Spain
Green Hydrogen and Social Sciences: Issues, Problems, and Future Challenges
Dec 2022
Publication
The article presents a review of the research on green hydrogen from the social sciences identifying its main lines of research its problems and the relevant challenges due to the benefits and impacts that this energy vector has on energy transitions and climate change. The review analyzes a corpus of 78 articles indexed in the Web of Science (WoS) and SCOPUS published between 1997 and 2022. The review identified three research areas related to green hydrogen and the challenges for the social sciences in the future: (a) risks socio-environmental impacts and public perception; (b) public policies and regulation and (c) social acceptance and willingness to use associated technologies. Our results show that Europe and Asia lead the research on green hydrogen from the social sciences. Also most of the works focus on the area of public policy and regulation and social acceptance. Instead the field of social perception of risk is much less developed. We found that little research from the social sciences has focused on assessments of the social and environmental impacts of hydrogen on local communities and indigenous groups as well as the participation of local authorities in rural locations. Likewise there are few integrated studies (technical and social) that would allow a better assessment of hydrogen and cleaner energy transitions. Finally the lack of familiarity with this technology in many cases constitutes a limitation when evaluating its acceptance.
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.
Decarbonizing Vehicle Transportation with Hydrogen from Biomass Gasification: An Assessment in the Nigerian Urban Environment
Apr 2022
Publication
Tailpipe emissions from vehicles consist of CO2 and other greenhouse gases which con‐ tribute immensely to the rise in global temperatures. Green hydrogen produced from the gasification of biomass can reduce the amount of CO2 emissions to zero. This study aims to provide a modelling framework to optimize the production of hydrogen from biomass waste obtained from different cities for use in the road transport sector in Nigeria. A gasification model with post‐treatment shift conversion and CO2 removal by adsorption is proposed. In this study six cities are simulated based on technical and environmental considerations using the Aspen Plus software package. The results revealed that Kaduna has the highest hydrogen generation potential of 0.148 million metric tons per year which could reduce CO2 emissions to 1.60 and 1.524 million metric tons by the dis‐ placement of an equivalent volume of gasoline and diesel. This amounts to cost savings of NGN 116 and 161.8 billion for gasoline and diesel respectively. In addition the results of the sensitivity analysis revealed that the steam‐to‐biomass ratio and the temperature of gasification are positively correlated with the amount of avoided CO2 emissions while the equivalence ratio shows a negative correlation.
Safe Processing Route for the Synthesis of MG Based Metallic Hydrides
Sep 2009
Publication
Metallic hydrides represent a safe way of storing hydrogen minimising explosion and flammability risks. Nowadays there are several methods for the storage of hydrogen and the more conventional techniques are high-pressure tanks for gaseous hydrogen and cryogenic vessels for liquid hydrogen. However there are two main drawbacks in the storage of gaseous and liquid hydrogen. First as a fuel hydrogen in the gaseous and liquid states is very combustible and the related law imposes strict regulations on its utilization storage and transportation. Secondly even under a high pressure hydrogen gas is not dense enough for compact storage. Moreover the gas storage at high pressure involves significant safety risks. Hydrogen storage in the metal hydrides does not have such deficiencies. Metal hydrides are safe and can be easily store and transported. For that reason it should be stressed that metallic hydrides represent a safe way of storing hydrogen minimising explosion and flammability risks. Among metallic hydrides one of the most promising hydrides in terms of absorbed hydrogen content is Mg2NiH4. However it is difficult to obtain Mg2Ni by the conventional melting method because of the large difference in vapour pressure and melting point between magnesium and nickel. This paper presents an alternative and safe method for obtaining such hydride: HCS (Hydriding Combustion Synthesis). This method presents some interesting advantages over its conventional counterpart: the process is carried out at lower reaction process which means safer process and the alloy stoichiometry is closer to the nominal (Mg2Ni) which allow better hydrogen absorption behaviour. The aim of this work is to investigate the formation mechanism of this compound and to study some parameters of the process.
Hydrogenation and Dehydrogenation of Liquid Organic Hydrogen Carriers: A New Opportunity for Carbon-Based Catalysts
Jan 2022
Publication
The development of a hydrogen-based economy is the perfect nexus between the need of discontinuing the use of fossil fuels (trying to mitigate climate change) the development of a system based on renewable energy (with the use of hydrogen allowing us to buffer the discontinuities produced in this generation) and the achievement of a local-based robust energy supply system. However extending the use of hydrogen as an energy vector must still overcome challenging issues with the key issues being related to its storage. Cryogenic or pressurized storage is relatively expensive technically complex and presents important safety concerns. As a promising alternative the use of organic hydrogen carriers has been suggested in recent years. The ideal carrier will be an organic compound with a low melting point and low viscosity with a significant number of unsaturated carbon–carbon bonds in addition to being easy to hydrogenate and dehydrogenate. These properties allow us to store and transport hydrogen in infrastructures designed for liquid fuels thus facilitating the replacement of fossil fuels by hydrogen
Compatibility of Materials with Hydrogen Particular Case- Hydrogen Assisted Stress Cracking of Titanium Alloys
Sep 2007
Publication
A review of the effect of hydrogen on materials is addressed in this paper. General aspects of the interaction of hydrogen and materials hydrogen embrittlement low temperature effects material suitability for hydrogen service and materials testing are the main subjects considered in the first part of the paper. As a particular case of the effect of hydrogen in materials the hydride formation of titanium alloys is considered. Alpha titanium alloys are considered corrosion resistant materials in a wide range of environments. However hydrogen absorption and the possible associated problems must be taken into account when considering titanium as a candidate material for high responsibility applications. The sensitivity of three different titanium alloys Ti Gr-2 Ti Gr-5 and Ti Gr-12 to the Hydrogen Assisted Stress Cracking phenomena has been studied by means of the Slow Strain Rate Technique (SSRT). The testing media has been sea water and hydrogen has been produced on the specimen surface during the test by cathodic polarization. Tested specimens have been characterized by metallography and scanning electron microscopy. Results obtained show that the microstructure of the materials particularly the β phase content plays an important role on the sensitivity of the studied alloys to the Hydrogen Assisted Stress Cracking Phenomena.
New Insights into the Electrochemical Behaviour of Porous Carbon Electrodes for Supercapacitors
Aug 2018
Publication
Activated carbons with different surface chemistry and porous textures were used to study the mechanism of electrochemical hydrogen and oxygen evolution in supercapacitor devices. Cellulose precursor materials were activated with different potassium hydroxide (KOH) ratios and the electrochemical behaviour was studied in 6 M KOH electrolyte. In situ Raman spectra were collected to obtain the structural changes of the activated carbons under severe electrochemical oxidation and reduction conditions and the obtained data were correlated to the cyclic voltammograms obtained at high anodic and cathodic potentials. Carbon-hydrogen bonds were detected for the materials activated at high KOH ratios which form reversibly under cathodic conditions. The influence of the specific surface area narrow microporosity and functional groups in the carbon electrodes on their chemical stability and hydrogen capture mechanism in supercapacitor applications has been revealed.
