy but presents a low penetration of electricity. The proposal is an alternative to increase the use of electricity in the country. Different plant sizes were investigated and for each of them ammonia production costs were determined and considered as a term of comparison with traditional ammonia synthesis plants where H2 is produced from methane steam reforming and then purified. The study was performed employing a software developed by the authors’ research group at the University of Genoa. Finally an energetic environmental and economic comparison with the standard production method from methane is presented.
Evaluation of CNG Engine Conversion to Hydrogen Fuel for Stationary and Transient Operations
Dec 2024
Publication
This study investigates the use of hydrogen (H2 ) as a substitute for compressed natural gas (CNG) in a heavyduty (HD) six-cylinder engine focusing on both port fuel injection (PFI) and direct injection (DI) systems. Numerical modeling in a 0D/1D environment was employed simulating engine operation under stationary conditions and during the worldwide harmonized transient cycle (WHTC) and worldwide harmonized vehicle cycle (WHVC) homologation cycles. Results indicated a reduction in torque (7% for direct injection and 21.5% for port fuel injection) and power (32% for direct injection and 35.5% for port fuel injection) when switching from CNG to H2 . Efficiency slightly decreased primarily due to knocking at high engine loads and speeds during H2 operation. The reduced torque and power were mainly attributed to the turbocharger being undersized for H2 given its low density and the lean mixture combustion strategy used. Upgrading the turbocharger or implementing a two-stage compressor could restore or even improve torque and power levels compared to CNG. Heat transfer losses in the H2 engine were lower than with CNG due to the lower incylinder temperature resulting from the lean mixture strategy which also contributed to a significant reduction in nitrogen oxides (NOx ) emissions approximately 2.5 times lower than those with CNG. Despite a notable exhaust energy loss during H2 operation caused by delayed combustion due to knocking the lower NOx emissions and absence of carbon emissions are crucial for reducing pollution. During vehicle cycles selecting an optimal gear-shift strategy is critical to mitigating the performance gap resulting from reduced torque and power with H2 fueling.
Experimental Characterization of Solid Oxide Fuel Cell Hydrogen Fueled in a Residential Small Villa
Jan 2025
Publication
The use of highly efficient cogeneration systems fueled by pure hydrogen such as Solid Oxide Fuel Cells (SOFCs) in the residential sector is one of the new frontiers for achieving the net zero greenhouse gas emissions tran sitions. The lack of experimental studies in this area prompted the authors to propose the present paper. It refers to hydrogen-fueled SOFC 1 kW-sized integrated into the plant system of a single-family villa configurated as a nearly Zero Energy Building. The multiple objectives are: show the technical feasibility of this technology in building; analyse the data of a continuous monitoring campaign in wintertime; highlight the real performance compared to the manufacturer’s declaration. The results demonstrate that in particular conditions of photo voltaic production it is possible to meet the home electric loads and have a surplus of energy to store or send to the national power grid. The calculated electrical efficiency is equal to 0.47 ÷ 0.48 while the maximum overall efficiency is 0.93.
Market Dynamics and Power Risks in Green Technology Materials: Platinum under the EU 2030 Hydrogen Target
Jan 2025
Publication
The central role of hydrogen in the EU’s decarbonization strategy has increased the importance of critical raw materials. To address this the EU has taken legislative steps including the 2023 Critical Raw Materials Act (CRMA) to ensure a stable supply. Using a leader–follower Stackelberg game framework this study analyzes CRM market dynamics integrating CRMA compliance through rules on sourcing and stockpiling value chain resilience via the inclusion of supply diversification strategies and geopolitical influences by modeling exporter behaviors and trade dependencies. Results highlight the potential for strategic behavior by major exporters stressing the benefits of diversifying export sources and maintaining strategic stockpiles to stabilize supply. The findings provide insights into the EU’s efforts to secure CRM supplies key to achieving decarbonization goals and fostering a sustainable energy transition. Future research should explore alternative cost-reduction strategies mitigate exporter market power and evaluate the implications for pricing mechanisms market outcomes and consumer welfare
Preliminary Analysis of Refilling Cold-adsorbed Hydrogen Tanks
Sep 2023
Publication
The effective storage of hydrogen is a critical challenge that needs to be overcome for it to become a widely used and clean energy source. Various methods exist for storing hydrogen including compression at high pressures liquefaction through extreme cooling (i.e. -253 °C) and storage with chemical compounds. Each method has its own advantages and disadvantages. MAST3RBoost (Maturing the Production Standards of Ultraporous Structures for High Density Hydrogen Storage Bank Operating on Swinging Temperatures and Low Compression) is a European funded Project aiming to establish a reliable benchmark for cold-adsorbed H2 storage (CAH2) at low compression levels (100 bar or below). This is achieved through the development of advanced ultraporous materials suitable for mobility applications such as hydrogen-powered vehicles used in road railway air and water transportation. The MAST3RBoost Project utilizes cutting-edge materials including Activated Carbons (ACs) and high-density MOFs (Metalorganic Frameworks) which are enhanced by Machine Learning techniques. By harnessing these materials the project seeks to create a groundbreaking path towards meeting industry goals. The project aims to develop the world's first adsorption-based demonstrator at a significant kg-scale. To support the design of the storage tank the project employs Computational Fluid Dynamics (CFD) software which allows for numerical investigations. In this paper a preliminary analysis of the tank refilling process is presented with a focus on the impact of the effect of the tank and hydrogen temperatures on quantity of hydrogen adsorbed.
