Italy
Experimental Comparison of Hydrogen Refueling with Directly Pressurized vs. Cascade Method
Aug 2023
Publication
This paper presents a comparative analysis of two hydrogen station configurations during the refueling process: the conventional “directly pressurized refueling process” and the innovative “cascade refueling process.” The objective of the cascade process is to refuel vehicles without the need for booster compressors. The experiments were conducted at the Hydrogen Research and Fueling Facility located at California State University Los Angeles. In the cascade refueling process the facility buffer tanks were utilized as high-pressure storage enabling the refueling operation. Three different scenarios were tested: one involving the cascade refueling process and two involving compressor-driven refueling processes. On average each refueling event delivered 1.6 kg of hydrogen. Although the cascade refueling process using the high-pressure buffer tanks did not achieve the pressure target it resulted in a notable improvement in the nozzle outlet temperature trend reducing it by approximately 8 ◦C. Moreover the overall hydrogen chiller load for the two directly pressurized refuelings was 66 Wh/kg and 62 Wh/kg respectively whereas the cascading process only required 55 Wh/kg. This represents a 20% and 12% reduction in energy consumption compared to the scenarios involving booster compressors during fueling. The observed refueling range of 150–350 bar showed that the cascade process consistently required 12–20% less energy for hydrogen chilling. Additionally the nozzle outlet temperature demonstrated an approximate 8 ◦C improvement within this pressure range. These findings indicate that further improvements can be expected in the high-pressure region specifically above 350 bar. This research suggests the potential for significant improvements in the high-pressure range emphasizing the viability of the cascade refueling process as a promising alternative to the direct compression approach.
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.
A Complete Assessment of the Emission Performance of an SI Engine Fueled with Methanol, Methane and Hydrogen
Feb 2024
Publication
This study explores the potentiality of low/zero carbon fuels such as methanol methane and hydrogen for motor applications to pursue the goal of energy security and environmental sustainability. An experimental investigation was performed on a spark ignition engine equipped with both a port fuel and a direct injection system. Liquid fuels were injected into the intake manifold to benefit from a homogeneous charge formation. Gaseous fuels were injected in direct mode to enhance the efficiency and prevent abnormal combustion. Tests were realized at a fixed indicated mean effective pressure and at three different engine speeds. The experimental results highlighted the reduction of CO and CO2 emissions for the alternative fuels to an extent depending on their properties. Methanol exhibited high THC and low NOx emissions compared to gasoline. Methane and even more so hydrogen allowed for a reduction in THC emissions. With regard to the impact of gaseous fuels on the NOx emissions this was strongly related to the operating conditions. A surprising result concerns the particle emissions that were affected not only by the fuel characteristics and the engine test point but also by the lubricating oil. The oil contribution was particularly evident for hydrogen fuel which showed high particle emissions although they did not contain carbon atoms.
A New Generation of Hydrogen-Fueled Hybrid Propulsion Systems for the Urban Mobility of the Future
Dec 2023
Publication
The H2-ICE project aims at developing through numerical simulation a new generation of hybrid powertrains featuring a hydrogen-fueled Internal Combustion Engine (ICE) suitable for 12 m urban buses in order to provide a reliable and cost-effective solution for the abatement of both CO2 and criteria pollutant emissions. The full exploitation of the potential of such a traction system requires a substantial enhancement of the state of the art since several issues have to be addressed. In particular the choice of a more suitable fuel injection system and the control of the combustion process are extremely challenging. Firstly a high-fidelity 3D-CFD model will be exploited to analyze the in-cylinder H2 fuel injection through supersonic flows. Then after the optimization of the injection and combustion process a 1D model of the whole engine system will be built and calibrated allowing the identification of a “sweet spot” in the ultra-lean combustion region characterized by extremely low NOx emissions and at the same time high combustion efficiencies. Moreover to further enhance the engine efficiency well above 40% different Waste Heat Recovery (WHR) systems will be carefully scrutinized including both Organic Rankine Cycle (ORC)-based recovery units as well as electric turbo-compounding. A Selective Catalytic Reduction (SCR) aftertreatment system will be developed to further reduce NOx emissions to near-zero levels. Finally a dedicated torque-based control strategy for the ICE coupled with the Energy Management Systems (EMSs) of the hybrid powertrain both optimized by exploiting Vehicle-To-Everything (V2X) connection allows targeting H2 consumption of 0.1 kg/km. Technologies developed in the H2-ICE project will enhance the know-how necessary to design and build engines and aftertreatment systems for the efficient exploitation of H2 as a fuel as well as for their integration into hybrid powertrains.