Hydrogen Roadmap: A Commitment to Renewable Hydrogen - Executive Summary
Oct 2020
Publication
This Hydrogen Roadmap aims to identify the challenges and opportunities for the full development of renewable hydrogen in Spain providing a series of measures aimed at boosting investment action taking advantage of the European consensus on the role that this energy vector should play in the context of green recovery. This Roadmap is therefore aligned with the 2021 Annual Sustainable Growth Strategy published by the European Commission which identifies the future Recovery and Resilience Mechanism as an opportunity to create emblematic areas of action at European level making two of these areas of action (Power up and Recharge and Refuel) an explicit mention of the development of renewable hydrogen in the European Union.
International Association for Hydrogen Safety ‘Research Priorities Workshop’, September 2018, Buxton, UK
Sep 2018
Publication
Hydrogen has the potential to be used by many countries as part of decarbonising the future energy system. Hydrogen can be used as a fuel ‘vector’ to store and transport energy produced in low-carbon ways. This could be particularly important in applications such as heating and transport where other solutions for low and zero carbon emission are difficult. To enable the safe uptake of hydrogen technologies it is important to develop the international scientific evidence base on the potential risks to safety and how to control them effectively. The International Association for Hydrogen Safety (known as IA HySAFE) is leading global efforts to ensure this. HSE hosted the 2018 IA HySAFE Biennial Research Priorities Workshop. A panel of international experts presented during nine key topic sessions: (1) Industrial and National Programmes; (2) Applications; (3) Storage; (4) Accident Physics – Gas Phase; (5) Accident Physics – Liquid/ Cryogenic Behaviour; (6) Materials; (7) Mitigation Sensors Hazard Prevention and Risk Reduction; (8) Integrated Tools for Hazard and Risk Assessment; (9) General Aspects of Safety.<br/>This report gives an overview of each topic made by the session chairperson. It also gives further analysis of the totality of the evidence presented. The workshop outputs are shaping international activities on hydrogen safety. They are helping key stakeholders to identify gaps in knowledge and expertise and to understand and plan for potential safety challenges associated with the global expansion of hydrogen in the energy system.
Optimization of a Solar Hydrogen Storage System: Safety Considerations
Sep 2007
Publication
Hydrogen has been extensively used in many industrial applications for more than 100 years including production storage transport delivery and final use. Nevertheless the goal of the hydrogen energy system implies the use of hydrogen as an energy carrier in a more wide scale and for a public not familiarised with hydrogen technologies and properties.<br/>The road to the hydrogen economy passes by the development of safe practices in the production storage distribution and use of hydrogen. These issues are essential for hydrogen insurability. We have to bear in mind that a catastrophic failure in any hydrogen project could damage the insurance public perception of hydrogen technologies at this early step of development of hydrogen infrastructures.<br/>Safety is a key issue for the development of hydrogen economy and a great international effort is being done by different stakeholders for the development of suitable codes and standards concerning safety for hydrogen technologies [1 2]. Additionally to codes and standards different studies have been done regarding safety aspects of particular hydrogen energy projects during the last years [3 4]. Most of such have been focused on hydrogen production and storage in large facilities transport delivery in hydrogen refuelling stations and utilization mainly on fuel cells for mobile and stationary applications. In comparison safety considerations for hydrogen storage in small or medium scale facilities as usual in hydrogen production plants from renewable energies have received relatively less attention.<br/>After a brief introduction to risk assessment for hydrogen facilities this paper reports an example of risk assessment of a small solar hydrogen storage system applied to the INTA Solar Hydrogen Production and Storage facility as particular case and considers a top level Preliminary Failure Modes and Effects Analysis (FMEA) for the identification of hazard associated to the specific characteristics of the facility.
Achievements of European Projects on Membrane Reactor for Hydrogen Production
May 2017
Publication
Membrane reactors for hydrogen production can increase both the hydrogen production efficiency at small scale and the electric efficiency in micro-cogeneration systems when coupled with Polymeric Electrolyte Membrane fuel cells. This paper discusses the achievements of three European projects (FERRET FluidCELL BIONICO) which investigate the application of the membrane reactor concept to hydrogen production and micro-cogeneration systems using both natural gas and biofuels (biogas and bio-ethanol) as feedstock. The membranes used to selectively separate hydrogen from the other reaction products (CH4 CO2 H2O etc.) are of asymmetric type with a thin layer of Pd alloy (<5 μm) and supported on a ceramic porous material to increase their mechanical stability. In FERRET the flexibility of the membrane reactor under diverse natural gas quality is validated. The reactor is integrated in a micro-CHP system and achieves a net electric efficiency of about 42% (8% points higher than the reference case). In FluidCELL the use of bio-ethanol as feedstock for micro-cogeneration Polymeric Electrolyte Membrane based system is investigated in off-grid applications and a net electric efficiency around 40% is obtained (6% higher than the reference case). Finally BIONICO investigates the hydrogen production from biogas. While BIONICO has just started FERRET and FluidCELL are in their third year and the two prototypes are close to be tested confirming the potentiality of membrane reactor technology at small scale.
End of Life of Fuel Cells and Hydrogen Products: From Technologies to Strategies
Feb 2019
Publication
End-of-Life (EoL) technologies and strategies are needed to support the deployment of fuel cells and hydrogen (FCH) products. This article explores current and novel EoL technologies to recover valuable materials from the stacks of proton exchange membrane fuel cells and water electrolysers alkaline water electrolysers and solid oxide fuel cells. Current EoL technologies are mainly based on hydrometallurgical and pyro-hydrometallurgical methods for the recovery of noble metals while novel methods attempt to recover additional materials through efficient safe and cost-competitive pathways. Strengths weaknesses opportunities and threats of the reviewed EoL technologies are identified under techno-economic environmental and regulatory aspects. Beyond technologies strategies for the EoL of FCH stacks are defined mainly based on the role of manufacturers and recovery centres in the short- mid- and long-term. In this regard a dual role manufacturer/recovery centre would characterise long-term scenarios within a potential context of a well-established hydrogen economy.
A Review of Techno-economic Data for Road Transportation Fuels
May 2019
Publication
Worldwide the road transport sector typically arises as one of the main sources of air pollutants due to its high energy intensity and the use of fossil fuels. Thus governments and social agents work on the development and prospective planning of decarbonisation strategies oriented towards sustainable transport. In this regard the increase in the use of alternative fuels is the recurrent approach to energy planning e.g. through the promotion of electric vehicles biofuels natural gas liquefied petroleum gas etc. However there is a lack of comprehensive information on the techno-economic performance of production pathways for alternative fuels. The acquisition of robust techno-economic data is still a challenge for energy planners modellers analysts and policy-makers when building their prospective models to support decision-making processes. Hence this article aims to fill this gap through a deep literature review including the most representative production routes for a wide range of road transportation fuels. This led to the development of datasets including investment costs operating and maintenance costs and transformation efficiencies for more than 40 production pathways. The techno-economic data presented in this work are expected to be especially useful to those energy actors interested in performing long-term studies on the transition to a sustainable transport system.
