Italy
Experimental Study of Hydrogen Releases in the Passenger Compartment of a Piaggio Porter
Sep 2011
Publication
There are currently projects and demonstration programs aiming at introducing Hydrogen powered Fuel Cell (HFC) vehicles into the market. Regione Toscana has been cofounder of the project “H2 Filiera Idrogeno” whose goal is to achieve a clean and sustainable mobility through HFC vehicle studies covering their production storage and use. Among the goals of the project was the substitution of the electric propulsion system with a hydrogen fuel cells propulsion system. This work presents a brief overview of the necessary modifications of the electric propulsion version of a Piaggio Porter to host a H2 fuel cell and experimental studies of realistic H2 releases from the vehicle. The scenarios covered H2 unintended releases underneath the vehicle when at rest and focused on three types of releases diffusive major and minor that might reach the interior of the vehicle and potentially pose a direct risk to the passengers.
Trends in Gas Sensor Development for Hydrogen Safety
Sep 2013
Publication
Gas sensors are applied for facilitating the safe use of hydrogen in for example fuel cell and hydrogen fuelled vehicles. New sensor developments aimed at meeting the increasingly stringent performance requirements in emerging applications are presented based on in-house technical developments and a literature study. The strategy of combining different detection principles i.e. sensors based on electrochemical cells semiconductors or field effects in combination with thermal conductivity sensor or catalytic combustion elements in one new measuring system is reported. This extends the dynamic measuring range of the sensor while improving sensor reliability to achieve higher safety integrity through diverse redundancy. The application of new nanoscaled materials nano wires carbon tubes and graphene as well as the improvements in electronic components of field-effect resistive-type and optical systems are evaluated in view of key operating parameters such as sensor response time low energy consumption and low working temperature.
CFD Simulations on Small Hydrogen Releases Inside a Ventilated Facility and Assessment of Ventilation Efficiency
Sep 2009
Publication
The use of stationary H2 and fuel cell systems is expected to increase rapidly in the future. In order to facilitate the safe introduction of this new technology the HyPer project funded by the EC developed a public harmonized Installation Permitting Guidance (IPG) document for the installation of small stationary H2 and fuel cell systems for use in various environments. The present contribution focuses on the safety assessment of a facility inside which a small H2 fuel cell system (4.8 kWe) is installed and operated. Dispersion experiments were designed and performed by partner UNIPI. The scenarios considered cover releases occurring inside the fuel cell at the valve of the inlet gas pipeline just before the pressure regulator which controls the H2 flow to the fuel cell system. H2 was expected to leak out of the fuel cell into the facility and then outdoors through the ventilation system. The initial leakage diameter was chosen based on the Italian technical guidelines for the enforcement of the ATEX European directive. Several natural ventilation configurations were examined. The performed tests were simulated by NCSRD using the ADREA-HF code. The numerical analysis took into account the full interior of the fuel cell in order to investigate for any potential accumulation effects. Comparisons between predicted and experimental H2 concentrations at 4 sensor locations inside the facility are reported. Finally an overall assessment of the ventilation efficiency was made based on the simulations and experiments.
Recent Developments in Pd-CeO2 Nano-composite Electrocatalysts for Anodic Reactions in Anion Exchange Membrane Fuel Cells
Jan 2022
Publication
In 2016 for the first time a polymer electrolyte fuel cell free of Pt electrocatalysts was shown to deliver more than 0.5 W cm-2 of peak power density from H2 and air (CO2 free). This was achieved with a silver-based oxygen reduction (ORR) cathode and a Pd-CeO2 hydrogen oxidation reaction (HOR) anodic electrocatalyst. The poor kinetics of the HOR under alkaline conditions is a considerable challenge to Anion Exchange Membrane Fuel Cell (AEMFC) development as high Pt loadings are still required to achieve reasonable performance. Previously the ameliorative combination of Pd and CeO2 nanocomposites has been exploited mostly in heterogeneous catalysis where the positive interaction is well documented. Carbon supported PdCeO2 HOR catalysts have now been prepared by different synthetic techniques and employed in AEMFCs as alternative to Pt and PtRu standards. Important research has also been recently reported delving into the origin of the HOR enhancement on Pd-CeO2. Such work has highlighted the importance of the bifunctional mechanism of the HOR at high pHs. Carefully prepared nano-structures of Pd and CeO2 that promote the formation of the Pd-O-Ce interface provide optimal binding of both Had and OHad species aspects which are crucial for enhanced HOR kinetics. This review paper discusses the recent advances in Pd-CeO2 electrocatalysts for AEMFC anodes.
Homogeneous and Inhomogeneous Hydrogen Deflagrations in 25 m3 Enclosure
Sep 2019
Publication
Explosion venting is a frequently used measure to mitigate the consequence of gas deflagrations in closed environments. Despite the effort to predict the vent area needed to achieved the protection through engineering formulas and CFD tools work has still to be done to reliably predict the outcome of a vented gas explosion. Most of available data derived from experimental campaigns performed in the past involved homogeneous conditions while especially in the case of a very buoyant gas such as hydrogen the most probable scenario that can follow and unintended release in a closed environment foresee the ignition of a stratified inhomogeneous mixture. University of Pisa performed experimental tests in a 25 m3 facility in homogeneous and inhomogeneous conditions. The present paper is aimed to share the results of hydrogen dispersion and deflagration tests and discuss the comparison of maximum peak overpressure generated in the two scenarios. Description of the experimental set-up includes all the details deemed necessary to reproduce the phenomenon with a CFD tool.
Safety Distances: Comparison of the Methodologies for Their Determination
Sep 2011
Publication
In this paper a study on the comparison between the different methodologies for the determination of the safety distances proposed by Standard Organizations and national Regulations is presented. The application of the risk-informed approach is one of the methodologies used for the determination of safety distances together with the risk-based approach. One of the main differences between the various methodologies is the risk criterion chosen. In fact a critical point is which level of risk should be used and then which are the harm events that must be considered. The harm distances are evaluated for a specified leak diameter that is a consequence of some parameters used in the various methodologies. The values of the safety distances proposed by Standard Organizations and national Regulations are a demonstration of the different approaches of the various methodologies especially in the choice of the leak diameter considered.
Integration of Open Slag Bath Furnace with Direct Reduction Reactors for New‐Generation Steelmaking
Jan 2022
Publication
The present paper illustrates an innovative steel processing route developed by employing hydrogen direct reduced pellets and an open slag bath furnace. The paper illustrates the direct reduction reactor employing hydrogen as reductant on an industrial scale. The solution allows for the production of steel from blast furnace pellets transformed in the direct reduction reactor. The reduced pellets are then melted in open slag bath furnaces allowing carburization for further refining. The proposed solution is clean for the decarbonization of the steel industry. The kinetic chemical and thermodynamic issues are detailed with particular attention paid to the slag conditions. The proposed solution is also supported by the economic evaluation compared to traditional routes.