Eco-Sustainable Energy Production in Healthcare: Trends and Challenges in Renewable Energy Systems
Oct 2023
Publication
The shift from fossil fuels to renewable energy systems represents a pivotal step toward the realization of a sustainable society. This study aims to analyze representative scientific literature on eco-sustainable energy production in the healthcare sector particularly in hospitals. Given hospitals’ substantial electricity consumption the adoption of renewable energy offers a reliable low-CO2 emission solution. The COVID-19 pandemic has underscored the urgency for energyefficient and environmentally-responsible approaches. This brief review analyzes the development of experimental simulation and optimization projects for sustainable energy production in healthcare facilities. The analysis reveals trends and challenges in renewable energy systems offering valuable insights into the potential of eco-sustainable solutions in the healthcare sector. The findings indicate that hydrogen storage systems are consistently coupled with photovoltaic panels or solar collectors but only 14% of the analyzed studies explore this potential within hospital settings. Hybrid renewable energy systems (HRES) could be used to meet the energy demands of healthcare centers and hospitals. However the integration of HRES in hospitals and medical buildings is understudied.
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.
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.
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.
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.
A Short Review on Ni Based Catalysts and Related Engineering Issues for Methane Steam Reforming
Mar 2020
Publication
Hydrogen is an important raw material in chemical industries and the steam reforming of light hydrocarbons (such as methane) is the most used process for its production. In this process the use of a catalyst is mandatory and if compared to precious metal-based catalysts Ni-based catalysts assure an acceptable high activity and a lower cost. The aim of a distributed hydrogen production for example through an on-site type hydrogen station is only reachable if a novel reforming system is developed with some unique properties that are not present in the large-scale reforming system. These properties include among the others (i) daily startup and shutdown (DSS) operation ability (ii) rapid response to load fluctuation (iii) compactness of device and (iv) excellent thermal exchange. In this sense the catalyst has an important role. There is vast amount of information in the literature regarding the performance of catalysts in methane steam reforming. In this short review an overview on the most recent advances in Ni based catalysts for methane steam reforming is given also regarding the use of innovative structured catalysts.
3E Analysis of a Virtual Hydrogen Valley Supported by Railway-based H2 Delivery for Multi-transportation Service
Nov 2023
Publication
In Southern Italy near the Mediterranean Sea mobility services like cars bicycles scooters and materialhandling forklifts are frequently required in addition to multimodal local transportation services such as trains ferry boats and airplanes. This research proposes an innovative concept of hydrogen valley virtually simulated in Matlab/Simulink environment located in Calabria. As a novelty hydrogen is produced centrally and delivered via fuel cell hybrid trains to seven hydrogen refueling stations serving various mobility hubs. The centralized production facility operates with a nominal capacity of about 4 tons/day producing hydrogen via PEM electrolysis and storing hydrogen at 200 bar with a hydrogen compressor. As the size of vehicle fleets and the cost of acquiring renewable energy through power purchase agreements vary the hydrogen valley is examined from both a technical and an economic perspective analyzing: the values of the levelized cost of hydrogen the energy consumption and the energy efficiency of the energy systems. Specifically the levelized cost of hydrogen reached competitive values close to 5 €/kg of hydrogen under the most optimistic scenarios with fleet conversions of more than 60 % and a power purchase agreement price lower than 150 €/MWh. Then the benefits of hydrogen rail transport in terms of emissions reduction and health from an economic standpoint are compared to conventional diesel trains and fully electric trains saving respectively 3.2 ktons/year and 0.4 ktons/year of carbon dioxide equivalent emissions and corresponding economic benefits of respectively 51 and 0.548 million euros.
