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Hydrogen Production from Methanol–Water Solution and Pure Water Electrolysis Using Nanocomposite Perfluorinated Sulfocationic Membranes Modified by Polyaniline
Oct 2022
Publication
In this work we report the preparation of Nafion membranes containing two different nanocomposite MF-4SC membranes modified with polyaniline (PANI) by the casting method through two different polyaniline infiltration procedures. These membranes were evaluated as a polymer electrolyte membrane for water electrolysis. Operating conditions were optimized in terms of current density stability and methanol concentration. A study was made on the effects on the cell performance of various parameters such as methanol concentration water and cell voltage. The energy required for pure water electrolysis was analyzed at different temperatures for the different membranes. Our experiments showed that PEM electrolyzers provide hydrogen production of 30 mL/min working at 160 mA/cm2 . Our composite PANI membranes showed an improved behavior over pristine perfluorinated sulfocationic membranes (around 20% reduction in specific energy). Methanol–water electrolysis required considerably less (around 65%) electrical power than water electrolysis. The results provided the main characteristics of aqueous methanol electrolysis in which the power consumption is 2.34 kW h/kg of hydrogen at current densities higher than 0.5 A/cm2 . This value is ~20-fold times lower than the electrical energy required to produce 1 kg of hydrogen by water electrolysis.
Study on the Effects of the Hydrogen Substitution Rate on the Performance of a Hydrogen–Diesel Dual-Fuel Engine under Different Loads
Aug 2023
Publication
Due to having zero carbon emissions and renewable advantages hydrogen has great prospects as a renewable form of alternate energy. Engine load and hydrogen substitution rate have a considerable influence on a hydrogen–diesel dual-fuel engine’s efficiency. This experiment’s objective is to study the influence of hydrogen substitution rate on engine combustion and emission under different loads and to study the impact of exhaust gas recirculation (EGR) technology or main injection timing on the engine’s capability under high load and high hydrogen substitution rate. The range of the maximum hydrogen substitution rate was determined under different loads (30%~90%) at 1800 rpm and then the effects of the EGR rate (0%~15%) and main injection timing (−8 ◦CA ATDC~0 ◦CA ATDC) on the engine performance under 90% high load were studied. The research results show that the larger the load the smaller the maximum hydrogen substitution rate that can be added to the dual-fuel engine. Under each load with the increase of the hydrogen substitution rate the cylinder pressure and the peak heat release rate (HRR) increase the equivalent brake-specific fuel consumption (BSFCequ) decreases the thermal efficiency increases the maximum thermal efficiency is 43.1% the carbon dioxide (CO2 ) emission is effectively reduced by 35.2% and the nitrogen oxide (NOx) emission decreases at medium and low loads and the maximum increase rate is 20.1% at 90% load. Under high load with the increase of EGR rate or the delay of main injection timing the problem of NOx emission increases after hydrogen doping can be effectively solved. As the EGR rate rises from 0% to 15% the maximum reduction of NOx is 63.1% and with the delay of main injection timing from −8 ◦CA ATDC to 0 ◦CA ATDC the maximum reduction of NOx is 44.5%.
Computational Fluid Dynamics Simulations of Hydrogen Releases and Vented Deflagrations in Large Enclosures
Nov 2019
Publication
This paper presents model predictions obtained with the CFD tool FLACS for hydrogen releases and vented deflagrations in containers and larger enclosures. The paper consists of two parts. The first part compares experimental results and model predictions for two test cases: experiments performed by Gexcon in 20-foot ISO containers (volume 33 m3 ) as part of the HySEA project and experiments conducted by SRI International and Sandia National Laboratories in a scaled warehouse geometry (volume 45.4 m3 ). The second part explores the use of the model system validated in the first part to accidental releases of hydrogen from forklift trucks inside a full-scale warehouse geometry (32 400 m3 ). The results demonstrate the importance of using realistic and reasonably accurate geometry models of the systems under consideration when performing CFD-based risk assessment studies. The discussion highlights the significant inherent uncertainty associated with quantitative risk assessments for vented hydrogen deflagrations in complex geometries. The suggestions for further work include a pragmatic approach for developing empirical correlations for pressure loads from vented hydrogen deflagrations in industrial warehouses with hydrogen-powered forklift trucks.
Hydrogen Refuelling Station Calibration with a Traceable Gravimetric Standard
Apr 2020
Publication
Of all the alternatives to hydrocarbon fuels hydrogen offers the greatest long-term potential to radically reduce the many problems inherent in fuel used for transportation. Hydrogen vehicles have zero tailpipe emissions and are very efficient. If the hydrogen is made from renewable sources such as nuclear power or fossil sources with carbon emissions captured and sequestered hydrogen use on a global scale would produce almost zero greenhouse gas emissions and greatly reduce air pollutant emissions. The aim of this work is to realise a traceability chain for hydrogen flow metering in the range typical for fuelling applications in a wide pressure range with pressures up to 875 bar (for Hydrogen Refuelling Station - HRS with Nominal Working Pressure of 700 bar) and temperature changes from −40 °C (pre-cooling) to 85 °C (maximum allowed vehicle tank temperature) in accordance with the worldwide accepted standard SAE J2601. Several HRS have been tested in Europe (France Netherlands and Germany) and the results show a good repeatability for all tests. This demonstrates that the testing equipment works well in real conditions. Depending on the installation configuration some systematic errors have been detected and explained. Errors observed for Configuration 1 stations can be explained by pressure differences at the beginning and end of fueling in the piping between the Coriolis Flow Meter (CFM) and the dispenser: the longer the distance the bigger the errors. For Configuration 2 where this distance is very short the error is negligible.
Techno-economic Analysis and Predictive Operation of a Power-to-hydrogen for Renewable Microgrids
Oct 2023
Publication
To enhance renewable energy (RE) generation and maintain power balance energy storage systems are of utmost importance. This research introduces a cutting-edge Power-to-Hydrogen (PtH) framework that harnesses hydrogen as a clean and versatile energy storage medium. The primary focus of this study lies in optimizing power flow within a microgrid (G) equipped with RE and energy storage systems considering various factors such as RE generation power demand battery charge cycles and operational costs. To achieve the optimal balance between power generation and consumption a sophisticated mathematical solution is devised. This solution governs the charging and discharging patterns for both battery and electrolyzer ensuring a harmonious power equilibrium. The use of short-term forecasting further refines the optimization process adapting the parameters based on anticipated RE sources and load requirements. To fine-tune the power management solution for day-to-day operations an artificial neural fuzzy inference system (ANFIS)-based shortterm prediction model is employed. The predictive analysis provides confidence intervals for crucial aspects including power generation demand battery charging cycles and hydrogen generation. This facilitates precise cost estimation across various hydrogen and heat price ranges. the proposed PtH optimization framework offers an efficient approach to balance power generation and consumption in Gs driven by RE sources and energy storage. To validate the proposed approach numerical simulations are performed based on data from wind and solar farms load requirements and cost of energy. The results show that the proposed energy management strategy significantly reduces operational costs and optimizes PtH generation while maintaining power balance within the microgrid (G). The predictive approach helps fine-tune the optimization process improving efficiency and cost-effectiveness. The research convincingly demonstrate the economic advantages of adopting hydrogen as an energy storage medium paving the way for a cleaner and more sustainable energy future.