Integration of Gas Switching Combustion and Membrane Reactors for Exceeding 50% Efficiency in Flexible IGCC Plants with Near-zero CO2 Emissions
Jul 2020
Publication
Thermal power plants face substantial challenges to remain competitive in energy systems with high shares of variable renewables especially inflexible integrated gasification combined cycles (IGCC). This study addresses this challenge through the integration of Gas Switching Combustion (GSC) and Membrane Assisted Water Gas Shift (MAWGS) reactors in an IGCC plant for flexible electricity and/or H2 production with inherent CO2 capture. When electricity prices are high H2 from the MAWGS reactor is used for added firing after the GSC reactors to reach the high turbine inlet temperature of the H-class gas turbine. In periods of low electricity prices the turbine operates at 10% of its rated power to satisfy the internal electricity demand while a large portion of the syngas heating value is extracted as H2 in the MAWGS reactor and sold to the market. This product flexibility allows the inflexible process units such as gasification gas treating air separation unit and CO2 compression transport and storage to operate continuously while the plant supplies variable power output. Two configurations of the GSC-MAWGS plant are presented. The base configuration achieves 47.2% electric efficiency and 56.6% equivalent hydrogen production efficiency with 94.8–95.6% CO2 capture. An advanced scheme using the GSC reduction gases for coal-water slurry preheating and pre-gasification reached an electric efficiency of 50.3% hydrogen efficiency of 62.4% and CO2 capture ratio of 98.1–99.5%. The efficiency is 8.4%-points higher than the pre-combustion CO2 capture benchmark and only 1.9%-points below the unabated IGCC benchmark.
Hydrogen Production by Steam Reforming of Ethanol on Rh-Pt Catalysts: Influence of CeO2, ZrO2, and La2O3 as Supports
Nov 2015
Publication
CeO2- ZrO2- and La2O3-supported Rh-Pt catalysts were tested to assess their ability to catalyze the steam reforming of ethanol (SRE) for H2 production. SRE activity tests were performed using EtOH:H2O:N2 (molar ratio 1:3:51) at a gaseous space velocity of 70600 h−1 between 400 and 700 °C at atmospheric pressure. The SRE stability of the catalysts was tested at 700 °C for 27 h time on stream under the same conditions. RhPt/CeO2 which showed the best performance in the stability test also produced the highest H2 yield above 600 °C followed by RhPt/La2O3 and RhPt/ZrO2. The fresh and aged catalysts were characterized by TEM XPS and TGA. The higher H2 selectivity of RhPt/CeO2 was ascribed to the formation of small (~5 nm) and stable particles probably consistent of Rh-Pt alloys with a Pt surface enrichment. Both metals were oxidized and acted as an almost constant active phase during the stability test owing to strong metal-support interactions as well as the superior oxygen mobility of the support. The TGA results confirmed the absence of carbonaceous residues in all the aged catalysts.
A Novel Self-Assembly Strategy for the Fabrication of Nano-Hybrid Satellite Materials with Plasmonically Enhanced Catalytic Activity
Jun 2021
Publication
The generation of hydrogen from water using light is currently one of the most promising alternative energy sources for humankind but faces significant barriers for large-scale applications due to the low efficiency of existing photo-catalysts. In this work we propose a new route to fabricate nano-hybrid materials able to deliver enhanced photo-catalytic hydrogen evolution combining within the same nanostructure a plasmonic antenna nanoparticle and semiconductor quantum dots (QDs). For each stage of our fabrication process we probed the chemical composition of the materials with nanometric spatial resolution allowing us to demonstrate that the final product is composed of a silver nanoparticle (AgNP) plasmonic core surrounded by satellite Pt decorated CdS QDs (CdS@Pt) separated by a spacer layer of SiO2 with well-controlled thickness. This new type of photoactive nanomaterial is capable of generating hydrogen when irradiated with visible light displaying efficiencies 300% higher than the constituting photo-active components. This work may open new avenues for the development of cleaner and more efficient energy sources based on photo-activated hydrogen generation.
Analysis of Environmentally Assisted Cracking Processes in Notched Steels Using the Point Method
Sep 2019
Publication
This paper proposes the use of the Point Method (PM) to analyse Environmentally Assisted Cracking (EAC) processes in steels containing U-shaped notches. The PM a methodology included within the Theory of Critical Distances (TCD) has been extensively validated by many authors for the analysis of fracture and fatigue phenomena of different types of materials containing notches. However it has never been applied to other critical or subcritical cracking processes such as EAC or creep crack propagation.<br/>This work provides a PM-based analysis of EAC emanating from notches which is validated by testing CT notched specimens of X80 and S420 steels subjected to aggressive environments under hydrogen embrittlement conditions.<br/>The results reveal that the PM accurately predicts the crack propagation onset condition as well as the evolution of the material’s apparent EAC resistance.
Techno-economic Modelling of Water Electrolysers in the Range of Several MW to Provide Grid Services While Generating Hydrogen for Different Applications: A Case Study in Spain Applied to Mobility with FCEVs
Jun 2019
Publication
The use of hydrogen as energy carrier is a promising option to decarbonize both energy and transport sectors. This paper presents an advanced techno-economic model for calculation of optimal dispatch of large-scale multi MW electrolysis plants in order to obtain a more accurate evaluation of the feasibility of business cases related to the supply of this fuel for different end uses combined with grid services' provision. The model is applied to the Spanish case using different scenarios to determine the minimum demand required from the FCEV market so that electrolysis facilities featuring several MW result in profitable business cases. The results show that grid services contribute to the profitability of hydrogen production for mobility given a minimum but considerable demand from FCEV fleets.
The Effect of Heat Treatments on the Constituent Materials of a Nuclear Reactor Pressure Vessel in Hydrogen Environment
Jul 2016
Publication
A nuclear reactor pressure vessel (NRPV) wall is formed by two layer of different materials: an inner layer of stainless steel (cladding material) and an outer layer of low carbon steel (base material) which is highly susceptible to corrosion related phenomena. A reduction of the mechanical properties of both materials forming the wall would appear due to the action of the harsh environment causing hydrogen embrittlement (HE) related phenomena. As a result of the manufacturing process residual stresses and strains appear in the NRPV wall thereby influencing the main stage in HE: hydrogen diffusion. A common engineering practice for reducing such states is to apply a tempering heat treatment. In this paper a numerical analysis is carried out for revealing the influence of the heat treatment parameters (tempering temperature and tempering time) on the HE of a commonly used NRPV. To achieve this goal a numerical model of hydrogen diffusion assisted by stress and strain was used considering diverse residual stress-strain states after tempering. This way the obtained hydrogen accumulation during operation time of the NRPV provides insight into the better tempering conditions from the structural integrity point of view.