The Potential of Hydrogen-battery Storage Systems for a Sustainable Renewable-based Electrification of Remote Islands in Norway
Oct 2023
Publication
Remote locations and off-grid regions still rely mainly on diesel generators despite the high operating costs and greenhouse gas emissions. The exploitation of local renewable energy sources (RES) in combination with energy storage technologies can be a promising solution for the sustainable electrification of these areas. The aim of this work is to investigate the potential for decarbonizing remote islands in Norway by installing RES-based energy systems with hydrogen-battery storage. A national scale assessment is presented: first Norwegian islands are characterized and classified according to geographical location number of inhabitants key services and current electrification system. Then 138 suitable installation sites are pinpointed through a multiple-step sorting procedure and finally 10 reference islands are identified as representative case studies. A site-specific methodology is applied to estimate the electrical load profiles of all the selected reference islands. An optimization framework is then developed to determine the optimal system configuration that minimizes the levelized cost of electricity (LCOE) while ensuring a reliable 100% renewable power supply. The LCOE of the RES-based energy systems range from 0.21 to 0.63 €/kWh and a clear linear correlation with the wind farm capacity factor is observed (R2 equal to 0.87). Hydrogen is found to be crucial to prevent the oversizing of the RES generators and batteries and ensure long-term storage capacity. The techno-economic feasibility of alternative electrification strategies is also investigated: the use of diesel generators is not economically viable (0.87–1.04 €/kWh) while the profitability of submarine cable connections is highly dependent on the cable length and the annual electricity consumption (0.14–1.47 €/kWh). Overall the cost-effectiveness of RES-based energy systems for off-grid locations in Northern Europe can be easily assessed using the correlations derived in this analysis.
Performance Analysis of a Diabatic Compressed Air Energy Storage System Fueled with Green Hydrogen
Oct 2023
Publication
The integration of an increasing share of Renewable Energy Sources (RES) requires the availability of suitable energy storage systems to improve the grid flexibility and Compressed Air Energy Storage (CAES) systems could be a promising option. In this study a CO2 -free Diabatic CAES system is proposed and analyzed. The plant configuration is derived from a down-scaled version of the McIntosh Diabatic CAES plant where the natural gas is replaced with green hydrogen produced on site by a Proton Exchange Membrane electrolyzer powered by a photovoltaic power plant. In this study the components of the hydrogen production system are sized to maximize the self-consumption share of PV energy generation and the effect of the design parameters on the H2 -CAES plant performance are analyzed on a yearly basis. Moreover a comparison between the use of natural gas and hydrogen in terms of energy consumption and CO2 emissions is discussed. The results show that the proposed hydrogen fueled CAES can effectively match the generation profile and the yearly production of the natural gas fueled plant by using all the PV energy production while producing zero CO2 emissions.
Enhancing Waste-to-Energy and Hydrogen Production through Urban–Industrial Symbiosis: A Multi-Objective Optimisation Model Incorporating a Bayesian Best-Worst Method
Feb 2024
Publication
A surging demand for sustainable energy and the urgency to lower greenhouse gas emissions is driving industrial systems towards more eco-friendly and cost-effective models. Biogas from agricultural and municipal organic waste is gaining momentum as a renewable energy source. Concurrently the European Hydrogen Strategy focuses on green hydrogen for decarbonising the industrial and transportation sectors. This paper presents a multi-objective network design model for urban–industrial symbiosis incorporating anaerobic digestion cogeneration photovoltaic and hydrogen production technologies. Additionally a Bayesian best-worst method is used to evaluate the weights of the sustainability aspects by decision-makers integrating these into the mathematical model. The model optimises industrial plant locations considering economic environmental and social parameters including the net present value energy consumption and carbon footprint. The model’s functionalities are demonstrated through a real-world case study based in Emilia Romagna Italy. It is subject to sensitivity analysis to evaluate how changes in the inputs affect the outcomes and highlights feasible trade-offs through the exploration of the ϵ-constraint. The findings demonstrate that the model substantially boosts energy and hydrogen production. It is not only economically viable but also reduces the carbon footprint associated with fossil fuels and landfilling. Additionally it contributes to job creation. This research has significant implications with potential future studies intended to focus on system resilience plant location optimisation and sustainability assessment.