Comparative Life Cycle Greenhouse Gas Analysis of Clean Hydrogen Pathways: Assessing Domestic Production and Overseas Import in South Korea
Sep 2023
Publication
The development of a Clean Hydrogen Standard based on life-cycle greenhouse gas (GHG) emissions is gaining prominence on the international agenda. Thus a framework for assessing life-cycle GHG emissions for clean hydrogen pathways is necessary. In this study the comprehensive datasets and effects of various scenarios encompassing hydrogen production carriers (liquid hydrogen ammonia methylcyclohexane) carbon capture and storage (CCS) target analysis year (2021 2030) to reflect trends of greening grid electricity and potential import countries on aggregated life-cycle GHG emissions were presented. South Korea was chosen as a case study region and the low-carbon alternatives were suggested for reducing aggregated emissions to meet the Korean standard (5 kgCO2e/kgH2). First capturing and storing nearly entire (>90%) CO2 from fossil- and waste-based production pathways is deemed essential. Second when repurposing the use of hydrogen that was otherwise used internally applying a penalty for substitution is appropriate leading to results notably exceeding the standard. Third for electrolysis-based hydrogen using renewable or nuclear electricity is essential. Lastly when hydrogen is imported in a well-to-point-of-delivery (WtP) perspective using renewable electricity during hydrogen conversion into a carrier and reusing the produced hydrogen for endothermic reconversion reaction are recommended. By implementing the developed calculation framework to other countries' cases it was observed that importing hydrogen to regions having scope of WtP or above (e.g. well-to-wheel) might not meet the threshold due to additional emissions from importation processes. Additionally for hydrogen carriers undergoing the endothermic reconversion the approach to reduce WtP emissions (reusing produced hydrogen) may conflict with the approach to reduce well-to-gate (WtG) emission (using external fossilbased fuel). The discrepancy highlights the need to set a broader scope of emissions assessment to effectively promote the life-cycle emission reduction efforts of hydrogen importers. This study contributes to the field of clean hydrogen GHG emission assessment offering a robust database and calculation framework while addressing the effects of greening grid electricity and CCS implementation proposing low-carbon alternatives and GHG assessment scope to achieve global GHG reduction.
Greenhouse Gas Reduction Potential and Economics of Green Hydrogen via Water Electrolysis: A Systematic Review of Value-Chain-Wide Decarbonization
May 2024
Publication
Green hydrogen generated via water electrolysis has become an essential energy carrier for achieving carbon neutrality globally because of its versatility in renewable energy consumption and decarbonization applications in hard-to-abate sectors; however there is a lack of systematic analyses of its abatement potential and economics as an alternative to traditional technological decarbonization pathways. Based on bibliometric analysis and systematic evaluation methods this study characterizes and analyzes the literature on the Web of Science from 1996 to 2023 identifying research hotspots methodological models and research trends in green hydrogen for mitigating climate change across total value chain systems. Our review shows that this research theme has entered a rapid development phase since 2016 with developed countries possessing more scientific results and closer partnerships. Difficult-to-abate sectoral applications and cleaner production are the most famous value chain links and research hotspots focus on three major influencing factors: the environment; techno-economics; and energy. Green hydrogen applications which include carbon avoidance and embedding to realize carbon recycling have considerable carbon reduction potential; however uncertainty limits the influence of carbon reduction cost assessment indicators based on financial analysis methods for policy guidance. The abatement costs in the decarbonization sector vary widely across value chains electricity sources baseline scenarios technology mixes and time scenarios. This review shows that thematic research trends are focused on improving and optimizing solutions to uncertainties as well as studying multisectoral synergies and the application of abatement assessment metrics.
CFD Thermo‑Hydraulic Evaluation of a Liquid Hydrogen Storage Tank with Different Insulation Thickness in a Small‑Scale Hydrogen Liquefier
Aug 2023
Publication
Accurate evaluation of thermo‑fluid dynamic characteristics in tanks is critically important for designing liquid hydrogen tanks for small‑scale hydrogen liquefiers to minimize heat leakage into the liquid and ullage. Due to the high costs most future liquid hydrogen storage tank designs will have to rely on predictive computational models for minimizing pressurization and heat leakage. Therefore in this study to improve the storage efficiency of a small‑scale hydrogen liquefier a three‑ dimensional CFD model that can predict the boil‑off rate and the thermo‑fluid characteristics due to heat penetration has been developed. The prediction performance and accuracy of the CFD model was validated based on comparisons between its results and previous experimental data and a good agreement was obtained. To evaluate the insulation performance of polyurethane foam with three different insulation thicknesses the pressure changes and thermo‑fluid characteristics in a partially liquid hydrogen tank subject to fixed ambient temperature and wind velocity were investigated nu‑ merically. It was confirmed that the numerical simulation results well describe not only the temporal variations in the thermal gradient due to coupling between the buoyance and convection but also the buoyancy‑driven turbulent flow characteristics inside liquid hydrogen storage tanks with differ‑ ent insulation thicknesses. In the future the numerical model developed in this study will be used for optimizing the insulation systems of storage tanks for small‑scale hydrogen liquefiers which is a cost‑effective and highly efficient approach.
Power Cost and CO2 Emissions for a Microgrid with Hydrogen Storage and Electric Vehicles
Nov 2023
Publication
Hydrogen is considered the primary energy source of the future. The best use of hydrogen is in microgrids that have renewable energy sources (RES). These sources have a small impact on the environment when it comes to carbon dioxide (CO2 ) emissions and a power generation cost close to that of conventional power plants. Therefore it is important to study the impact on the environment and the power cost. The proposed microgrid comprises loads RESs (micro-hydro and photovoltaic power plants) a hydrogen storage tank an electric battery and fuel cell vehicles. The power cost and CO2 emissions are calculated and compared for various scenarios including the four seasons of the year compared with the work of other researchers. The purpose of this paper is to continuously supply the loads and vehicles. The results show that the microgrid sources and hydrogen storage can supply consumers during the spring and summer. For winter and autumn the power grid and steam reforming of natural gas must be used to cover the demand. The highest power costs and CO2 emissions are for winter while the lowest are for spring. The power cost increases during winter between 20:00 and 21:00 by 336%. The CO2 emissions increase during winter by 8020%.
Review of the Status and Prospects of Fiber Optic Hydrogen Sensing Technology
Aug 2023
Publication
With the unprecedented development of green and renewable energy sources the proportion of clean hydrogen (H2 ) applications grows rapidly. Since H2 has physicochemical properties of being highly permeable and combustible high-performance H2 sensors to detect and monitor hydrogen concentration are essential. This review discusses a variety of fiber-optic-based H2 sensor technologies since the year 1984 including: interferometer technology fiber grating technology surface plasma resonance (SPR) technology micro lens technology evanescent field technology integrated optical waveguide technology direct transmission/reflection detection technology etc. These technologies have been evolving from simply pursuing high sensitivity and low detection limits (LDL) to focusing on multiple performance parameters to match various application demands such as: high temperature resistance fast response speed fast recovery speed large concentration range low cross sensitivity excellent long-term stability etc. On the basis of palladium (Pd)-sensitive material alloy metals catalysts or nanoparticles are proposed to improve the performance of fiberoptic-based H2 sensors including gold (Au) silver (Ag) platinum (Pt) zinc oxide (ZnO) titanium oxide (TiO2 ) tungsten oxide (WO3 ) Mg70Ti30 polydimethylsiloxane (PDMS) graphene oxide (GO) etc. Various microstructure processes of the side and end of optical fiber H2 sensors are also discussed in this review.
Assessment of the Green Hydrogen Value Chain in Cases of the Local Industry in Chile Applying an Optimization Model
May 2024
Publication
This study assessed the feasibility of integrating a green hydrogen value chain into the local industry examining two case studies by comparing four scenarios. The optimization focused on generating electricity from stationary renewable sources such as solar or through Power Purchase Agreements to produce sufficient hydrogen in electrolyzers. Current demand profiles renewable participation targets electricity supply sources levelized costs of energy and hydrogen and technology options were considered. The most cost-effective scenario showed a levelized cost of energy of 0.032 and 0.05 US$/kWh and a hydrogen cost below 1.0 US$/kgH2 for cases 1 and 2 respectively. A sensitivity analysis highlighted the critical influence of fuel cell technology on cost modification underscoring the importance of focusing cost reduction strategies on these technologies to enhance the economic viability of the green hydrogen value chain. Specifically a high sensitivity towards reducing the levelized costs of energy and hydrogen in the port sector with adjustments in fuel cell technology costs was identified indicating the need for specific policies and supports to facilitate their adoption.