The Role of the Testing Rate on Small Punch Tests for the Estimation of Fracture Toughness in Hydrogen Embrittlement
Dec 2020
Publication
In this paper different techniques to test notched Small Punch (SPT) samples in fracture conditions in aggressive environments are studied based on the comparison of the micromechanisms at different rates. Pre-embrittled samples subsequently tested in air at rates conventionally employed (0.01 and 0.002 mm/s) are compared to embrittled ones tested in environment at the same rates (0.01 and 0.002 mm/s) and at a very slow rate (5E-5 mm/s). A set of samples tested in environment under a set of constant loads that produce very slow rates completes the experimental results. As a conclusion it is recommended to test SPT notched specimens in environment at very slow rates of around E-6 mm/s when characterizing in Hydrogen Embrittlement (HE) scenarios in order to allow the interaction material-environment to govern the process.
Enabling Large-scale Hydrogen Storage in Porous Media – The Scientific Challenges
Jan 2021
Publication
Niklas Heinemann,
Juan Alcalde,
Johannes M. Miocic,
Suzanne J. T. Hangx,
Jens Kallmeyer,
Christian Ostertag-Henning,
Aliakbar Hassanpouryouzband,
Eike M. Thaysen,
Gion J. Strobel,
Cornelia Schmidt-Hattenberger,
Katriona Edlmann,
Mark Wilkinson,
Michelle Bentham,
Stuart Haszeldine,
Ramon Carbonell and
Alexander Rudloff
Expectations for energy storage are high but large-scale underground hydrogen storage in porous media (UHSP) remains largely untested. This article identifies and discusses the scientific challenges of hydrogen storage in porous media for safe and efficient large-scale energy storage to enable a global hydrogen economy. To facilitate hydrogen supply on the scales required for a zero-carbon future it must be stored in porous geological formations such as saline aquifers and depleted hydrocarbon reservoirs. Large-scale UHSP offers the much-needed capacity to balance inter-seasonal discrepancies between demand and supply decouple energy generation from demand and decarbonise heating and transport supporting decarbonisation of the entire energy system. Despite the vast opportunity provided by UHSP the maturity is considered low and as such UHSP is associated with several uncertainties and challenges. Here the safety and economic impacts triggered by poorly understood key processes are identified such as the formation of corrosive hydrogen sulfide gas hydrogen loss due to the activity of microbes or permeability changes due to geochemical interactions impacting on the predictability of hydrogen flow through porous media. The wide range of scientific challenges facing UHSP are outlined to improve procedures and workflows for the hydrogen storage cycle from site selection to storage site operation. Multidisciplinary research including reservoir engineering chemistry geology and microbiology more complex than required for CH4 or CO2 storage is required in order to implement the safe efficient and much needed large-scale commercial deployment of UHSP.
Hydrogen Effects on Progressively Cold-Drawn Pearlitic Steels: Between Donatello and Michelangelo
Sep 2017
Publication
This paper reviews previous research by the author in the field of hydrogen effects on progressively cold-drawn pearlitic steels in terms of hydrogen degradation (HD) hydrogen embrittlement (HE) or at the micro-level hydrogen-assisted micro-damage (HAMD) thus affecting their microstructural integrity and compromising the (macro-)structural integrity of civil engineering structures such as prestressed concrete bridges. It is seen that hydrogen effects in pearlitic microstructure (either oriented or not) are produced at the finest micro-level by plastic tearing in the form in general of hydrogen damage topography (HDT) with different appearances depending of the cold drawing degree evolving from the so-called tearing topography surface (TTS) in hot-rolled (not cold-drawn at all) or slightly cold-drawn pearlitic steels to a sort of enlarged and oriented TTS (EOTTS) in heavily drawn steels (the pronounced enlargement and marked orientation being along the wire axis or cold drawing direction). Whereas the pure TTS mode (null or low degree of cold drawing) resembles the Michelangello stone sculpture texture (MSST) the EOTTS mode does the same in relation to the Donatello wooden sculpture texture (DWST).
Optimal Energy Management System Using Biogeography Based Optimization for Grid-connected MVDC Microgrid with Photovoltaic, Hydrogen System, Electric Vehicles and Z-source Converters
Oct 2021
Publication
Currently the technology associated with charging stations for electric vehicles (EV) needs to be studied and improved to further encourage its implementation. This paper presents a new energy management system (EMS) based on a Biogeography-Based Optimization (BBO) algorithm for a hybrid EV charging station with a configuration that integrates Z-source converters (ZSC) into medium voltage direct current (MVDC) grids. The EMS uses the evolutionary BBO algorithm to optimize a fitness function defining the equivalent hydrogen consumption/generation. The charging station consists of a photovoltaic (PV) system a local grid connection two fast charging units and two energy storage systems (ESS) a battery energy storage (BES) and a complete hydrogen system with fuel cell (FC) electrolyzer (LZ) and hydrogen tank. Through the use of the BBO algorithm the EMS manages the energy flow among the components to keep the power balance in the system reducing the equivalent hydrogen consumption and optimizing the equivalent hydrogen generation. The EMS and the configuration of the charging station based on ZSCs are the main contributions of the paper. The behaviour of the EMS is demonstrated with three EV connected to the charging station under different conditions of sun irradiance. In addition the proposed EMS is compared with a simpler EMS for the optimal management of ESS in hybrid configurations. The simulation results show that the proposed EMS achieves a notable improvement in the equivalent hydrogen consumption/generation with respect to the simpler EMS. Thanks to the proposed configuration the output voltage of the components can be upgraded to MVDC while reducing the number of power converters compared with other configurations without ZSC.
Hydrogen vs. Battery in the Long-term Operation. A Comparative Between Energy Management Strategies for Hybrid Renewable Microgrids
Apr 2020
Publication
The growth of the world’s energy demand over recent decades in relation to energy intensity and demography is clear. At the same time the use of renewable energy sources is pursued to address decarbonization targets but the stochasticity of renewable energy systems produces an increasing need for management systems to supply such energy volume while guaranteeing at the same time the security and reliability of the microgrids. Locally distributed energy storage systems (ESS) may provide the capacity to temporarily decouple production and demand. In this sense the most implemented ESS in local energy districts are small–medium-scale electrochemical batteries. However hydrogen systems are viable for storing larger energy quantities thanks to its intrinsic high mass-energy density. To match generation demand and storage energy management systems (EMSs) become crucial. This paper compares two strategies for an energy management system based on hydrogen-priority vs. battery-priority for the operation of a hybrid renewable microgrid. The overall performance of the two mentioned strategies is compared in the long-term operation via a set of evaluation parameters defined by the unmet load storage efficiency operating hours and cumulative energy. The results show that the hydrogen-priority strategy allows the microgrid to be led towards island operation because it saves a higher amount of energy while the battery-priority strategy reduces the energy efficiency in the storage round trip. The main contribution of this work lies in the demonstration that conventional EMS for microgrids’ operation based on battery-priority strategy should turn into hydrogen-priority to keep the reliability and independence of the microgrid in the long-term operation.