Non-monotonic Overpressure vs. H2 Concentration Behaviour During Vented Deflagration. Experimental Results
Oct 2015
Publication
Explosion relief panels or doors are often used in industrial buildings to reduce damages caused by gas explosions. Decades of research have contributed to the understanding of the phenomena involved in gas explosions in order to establish an effective method to predict reliably the explosion overpressure. All the methods predict a monotonic increase of the overpressure with the concentration of the gas in the range from the lower explosion limit to the stoichiometric one. Nevertheless in few cases a non-monotonic behaviour of the maximum developed pressure as a function of hydrogen concentration was reported in the literature. The non-monotonic behaviour was also observed during experimental tests performed at the Scalbatraio laboratory at the University of Pisa in a 25 m3 vented combustion test facility with a vent area of 112 m2. This paper presents the results obtained during the tests and investigates the possible explanations of the phenomena.
Green H2 Production by Water Electrolysis Using Cation Exchange Membrane: Insights on Activation and Ohmic Polarization Phenomena
Dec 2021
Publication
Low-temperature electrolysis by using polymer electrolyte membranes (PEM) can play an important role in hydrogen energy transition. This work presents a study on the performance of a proton exchange membrane in the water electrolysis process at room temperature and atmospheric pressure. In the perspective of applications that need a device with small volume and low weight a miniaturized electrolysis cell with a 36 cm2 active area of PEM over a total surface area of 76 cm2 of the device was used. H2 and O2 production rates electrical power energy efficiency Faradaic efficiency and polarization curves were determined for all experiments. The effects of different parameters such as clamping pressure and materials of the electrodes on polarization phenomena were studied. The PEM used was a catalyst-coated membrane (Ir-Pt-Nafion™ 117 CCM). The maximum H2 production was about 0.02 g min−1 with a current density of 1.1 A cm−2 and a current power about 280 W. Clamping pressure and the type of electrode materials strongly influence the activation and ohmic polarization phenomena. High clamping pressure and electrodes in titanium compared to carbon electrodes improve the cell performance and this results in lower ohmic and activation resistances.
European Hydrogen Safety Training Programme for First Responders: Hyresponse Outcomes and Perspectives
Sep 2017
Publication
The paper presents the outcomes of the HyResponse project i.e. the European Hydrogen Safety Training Programme for first responders. The threefold training is described: the content of the educational training is presented the operational training platform and its mock-up real scale transport and hydrogen stationary installations are detailed and the innovative virtual tools and training exercises are highlighted. The paper underlines the outcomes the three pilot sessions as well as the Emergency Response Guide available on the HyResponse’s public website. The next steps for widespread dissemination into the community are discussed.
Cylinders and Tubes Used as Buffers in Filling Stations
Oct 2015
Publication
Buffers are key components for hydrogen filling stations that are currently being developed. Type 1 or composite cylinders are used for this application. The type used depends on many parameters including pressure level cost and space available for the filling station. No international standards exist for such high pressure vessels whereas many standards exist covering Types 123 and 4 used for transport of gas or on-board fuel tanks. It is suggested to use the cylinders approved for transport or on-board applications as buffers. This solution appears to be safe if at least one issue is solved. The main difference is that transport or on-board cylinders are cycled from a low pressure to a high pressure during service whereas buffers are cycled from a relatively high pressure (corresponding to the vehicle’s filling pressure) to the MAWP. Another difference is that buffers are cycled many times per day. For standards developers requesting to systematically verify that buffers pass millions of cycles at low pressure amplitude would be impractical. Several standards and codes give formulae to estimate the number of shallow cycles when number of deep cycles are known. In this paper we describe tests performed on all types of composite cylinders to verify or determine the appropriate formulae.
Soft-linking of a Behavioral Model for Transport with Energy System Cost optimization Applied to Hydrogen in EU
Sep 2019
Publication
Fuel cell electric vehicles (FCEV) currently have the challenge of high CAPEX mainly associated to the fuel cell. This study investigates strategies to promote FCEV deployment and overcome this initial high cost by combining a detailed simulation model of the passenger transport sector with an energy system model. The focus is on an energy system with 95% CO2 reduction by 2050. Soft-linking by taking the powertrain shares by country from the simulation model is preferred because it considers aspects such as car performance reliability and safety while keeping the cost optimization to evaluate the impact on the rest of the system. This caused a 14% increase in total cost of car ownership compared to the cost before soft-linking. Gas reforming combined with CO2 storage can provide a low-cost hydrogen source for FCEV in the first years of deployment. Once a lower CAPEX for FCEV is achieved a higher hydrogen cost from electrolysis can be afforded. The policy with the largest impact on FCEV was a purchase subsidy of 5 k€ per vehicle in the 2030–2034 period resulting in 24.3 million FCEV (on top of 67 million without policy) sold up to 2050 with total subsidies of 84 bln€. 5 bln€ of R&D incentives in the 2020–2024 period increased the cumulative sales up to 2050 by 10.5 million FCEV. Combining these two policies with infrastructure and fuel subsidies for 2030–2034 can result in 76 million FCEV on the road by 2050 representing more than 25% of the total car stock. Country specific incentives split of demand by distance or shift across modes of transport were not included in this study.
Micro-wrinkled Pd Surface for Hydrogen Sensing and Switched Detection of Lower Explosive Limit
Sep 2011
Publication
We report the development and testing of a novel hydrogen sensor that shows a very peculiar response to hydrogen exposure due to its micro-structured palladium surface. The fabrication of the wrinkled Pd surface is obtained using an innovative fast and cheap technique based on the deposition of a thin Pd film on to a thermo-retractable polystyrene sheet that shrinks to 40% of its original size when heated. The buckling of the Pd surface induced by shrinking of the substrate produces nano and micro-wrinkles on the sensor surface. The micro-structured sensor surface is very stable even after repeated hydrogen sorption/desorption cycles. The hydrogen sensing mechanism is based on the transitory absorption of hydrogen atoms into the Pd layer leading to the reversible change of its electrical resistance. Interestingly depending on hydrogen concentration the proposed sensor shows the concurrent effect of both the usually described behaviors of increase or decrease of resistance related to different phenomena occurring upon hydrogen exposure and formation of palladium hydride. The study reports and discusses evidences for an activation threshold of hydrogen concentration in air switching the behavior of sensor performances from e.g. poor negative to large positive sensitivity and from slow to fast detection.
Hydrogen Permeation in X65 Steel under Cyclic Loading
May 2020
Publication
This experimental work analyzes the hydrogen embrittlement mechanism in quenched and tempered low-alloyed steels. Experimental tests were performed to study hydrogen diffusion under applied cyclic loading. The permeation curves were fitted by considering literature models in order to evaluate the role of trapping—both reversible and irreversible—on the diffusion mechanism. Under loading conditions a marked shift to the right of the permeation curves was noticed mainly at values exceeding the tensile yield stress. In the presence of a relevant plastic strain the curve changes due to the presence of irreversible traps which efficiently subtract diffusible atomic hydrogen. A significant reduction in the apparent diffusion coefficient and a considerable increase in the number of traps were noticed as the maximum load exceeded the yield strength. Cyclic loading at a tensile stress slightly higher than the yield strength of the material increases the hydrogen entrapment phenomena. The tensile stress causes a marked and instant reduction in the concentration of mobile hydrogen within the metal lattice from 55% of the yield strength and it increases significantly in the plastic field.