Science and Technology of Ammonia Combustion
Nov 2018
Publication
This paper focuses on the potential use of ammonia as a carbon-free fuel and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the COP21 Paris Agreement requires the de-carbonization of energy generation through utilization of carbon-neutral and overall carbon-free fuels produced from renewable sources. Hydrogen is one of such fuels which is a potential energy carrier for reducing greenhouse-gas emissions. However its shipment for long distances and storage for long times present challenges. Ammonia on the other hand comprises 17.8% of hydrogen by mass and can be produced from renewable hydrogen and nitrogen separated from air. Furthermore thermal properties of ammonia are similar to those of propane in terms of boiling temperature and condensation pressure making it attractive as a hydrogen and energy carrier. Ammonia has been produced and utilized for the past 100 years as a fertilizer chemical raw material and refrigerant. Ammonia can be used as a fuel but there are several challenges in ammonia combustion such as low flammability high NOx emission and low radiation intensity. Overcoming these challenges requires further research into ammonia flame dynamics and chemistry. This paper discusses recent successful applications of ammonia fuel in gas turbines co-fired with pulverize coal and in industrial furnaces. These applications have been implemented under the Japanese ‘Cross-ministerial Strategic Innovation Promotion Program (SIP): Energy Carriers’. In addition fundamental aspects of ammonia combustion are discussed including characteristics of laminar premixed flames counterflow twin-flames and turbulent premixed flames stabilized by a nozzle burner at high pressure. Furthermore this paper discusses details of the chemistry of ammonia combustion related to NOx production processes for reducing NOx and validation of several ammonia oxidation kinetics models. Finally LES results for a gas-turbine-like swirl-burner are presented for the purpose of developing low-NOx single-fuelled ammonia gas turbine combustors.
An Integrated Demand Response Dispatch Strategy for Low-carbon Energy Supply Park Considering Electricity-Hydrogen-Carbon Coordination
Apr 2023
Publication
Driven by the goal of ‘carbon peak carbon neutrality’ an integrated demand response strategy for integrated electricity– hydrogen energy systems is proposed for low-carbon energy supply parks considering the multi-level and multi-energy characteristics of campus-based microgrids. Firstly considering the spatial and temporal complementary nature of wind and photovoltaic generation and energy utilization the energy flow framework of the park is built based on the electricity and hydrogen energy carriers. Clean energy is employed as the main energy supply and power heat cooling and gas loads are considered energy consumption. Secondly the operation mechanism of coupled hydrogen storage hydrogen fuel cell and carbon capture equipment is analyzed in the two-stage power-to-gas conversion process. Thirdly considering the operating costs and environmental costs of the park an integrated demand response dispatch model is constructed for the coupled electricity– hydrogen–carbon system while satisfying the system equipment constraints network constraints and energy balance constraints of the park system. Finally Case study in an energy supply park system is implemented. The dispatch results of the integrated demand response with customer participation in the conventional electricity–hydrogen and electricity–hydrogen–carbon modes are compared to verify the effectiveness of the proposed strategy in renewable accommodation environmental protection and economic benefits.
Assessment of Hydrogen Energy Industry Chain Based on Hydrogen Production Methods, Storage, and Utilization
Apr 2024
Publication
To reach climate neutrality by 2050 a goal that the European Union set itself it is necessary to change and modify the whole EU’s energy system through deep decarbonization and reduction of greenhouse-gas emissions. The study presents a current insight into the global energy-transition pathway based on the hydrogen energy industry chain. The paper provides a critical analysis of the role of clean hydrogen based on renewable energy sources (green hydrogen) and fossil-fuels-based hydrogen (blue hydrogen) in the development of a new hydrogen-based economy and the reduction of greenhouse-gas emissions. The actual status costs future directions and recommendations for low-carbon hydrogen development and commercial deployment are addressed. Additionally the integration of hydrogen production with CCUS technologies is presented.
Perspectives on the Development of Technologies for Hydrogen as a Carrier of Sustainable Energy
Aug 2023
Publication
Hydrogen is a prospective energy carrier because there are practically no gaseous emissions of greenhouse gases in the atmosphere during its use as a fuel. The great benefit of hydrogen being a practically inexhaustible carbon-free fuel makes it an attractive alternative to fossil fuels. I.e. there is a circular process of energy recovery and use. Another big advantage of hydrogen as a fuel is its high energy content per unit mass compared to fossil fuels. Nowadays hydrogen is broadly used as fuel in transport including fuel cell applications as a raw material in industry and as an energy carrier for energy storage. The mass exploitation of hydrogen in energy production and industry poses some important challenges. First there is a high price for its production compared to the price of most fossil fuels. Next the adopted traditional methods for hydrogen production like water splitting by electrolysis and methane reforming lead to the additional charging of the atmosphere with carbon dioxide which is a greenhouse gas. This fact prompts the use of renewable energy sources for electrolytic hydrogen production like solar and wind energy hydropower etc. An important step in reducing the price of hydrogen as a fuel is the optimal design of supply chains for its production distribution and use. Another group of challenges hindering broad hydrogen utilization are storage and safety. We discuss some of the obstacles to broad hydrogen application and argue that they should be overcome by new production and storage technologies. The present review summarizes the new achievements in hydrogen application production and storage. The approach of optimization of supply chains for hydrogen production and distribution is considered too.
PEM Water Electrolysis for Hydrogen Production: Fundamentals, Advances, and Prospects
Jun 2022
Publication
Hydrogen as a clean energy carrier is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies has ignited much attention in the past decades based on the high current density greater energy efficiency small mass-volume characteristic easy handling and maintenance. To date substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review we firstly compare the alkaline water electrolysis (AWE) solid oxide electrolysis (SOE) and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly current collector and bipolar plate). Finally the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.
Thermal Design of a Biohydrogen Production System Driven by Integrated Gasification Combined Cycle Waste Heat Using Dynamic Simulation
Apr 2022
Publication
Utilizing biological processes for hydrogen production via gasification is a promising alternative method to coal gasification. The present study proposes a dynamic simulation model that uses a one-dimensional heat-transfer analysis method to simulate a biohydrogen production system. The proposed model is based on an existing experimental design setup. It is used to simulate a biohydrogen production system driven by the waste heat from an integrated gasification combined cycle (IGCC) power plant equipped with carbon capture and storage technologies. The data from the simulated results are compared with the experimental measurement data to validate the developed model’s reliability. The results show good agreement between the experimental data and the developed model. The relative root-mean-square error for the heat storage feed-mixing and bioreactor tanks is 1.26% 3.59% and 1.78% respectively. After the developed model’s reliability is confirmed it is used to simulate and optimize the biohydrogen production system inside the IGCC power plant. The bioreactor tank’s time constant can be improved when reducing the operating volume of the feed-mixing tank by the scale factors of 0.75 and 0.50 leading to a 15.76% and 31.54% faster time constant respectively when compared with the existing design.
Small-Scale High-Pressure Hydrogen Storage Vessels: A Review
Feb 2024
Publication
Nowadays high-pressure hydrogen storage is the most commercially used technology owing to its high hydrogen purity rapid charging/discharging of hydrogen and low-cost manufacturing. Despite numerous reviews on hydrogen storage technologies there is a relative scarcity of comprehensive examinations specifically focused on high-pressure gaseous hydrogen storage and its associated materials. This article systematically presents the manufacturing processes and materials used for a variety of high-pressure hydrogen storage containers including metal cylinders carbon fiber composite cylinders and emerging glass material-based hydrogen storage containers. Furthermore it introduces the relevant principles and theoretical studies showcasing their advantages and disadvantages compared to conventional high-pressure hydrogen storage containers. Finally this article provides an outlook on the future development of high-pressure hydrogen storage containers.
Investigation of a Community-based Clean Energy System Holistically with Renewable and Hydrogen Energy Options for Better Sustainable Development
Jan 2024
Publication
This study develops a novel community-based integrated energy system where hydrogen and a combination of renewable energy sources are considered uniquely for implementation. In this regard three different communities situated in Kenya the United States and Australia are studied for hydrogen production and meeting the energy demands. To provide a variety of energy demands this study combines a multigenerational geothermal plant with a hybrid concentrated solar power and photovoltaic solar plant. Innovations in hydrogen production and renewable energy are essential for reducing carbon emissions. By combining the production of hydrogen with renewable energy sources this system seeks to move away from the reliance on fossil fuels and toward sustainability. The study investigates various research subjects using a variety of methods. The performance of the geothermal source is considered through energetic and exergetic thermodynamic analysis. The software System Advisor Model (SAM) and RETscreen software packages are used to analyze the other sub-systems including Concentrate Solar PV solar and Combined Heat and Power Plant. Australian American and Kenyan communities considered for this study were found to have promising potential for producing hydrogen and electricity from renewable sources. The geothermal output is expected to be 35.83 MW 122.8 MW for space heating 151.9 MW for industrial heating and 64.25 MW for hot water. The overall geothermal energy and exergy efficiencies are reported as 65.15% and 63.54% respectively. The locations considered are expected to have annual solar power generation and hydrogen production capacities of 158MW 237MW 186MW 235 tons 216 tons and 313 tons respectively.