Estimating Greenhouse Gas Emissions from Hydrogen-Blended Natural Gas Networks
Dec 2024
Publication
Methane is a significant contributor to anthropogenic greenhouse gas emissions. Blending hydrogen with natural gas in existing networks presents a promising strategy to reduce these emissions and support the transition to a carbon-neutral energy system. However hydrogen’s potential for atmospheric release raises safety and environmental concerns necessitating an assessment of its impact on methane emissions and leakage behavior. This study introduces a methodology for estimating how fugitive emissions change when a natural gas network is shifted to a 10% hydrogen blend by combining analytical flowrate models with data from sampled leaks across a natural gas network. The methodology involves developing conversion factors based on existing methane emission rates to predict corresponding hydrogen emissions across different sections of the network including mainlines service lines and facilities. Our findings reveal that while the overall volumetric emission rates increase by 5.67% on the mainlines and 3.04% on the service lines primarily due to hydrogen’s lower density methane emissions decrease by 5.95% on the mainlines and 8.28% on the service lines. However when considering the impact of a 10% hydrogen blend on the Global Warming Potential the net reduction in greenhouse gas emissions is 5.37% for the mainlines and 7.72% for the service lines. This work bridges the gap between research on hydrogen leakage and network readiness which traditionally focuses on safety and environmental sustainability studies on methane emission.
Hydrogen Gas Compression for Efficient Storage: Balancing Energy and Increasing Density
May 2024
Publication
This article analyzes the processes of compressing hydrogen in the gaseous state an aspect considered important due to its contribution to the greater diffusion of hydrogen in both the civil and industrial sectors. This article begins by providing a concise overview and comparison of diverse hydrogen-storage methodologies laying the groundwork with an in-depth analysis of hydrogen’s thermophysical properties. It scrutinizes plausible configurations for hydrogen compression aiming to strike a delicate balance between energy consumption derived from the fuel itself and the requisite number of compression stages. Notably to render hydrogen storage competitive in terms of volume pressures of at least 350 bar are deemed essential albeit at an energy cost amounting to approximately 10% of the fuel’s calorific value. Multi-stage compression emerges as a crucial strategy not solely for energy efficiency but also to curtail temperature rises with an upper limit set at 200 ◦C. This nuanced approach is underlined by the exploration of compression levels commonly cited in the literature particularly 350 bar and 700 bar. The study advocates for a three-stage compression system as a pragmatic compromise capable of achieving high-pressure solutions while keeping compression work below 10 MJ/kg a threshold indicative of sustainable energy utilization.
China and Italy’s Energy Development Trajectories: Current Landscapes and Future Cooperation Potential
Feb 2024
Publication
In order to achieve the ambitious goal of “carbon neutrality” countries around the world are striving to develop clean energy. Against this background this paper takes China and Italy as representatives of developing and developed countries to summarize the energy structure composition and development overview of the two countries. The paper analyzes the serious challenges facing the future energy development of both countries and investigates the possibilities of energy cooperation between the two countries taking into account their respective advantages in energy development. By comparing the policies issued by the two governments to encourage clean energy development this paper analyzes the severe challenges faced by the two countries’ energy development in the future and combines their respective energy development advantages to look forward to the possibility of energy cooperation between the two countries in the future. This lays the foundation for China and Italy to build an “Energy Road” after the “Silk Road”.
Energy Transition Technology Comes With New Process Safety Challenges and Risks
Jul 2023
Publication
This paper intends to give an impression of new technologies and processes that are in development for application to achieve decarbonization and about which less or no experience on associated hazards exists in the process industry. More or less an exception is hydrogen technology because its hazards are relatively known and there is industry experience in handling it safely but problems will arise when it is produced stored and distributed on a large scale. So when its use spreads to communities and it becomes as common as natural gas now measures to control the risks will be needed. And even with hydrogen surprise findings have been shown lately e.g. its BLEVE behavior when in a liquified form stored in a vessel heated externally. Substitutes for hydrogen are not without hazard concern either. The paper will further consider the hazards of energy storage in batteries and the problems to get those hazards under control. Relatively much attention will be paid to the electrification of the process industry. Many new processes are being researched which given green energy will be beneficial to reduce greenhouse gases and enhance sustainability but of which hazards are rather unknown. Therefore as last chapter the developments with respect to the concept of hazard identification and scenario definition will be considered in quite detail. Improvements in that respect are also being possible due to the digitization of the industry and the availability of data and considering the entire life cycle all facilitated by the data model standard ISO 15926 with the scope of integration of life-cycle data for process plants including oil and gas production facilities. Conclusion is that the new technologies and processes entail new process and personal hazards and that much effort is going into renewal but safety analyses are scarce. Right in a period of process renewal attention should be focused on possibilities to implement inherently safer design.
No more items...