Experimental Measurements of Structural Displacement During Hydrogen Vented Deflagrations for FE Model Validation
Sep 2017
Publication
Vented deflagration tests were conducted by UNIPI at B. Guerrini Laboratory during the experimental campaign for HySEA project. Experiments included homogeneous hydrogen-air mixture in a 10-18% vol. range of concentrations contained in an about 1 m3 enclosure called SSE (Small Scale Enclosure). Displacement measurements of a test plate were taken in order to acquire useful data for the validation of FE model developed by IMPETUS Afea. In this paper experimental facility displacement measurement system and FE model are briefly described then comparison between experimental data and simulation results is discussed.
Seasonal Energy Storage for Zero-emissions Multi-energy Systems Via Underground Hydrogen Storage
Jan 2020
Publication
The deployment of diverse energy storage technologies with the combination of daily weekly and seasonal storage dynamics allows for the reduction of carbon dioxide (CO2) emissions per unit energy provided. In particular the production storage and re-utilization of hydrogen starting from renewable energy has proven to be one of the most promising solutions for offsetting seasonal mismatch between energy generation and consumption. A realistic possibility for large-scale hydrogen storage suitable for long-term storage dynamics is presented by salt caverns. In this contribution we provide a framework for modelling underground hydrogen storage with a focus on salt caverns and we evaluate its potential for reducing the CO2 emissions within an integrated energy systems context. To this end we develop a first-principle model which accounts for the transport phenomena within the rock and describes the dynamics of the stored energy when injecting and withdrawing hydrogen. Then we derive a linear reduced order model that can be used for mixed-integer linear program optimization while retaining an accurate description of the storage dynamics under a variety of operating conditions. Using this new framework we determine the minimum-emissions design and operation of a multi-energy system with H2 storage. Ultimately we assess the potential of hydrogen storage for reducing CO2 emissions when different capacities for renewable energy production and energy storage are available mapping emissions regions on a plane defined by storage capacity and renewable generation. We extend the analysis for solar- and wind-based energy generation and for different energy demands representing typical profiles of electrical and thermal demands and different CO2 emissions associated with the electric grid.
Modelling and Optimization of a Flexible Hydrogen-fueled Pressurized PEMFC Power Plant for Grid Balancing Purposes
Feb 2021
Publication
In a scenario characterized by an increasing penetration of non-dispatchable renewable energy sources and the need of fast-ramping grid-balancing power plants the EU project GRASSHOPPER aims to setup and demonstrate a highly flexible PEMFC Power Plant hydrogen fueled and scalable to MW-size designed to provide grid support.<br/>In this work different layouts proposed for the innovative MW-scale plant are simulated to optimize design and off-design operation. The simulation model details the main BoP components performances and includes a customized PEMFC model validated through dedicated experiments.<br/>The system may operate at atmospheric or mild pressurized conditions: pressurization to 0.7 barg allows significantly higher net system efficiency despite the increasing BoP consumptions. The additional energy recovery from the cathode exhaust with an expander gives higher net power and net efficiency adding up to 2%pt and reaching values between 47%LHV and 55%LHV for currents between 100% and 20% of the nominal value.
Feasibility Investigation of Hydrogen Refuelling Infrastructure for Heavy‐Duty Vehicles in Canada
Apr 2022
Publication
A potentially viable solution to the problem of greenhouse gas emissions by vehicles in the transportation sector is the deployment of hydrogen as alternative fuel. A limitation to the diffusion of the hydrogen‐fuelled vehicles option is the intricate refuelling stations that vehicles will require. This study examines the practical use of hydrogen fuel within the internal combustion engine (ICE)‐powered long‐haul heavy‐duty trucking vehicles. Specifically it appraises the techno‐ economic feasibility of constructing a network of long‐haul truck refuelling stations using hydrogen fuel across Canada. Hydrogen fuel is chosen as an option for this study due to its low carbon emissions rate compared to diesel. This study also explores various operational methods including variable technology integration levels and truck traffic flows truck and pipeline delivery of hydrogen to stations and the possibility of producing hydrogen onsite. The proposed models created for this work suggest important parameters for economic development such as capital costs for station construction the selling price of fuel and the total investment cost for the infrastructure of a nation‐ wide refuelling station. Results showed that the selling price of hydrogen gas pipeline delivery op‐ tion is more economically stable. Specifically it was found that at 100% technology integration the range in selling prices was between 8.3 and 25.1 CAD$/kg. Alternatively at 10% technology integration the range was from 12.7 to 34.1 CAD$/kg. Moreover liquid hydrogen which is delivered by trucks generally had the highest selling price due to its very prohibitive storage costs. However truck‐delivered hydrogen stations provided the lowest total investment cost; the highest is shown by pipe‐delivered hydrogen and onsite hydrogen production processes using high technology integration methods. It is worth mentioning that once hydrogen technology is more developed and deployed the refuelling infrastructure cost is likely to decrease considerably. It is expected that the techno‐economic model developed in this work will be useful to design and optimize new and more efficient hydrogen refuelling stations for any ICE vehicles or fuel cell vehicles.
Statistics, Lessons Learned and Recommendations from Analysis of HIAD 2.0 Database
Mar 2022
Publication
The manuscript firstly describes the data collection and validation process for the European Hydrogen Incidents and Accidents Database (HIAD 2.0) a public repository tool collecting systematic data on hydrogen-related incidents and near-misses. This is followed by an overview of HIAD 2.0 which currently contains 706 events. Subsequently the approaches and procedures followed by the authors to derive lessons learned and formulate recommendations from the events are described. The lessons learned have been divided into four categories including system design; system manufacturing installation and modification; human factors and emergency response. An overarching lesson learned is that minor events which occurred simultaneously could still result in serious consequences echoing James Reason's Swiss Cheese theory. Recommendations were formulated in relation to the established safety principles adapted for hydrogen by the European Hydrogen Safety Panel considering operational modes industrial sectors and human factors. This work provide an important contribution to the safety of systems involving hydrogen benefitting technical safety engineers emergency responders and emergency services. The lesson learned and the discussion derived from the statistics can also be used in training and risk assessment studies being of equal importance to promote and assist the development of sound safety culture in organisations.
Hydrogen as a Clean and Sustainable Energy Vector for Global Transition from Fossil-Based to Zero-Carbon
Dec 2021
Publication
Hydrogen is recognized as a promising and attractive energy carrier to decarbonize the sectors responsible for global warming such as electricity production industry and transportation. However although hydrogen releases only water as a result of its reaction with oxygen through a fuel cell the hydrogen production pathway is currently a challenging issue since hydrogen is produced mainly from thermochemical processes (natural gas reforming coal gasification). On the other hand hydrogen production through water electrolysis has attracted a lot of attention as a means to reduce greenhouse gas emissions by using low-carbon sources such as renewable energy (solar wind hydro) and nuclear energy. In this context by providing an environmentally-friendly fuel instead of the currently-used fuels (unleaded petrol gasoline kerosene) hydrogen can be used in various applications such as transportation (aircraft boat vehicle and train) energy storage industry medicine and power-to-gas. This article aims to provide an overview of the main hydrogen applications (including present and future) while examining funding and barriers to building a prosperous future for the nation by addressing all the critical challenges met in all energy sectors.