A Model-based Parametric and Optimal Sizing of a Battery/Hydrogen Storage of a Real Hybrid Microgrid Supplying a Residential Load: Towards Island Operation
Jun 2021
Publication
In this study the optimal sizing of a hybrid battery/hydrogen Energy Storage System “ESS” is assessed via a model-based parametric analysis in the context of a real hybrid renewable microgrid located in Huelva Spain supplying a real-time monitored residential load (3.5 kW; 5.6 MWh/year) in island mode. Four storage configurations (battery-only H2-only hybrid battery priority and hybrid H2 priority) are assessed under different Energy Management Strategies analysing system performance parameters such as Loss of Load “LL” (kWh;%) Over Production “OP” (kWh;%) round-trip storage efficiency ESS (%) and total storage cost (€) depending on the ESS sizing characteristics. A parallel approach to the storage optimal sizing via both multi-dimensional sensitivity analysis and PSO is carried out in order to address both sub-optimal and optimal regions respectively. Results show that a hybridised ESS capacity is beneficial from an energy security and efficiency point of view but can represent a substantial additional total cost (between 100 and 300 k€) to the hybrid energy system especially for the H2 ESS which presents higher costs. Reaching 100% supply from renewables is challenging and introducing a LL threshold induces a substantial relaxation of the sizing and cost requirements. Increase in battery capacity is more beneficial for the LL abatement while increasing H2 capacity is more useful to absorb large quantities of excess energy. The optimal design via PSO technique is complemented to the parametric study.
Polymer–Ceramic Composite Membranes for Water Removal in Membrane Reactors
Jun 2021
Publication
Methanol can be obtained through CO2 hydrogenation in a membrane reactor with higher yield or lower pressure than in a conventional packed bed reactor. In this study we explore a new kind of membrane with the potential suitability for such membrane reactors. Silicone–ceramic composite membranes are synthetized and characterized for their capability to selectively remove water from a mixture containing hydrogen CO2 and water at temperatures typical for methanol synthesis. We show that this membrane can achieve selective permeation of water under such harsh conditions and thus is an alternative candidate for use in membrane reactors for processes where water is one of the products and the yield is limited by thermodynamic equilibrium.
Optimal Sizing of Storage Elements for a Vehicle Based on Fuel Cells, Supercapacitors, and Batteries
Mar 2019
Publication
To achieve a vehicle-efficient energy management system an architecture composed of a PEM fuel cell as the main energy source and a hybrid storage system based on battery banks and supercapacitors is proposed. This paper introduces a methodology for the optimal component sizing aiming at minimizing the total cost achieving a cheaper system that can achieve the requirements of the speed profiles. The chosen vehicle is an urban transport bus which must meet the Buenos Aires Driving Cycle and the Manhattan Driving Cycle. The combination of batteries and supercapacitors allows a better response to the vehicle’s power demand since it combines the high energy density of the batteries with the high power density of the supercapacitors allowing the best absorption of energy coming from braking. In this way we address the rapid changes in power without reducing the global efficiency of the system. Optimum use of storage systems and fuel cell is analyzed through dynamic programming.
Enhancing Energy Recovery in Form of Biogas, from Vegetable and Fruit Wholesale Markets By-Products and Wastes, with Pretreatments
Jun 2021
Publication
Residues and by-products from vegetables and fruit wholesale markets are suitable for recovery in the form of energy through anaerobic digestion allowing waste recovery and introducing them into the circular economy. This suitability is due to their composition structural characteristics and to the biogas generation process which is stable and without inhibition. However it has been observed that the proportion of methane and the level of degradation of the substrate is low. It is decided to study whether the effect of pretreatments on the substrate is beneficial. Freezing ultrafreezing and lyophilization pretreatments are studied. A characterization of the substrates has been performed the route of action of pretreatment determined and the digestion process studied to calculate the generation of biogas methane hydrogen and the proportions among these. Also a complete analysis of the process has been performed by processing the data with mathematical and statistical methods to obtain disintegration constants and levels of degradation. It has been observed that the three pretreatments have positive effects when increasing the solubility of the substrate increasing porosity and improving the accessibility of microorganisms to the substrate. Generation of gases are greatly increased reaching a methane enrichment of 59.751%. Freezing seems to be the best pretreatment as it increases the biodegradation level the speed of the process and the disintegration constant by 306%.
Grand Canonical Monte Carlo Simulations of the Hydrogen Storage Capacities of Slit-shaped Pores, Nanotubes and Torusenes
Jan 2022
Publication
Grand Canonical Monte Carlo GCMC simulations are used to study the gravimetric and volumetric hydrogen storage capacities of different carbon nanopores shapes: Slit-shaped nanotubes and torusenes at room temperature 298.15 K and at pressures between 0.1 and 35 MPa and for pore diameter or width between 4 and 15 A. The influence of the pore shape or curvature on the storage capacities as a function of pressure temperature and pore diameter is investigated and analyzed. A large curvature of the pores means in general an increase of the storage capacities of the pores. While torusenes and nanotubes have surfaces with more curvature than the slit-shaped planar pores their capacities are lower than those of the slit-shaped pores according to the present GCMC simulations. Torusene a less studied carbon nanostructure has two radii or curvatures but their storage capacities are similar or lower than those of nanotubes which have only one radius or curvature. The goal is to obtain qualitative and quantitative relationships between the structure of porous materials and the hydrogen storage capacities in particular or especially the relationship between shape and width of the pores and the hydrogen storage capacities of carbon-based porous materials.
Analysis of Hydrogen Production Potential from Waste Plastics by Pyrolysis and In Line Oxidative Steam Reforming
Oct 2021
Publication
A study was carried out on the valorization of different waste plastics (HDPE PP PS and PE) their mixtures and biomass/HDPE mixtures by means of pyrolysis and in line oxidative steam reforming. A thermodynamic equilibrium simulation was used for determining steam reforming data whereas previous experimental results were considered for setting the pyrolysis volatile stream composition. The adequacy of this simulation tool was validated using experimental results obtained in the pyrolysis and in line steam reforming of different plastics. The effect the most relevant process conditions i.e. temperature steam/plastic ratio and equivalence ratio have on H2 production and reaction enthalpy was evaluated. Moreover the most suitable conditions for the oxidative steam reforming of plastics of different nature and their mixtures were determined. The results obtained are evidence of the potential interest of this novel valorization route as H2 productions of up to 25 wt% were obtained operating under autothermal conditions.