Renewable Hydrogen Requirements and Impacts for Network Balancing: A Queensland Cae Study
Dec 2023
Publication
Hydrogen is the gas of the moment: an abundant element that can be created using renewable energy transported in gaseous or liquid form and offering the ability to provide energy with only water vapour as an emission. Hydrogen can also be used in a fuel blend in electricity generation gas turbines providing a low carbon option for providing the peak electricity to cover high demand and firming.<br/>While the electricity grid is itself transforming to decarbonising hard-to-abate industries such as cement and bauxite refineries are slower to reduce emissions constrained by their high temperature process requirements. Hydrogen offers a solution allowing onsite production process heat with waste heat recovery supporting blended gas turbine generation for onsite electricity supply.<br/>This article builds on decarbonisation pathway simulation results from an ANEM model of the electricity grid identifying the amount of peak demand energy required from gas turbines. The research then examines the quantity flow rate storage requirements and emissions reduction if this peak generation were supplied by open cycle hydrogen capable gas turbines.
Decarbonizing the European Energy System in the Absence of Russian Gas: Hydrogen Uptake and Carbon Capture Developments in the Power, Heat and Industry Sectors
Dec 2023
Publication
Hydrogen and carbon capture and storage are pivotal to decarbonize the European energy system in a broad range of pathway scenarios. Yet their timely uptake in different sectors and distribution across countries are affected by supply options of renewable and fossil energy sources. Here we analyze the decarbonization of the European energy system towards 2060 covering the power heat and industry sectors and the change in use of hydrogen and carbon capture and storage in these sectors upon Europe’s decoupling from Russian gas. The results indicate that the use of gas is significantly reduced in the power sector instead being replaced by coal with carbon capture and storage and with a further expansion of renewable generators. Coal coupled with carbon capture and storage is also used in the steel sector as an intermediary step when Russian gas is neglected before being fully decarbonized with hydrogen. Hydrogen production mostly relies on natural gas with carbon capture and storage until natural gas is scarce and costly at which time green hydrogen production increases sharply. The disruption of Russian gas imports has significant consequences on the decarbonization pathways for Europe with local energy sources and carbon capture and storage becoming even more important. Given the highlighted importance of carbon capture and storage in reaching the climate targets it is essential that policymakers ameliorate regulatory challenges related to these value chains.
Prospectivity Analysis for Underground Hydrogen Storage, Taranaki Basin, Aotearoa New Zealand: A Multi-criteria Decision-making Approach
May 2024
Publication
Seasonal underground hydrogen storage (UHS) in porous media provides an as yet untested method for storing surplus renewable energy and balancing our energy demands. This study investigates the technical suitability for UHS in depleted hydrocarbon fields and one deep aquifer site in Taranaki Basin Aotearoa New Zealand. Prospective sites are assessed using a decision tree approach providing a “fast-track” method for identifying potential sites and a decision matrix approach for ranking optimal sites. Based on expert elicitation the most important factors to consider are storage capacity reservoir depth and parameters that affect hydrogen injectivity/withdrawal and containment. Results from both approaches suggest that Paleogene reservoirs from gas (or gas cap) fields provide the best option for demonstrating UHS in Aotearoa New Zealand and that the country’s projected 2050 hydrogen storage demand could be exceeded by developing one or two high ranking sites. Lower priority is assigned to heterolithic and typically finer grained labile and clay-rich Miocene oil reservoirs and to deep aquifers that have no proven hydrocarbon containment.
Recent Advances in Power-to-X Technology for the Production of Fuels and Chemicals
Jun 2019
Publication
Environmental issues related to greenhouse gas emissions are progressively pushing the transition toward fossil-free energy scenario in which renewable energies such as solar and wind power will unavoidably play a key role. However for this transition to succeed significant issues related to renewable energy storage have to be addressed. Power-to-X (PtX) technologies have gained increased attention since they actually convert renewable electricity to chemicals and fuels that can be more easily stored and transported. H2 production through water electrolysis is a promising approach since it leads to the production of a sustainable fuel that can be used directly in hydrogen fuel cells or to reduce carbon dioxide (CO2) in chemicals and fuels compatible with the existing infrastructure for production and transportation. CO2 electrochemical reduction is also an interesting approach allowing the direct conversion of CO2 into value-added products using renewable electricity. In this review attention will be given to technologies for sustainable H2 production focusing on water electrolysis using renewable energy as well as on its remaining challenges for large scale production and integration with other technologies. Furthermore recent advances on PtX technologies for the production of key chemicals (formic acid formaldehyde methanol and methane) and fuels (gasoline diesel and jet fuel) will also be discussed with focus on two main pathways: CO2 hydrogenation and CO2 electrochemical reduction.
Storage Integrity During Underground Hydrogen Storage in Depleted Gas Reservoirs
Nov 2023
Publication
The transition from fossil fuels to renewable energy sources particularly hydrogen has emerged as a central strategy for decarbonization and the pursuit of net-zero carbon emissions. Meeting the demand for large-scale hydrogen storage a crucial component of the hydrogen supply chain has led to the exploration of underground hydrogen storage as an economically viable solution to global energy needs. In contrast to other subsurface storage options such as salt caverns and aquifers which are geographically limited depleted gas reservoirs have garnered increasing attention due to their broader distribution and higher storage capacity. However the safe storage and cycling of hydrogen in depleted gas reservoirs require the preservation of high stability and integrity in the caprock reservoir and wellbore. Nevertheless there exists a significant gap in the current research concerning storage integrity in underground hydrogen storage within depleted gas reservoirs and a systematic approach is lacking. This paper aims to address this gap by reviewing the primary challenges associated with storage integrity including geochemical reactions microbial activities faults and fractures and perspectives on hydrogen cycling. The study comprehensively reviews the processes and impacts such as abiotic and biotic mineral dissolution/precipitation reactivation and propagation of faults and fractures in caprock and host-rock wellbore instability due to cement degradation and casing corrosion and stress changes during hydrogen cycling. To provide a practical solution a technical screening tool has been developed considering controlling variables risks and consequences affecting storage integrity. Finally this paper highlights knowledge gaps and suggests feasible methods and pathways to mitigate these risks facilitating the development of large-scale underground hydrogen storage in depleted gas reservoirs.
The Fuel Flexibility of Gas Turbines: A Review and Retrospective Outlook
May 2023
Publication
Land-based gas turbines (GTs) are continuous-flow engines that run with permanent flames once started and at stationary pressure temperature and flows at stabilized load. Combustors operate without any moving parts and their substantial air excess enables complete combustion. These features provide significant space for designing efficient and versatile combustion systems. In particular as heavy-duty gas turbines have moderate compression ratios and ample stall margins they can burn not only high- and medium-BTU fuels but also low-BTU ones. As a result these machines have gained remarkable fuel flexibility. Dry Low Emissions combustors which were initially confined to burning standard natural gas have been gradually adapted to an increasing number of alternative gaseous fuels. The paper first delivers essential technical considerations that underlie this important fuel portfolio. It then reviews the spectrum of alternative GT fuels which currently extends from lean gases (coal bed coke oven blast furnace gases . . . ) to rich refinery streams (LPG olefins) and from volatile liquids (naphtha) to heavy hydrocarbons. This “fuel diet” also includes biogenic products (biogas biodiesel and ethanol) and especially blended and pure hydrogen the fuel of the future. The paper also outlines how historically land-based GTs have gradually gained new fuel territories thanks to continuous engineering work lab testing experience extrapolation and validation on the field.