Experimental Study of Vented Hydrogen Deflagration with Ignition Inside and Outside the Vented Volume
Sep 2013
Publication
Experiments were carried out inside a 25 m3 vented combustion test facility (CVE) with a fixed vent area sealed by a plastic sheet vent. Inside the CVE a 0.64 m3 open vent box called RED-CVE was placed. The vent of the RED-CVE was left open and three different vent area were tested. Two different mixing fans one for each compartment were used to establish homogeneous H2 concentrations. This study examined H2 concentrations in the range between 8.5% vol. to 12.5% vol. and three different ignition locations (1) far vent ignition (2) inside the RED-CVE box ignition and (3) near vent ignition (the vent refers to the CVE vent). Peak overpressures generated inside the test facility and the smaller compartment were measured. The results indicate that the near vent ignition generates negligible peak overpressures inside the test facility as compared to those originated by far vent ignition and ignition inside the RED-CVE box. The experiments with far vent ignition showed a pressure increase with increasing hydrogen concentration which reached a peak value at 11% vol. concentration and then decreased showing a non-monotonic behaviour. The overpressure measured inside the RED-CVE was higher when the ignition was outside the box whereas the flame entered the box through the small vent.
Integration of Experimental Facilities: A Joint Effort for Establishing a Common Knowledge Base in Experimental Work on Hydrogen Safety
Sep 2009
Publication
With regard to the goals of the European HySafe Network research facilities are essential for the experimental investigation of relevant phenomena for testing devices and safety concepts as well as for the generation of validation data for the various numerical codes and models. The integrating activity ‘Integration of Experimental Facilities (IEF)’ has provided basic support for jointly performed experimental work within HySafe. Even beyond the funding period of the NoE HySafe in the 6th Framework Programme IEF represents a long lasting effort for reaching sustainable integration of the experimental research capacities and expertise of the partners from different research fields. In order to achieve a high standard in the quality of experimental data provided by the partners emphasis was put on the know-how transfer between the partners. The strategy for reaching the objectives consisted of two parts. On the one hand a documentation of the experimental capacities has been prepared and analysed. On the other hand a communication base has been established by means of biannual workshops on experimental issues. A total of 8 well received workshops has been organised covering topics from measurement technologies to safety issues. Based on the information presented by the partners a working document on best practice including the joint experimental knowledge of all partners with regard to experiments and instrumentation was created. Preserving the character of a working document it was implemented in the IEF wiki website which was set up in order to provide a central communication platform. The paper gives an overview of the IEF network activities over the last 5 years.
Risk Analysis of Complex Hydrogen Infrastructures
Oct 2015
Publication
Building a network of hydrogen refuelling stations is essential to develop the hydrogen economy within transport. Additional hydrogen is regarded a likely key component to store and convert back excess electrical power to secure future energy supply and to improve the quality of biomass-based fuels. Therefore future hydrogen supply and distribution chains will have to address several objectives. Such a complexity is a challenge for risk assessment and risk management of these chains because of the increasing interactions. Improved methods are needed to assess the supply chain as a whole. The method of “Functional modelling” is discussed in this paper. It will be shown how it could be a basis for other decision support methods for comprehensive risk and sustainability assessments.
Mixing of Dense or Light Gases with Turbulent Air- a Fast-Running Model for Lumped Parameter Codes
Sep 2005
Publication
The release of gases heavier than air like propane at ground level or lighter than air like hydrogen close to a ceiling can both lead to fire and explosion hazards that must be carefully considered in safety analyses. Even if the simulation of accident scenarios in complex installations and long transients often appears feasible only using lumped parameter computer codes the phenomenon of denser or lighter gas dispersion is not implicitly accounted by these kind of tools. In the aim to set up an ad hoc model to be used in the computer code ECART fluid-dynamic simulations by the commercial FLUENT 6.0 CFD code are used. The reference geometry is related to cavities having variable depth (2 to 4 m) inside long tunnels filled with a gas heavier or lighter than air (propane or hydrogen). Three different geometrical configurations with a cavity width of 3 6 and 9 m are considered imposing different horizontal air stream velocities ranging from 1 to 5 m/s. A stably-stratified flow region is observed inside the cavity during gas shearing. In particular it is found that the density gradient tends to inhibit turbulent mixing thus reducing the dispersion rate. The obtained data are correlated in terms of main dimensionless groups by means of a least squares method. In particular the Sherwood number is correlated as a function of Reynolds a density ratio modified Froude numbers and in terms of the geometrical parameter obtained as a ratio between the depth of the air-dense gas interface and the length of the cavity. This correlation is implemented in the ECART code to add the possibility to simulate large installations during complex transients lasting many hours with reasonable computation time. An example of application to a typical case is presented.
Development of an Italian Fire Prevention Technical Rule For Hydrogen Pipelines
Sep 2011
Publication
This paper summarizes the current results of the theoretical and experimental activity carried out by the Italian Working Group on the fire prevention safety issues in the field of the hydrogen transport in pipelines. From the theoretical point of view a draft document has been produced beginning from the regulations in force on the natural gas pipelines; these have been reviewed corrected and integrated with the instructions suitable to the use of hydrogen. From the experimental point of view an apparatus has been designed and installed at the University of Pisa; this apparatus has allowed the simulation of hydrogen releases from a pipeline with and without ignition of hydrogen-air mixture. The experimental data have helped the completion of the above-mentioned draft document with the instructions about the safety distances. The document has been improved for example pipelines above ground (not buried) are allowed due to the knowledge acquired by means of the experimental campaign. The safety distances related to this kind of piping has been chosen on the base of risk analysis. The work on the text contents is concluded and the document is currently under discussion with the Italian stakeholders involved in the hydrogen applications.
On the Use of Hydrogen in Confined Spaces: Results from the Internal Project InsHyde
Sep 2009
Publication
Alexandros G. Venetsanos,
Paul Adams,
Inaki Azkarate,
A. Bengaouer,
Marco Carcassi,
Angunn Engebø,
E. Gallego,
Olav Roald Hansen,
Stuart J. Hawksworth,
Thomas Jordan,
Armin Keßler,
Sanjay Kumar,
Vladimir V. Molkov,
Sandra Nilsen,
Ernst Arndt Reinecke,
M. Stöcklin,
Ulrich Schmidtchen,
Andrzej Teodorczyk,
D. Tigreat,
N. H. A. Versloot and
L. Boon-Brett
The paper presents an overview of the main achievements of the internal project InsHyde of the HySafe NoE. The scope of InsHyde was to investigate realistic small-medium indoor hydrogen leaks and provide recommendations for the safe use/storage of indoor hydrogen systems. Additionally InsHyde served to integrate proposals from HySafe work packages and existing external research projects towards a common effort. Following a state of the art review InsHyde activities expanded into experimental and simulation work. Dispersion experiments were performed using hydrogen and helium at the INERIS gallery facility to evaluate short and long term dispersion patterns in garage like settings. A new facility (GARAGE) was built at CEA and dispersion experiments were performed there using helium to evaluate hydrogen dispersion under highly controlled conditions. In parallel combustion experiments were performed by FZK to evaluate the maximum amount of hydrogen that could be safely ignited indoors. The combustion experiments were extended later on by KI at their test site by considering the ignition of larger amounts of hydrogen in obstructed environments outdoors. An evaluation of the performance of commercial hydrogen detectors as well as inter-lab calibration work was jointly performed by JRC INERIS and BAM. Simulation work was as intensive as the experimental work with participation from most of the partners. It included pre-test simulations validation of the available CFD codes against previously performed experiments with significant CFD code inter-comparisons as well as CFD application to investigate specific realistic scenarios. Additionally an evaluation of permeation issues was performed by VOLVO CEA NCSRD and UU by combining theoretical computational and experimental approaches with the results being presented to key automotive regulations and standards groups. Finally the InsHyde project concluded with a public document providing initial guidance on the use of hydrogen in confined spaces.