Life Cycle Assessment of Improved High Pressure Alkaline Electrolysis
Aug 2015
Publication
This paper investigates environmental impacts of high pressure alkaline water electrolysis systems. An advanced system with membranes on polymer basis is compared to a state-of-the-art system with asbestos membranes using a Life Cycle Assessment (LCA) approach. For the advanced system a new improved membrane technology has been investigated within the EU research project “ELYGRID”. Results indicate that most environmental impacts are caused by the electricity supply necessary for operation. During the construction phase cell stacks are the main contributor to environmental impacts. New improved membranes have relatively small contributions to impacts caused by cell construction within the advanced systems. As main outcome the systems comparison illustrates a better ecological performance of the new developed system
Techno-Economics Optimization of H2 and CO2 Compression for Renewable Energy Storage and Power-to-Gas Applications
Nov 2021
Publication
The decarbonization of the industrial sector is imperative to achieve a sustainable future. Carbon capture and storage technologies are the leading options but lately the use of CO2 is also being considered as a very attractive alternative that approaches a circular economy. In this regard power to gas is a promising option to take advantage of renewable H2 by converting it together with the captured CO2 into renewable gases in particular renewable methane. As renewable energy production or the mismatch between renewable production and consumption is not constant it is essential to store renewable H2 or CO2 to properly run a methanation installation and produce renewable gas. This work analyses and optimizes the system layout and storage pressure and presents an annual cost (including CAPEX and OPEX) minimization. Results show the proper compression stages need to achieve the storage pressure that minimizes the system cost. This pressure is just below the supercritical pressure for CO2 and at lower pressures for H2 around 67 bar. This last quantity is in agreement with the usual pressures to store and distribute natural gas. Moreover the H2 storage costs are higher than that of CO2 even with lower mass quantities; this is due to the lower H2 density compared with CO2 . Finally it is concluded that the compressor costs are the most relevant costs for CO2 compression but the storage tank costs are the most relevant in the case of H2.
Validation of GreenH2armony® as a Tool for the Computation of Harmonised Life-Cycle Indicators of Hydrogen
Apr 2020
Publication
The Life Cycle Assessment (LCA) methodology is often used to check the environmental suitability of hydrogen energy systems usually involving comparative studies. However these comparative studies are typically affected by inconsistent methodological choices between the case studies under comparison. In this regard protocols for the harmonisation of methodological choices in LCA of hydrogen are available. The step-by-step application of these protocols to a large number of case studies has already resulted in libraries of harmonised carbon energy and acidification footprints of hydrogen. In order to foster the applicability of these harmonisation protocols a web-based software for the calculation of harmonised life-cycle indicators of hydrogen has recently been developed. This work addresses—for the first time—the validation of such a tool by checking the deviation between the available libraries of harmonised carbon energy and acidification footprints of hydrogen and the corresponding tool-based harmonised results. A high correlation (R2 > 0.999) was found between the library- and tool-based harmonised life-cycle indicators of hydrogen thereby successfully validating the software. Hence this tool has the potential to effectively promote the use of harmonised life-cycle indicators for robust comparative LCA studies of hydrogen energy systems significantly mitigating misinterpretation.
Flammability Reduction in a Pressurised Water Electrolyser Based on a Thin Polymer Electrolyte Membrane through a Pt-alloy Catalytic Approach
Jan 2019
Publication
Various Pt-based materials (unsupported Pt PtRu PtCo) were investigated as catalysts for recombining hydrogen and oxygen back into water. The recombination performance correlated well with the surface Pt metallic state. Alloying cobalt to platinum was observed to produce an electron transfer favouring the occurrence of a large fraction of the Pt metallic state on the catalyst surface. Unsupported PtCo showed both excellent recombination performance and dynamic behaviour. In a packed bed catalytic reactor when hydrogen was fed at 4% vol. in the oxygen stream (flammability limit) 99.5% of the total H2 content was immediately converted to water in the presence of PtCo thus avoiding safety issues. The PtCo catalyst was thus integrated in the anode of the membrane-electrode assembly of a polymer electrolyte membrane electrolysis cell. This catalyst showed good capability to reduce the concentration of hydrogen in the oxygen stream under differential pressure operation (1–20 bar) in the presence of a thin (90 μm) Aquivion® membrane. The modified system showed lower hydrogen concentration in the oxygen flow than electrolysis cells based on state-of-the-art thick polymer electrolyte membranes and allowed to expand the minimum current density load down to 0.15 A cm−2 . This was mainly due to the electrochemical oxidation of permeated H2 to protons that were transported back to the cathode. The electrolysis cell equipped with a dual layer PtCo/IrRuOx oxidation catalyst achieved a high operating current density (3 A cm−2 ) as requested to decrease the system capital costs under high efficiency conditions (about 77% efficiency at 55 °C and 20 bar). Moreover the electrolysis system showed reduced probability to reach the flammability limit under both high differential pressure (20 bar) and partial load operation (5%) as needed to properly address grid-balancing service
Recent Advances in Pd-Based Membranes for Membrane Reactors
Jan 2017
Publication
Palladium-based membranes for hydrogen separation have been studied by several research groups during the last 40 years. Much effort has been dedicated to improving the hydrogen flux of these membranes employing different alloys supports deposition/production techniques etc. High flux and cheap membranes yet stable at different operating conditions are required for their exploitation at industrial scale. The integration of membranes in multifunctional reactors (membrane reactors) poses additional demands on the membranes as interactions at different levels between the catalyst and the membrane surface can occur. Particularly when employing the membranes in fluidized bed reactors the selective layer should be resistant to or protected against erosion. In this review we will also describe a novel kind of membranes the pore-filled type membranes prepared by Pacheco Tanaka and coworkers that represent a possible solution to integrate thin selective membranes into membrane reactors while protecting the selective layer. This work is focused on recent advances on metallic supports materials used as an intermetallic diffusion layer when metallic supports are used and the most recent advances on Pd-based composite membranes. Particular attention is paid to improvements on sulfur resistance of Pd based membranes resistance to hydrogen embrittlement and stability at high temperature.
Unconventional Pearlitic Pseudocolonies Affecting Macro-, Micro- and Nano-structural Integrity of Cold-drawn Pearlitic Steel Wires: Resembling van Gogh, Bernini, Mantegna and Picasso
Dec 2020
Publication
Prestressing steel wires are manufactured by cold drawing during which a preferential orientation is achieved in the matter of pearlitic colonies and lamellae. In addition to this general trend special (unconventional) pearlitic pseudocolonies evolve during the heavy-drawing manufacture process affecting the posterior macro- micro- and nano-structural integrity of the material. This paper discusses the important role of such a special microstructural unit (the pearlitic pseudocolony) in the fracture process in air (inert) environment in the presence of crack-like defects as well as in the case of environmentally assisted cracking (stress corrosion cracking by localized anodic dissolution) or hydrogen embrittlement. Results clearly demonstrate the key role of pearlitic pseudocolonies in promoting crack deflection (and thus mixed-mode propagation) after a global mode I cracking especially in the case of fracture in air and stress corrosion cracking.
Spin Pinning Effect to Reconstructed Oxyhydroxide Layer on Ferromagnetic Oxides for Enhanced Water Oxidation
Jun 2021
Publication
Producing hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. With spin-dependent kinetics in OER to manipulate the spin ordering of ferromagnetic OER catalysts (e.g. by magnetization) can reduce the kinetic barrier. However most active OER catalysts are not ferromagnetic which makes the spin manipulation challenging. In this work we report a strategy with spin pinning effect to make the spins in paramagnetic oxyhydroxides more aligned for higher intrinsic OER activity. The spin pinning effect is established in oxideFM/oxyhydroxide interface which is realized by a controlled surface reconstruction of ferromagnetic oxides. Under spin pinning simple magnetization further increases the spin alignment and thus the OER activity which validates the spin effect in rate-limiting OER step. The spin polarization in OER highly relies on oxyl radicals (O∙) created by 1st dehydrogenation to reduce the barrier for subsequent O-O coupling.