Energy Storage Strategy - Phase 2
Feb 2023
Publication
This document is phase 2 of the energy storage strategy study and it covers the storage challenges of the energy transition. We start in section 3 by covering historical and current natural gas imports into the UK and what these could look like in the future. In section 4 we explore what demand for hydrogen could look like – this has a high level of uncertainty and future policy decisions will have significant impacts on hydrogen volumes and annual variations. We generated two hydrogen storage scenarios based on National Grid’s Future Energy Scenarios and the Climate Change Committee’s Sixth Carbon Budget to assess the future need for hydrogen storage in the UK. We also looked at an extreme weather scenario resulting from an area of high-pressure settled over the British Isles resulting in very low ambient temperatures an unusually high demand for heating and almost no wind generation. In section 5 we investigate options for hydrogen storage and build on work previously carried out by SGN. We discuss the differences between the properties of hydrogen and natural gas and how this affects line pack and depletion of line pack. We discuss flexibility on the supply and demand side and how this can impact on hydrogen storage. We provide a summary table which compares the various options for storage. In section 5 we explore hydrogen trade and options for import and export. Using information from other innovation projects we also discuss production of hydrogen from nuclear power and the impact of hybrid appliances on gas demand for domestic heat. In section 7 we discuss the outputs from a stakeholder workshop with about 40 stakeholders across industry academia and government. The workshop covered UK gas storage strategy to date hydrogen demand and corresponding storage scenarios to 2050 including consideration of seasonal variation and storage options.
The Effect of Natural Ventilation through Roof Vents Following Hydrogen Leaks in Confined Spaces
Sep 2023
Publication
Hydrogen energy is gaining global popularity as a green energy source and its use is increasing. However hydrogen has a rapid diffusion rate and a broad combustion range; thus it is vital to take safety precautions during its storage. In this study we examined the change of hydrogen concentration in a confined space exposed to a hydrogen leak according to the size of the leakage hole and the leakage flow rate assuming an extreme situation. In addition we investigated rectangular vents (that serve as explosion panels in the event of an explosion) to assess their ventilation performance according to the area of the vent when used for emergency natural ventilation. The vent areas tested represented 12% 24% and 36% of the floor area and they were installed in the ceiling of the test enclosure. When exposed to a simulated hydrogen leak the enclosure acquired a hydrogen concentration of 1% which is 25% of the lower flammability limit (LFL) in less than 6 s across all test cases. The time to LFL varied from approximately 4–81 s. In an assessment of the emergency ventilation duration the ventilation time required to reach safe hydrogen concentrations decreased and showed less deviation as the vent size was increased. For the largest vent size tested the LFL was reached in <1 min; it took 145.6 s to acquire a 1 vol% of hydrogen which is relatively fast. However there were no significant differences between the performance of large and medium-sized vent areas. Therefore through the results we found that it is reasonable to apply the area Kv = 3.31 (24% of the floor area) or less when considering the design of a roof vent that can serve as both an emergency ventilation and an explosion vent. This suggests that it is difficult to expect an improvement in ventilation performance by simply increasing the area of the vent beyond a certain area. Through these results this study proposes a practical and novel method for future design and parameters of safety functions that protect areas where hydrogen is present.
Populating the Hydrogen Component Reliability Database (HYCRED) with Incident Data from Hydrogen Dispensing
Sep 2023
Publication
Safety risk and reliability issues are vital to ensure the continuous and profitable operation of hydrogen technologies. Quantitative risk assessment (QRA) has been used to enable the safe deployment of engineering systems especially hydrogen fueling stations. However QRA studies require reliability data which are essential to collect to make the studies as realistic and relevant as possible. These data are currently lacking and data from other industries such as oil and gas are used in hydrogen system QRAs. This may lead to inaccurate results since hydrogen fueling stations have differences in physical properties system design and operational parameters when compared to other fueling stations thus necessitating new data sources are necessary to capture the effects of these differences. To address this gap we developed a structure for a hydrogen component reliability database (HyCReD) [1] which could be used to generate reliability data to be used in QRA studies. In this paper we demonstrate populating the HyCReD database with information extracted from new narrative reports on hydrogen fueling station incidents specifically focused on the dispensing processes. We analyze five new events and demonstrate the feasibility of populating the database and types of meaningful insights that can be obtained at this stage.
CFD Analysis of Hydrogen Leakage from a Small Hole in a Sloping Roof Hydrogen Refueling Station
Sep 2023
Publication
As a key link in the application of hydrogen energy hydrogen refueling stations are significant for their safe operation. This paper established a three-dimensional 1:1 model for a seaport hydrogen refueling station in Ningbo City. In this work the CFD software FLUENT was used to study the influence of leakage angles on the leakage of high-pressure hydrogen through a small hole. Considering the calculation accuracy and efficiency this paper adopted the pseudo-diameter model. When the obstacle was far from the leakage hole it had almost no obstructive effect on the jet's main body. Still it affected the hydrogen whose momentum in the outer layer of the jet has been significantly decayed. In this condition there would be more hydrogen in stagnation. Thus the volume of the flammable hydrogen cloud was hardly affected while there was a significant increase in the volume of the hazardous hydrogen cloud. When the obstacle was close to the leakage hole it directly affected the jet's main body. Therefore the volume of the flammable hydrogen cloud increased. However the air impeded the hydrogen jet relatively less because the hydrogen jet contacted the obstacle more quickly. The hydrogen jet blocked by the obstacle still has some momentum. Therefore there was no more hydrogen in stagnation and no significant increase in the volume of the hazardous hydrogen cloud.
The NREL Sensor Laboratory: Hydrogen Leak Detection for Large Scale Deployments
Sep 2023
Publication
The NREL Hydrogen Sensor Laboratory was commissioned in 2010 as a resource for sensor developers end-users and regulatory agencies within the national and international hydrogen community. The Laboratory continues to provide as its core capability the unbiased verification of hydrogen sensor performance to assure sensor availability and their proper use. However the mission and strategy of the NREL Sensor Laboratory has evolved to meet the needs of the growing hydrogen market. The Sensor Laboratory program has expanded to support research in conventional and alternative detection methods as hydrogen use expands to large-scale markets as envisioned by the DOE National Clean Hydrogen Strategy and Roadmap. Current research encompasses advanced methods of hydrogen leak detection including stand-off and wide area monitoring approaches for large scale and distributed applications. In addition to safety applications low-level detection strategies to support the potential environmental impacts of hydrogen and hydrogen product losses along the value chain are being explored. Many of these applications utilize detection strategies that supplement and may supplant the use of traditional point sensors. The latest results of the hydrogen detection strategy research at NREL will be presented.
Detailed Assessment of Dispersion for High-pressure H2 in Multi-fuel Environment
Sep 2023
Publication
The MultHyFuel project notably aims to produce the data missing for usable risk analysis and mitigation activity for Hydrogen Refuelling Stations (HRS) in a multi-fuel context. In this framework realistic releases of hydrogen that could occur in representative multi-fuel forecourts were studied. These releases can occur inside or outside fuel dispensers and they can interact with a complex environment notably made of parked cars and trucks. This paper is focused on the most critical scenarios that were addressed by a sub-group through the use of Computational Fluid Dynamics (CFD) modelling. Once the corresponding source terms for hydrogen releases were known two stages are followed:<br/>♦ Model Validation – to evaluate the CFD models selected by the task partners and to evaluate their performance through comparison to experimental data.<br/>♦ Realistic Release Modelling – to perform demonstration simulations of a range of critical scenarios.<br/>The CFD models selected for the Model Validation have been tested against measured data for a set of experiments involving hydrogen releases. Each experiment accounts for physical features that are encountered in the realistic cases. The selected experiments include an under-expanded hydrogen jet discharging into the open atmosphere with no obstacles or through an array of obstacles. Additionally a very different set-up was studied with buoyancy-driven releases inside a naturally ventilated enclosure. The results of the Model Validation exercise show that the models produce acceptable solutions when compared to measured data and give confidence in the ability of the models and the modellers to capture the behaviour of the realistic releases adequately. The Realistic Release Modelling phase will provide estimation of the flammable gas cloud volume for a set of critical scenarios and will be described at the second stage.