Effects of Steam Injection on the Permissible Hydrogen Content and Gaseous Emissions in a Micro Gas Turbine Supplied by a Mixture of CH4 and H2: A CFD Analysis
Apr 2022
Publication
The use of hydrogen in small scale gas turbines is currently limited by several issues. Blending hydrogen with methane or other gaseous fuels can be considered a low medium-term viable solution with the goal of reducing greenhouse gas emissions. In fact only small amounts can be mixed with methane in premixed combustors due to the risk of flashback. The aim of this article is to investigate the injection of small quantities of steam as a method of increasing the maximum permissible hydrogen content in a mixture with methane. The proposed approach involves introducing the steam directly into the combustion chamber into the main fuel feeding system of a Turbec T100. The study is carried out by means of CFD analysis of the combustion process. A thermodynamic analysis of the energy system is used to determine boundary conditions. The combustion chamber is discretized using a three-dimensional mesh consisting of 4.7 million nodes and the RANS RSM model is used to simulate the effects of turbulence. The results show that the addition of steam may triple the permissible percentage of hydrogen in the mixture for the considered MGT passing from 10% to over 30% by volume also leading to a reduction in NOx emissions without a significant variation in CO emissions.
Fire Prevention Technical Rule for Gaseous Hydrogen Transport in Pipelines
Sep 2007
Publication
This paper presents the current results of the theoretical and experimental activity carried out by the Italian Working Group on the fire prevention safety issues in the field of the hydrogen transport in pipelines. From the theoretical point of view a draft document has been produced beginning from the regulations in force on the natural gas pipelines; these have been reviewed corrected and integrated with the instructions suitable to the use with hydrogen gas. From the experimental point of view a suitable apparatus has been designed and installed at the University of Pisa; this apparatus will allow the simulation of hydrogen releases from a pipeline with or without ignition of the hydrogen-air mixture. The experimental data will help the completion of the above-mentioned draft document with the instructions about the safety distances. However in the opinion of the Group the work on the text contents is concluded and the document is ready to be discussed with the Italian stakeholders involved in the hydrogen applications.
Consequence Assessment of the BBC Hydrogen Refuelling Station, Using The Adrea-Hf Code
Sep 2009
Publication
Within the framework of the internal project HyQRA of the HYSAFE Network of Excellence (NoE) funded by the European Commission (EC) the participating partners were requested to apply their Quantitative Risk Assessment (QRA) methodologies on a predefined hypothetical gaseous H2 refuelling station named BBC (Benchmark Base Case). The overall aim of the HyQRA project was to perform an inter-comparison of the various QRA approaches and to identify the knowledge gaps on data and information needed in the QRA steps specifically related to H2. Partners NCSRD and UNIPI collaborated on a common QRA. UNIPI identified the hazards on site selected the most critical ones defined the events that could be the primary cause of an accident and provided to NCSRD the scenarios listed in risk order for the evaluation of the consequences. NCSRD performed the quantitative analysis using the ADREA-HF CFD code. The predicted risk assessment parameters (flammable H2 mass and volume time histories and maximum horizontal and vertical distances of the LFL from the source) were provided to UNIPI to analyze the consequences and to evaluate the risk and distances of damage. In total 15 scenarios were simulated. Five of them were H2 releases in confined ventilated spaces (inside the compression and the purification/drying buildings). The remaining 10 scenarios were releases in open/semi-confined spaces (in the storage cabinet storage bank and refuelling hose of one dispenser). This paper presents the CFD methodology applied for the quantitative analysis of the common UNIPI/NCSRD QRA and discusses the results obtained from the performed calculations.
Numerical Analysis of VPSA Technology Retrofitted to Steam Reforming Hydrogen Plants to Capture CO2 and Produce Blue H2
Feb 2022
Publication
The increasing demand for energy and commodities has led to escalating greenhouse gas emissions the chief of which is represented by carbon dioxide (CO2). Blue hydrogen (H2) a lowcarbon hydrogen produced from natural gas with carbon capture technologies applied has been suggested as a possible alternative to fossil fuels in processes with hard-to-abate emission sources including refining chemical petrochemical and transport sectors. Due to the recent international directives aimed to combat climate change even existing hydrogen plants should be retrofitted with carbon capture units. To optimize the process economics of such retrofit it has been proposed to remove CO2 from the pressure swing adsorption (PSA) tail gas to exploit the relatively high CO2 concentration. This study aimed to design and numerically investigate a vacuum pressure swing adsorption (VPSA) process capable of capturing CO2 from the PSA tail gas of an industrial steam methane reforming (SMR)-based hydrogen plant using NaX zeolite adsorbent. The effect of operating conditions such as purge-to-feed ratio and desorption pressure were evaluated in relation to CO2 purity CO2 recovery bed productivity and specific energy consumption. We found that conventional cycle configurations namely a 2-bed 4-step Skarstrom cycle and a 2-bed 6-step modified Skarstrom cycle with pressure equalization were able to concentrate CO2 to a purity greater than 95% with a CO2 recovery of around 77% and 90% respectively. Therefore the latter configuration could serve as an efficient process to decarbonize existing hydrogen plants and produce blue H2.
Comprehensive Review on Fuel Cell Technology for Stationary Applications as Sustainable and Efficient Poly-Generation Energy Systems
Aug 2021
Publication
Fuel cell technologies have several applications in stationary power production such as units for primary power generation grid stabilization systems adopted to generate backup power and combined-heat-and-power configurations (CHP). The main sectors where stationary fuel cells have been employed are (a) micro-CHP (b) large stationary applications (c) UPS and IPS. The fuel cell size for stationary applications is strongly related to the power needed from the load. Since this sector ranges from simple backup systems to large facilities the stationary fuel cell market includes few kWs and less (micro-generation) to larger sizes of MWs. The design parameters for the stationary fuel cell system differ for fuel cell technology (PEM AFC PAFC MCFC and SOFC) as well as the fuel type and supply. This paper aims to present a comprehensive review of two main trends of research on fuel-cell-based poly-generation systems: tracking the market trends and performance analysis. In deeper detail the present review will list a potential breakdown of the current costs of PEM/SOFC production for building applications over a range of production scales and at representative specifications as well as broken down by component/material. Inherent to the technical performance a concise estimation of FC system durability efficiency production maintenance and capital cost will be presented.
The Deltah Lab, a New Multidisciplinary European Facility to Support the H2 Distribution & Storage Economy
Apr 2021
Publication
The target for European decarburization encourages the use of renewable energy sources and H2 is considered the link in the global energy system transformation. So research studies are numerous but only few facilities can test materials and components for H2 storage. This work offers a brief review of H2 storage methods and presents the preliminary results obtained in a new facility. Slow strain rate and fatigue life tests were performed in H2 at 80 MPa on specimens and a tank of AISI 4145 respectively. Besides the storage capacity at 30 MPa of a solid-state system they were evaluated on kg scale by adsorption test. The results have shown the H2 influence on mechanical properties of the steel. The adsorption test showed a gain of 26% at 12 MPa in H2 storage with respect to the empty condition. All samples have been characterized by complementary techniques in order to connect the H2 effect with material properties.