Analysis of the Environmental Degradation Effects on the Cables of “La Arena” Bridge (Spain)
Sep 2017
Publication
After nearly 25 years of service some of the wires of the tendons of “La Arena” bridge (Spain) started to exhibit the effects of environmental degradation processes. “La Arena” is cable-stayed bridge with 6 towers and a reference span between towers of about 100 meters. After a maintenance inspection of the bridge evidences of corrosion were detected in some of the galvanized wires of the cables. A more in-deep analysis of these wires revealed that many of them exhibited loss of section due to the corrosion process. In order to clarify the causes of this degradation event and to suggest some remedial actions an experimental program was designed. This program consisted of tensile and fatigue tests on some strand samples of the bridge together with a fractographic analysis of the fracture surfaces of the wires its galvanized layer thickness and some hydrogen measurements (hydrogen embrittlement could be another effect of the environmental degradation process).Once the type and extension of the flaws in the wires was characterized a structural integrity assessment of the strands was performed with the aim of quantifying the margins until failure and establishing some maintenance recommendations.
Acoustic and Psychoacoustic Levels from an Internal Combustion Engine Fueled by Hydrogen vs. Gasoline
Feb 2022
Publication
Whereas noise generated by road traffic is an important factor in urban pollution little attention has been paid to this issue in the field of hydrogen-fueled vehicles. The objective of this study is to analyze the influence of the type of fuel (gasoline or hydrogen) on the sound levels produced by a vehicle with an internal combustion engine. A Volkswagen Polo 1.4 vehicle adapted for its bi-fuel hydrogen-gasoline operation has been used. Tests were carried out with the vehicle when stationary to eliminate rolling and aerodynamic noise. Acoustics and psychoacoustics levels were measured both inside and outside the vehicle. A slight increase in the noise level has only been found outside when using hydrogen as fuel compared to gasoline. The increase is statistically significant can be quantified between 1.1 and 1.7 dBA and is mainly due to an intensification of the 500 Hz band. Loudness is also higher outside the vehicle (between 2 and 4 sones) when the fuel is hydrogen. Differences in sharpness and roughness values are lower than the just-noticeable difference (JND) values of the parameters. Higher noise levels produced by hydrogen can be attributed to its higher reactivity compared to gasoline.
Light-Driven Hydrogen Evolution Assisted by Covalent Organic Frameworks
Jun 2021
Publication
Covalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units such as triazine rings or diacetylene bridges. The bandgap charge separation capacity porosity wettability and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks by extension of conjugation by adjustment of the size and crystallinity of the pores and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER) in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally the aspects that need to be improved in the coming years will be discussed such as the degree of dispersibility in water the global photocatalytic efficiency and the robustness and stability of the hybrid systems putting emphasis on both the COF and the metal co-catalyst.
Solid State Hydrogen Storage in Alanates and Alanate-Based Compounds: A Review
Jul 2018
Publication
The safest way to store hydrogen is in solid form physically entrapped in molecular form in highly porous materials or chemically bound in atomic form in hydrides. Among the different families of these compounds alkaline and alkaline earth metals alumino-hydrides (alanates) have been regarded as promising storing media and have been extensively studied since 1997 when Bogdanovic and Schwickardi reported that Ti-doped sodium alanate could be reversibly dehydrogenated under moderate conditions. In this review the preparative methods; the crystal structure; the physico-chemical and hydrogen absorption-desorption properties of the alanates of Li Na K Ca Mg Y Eu and Sr; and of some of the most interesting multi-cation alanates will be summarized and discussed. The most promising alanate-based reactive hydride composite (RHC) systems developed in the last few years will also be described and commented on concerning their hydrogen absorption and desorption performance.
Comparative Analysis of Energy and Exergy Performance of Hydrogen Production Methods
Nov 2020
Publication
The study of the viability of hydrogen production as a sustainable energy source is a current challenge to satisfy the great world energy demand. There are several techniques to produce hydrogen either mature or under development. The election of the hydrogen production method will have a high impact on practical sustainability of the hydrogen economy. An important profile for the viability of a process is the calculation of energy and exergy efficiencies as well as their overall integration into the circular economy. To carry out theoretical energy and exergy analyses we have estimated proposed hydrogen production using different software (DWSIM and MATLAB) and reference conditions. The analysis consolidates methane reforming or auto-thermal reforming as the viable technologies at the present state of the art with reasonable energy and exergy efficiencies but pending on the impact of environmental constraints as CO2 emission countermeasures. However natural gas or electrolysis show very promising results and should be advanced in their technological and maturity scaling. Electrolysis shows a very good exergy efficiency due to the fact that electricity itself is a high exergy source. Pyrolysis exergy loses are mostly in the form of solid carbon material which has a very high integration potential into the hydrogen economy.
Optimal Strategies of Deployment of Far Offshore Co-located Wind-wave Energy Farms
Nov 2021
Publication
The most profitable offshore energy resources are usually found away from the coast. Nevertheless the accessibility and grid integration in those areas are more complicated. To avoid this problematic large scale hydrogen production is being promoted for far offshore applications. The main objective of this paper is to analyze the ability of wave energy converters to maximize hydrogen production in hybrid wind and wave far offshore farms. To that end wind and wave resource data are obtained from ERA5 for different locations in the Atlantic ocean and a Maximum Covariance Analysis is proposed for the selection of the most representative locations. Furthermore the suitability of different sized wave energy converters for auxiliary hydrogen production in the far offshore wind farms is also analysed. On that account the hydrodynamic parameters of the oscillating bodies are obtained via simulations with a Boundary Element Method based code and their operation is modelled using the software tool Matlab. The combination of both methodologies enables to perform a realistic assessment of the contribution of the wave energy converters to the hydrogen generation of an hybrid energy farm especially during those periods when the wind turbines would be stopped due to the variability of the wind. The obtained results show a considerable hydrogen generation capacity of the wave energy converters up to 6.28% of the wind based generation which could remarkably improve the efficiency of the far offshore farm and bring important economical profit. Wave energy converters are observed to be most profitable in those farms with low covariance between wind and waves where the disconnection times of the wind turbines are prone to be more prolonged but the wave energy is still usable. In such cases a maximum of 101.12 h of equivalent rated production of the wind turbine has been calculated to be recovered by the wave energy converters.
Life Cycle Environmental and Cost Comparison of Current and Future Passenger Cars under Different Energy Scenarios
Apr 2020
Publication
In this analysis life cycle environmental burdens and total costs of ownership (TCO) of current (2017) and future (2040) passenger cars with different powertrain configurations are compared. For all vehicle configurations probability distributions are defined for all performance parameters. Using these a Monte Carlo based global sensitivity analysis is performed to determine the input parameters that contribute most to overall variability of results. To capture the systematic effects of the energy transition future electricity scenarios are deeply integrated into the ecoinvent life cycle assessment background database. With this integration not only the way how future electric vehicles are charged is captured but also how future vehicles and batteries are produced. If electricity has a life cycle carbon content similar to or better than a modern natural gas combined cycle powerplant full powertrain electrification makes sense from a climate point of view and in many cases also provides reductions in TCO. In general vehicles with smaller batteries and longer lifetime distances have the best cost and climate performance. If a very large driving range is required or clean electricity is not available hybrid powertrain and compressed natural gas vehicles are good options in terms of both costs and climate change impacts. Alternative powertrains containing large batteries or fuel cells are the most sensitive to changes in the future electricity system as their life cycles are more electricity intensive. The benefits of these alternative drivetrains are strongly linked to the success of the energy transition: the more the electricity sector is decarbonized the greater the benefit of electrifying passenger vehicles.