Gas Crossover Predictive Modelling Using Artificial Neural Networks Based on Original Dataset Through Aspen Custom Modeler for Proton Exchange Membrane Electrolyte System
Sep 2023
Publication
Proton exchange membrane electrolyzer cell (PEMEC) will play a central role in future power-to-H2 plants. Current research focuses on the materials and operation parameters. Setting up experiments to explore operational accident scenarios about safety feasibility is not always practical. This paper focuses on building mathematical and prediction models of hydrogen and oxygen mixing scenarios of PEMEC. A mathematical model of the PEMEC device was customized in the Aspen Custom Model (ACM) software and integrated various critical Physico-chemical phenomena as the original data set for the prediction model. The results of the mathematical simulation verified the experimental results. The prediction model proposes an artificial neural network (ANN) framework to predict component distribution in the gas stream to prevent hydrogen-oxygen explosion scenarios. The presented approach by training ANN to 1000 sets of hydrogen-oxygen mixing simulation data from ACM is applicable to bypass tedious and non-smooth systems of equations for PEMEC.
Hydrogen Jet Fires in a Full-scale Road Tunnel: Experimental Results
Sep 2023
Publication
Hydrogen Fuel Cell Electric Vehicles (HFC EVs) represent an alternative to replace current internal combustion engine vehicles. The use of these vehicles with storage of compressed gaseous hydrogen (CGH2) or cryogenic liquid hydrogen (LH2) in confined spaces such as tunnels underground car parks etc. creates new challenges to ensure the protection of people and property and to keep the risk at an acceptable level. Several studies have shown that confinement or congestion can lead to severe accidental consequences compared to accidents in an open atmosphere. It is therefore necessary to develop validated hazard and risk assessment tools for the behaviour of hydrogen in tunnels. The HYTUNNEL-CS project sponsored by the FCH-JU pursues this objective. Among the experiments carried out in support of the validation of the hydrogen safety tools the CEA conducted tests on large-scale jet fires in a full-scale tunnel geometry.<br/>The tests were performed in a decommissioned road tunnel in two campaigns. The first one with 50 liters type II tanks under a pressure of 20 MPa and the second one with 78 liters type IV tanks under 70 MPa. In both cases a flate plate was used to simulate the vehicle. Downward and upward gas discharges to simulate a rollover have been investigated with various release diameters. For the downward discharge the orientation varied from normal to the road to a 45° rearward inclination. The first campaign took place under a concrete vault while the second under a rocky vault. Additional tests with the presence of a propane fire simulating a hydrocarbon powered vehicle fire were performed to study the interaction between the two reactive zones.<br/>In the paper all the results obtained during the second campaign for the evolution of the hydrogen jet-fire size the radiated heat fluxes and the temperature of the hot gases released in the tunnel are reported. Comparisons with the classical correlations from open field tests used in engineering models are also presented and conclusions are given as to their applicability.
Explosion Free in Fire Self-venting (TPRD-less) Composite Tanks: Performance Under Fire Intervention Conditions
Sep 2023
Publication
This paper describes the performance of explosion free in fire self-venting (TPRD-less) composite tanks of Type IV in fires of realistic intensity HRR/A=1 MW/m2 in conditions of first responders’ intervention. This breakthrough safety technology does not require the use of thermally activated pressure relief devices (TPRD). It provides microleaks-no-burst (LNB) performance of high-pressure hydrogen storage tanks in a fire. Two fire intervention strategies are investigated one is the removal of a vehicle with LNB tank from the fire and another is the extinction of the fire. The removal from the fire scenario is investigated for one carbon-carbon and one carbon-basalt double-composite wall tank prototype. The fire extinction scenario is studied for four carbon-basalt prototypes. All six prototypes of 7.5 L volume and nominal working pressure of 70 MPa demonstrated safe release of hydrogen through microchannels of the composite wall after melting a liner. The technology allows fire brigades to apply standard intervention strategies and tactics at the fire scene with hydrogen vehicles if LNB tanks are used in the vehicle.
Deflagrations of Non-uniform Hydrogen/Air Clouds in a Tunnel
Sep 2023
Publication
This paper presents work undertaken by the HSE as part of the Hytunnel-CS project a consortium investigating safety considerations for fuel cell hydrogen (FCH) vehicles in tunnels and similar confined spaces.<br/>Hydrogen vehicles typically have a Thermally activated Pressure Release Device (TPRD) providing protection to the on-board storage of the vehicle. Upon activation the content of the vessel is released in a blowdown. The release of this hydrogen gas poses a significant hazard of ignition. The consequences of such an ignition could also be compounded by confinement or congestion.<br/>HSE undertook a series of experiments investigating the consequences of these events by releasing hydrogen into a tunnel and causing ignitions. A sub-section of these tests involved steel structures providing congestion in the tunnel. The mass of hydrogen released into the tunnel prior to ignition was varied by storage pressure (up to 59 MPa) release diameter and ignition delay. The ignition delays were set based on the expected worst-case predicted by pre-simulation models. To assess the consequences overpressure measurements were made down the tunnel walls and for the tests with congestion at the face and rear of the congestion structures. The flame arrival time was also measured using exposed-tip thermocouples resulting in an estimate for flame speed down the tunnel. The measured overpressure and flame extent results are presented and compared against overpressure levels of concern.
Numerical Simulation of Pressure Recovery Phenomenon in Liquid Ammonia Tank
Sep 2023
Publication
A phase transition develops when a pressurised ammonia vessel is vented through a relieve valve or as a result of shell cracking. Significant pressure recovery in the vessel can occur as a consequence of this phase transition following initial depressurisation and may lead to complete vessel failure. It is critical for safety engineering to predict the flash boiling behaviour and pressure dynamics during the depressurization of liquid ammonia tank. This research aims to develop and compare against available experimental data a CFD model that can predict two-phase behaviour of ammonia and resulting pressure dynamics in the storage tank during its venting to the atmosphere. The CFD model is based on the Volume-of-Fluid (VOF) method and Lee evaporation/condensation approach. The numerical simulation demonstrated that liquid ammonia which is initially at equilibrium state begins to boil throughout due to the decrease of its saturation temperature with the pressure drop during tank venting. In order to understand phenomena underlying the pressure recovery this paper analyses dynamics of superheated ammonia formation its swelling vaporisation contribution to gaseous ammonia mass and volume in ullage space and gaseous ammonia venting. Performed in the study quantitative analysis demonstrated that the flash boiling and gaseous ammonia produced by this phase change were the major reasons behind the pressure recovery. The simulation results of flash boiling delay accurately matched the analytical calculation of bubble rise time. The developed CFD model can be used as a contemporary tool for inherently safer design of ammonia tanks and their depressurisation process.
Hydrogen Equipment Enclosure Risk Reduction through Earlier Detection of Component Failures
Sep 2023
Publication
Hydrogen component reliability and the hazard associated with failure rates is a critical area of research for the successful implementation and growth of hydrogen technology across the globe. The research team has partnered to quantify system risk reduction through earlier detection of hydrogen component failures. A model of hydrogen dispersion in a hydrogen equipment enclosure has been developed utilizing experimentally quantified hydrogen component leak rates as inputs. This model provides insight into the impact of hydrogen safety sensors and ventilation on the flammable mass within a hydrogen equipment enclosure. This model also demonstrates the change in safety sensor response time due to detector placement under various leak scenarios. The team looks to improve overall hydrogen system safety through an improved understanding of hydrogen component reliability and risk mitigation methods. This collaboration fits under the work program of IEA Hydrogen Task 43 Subtask E Hydrogen System Safety.
Experimental Investigation of Fluid-structure Interaction in the Case of Hydrogen/Air Detonation Impacting a Thin Plate
Sep 2023
Publication
In recent years the use and development of hydrogen as a carbon-free energy carrier have grown. However as hydrogen is flammable with air safety issues are raised. In the case of ignition especially in confined space the flame can accelerate and reach the detonation regime causing severe structural damage [1].<br/>To assess these safety issues it is required to understand the fluid-structure interaction in the case of a detonation impacting a deformable structure and to quantify and model this interaction [2]. At the CEA (Commissariat à l’énergie atomique et aux energies alternatives) a combustion tube experimental facility [3] for studying the fluid-structure interaction in the case of hydrogen combustion has been developed. Several Photomultipliers and Pressure sensors are placed along the tube to monitor the flame acceleration and the detonation location. A fluid-structure interaction (FSI) module or a non-deformable flange can be placed at the end of the tube. Post-processing of the sensor’s signal will provide insight into the occurring phenomena inside the tube.<br/>Several experimental campaigns have been conducted with various initial conditions and configurations at the end of the tube. In this contribution the experiments resulting in a detonation are presented. First the recorded pressure and velocities will be compared to theoretical values coming from combustion models [4] [5]. Secondly the impulse before and after reflection for thin plate and non-deformable flange will be compared to quantify the energy transmitted to the plate and the influence of the fluid-structure interaction on the reflected shock.