Engineering Thoughts on Hydrogen Embrittlement
Jul 2018
Publication
Hydrogen Embrittlement (HE) is a topical issue for pipelines transporting sour products. Engineers need a simple and effective approach in materials selection at design stage. In other words they must know if a material is susceptible to cracking to be able of:
As an example material selection for sour service pipeline is the object of well-known standards e.g. by Nace International and EFC: they pose some limits in the sour service of steels with reference to surface hardness. These standards have shown some weak points namely:
- selecting the right material
- and apply correct operational measures during the service life.
As an example material selection for sour service pipeline is the object of well-known standards e.g. by Nace International and EFC: they pose some limits in the sour service of steels with reference to surface hardness. These standards have shown some weak points namely:
- In the definition of sour service;
- In defining the role of crack initiation and propagation considering that in Hydrogen embrittlement stress state and stress variations are very important.
Hydrogen Embrittlement in Advanced High Strength Steels and Ultra High Strength Steels: A New Investigation Approach
Dec 2018
Publication
In order to reduce CO2 emissions and fuel consumption and to respect current environmental norms the reduction of vehicles weight is a primary target of the automotive industry. Advanced High Strength Steels (AHSS) and Ultra High Strength Steel (UHSS) which present excellent mechanical properties are consequently increasingly used in vehicle manufacturing. The increased strength to mass ratio compensates the higher cost per kg and AHSS and UHSS are proving to be cost-effective solutions for the body-in-white of mass market products.
In particular aluminized boron steel can be formed in complex shapes with press hardening processes acquiring high strength without distortion and increasing protection from crashes. On the other hand its characteristic martensitic microstructure is sensitive to hydrogen delayed fracture phenomena and at the same time the dew point in the furnace can produce hydrogen consequently to the high temperature reaction between water and aluminum. The high temperature also promotes hydrogen diffusion through the metal lattice under the aluminum-silicon coating thus increasing the diffusible hydrogen content. However after cooling the coating acts as a strong barrier preventing the hydrogen from going out of the microstructure. This increases the probability of delayed fracture. As this failure brings to the rejection of the component during production or even worse to the failure in its operation diffusible hydrogen absorbed in the component needs to be monitored during the production process.
For fast and simple measurements of the response to diffusible hydrogen of aluminized boron steel one of the HELIOS innovative instruments was used HELIOS II. Unlike the Devanathan cell that is based on a double electrochemical cell HELIOS II is based on a single cell coupled with a solid-state sensor. The instrument is able to give an immediate measure of diffusible hydrogen content in sheet steels semi-products or products avoiding time-consuming specimen palladium coating with a guided procedure that requires virtually zero training.
Two examples of diffusible hydrogen analyses are given for Usibor®1500-AS one before hot stamping/ quenching and one after hot stamping suggesting that the increase in the number of dislocations during hot stamping could be the main responsible for the lower apparent diffusivity of hydrogen.
In particular aluminized boron steel can be formed in complex shapes with press hardening processes acquiring high strength without distortion and increasing protection from crashes. On the other hand its characteristic martensitic microstructure is sensitive to hydrogen delayed fracture phenomena and at the same time the dew point in the furnace can produce hydrogen consequently to the high temperature reaction between water and aluminum. The high temperature also promotes hydrogen diffusion through the metal lattice under the aluminum-silicon coating thus increasing the diffusible hydrogen content. However after cooling the coating acts as a strong barrier preventing the hydrogen from going out of the microstructure. This increases the probability of delayed fracture. As this failure brings to the rejection of the component during production or even worse to the failure in its operation diffusible hydrogen absorbed in the component needs to be monitored during the production process.
For fast and simple measurements of the response to diffusible hydrogen of aluminized boron steel one of the HELIOS innovative instruments was used HELIOS II. Unlike the Devanathan cell that is based on a double electrochemical cell HELIOS II is based on a single cell coupled with a solid-state sensor. The instrument is able to give an immediate measure of diffusible hydrogen content in sheet steels semi-products or products avoiding time-consuming specimen palladium coating with a guided procedure that requires virtually zero training.
Two examples of diffusible hydrogen analyses are given for Usibor®1500-AS one before hot stamping/ quenching and one after hot stamping suggesting that the increase in the number of dislocations during hot stamping could be the main responsible for the lower apparent diffusivity of hydrogen.
An Energy Autonomous House Equipped with a Solar PV Hydrogen Conversion System
Dec 2015
Publication
The use of RES in buildings is difficult for their random nature; therefore the plants using photovoltaic solar collectors must be connected to a power supply or interconnected with Energy accumulators if the building is isolated. The conversion of electricity into hydrogen technology is best suited to solve the problem and allows you to transfer the solar energy captured from day to night from summer to winter. This paper presents the feasibility study for a house powered by PV cogeneration solar collectors that reverse the electricity on the control unit that you command by a PC to power the household using a heat pump an electrolytic cell for the production of hydrogen to accumulate; control units sorting to the utilities the electricity produced by the fuel cell. The following are presented: The Energy analysis of the building the plant design economic analysis.
Micro Gas Turbine Role in Distributed Generation with Renewable Energy Sources
Jan 2023
Publication
To become sustainable the production of electricity has been oriented towards the adoption of local and renewable sources. Distributed electric and thermal energy generation is more suitable to avoid any possible waste and the Micro Gas Turbine (MGT) can play a key role in this scenario. Due to the intrinsic properties and the high flexibility of operation of this energy conversion system the exploitation of alternative fuels and the integration of the MGT itself with other energy conversion systems (solar field ORC fuel cells) represent one of the most effective strategies to achieve higher conversion efficiencies and to reduce emissions from power systems. The present work aims to review the results obtained by the researchers in the last years. The different technologies are analyzed in detail both separately and under a more complete view considering two or more solutions embedded in micro-grid configurations.
Willingness to Pay and Public Acceptance for Hydrogen Buses: A Case Study of Perugia
Sep 2015
Publication
Sustainability transportation is characterized by a positive externality on the environment health social security land use and social inclusion. The increasing interest in global warming has caused attention to be paid to the introduction of the hydrogen bus (H2B). When introducing new environmental technologies such as H2B it is often necessary to assess the environmental benefits related to this new technology. However such benefits are typically non-priced due to their public good nature. Therefore we have to address this problem using the contingent valuation (CV) method. This method has been developed within environmental economics as a means to economically assess environmental changes which are typically not traded in the market. So far several big cities have been analyzed to evaluate the perceived benefit related to H2B introduction but to the best of our knowledge no one has performed a CV analysis of a historical city where smog also damages historical buildings. This paper presents the results obtained using a multi-wave survey. We have investigated user preferences to elicit their willingness to pay for H2B introduction in Perugia taking into account all types of negative externalities due to the traffic pollution. The results confirm that residents in Perugia are willing to pay extra to support the introduction of H2B.