Sustainability Indicators for the Manufacturing and Use of a Fuel Cell Prototype and Hydrogen Storage for Portable Uses
Oct 2021
Publication
A sustainability assessment regarding the manufacturing process and the use of a new proton exchange membrane fuel cell (PEMFC) specially designed for portable hydrogen applications is presented. The initial fuel cell prototype has been configured by taking into account exclusively technical issues. However a life cycle analysis considering environmental and socioeconomic impacts is crucial to improve the model to develop a more sustainable product. From the environ‐ mental perspective the durability of the system and its efficiency are key elements required to de‐ crease the potential overall impacts. High electricity consumption for manufacturing requires a commitment to the use of renewable energies due to the high current value of the projected impact of climate change (42.5 tonnes of CO2 eq). From the socioeconomic point of view the dependence of imported components required for the synthesis of some materials displaces the effects of value added and employment in Spain potentially concentrating the largest impact on countries such as Singapore Japan and the UK whereas the cell assembly would have a greater benefit for the country of fabrication. These results provide a basis for new research strategies since they can be considered standard values for improving future upgrades of the fuel cell in terms of sustainability.
Tetrahydroborates: Development and Potential as Hydrogen Storage Medium
Oct 2017
Publication
The use of fossil fuels as an energy supply becomes increasingly problematic from the point of view of both environmental emissions and energy sustainability. As an alternative hydrogen is widely regarded as a key element for a potential energy solution. However differently from fossil fuels such as oil gas and coal the production of hydrogen requires energy. Alternative and intermittent renewable energy sources such as solar power wind power etc. present multiple advantages for the production of hydrogen. On the one hand the renewable sources contribute to a remarkable reduction of pollutants released to the air and on the other hand they significantly enhance the sustainability of energy supply. In addition the storage of energy in form of hydrogen has a huge potential to balance an effective and synergetic utilization of renewable energy sources. In this regard hydrogen storage technology is a key technology towards the practical application of hydrogen as “energy carrier”. Among the methods available to store hydrogen solid-state storage is the most attractive alternative from both the safety and the volumetric energy density points of view. Because of their appealing hydrogen content complex hydrides and complex hydride-based systems have attracted considerable attention as potential energy vectors for mobile and stationary applications. In this review the progresses made over the last century on the synthesis and development of tetrahydroborates and tetrahydroborate-based systems for hydrogen storage purposes are summarized.
Hybrid Power-heat Microgrid Solution Using Hydrogen as an Energy Vector for Residential Houses in Spain. A Case Study
May 2022
Publication
In order to favor a transition to a renewable energy economy it is necessary to study the possible permeation of renewable energy sources not only in the electric grid or industrial scale but also in the small householding scale. One of the most interesting technologies available for this purpose is solar energy since it is a mature technology that can be easily installed in every rooftop. Thus a techno-economic assessment was carried out to evaluate the installation of a solar-based power-heat hybrid microgrid considering the use of hydrogen as an energy vector in a typical residential house in Spain. Lead-acid batteries plus the photovoltaic and solar thermal energy installation are complemented with a hydrogen system composed of an electrolyzer two metal hydride bottles and a fuel cell. A simulation tool has been generated using experimental models developed and validated with real equipment for each one of the electric microgrid component. Three operating modes were tested making use of this tool to better manage the energy consumed/produced and optimize the economic output of the facility. The results show that setting up a hydrogen-based microgrid in a residential house is unviable today mainly due to the high cost of hydrogen generation and consumption equipment. If only solar energy is considered the microgrid inversion (12.500 €) is recovered in ten years. On the other hand selling the electricity output has almost no repercussions considering current electrical rates in Spain. Finally while using an optimization algorithm to manage energy use battery life-spam and economic benefit slightly increase. However this profit may not be enough to justify the use of a more complex control system. The results of this research will help users renewable energy companies investigators and policymakers to better understand the different factors influencing the spread of renewable smart grids in households and propose solutions to address these.
Flexible Electricity Dispatch of an Integrated Solar Combined Cycle through Thermal Energy Storage and Hydrogen Production
Jun 2021
Publication
In this work the flexible operation of an Integrated Solar Combined Cycle (ISCC) power plant has been optimized considering two different energy storage approaches. The objective of this proposal is to meet variable users’ grid demand for an extended period at the lowest cost of electricity. Medium temperature thermal energy storage (TES) and hydrogen generation configurations have been analyzed from a techno-economic point of view. Results found from annual solar plant performance indicate that molten salts storage solution is preferable based on the lower levelized cost of electricity (0.122 USD/kWh compared to 0.158 USD/kWh from the hydrogen generation case) due to the lower conversion efficiencies of hydrogen plant components. However the hydrogen plant configuration exceeded in terms of plant availability and grid demand coverage as fewer design constraints resulted in a total demand coverage of 2155 h per year. It was also found that grid demand curves from industrial countries limit the deployment of medium-temperature TES systems coupled to ISCC power plants since their typical demand curves are characterized by lower power demand around solar noon when solar radiation is higher. In such scenarios the Brayton turbine design is constrained by noon grid demand which limits the solar field and receiver thermal power design. View Full-Text
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.
Environmental Sustainability of Alternative Marine Propulsion Technologies Powered by Hydrogen - A Life Cycle Assessment Approach
Jan 2022
Publication
Shipping is a very important source of pollution worldwide. In recent years numerous actions and measures have been developed trying to reduce the levels of greenhouse gases (GHG) from the marine exhaust emissions in the fight against climate change boosting the Sustainable Development Goal 13. Following this target the action of hydrogen as energy vector makes it a suitable alternative to be used as fuel constituting a very promising energy carrier for energy transition and decarbonization in maritime transport. The objective of this study is to develop an ex-ante environmental evaluation of two promising technologies for vessels propulsion a H2 Polymeric Electrolytic Membrane Fuel Cell (PEMFC) and a H2 Internal Combustion Engine (ICE) in order to determine their viability and eligibility compared to the traditional one a diesel ICE. The applied methodology follows the Life Cycle Assessment (LCA) guidelines considering a functional unit of 1 kWh of energy produced. LCA results reveal that both alternatives have great potential to promote the energy transition particularly the H2 ICE. However as technologies readiness level is quite low it was concluded that the assessment has been conducted at a very early stage so their sustainability and environmental performance may change as they become more widely developed and deployed which can be only achieved with political and stakeholder’s involvement and collaboration.
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