Hydrogen Behavior and Mitigation Measures: State of Knowledge and Database from Nuclear Community
Sep 2023
Publication
Hydrogen has become a key enabler for decarbonization as countries pledge to reach net zero carbon emissions by 2050. With hydrogen infrastructure expanding rapidly beyond its established applications there is a requirement for robust safety practices solutions and regulations. Since the 1980s considerable efforts have been undertaken by the nuclear community to address hydrogen safety issues because in severe accidents of water-cooled nuclear reactors a large amount of hydrogen can be produced from the oxidation of metallic components with steam. As evidenced in the Fukushima accident hydrogen combustion can cause severe damage to reactor building structures promoting the release of radioactive fission products to the environment. A number of large-scale experiments were conducted in the framework of national and international projects to understand the hydrogen dispersion and combustion behaviour under postulated accidental conditions. Empirical engineering models and numerical codes were developed and validated for safety analysis. Hydrogen recombiners known as Passive Autocatalytic Recombiner (PAR) were developed and have been widely installed in nuclear containments to mitigate hydrogen risk. Complementary actions and strategies were established as part of severe accident management guidelines to prevent or limit the consequences of hydrogen explosions. In addition hydrogen monitoring systems were developed and implemented in nuclear power plants. The experience and knowledge gained from the nuclear community on hydrogen safety is valuable and applicable for other industries involving hydrogen production transport storage and use.
AMHYCO Project - Advances in H2/CO Combustion, Recombination and Containment Modelling
Sep 2023
Publication
During a severe accident in a nuclear power plant one of the potential threats to the containment is the occurrence of energetic combustion events. In modern plants Severe Accident Management Guidelines (SAMG) as well as dedicated mitigation hardware are in place to minimize/mitigate this combustion risk and thus avoid the release of radioactive material into the environment. Advancements in SAMGs are in the focus of AMHYCO an EU-funded Horizon 2020 project officially launched on October 1st 2020. The project consortium consists of 12 organizations (from six European countries and one from Canada) and is coordinated by the Universidad Politécnica de Madrid (UPM). The progress made in the first two years of the AMHYCO project is here presented. A comprehensive bibliographic review has been conducted providing a common foundation to build the knowledge gained during the project. After an extensive set of accident transients simulated both for phases occurring inside and outside the reactor pressure vessel a set of challenging sequences from the combustion risk perspective for different power plant types were identified. At the same time three generic containment models for the three considered reactor designs have been created to provide the full containment analysis simulations with lumped parameter models 3-dimensional containment codes and CFD codes. In order to further consolidate the model base combustion experiments and performance tests on passive auto-catalytic recombiners under explosion prone H2/CO atmospheres were performed at CNRS (France) and FZJ (Germany). Finally it is worth saying that the experimental data and engineering models generated from the AMHYCO project are useful for other industries outside the nuclear one.
European Hydrogen Train the Trainer Framework for Responders: Outcomes of the Hyresponder Project
Sep 2023
Publication
Síle Brennan,
Didier Bouix,
Christian Brauner,
Dominic Davis,
Natalie DeBacker,
Alexander Dyck,
André Vagner Gaathaug,
César García Hernández,
Laurence Grand-Clement,
Etienne Havret,
Deborah Houssin-Agbomson,
Petr Kupka,
Laurent Lecomte,
Eric Maranne,
Vladimir V. Molkov,
Pippa Steele,
Adolfo Pinilla,
Paola Russo and
Gerhard Schoepf
HyResponder is a European Hydrogen Train the Trainer programme for responders. This paper describes the key outputs of the project and the steps taken to develop and implement a long-term sustainable train the trainer programme in hydrogen safety for responders across Europe and beyond. This FCH2 JU (now Clean Hydrogen Joint Undertaking) funded project has built on the successful outcomes of the previous HyResponse project. HyResponder has developed further and updated educational operational and virtual reality training for trainers of responders to reflect the state-of-the-art in hydrogen safety including liquid hydrogen and expand the programme across Europe and specifically within the 10 countries represented directly within the project consortium: Austria Belgium the Czech Republic France Germany Italy Norway Spain Switzerland and the United Kingdom. For the first time four levels of educational materials from fire fighter through to specialist have been developed. The digital training resources are available on the e-Platform (https://hyresponder.eu/e-platform/). The revised European Emergency Response Guide is now available to all stakeholders. The resources are intended to be used to support national training programs. They are available in 8 languages: Czech Dutch English French German Italian Norwegian and Spanish. Through the HyResponder activities trainers from across Europe have undertaken joint actions which are in turn being used to inform the delivery of regional and national training both within and beyond the project. The established pan-European network of trainers is shaping the future in the important for inherently safer deployment of hydrogen systems and infrastructure across Europe and enhancing the reach and impact of the programme.
A Priority-based Failure Mode and Effects Analysis (FMEA) Method for Risk Assessment of Hydrogen Applications Onboard Maritime Vessels
Sep 2023
Publication
The maritime industry is gaining momentum towards a more decarbonized and sustainable path. However most of the worldwide fleet still relies on fossil fuels for power producing harmful environmental emissions. Hydrogen as a clean fuel is a promising alternative but its unique properties pose significant safety challenges. For instance hydrogen has a wide flammability range inherently increasing the risk of ignition. Moreover its comparatively low volumetric energy density necessitates faster filling rates and larger volumes for bunkering and onboard storage leading to higher risk rates. Therefore the use of hydrogen for maritime applications requires the development of specialized riskbased approaches according to safety engineering principles and techniques. The key safety implications are discussed and reviewed with focus on onboard hydrogen storage handling and refueling while a priority-based Failure Mode and Effects Analysis (FMEA) method for risk assessment is proposed based on the revised guidelines of Automotive Industry Action Group (AIAG) and German Association of the Automotive Industry (VDA). The revised AIAG-VDA FMEA method replaces the conventional Risk Priority Number (RPN) with a new Action Priority (AP) rating enabling the prioritization of recommended actions for risk reduction. The paper aims to a more profound understanding of the safety risks associated with hydrogen as a maritime fuel and to provide an effective risk assessment method for hydrogen applications onboard maritime vessels.
The Global Shift to Hydrogen and Lessons from Outside Industry
Sep 2023
Publication
The recognition of hydrogen as a technically viable combustion fuel and as an alternative to more carbon intensive technologies for all forms of industrial applications has resulted in significant global interest leading to both public and private investment. As with most shifts in technology public acceptance and its safe production and handling will be key to its growth as a widespread energy vector. Specific properties of hydrogen that may prompt concern from the public and that need to be considered in terms of its use and safe handling include the following:<br/>• Hydrogen in its natural state is a colourless odourless and tasteless gas that is combustible with very low ignition energy burns nearly invisibly and is explosive at a very wide range of concentrations with an oxidate.<br/>• Hydrogen as any other gas except oxygen is an asphyxiant in a confined space.<br/>• Hydrogen is an extremely small molecule and interacts with many materials which over time can alter the physical properties and can lead to embrittlement and failure. Additionally due to the small molecular size its permeation and diffusion characteristics make it more difficult to contain compared to other gases.<br/>As hydrogen production use and storage increases these properties will come under greater scrutiny and may raise questions surrounding the cost/benefit of the technology. Understanding how the public sees this technology in relation to their safety and daily lives is important in hydrogen’s adoption as a low carbon alternative. A review of deployable experience relevant to the handling of hydrogen in other industries will help us to understand the technology and experience necessary for ensuring the success of the scaling up of a hydrogen economy. The social considerations of the impacts should also be examined to consider acceptance of the technology as it moves into the mainstream.