Magnesium Based Materials for Hydrogen Based Energy Storage: Past, Present and Future
Jan 2019
Publication
Volodymyr A. Yartys,
Mykhaylo V. Lototskyy,
Etsuo Akiba,
Rene Albert,
V. E. Antonov,
Jose-Ramón Ares,
Marcello Baricco,
Natacha Bourgeois,
Craig Buckley,
José Bellosta von Colbe,
Jean-Claude Crivello,
Fermin Cuevas,
Roman V. Denys,
Martin Dornheim,
Michael Felderhoff,
David M. Grant,
Bjørn Christian Hauback,
Terry D. Humphries,
Isaac Jacob,
Petra E. de Jongh,
Jean-Marc Joubert,
Mikhail A. Kuzovnikov,
Michel Latroche,
Mark Paskevicius,
Luca Pasquini,
L. Popilevsky,
Vladimir M. Skripnyuk,
Eugene I. Rabkin,
M. Veronica Sofianos,
Alastair D. Stuart,
Gavin Walker,
Hui Wang,
Colin Webb,
Min Zhu and
Torben R. Jensen
Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The “Magnesium group” of international experts contributing to IEA Task 32 “Hydrogen Based Energy Storage” recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures kinetics and thermodynamics of the systems based on MgH2 nanostructuring new Mg-based compounds and novel composites and catalysis in the Mg based H storage systems. Finally thermal energy storage and upscaled H storage systems accommodating MgH2 are presented.
Toward a Non-destructive Diagnostic Analysis Tool of Exercises Pipelines: Models and Experiences
Dec 2018
Publication
Strategic networks of hydrocarbon pipelines in long time service are adversely affected by the action of aggressive chemicals transported with the fluids and dissolved in the environment. Material degradation phenomena are amplified in the presence of hydrogen and water elements that increase the material brittleness and reduce the safety margins. The risk of failure during operation of these infrastructures can be reduced if not prevented by the continuous monitoring of the integrity of the pipe surfaces and by the tracking of the relevant bulk properties. A fast and potentially non-destructive diagnostic tool of material degradation which may be exploited in this context is based on the instrumented indentation tests that can be performed on metals at different scales. Preliminary validation studies of the significance of this methodology for the assessment of pipeline integrity have been carried out with the aid of interpretation models of the experiments. The main results of this ongoing activity are illustrated in this contribution.
Optimisation-based System Designs for Deep Offshore Wind Farms including Power to Gas Technologies
Feb 2022
Publication
A large deployment of energy storage solutions will be required by the stochastic and non-controllable nature of most renewable energy sources when planning for higher penetration of renewable electricity into the energy mix. Various solutions have been suggested for dealing with medium- and long-term energy storage. Hydrogen and ammonia are two of the most frequently discussed as they are both carbon-free fuels. In this paper the authors analyse the energy and cost efficiency of hydrogen and ammonia-based pathways for the storage transportation and final use of excess electricity from an offshore wind farm. The problem is solved as a linear programming problem simultaneously optimising the size of each problem unit and the respective time-dependent operational conditions. As a case study we consider an offshore wind farm of 1.5 GW size located in a reference location North of Scotland. The energy efficiency and cost of the whole chain are evaluated and compared with competitive alternatives namely batteries and liquid hydrogen storage. The results show that hydrogen and ammonia storage can be part of the optimal solution. Moreover their use for long-term energy storage can provide a significant cost-effective contribution to an extensive penetration of renewable energy sources in national energy systems.
Evaluation of the Impact of Green Hydrogen Blending Scenarios in the Italian Gas Network: Optimal Design and Dynamic Simulation of Operation Strategies
Apr 2022
Publication
Blending hydrogen (H2) produced from PEM electrolysis coupled to Renewable Energy Sources (RES) in the existing Natural Gas (NG) network is a promising option for the deep decarbonization of the gas sector. However blending H2 with NG significantly affects the thermophysical properties of the gas mixture changing the gas supply requirements to meet the demand. In this work different scenarios of green hydrogen blending (Blend Ratio BR equal to 5/10/15/20%vol) are analyzed at the national level with different temporal constraints (hour/day/week/month/year) based on real gas demand data in Italy addressing both design requirements (RES and PEM electrolyzer capacity) via Linear Programming (LP) and carrying out dynamic simulations of different operational strategies (constant or variable blend). Although H2/NG blending provides a huge opportunity in terms of deployed H2 volume higher BRs show rapidly increasing design requirements (1.3-1.5 GWe/%vol and 2.5-3 GWe/%vol for PEM electrolyzers and RES capacity respectively) and a significative increase of the total gas mixture volume (0.83 %/%vol) which hinders the CO2 reduction potential (0.37 %/%vol). A variable blend operation strategy (allowing a variation of BR within the analyzed period) allows to balance a variable H2 production from RES. Wider temporal constraints imply several beneficial effects such as relaxing design constraints and avoiding the implementation of an external storage. The Levelized Cost Of Hydrogen (LCOH) is preliminarily estimated at around 7.3 $/kg for yearly scenarios (best-case) although shorter temporal constraints entail significant excess hydrogen which would increase the LCOH if not deployed for other applications.
Green Hydrogen in Europe – A Regional Assessment: Substituting Existing Production with Electrolysis Powered by Renewables
Nov 2020
Publication
The increasing ambition of climate targets creates a major role for hydrogen especially in achieving carbon-neutrality in sectors presently difficult to decarbonise. This work examines to what extent the currently carbon-intensive hydrogen production in Europe could be replaced by water electrolysis using electricity from renewable energy resources (RES) such as solar photovoltaic onshore/offshore wind and hydropower (green hydrogen). The study assesses the technical potential of RES at regional and national levels considering environmental constraints land use limitations and various techno-economic parameters. It estimates localised clean hydrogen production and examines the capacity to replace carbon-intensive hydrogen hubs with ones that use RES-based water electrolysis. Findings reveal that -at national level- the available RES electricity potential exceeds the total electricity demand and the part for hydrogen production from electrolysis in all analysed countries. At regional level from the 109 regions associated with hydrogen production (EU27 and UK) 88 regions (81%) show an excess of potential RES generation after covering the annual electricity demand across all sectors and hydrogen production. Notably 84 regions have over 50% excess RES electricity potential after covering the total electricity demand and that for water electrolysis. The study provides evidence on the option to decarbonize hydrogen production at regional level. It shows that such transformation is possible and compatible with the ongoing transition towards carbon–neutral power systems in the EU. Overall this work aims to serve as a tool for designing hydrogen strategies in harmony with renewable energy policies.
Methanol Steam Reforming for Hydrogen Generation Via Conventional and Membrane Reactors: A Review
Sep 2013
Publication
Variable renewable energy (VRE) is expected to play a major role in the decarbonization of the electricity sector. However decarbonization via VRE requires a fleet of flexible dispatchable plants with low CO2 emissions to supply clean power during times with limited wind and sunlight. These plants will need to operate at reduced capacity factors with frequent ramps in electricity output posing techno-economic challenges. This study therefore presents an economic assessment of a new near-zero emission power plant designed for this purpose. The gas switching reforming combined cycle (GSR-CC) plant can produce electricity during times of low VRE output and hydrogen during times of high VRE output. This product flexibility allows the plant to operate continuously even when high VRE output makes electricity production uneconomical. Although the CO2 avoidance cost of the GSR-CC plant (€61/ton) was similar to the benchmark post-combustion CO2 capture plant under baseload operation GSR-CC clearly outperformed the benchmark in a more realistic scenario where continued VRE expansion forces power plants into mid-load operation (45% capacity factor). In this scenario GSR-CC promises a 5 %-point higher annualized investment return than the post-combustion benchmark. GSR-CC therefore appears to be a promising concept for a future scenario with high VRE market share and CO2 prices provided that a large market for clean hydrogen is established.
Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO2: Effect of Reaction Parameters on the Activity
May 2021
Publication
In the present work an Ir/CeO2 catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques i.e. X-ray photoelectron spectroscopy (XPS) transmission electron microscopy (TEM) scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study modifying parameters such as temperature the mass of the catalyst stirring speed and concentration of base in order to find the optimal conditions of reaction which allow performing the test in a kinetically limited regime.
Numerical Evaluation of the Effect of Fuel Blending with CO2 and H2 on the Very Early Corona‐Discharge Behavior in Spark Ignited Engines
Feb 2022
Publication
Reducing green‐house gases emission from light‐duty vehicles is compulsory in order to slow down the climate change. The application of High Frequency Ignition systems based on the Corona discharge effect has shown the potential to extend the dilution limit of engine operating conditions promoting lower temperatures and faster combustion events thus higher thermal and indicating efficiency. Furthermore predicting the behavior of Corona ignition devices against new sustainable fuel blends including renewable hydrogen and biogas is crucial in order to deal with the short‐intermediate term fleet electric transition. The numerical evaluation of Corona‐induced discharge radius and radical species under those conditions can be helpful in order to capture local effects that could be reached only with complex and expensive optical investigations. Using an ex‐ tended version of the Corona one‐dimensional code previously published by the present authors the simulation of pure methane and different methane–hydrogen blends and biogas–hydrogen blends mixed with air was performed. Each mixture was simulated both for 10% recirculated exhaust gas dilution and for its corresponding dilute upper limit which was estimated by means of chemical kinetics simulations integrated with a custom misfire detection criterion.
A Battery-Free Sustainable Powertrain Solution for Hydrogen Fuel Cell City Transit Bus Application
Apr 2022
Publication
The paper presents a sustainable electric powertrain for a transit city bus featuring an electrochemical battery-free power unit consisting of a hydrogen fuel cell stack and a kinetic energy storage system based on high-speed flywheels. A rare-earth free high-efficiency motor technology is adopted to pursue a more sustainable vehicle architecture by limiting the use of critical raw materials. A suitable dynamic energetic model of the full vehicle powertrain has been developed to investigate the feasibility of the traction system and the related energy management control strategy. The model includes losses characterisation as a function of the load of the main components of the powertrain by using experimental tests and literature data. The performance of the proposed solution is evaluated by simulating a vehicle mission on an urban path in real traffic conditions. Considerations about the effectiveness of the traction system are discussed.
Moving Gas Turbine Package from Conventional Gas to Hydrogen Blend
Sep 2021
Publication
The current greatest challenge that all gas turbine manufactures and users have in front of them for the years to come is the energy transition while reducing CO2 footprint and to contrast climate change. To this aim the introduction of hydrogen as fuel gas (or its blend) is playing a very important role. The benefit from an environmental point of view is undisputed but the presence of hydrogen introduces a series of safety related aspects to be considered for the design of all systems of a gas turbine package. Most of the design standards developed and adopted in the past are based on conventional natural gas however physical properties of hydrogen require to analyze additional aspects or revise the current ones. In this context the design for safety is paramount as it is strongly impacted by the low energy ignition of hydrogen blend fuels. Baker Hughes has built its experience on several sites different Customers and applications currently installed. These gas turbines run with a variety of hydrogen blends with concentration as high as 100% hydrogen. Baker Hughes has achieved several milestones moving from design to experimental set up leveraging the internal infrastructures consolidating design assumptions. In this work the critical aspects such as material selection instrumentation electrical devices and components are discussed in the framework of package safety with the aim to evolve conventional design minimizing the impacts on package configurations.
Lock-In Effects on the Energy Sector: Evidence from Hydrogen Patenting Activities
Apr 2022
Publication
The aim of the paper is to analyze how regulatory design and its framework’s topics other than macroeconomic factors might impact green innovation by taking into consideration a brand-new renewable source of energy that is becoming more and more important in recent years: hydrogen and fuel cell patenting activities. Such activities have been used as a proxy for green technological change in a panel data of 52 countries over a 6-year period. A series of sectorial energy regulation and macroeconomic variables were tested to assess their impact on that technological frontier of green energy transition policy. As might have been expected the empirical analysis carried out with the model that was prefigured confirms significant evidence of lock-in effects on fossil fuel policies. The model confirms however another evidence: countries already investing in renewables might be willing to invest in hydrogen projects. A sort of reinforcement to the further development of green sustainable strategies seems to derive from having already concretely undertaken this direction. Future research should exploit different approaches to the research question and address the econometric criticalities mentioned in the paper along with exploiting results of the paper with further investigations.
Improved Hydrogen-Production-Based Power Management Control of a Wind Turbine Conversion System Coupled with Multistack Proton Exchange Membrane Electrolyzers
Mar 2020
Publication
This paper deals with two main issues regarding the specific energy consumption in an electrolyzer (i.e. the Faraday efficiency and the converter topology). The first aspect is addressed using a multistack configuration of proton exchange membrane (PEM) electrolyzers supplied by a wind turbine conversion system (WTCS). This approach is based on the modeling of the wind turbine and the electrolyzers. The WTCS and the electrolyzers are interfaced through a stacked interleaved DC–DC buck converter (SIBC) due to its benefits for this application in terms of the output current ripple and reliability. This converter is controlled so that it can offer dynamic behavior that is faster than the wind turbine avoiding overvoltage during transients which could damage the PEM electrolyzers. The SIBC is designed to be connected in array configuration (i.e. parallel architecture) so that each converter operates at its maximum efficiency. To assess the performance of the power management strategy experimental tests were carried out. The reported results demonstrate the correct behavior of the system during transient operation.
Multi-Objective Optimization of a Hydrogen Hub for the Decarbonization of a Port Industrial Area
Feb 2022
Publication
Green hydrogen is addressed as a promising solution to decarbonize industrial and mobility sectors. In this context ports could play a key role not only as hydrogen users but also as suppliers for industrial plants with which they have strong commercial ties. The implementation of hydrogen technologies in ports has started to be addressed as a strategy for renewable energy transition but still requires a detailed evaluation of the involved costs which cannot be separated from the correct design and operation of the plant. Hence this study proposes the design and operation optimization of a hydrogen production and storage system in a typical Italian port. Multi-objective optimization is performed to determine the optimal levelized cost of hydrogen in environmental and techno-economic terms. A Polymer Electrolyte Membrane (PEM) electrolyzer powered by a grid-integrated photovoltaic (PV) plant a compression station and two-pressure level storage systems are chosen to provide hydrogen to a hydrogen refueling station for a 20-car fleet and satisfy the demand of the hydrogen batch annealing in a steel plant. The results report that a 341 kWP PV plant 89 kW electrolyzer and 17 kg hydrogen storage could provide hydrogen at 7.80 €/kgH2 potentially avoiding about 153 tCO2eq/year (120 tCO2eq/year only for the steel plant).
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