A Multi-Criteria Decision-Making Framework for Zero Emission Vehicle Fleet Renewal Considering Lifecycle and Scenario Uncertainty
Mar 2024
Publication
: In the last decade with the increased concerns about the global environment attempts have been made to promote the replacement of fossil fuels with sustainable sources. For transport which accounts for around a quarter of total greenhouse gas emissions meeting climate neutrality goals will require replacing existing fleets with electric or hydrogen-propelled vehicles. However the lack of adequate decision support approach makes the introduction of new propulsion technologies in the transportation sector a complex strategic decision problem where distorted non-optimal decisions may easily result in long-term negative effects on the performance of logistic operators. This research addresses the problem of transport fleet renewal by proposing a multi-criteria decision-making approach and takes into account the multiple propulsion technologies currently available and the objectives of the EU Green Deal as well as the inherent scenario uncertainty. The proposed approach based on the TOPSIS model involves a novel decision framework referred to as a generalized life cycle evaluation of the environmental and cost objectives which is necessary when comparing green and traditional propulsion systems in a long-term perspective to avoid distorted decisions. Since the objective of the study is to provide a practical methodology to support strategic decisions the framework proposed has been validated against a practical case referred to the strategic fleet renewal decision process. The results obtained demonstrate how the decision maker’s perception of the technological evolution of the propulsion technologies influences the decision process thus leading to different optimal choices.
Optimal Design of a Hydrogen-powered Fuel Cell System for Aircraft Applications
Mar 2024
Publication
Recently hydrogen and fuel cells have gained interest as an emerging technology to mitigate the effects of climate change caused by the aviation sector. The aim of this work is to evaluate the applicability of this technology to an existing regional aircraft in order to assess its electrification with the aim of reducing greenhouse gas emissions and achieving sustainability goals. The design of a proton-exchange membrane fuel cell system (PEMFC) with the inclusion of liquid hydrogen storage is carried out. Specifically a general mathematical model is developed which involves multiple scales ranging from individual cells to aircraft scale. First the fuel cell electrochemical model is developed and validated against published polarization curves. Then different sizing approaches are used to compute the overall weight of the hydrogen-based propulsion system in order to optimize the system and minimize its weight. Crucially this work underscores that the feasibility of hydrogenbased fuel cell systems relies not only on hydrogen storage but especially on the electrochemical cell performance which influences the size of the balance of plant and especially its thermal management section. In particular the strategic significance of working with fuel cells at partial loads is demonstrated. This entails achieving an optimal balance between the stacks oversizing and the weights of both hydrogen storage and balance of plant thereby minimizing the overall weight of the system. It is thus shown that an integrated approach is imperative to guide progress towards efficient and implementable hydrogen technology in regional aviation. Furthermore a high-performance PEMFC is analyzed resulting in an overall weight reduction up to nearly 10% compared to the baseline case study. In this way it is demonstrated as technological advancements in PEMFCs can offer further prospects for improving system efficiency.
A Hydrogen-fuelled Compressed Air Energy Storage System for Flexibility Reinforcement and Variable Renewable Energy Integration in Grids with High Generation Curtailment
Mar 2024
Publication
Globally the increasing share of renewables prominently driven by intermittent sources such as solar and wind power poses significant challenges to the reliability of current electrical infrastructures leading to the adoption of extreme measures such as generation curtailment to preserve grid security. Within this framework it is essential to develop energy storage systems that contribute to reinforce the flexibility and security of power grids while simultaneously reducing the share of generation curtailment. Therefore this study investigates the performance of an integrated photovoltaic-hydrogen fuelled-compressed air energy storage system whose configuration is specifically conceived to enable the connection of additional intermittent sources in already saturated grids. The yearly and seasonal performance of the integrated energy storage system specifically designed to supply flexibility services are evaluated for a scenario represented by a real grid with high-variable renewables penetration and frequent dispatchability issues. Results show that the integrated system with performanceoptimized components and a new energy management strategy minimizes photovoltaic energy curtailment otherwise around 50% to as low as 4% per year achieving system efficiencies of up to 62% and reinforces the grid by supplying inertial power for up to 20% of nighttime hours. In conclusion the integrated plant operating with zero emissions on-site hydrogen production and optimized for non-dispatchable photovoltaic energy utilization proves to be effective in integrating new variable renewable sources and reinforcing saturated grids particularly during spring and summer.
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