Numerical Simulation of Liquid Hydrogen Evaporation in the Pressurized Tank During Venting
Sep 2023
Publication
CFD modelling of liquified hydrogen boiling and evaporation during the pressurised tank venting is presented. The model is based on the volume-of-fluid method for tracking liquid and gas phases and Lee’s model for phase change. The simulation results are compared against the liquid hydrogen evaporation experiment performed by Tani et al. (2021) in a large-scale pressurised storage tank using experimental pressure dynamics and temperatures measured in gas and liquid phases. The study focuses on tank pressure decrease and recovery phenomena during the first 15 s of the venting process. The model sensitivity have been studied applying different Lee’s model evaporisation-condensation coefficients. The CFD model provided reasonable agreement with the observed pressure and gas phase temperature dynamics during the liquid hydrogen storage depressurisation using Lee’s model coefficient =0.05 s-1. Experimentalists’ hypothesis about particularly intensive boiling in the proximity of thermocouples was supported by close agreement between simulated and experimental saturation temperatures obtained from pressure dynamics.
Visualisation and Quantification of Wind-induced Variability in Hydrogen Clouds Following Releases of Liquid Hydrogen
Sep 2023
Publication
Well characterized experimental data for consequence model validation is important in progressing the use of liquid hydrogen as an energy carrier. In 2019 the Health and Safety Executive (HSE) undertook a series of liquid hydrogen dispersion and combustion experiments as a part of the Pre-normative Research for Safe Use of Liquid Hydrogen (PRESLHY) project. In partnership between the National Renewable Energy Laboratory (NREL) and HSE time and spatially varying hydrogen concentration measurements were made in 25 dispersion experiments and 23 congested ignition experiments associated with PRESLHY WP3 and WP5 respectively. These measurements were undertaken using the hydrogen wide area monitoring system developed by NREL. During the 23 congested ignition experiments high variability was observed in the measured explosion severity during experiments with similar initial conditions. This led to the conclusion that wind including localized gusts had a large influence on the dispersion of the hydrogen and therefore the quantity of hydrogen that was present in the congested region of the explosions. Using the hydrogen concentration measurements taken immediately prior to ignition the hydrogen clouds were visualized in an attempt to rationalize the variability in overpressure between the tests. Gaussian process regression was applied to quantify the variability of the measured hydrogen concentrations. This analysis could also be used to guide modifications in experimental designs for future research on hydrogen combustion behavior.
Application of Passive Autocatalytic Recombiners for Hydrogen Mitigation: 2D Numerical Modeling and Experimental Validation
Sep 2023
Publication
The widespread production and use of hydrogen (H2) requires safe handling due to its wide range of flammability and low ignition energy. In confined and semi-confined areas such as garages and tunnels a hydrogen leak will create a potential accumulation of flammable gases. Hence forced ventilation is required in such confined spaces to prevent hydrogen hazards. However this practice may incur higher operating costs and could become ineffective during a power outage. Passive Autocatalytic Recombiners (PARs) are defined as safety devices for preventing hydrogen accumulation in confined spaces. PARs have been widely adopted for hydrogen mitigation in nuclear containment buildings in worst case accident scenarios where forced ventilation is not feasible. PARs are equipped with catalyst plates that self-start due to hydrogen reacting with oxygen at relatively low concentrations (<2 vol. % H2 in air). The heat generated from the reaction creates a self-sustained flow continuously supplying the catalyst surface with fresh hydrogen and oxygen. In this study a 2D transient numerical model has been developed in COMSOL Multiphysics to simulate the operation of PARs. The model was used to analyze the effect of surface reactions on the catalyst temperature flow dynamics self-start behaviour forced versus natural convective flow and steady-state hydrogen recombination rates. The model was also used to simulate carbon monoxide poisoning and its influence on the catalyst performance. Experimental data were used for model calibration and validation showing good agreement for different conditions. Overall the model provides novel insights into PARs operation such as radiation and poisoning effects on the catalyst plate. As a next step assessment of the effectiveness of PARs is underway to mitigate hydrogen hazards in selected confined and semi-confined areas including nuclear and non-nuclear applications.
Methodology for Consequence-based Setback Distance Calculations for Bulk Liquid Hydrogen Storage Systems
Sep 2023
Publication
Updates to the separation distances between different exposures and bulk liquid hydrogen systems are included in the 2023 version of NFPA 2: Hydrogen Technologies Code. This work details the models and calculations leading to those distances. The specific models used including the flow of liquid hydrogen through an orifice within the Hydrogen Plus Other Alternative Fuels Risk Assessment Models (HyRAM+) toolkit are described and discussed to emphasize challenges specific to liquid hydrogen systems. Potential hazards and harm affecting individual exposures (e.g. ignition sources air intakes) for different unignited concentrations overpressures and heat flux levels were considered and exposures were grouped into three bins. For each group the distances to a specific hazard criteria (e.g. heat flux level) for a characteristic leak size informed by a risk-analysis led to a hazard distance. The maximum hazard distance within each group was selected to determine a table of separation distances based on internal pressure and pipe size rather than storage volume similar to the bulk gaseous separation distance tables in NFPA 2. The new separation distances are compared to the previous distances and some implications of the updated distances are given.
Effect of Wall Friction on Shock-flame Interactions in a Hydrogen-air Mixture
Sep 2023
Publication
Shock-flame interactions (SFI) occur in a variety of combustion scenarios of scientific and engineering interest which can distort the flame extend the flame surface area and subsequently enhance heat release. This process is dominated by Richtmyer-Meshkov instability (RMI) that features the perturbation growth of a density-difference interface (flame) after the shock passage. The main mechanism of RMI is the vorticity deposition results from a misalignment between pressure and density gradients. This paper focuses on the multi-dimensional interactions between shock wave and flame in a hydrogen-air mixture. The simulations of this work were conducted by solving three-dimensional fully-compressible reactive Navier-Stokes equations using a high-order numerical method on a dynamically adapting mesh. The effect of wall friction on the SFI was examined by varying wall boundary condition (free-slip/no-slip) on sidewall. The results show that the global flame perturbation grows faster with the effect of wall friction in the no-slip case than that in the free-slip case in the process of SFI. Two effects of wall friction on SFI were found: (1) flame stretching close to the no-slip wall and (2) damping of local flame perturbation at the no-slip wall. The flame stretch effect leads to a significantly higher growth rate in the global flame perturbation. By contrast the damping effect locally moderates the flame perturbation induced by RMI in close proximity to the no-slip wall because less vorticity is deposited on this part of flame during SFI.
Flame Visibility in Hydrogen Appliances
Sep 2023
Publication
One of the benefits of the direct use of hydrogen is its ability to be burned in a similar way to natural gas using appliances with which the community is already familiar. This is particularly true for applications where electrification is neither practicable nor desirable. One common example is domestic cooking stoves where the open flame offers numerous real and perceived benefits to the chef. Similarly many commercial and industrial appliances rely on the unique properties of combustion to achieve a desired purpose that cannot readily be replaced by an alternative to an open flame. Despite the enormous decarbonisation potential of the direct replacement of natural gas with hydrogen there are some operational constraints due to the different burning characteristics of hydrogen. One of the challenges is the low visible light emission from hydrogen flames. The change in visible radiation from the combustion of hydrogen compared with natural gas is a safety concern whereby visual observation of a flame may be difficult. This paper aims to provide clarity on the visual appearance of hydrogen flames via a series of measurements of flame visibility and emission spectra accompanied by the assessment of strategies to improve the safe use of hydrogen.
Lessons Learned from Large Scale Hydrogen Production Project
Sep 2023
Publication
In August 2022 Shell started construction of Holland Hydrogen I (HH I) a 200 MW electrolyser plant in the port of Rotterdam’s industrial zone on Maasvlakte II in the Netherlands. HH I will produce up to 60000 kg of renewable hydrogen per day. The development and demonstration of a safe layout and plant design had been challenging due to ambitious HH I project premises many technical novelties common uncertainties in hydrogen leak effect prediction a lack of large-scale water electrolyzer operating history and limited standardization in this industry sector. This paper provides an industry perspective of the major challenges in commercial electrolyzer plant HSSE risk assessment and risk mitigation work processes required to develop and demonstrate a safe design and it describes lessons learned in this area during the HH I project. Furthermore the paper lists major common gaps in relevant knowledge engineering tools standards and OEM deliverables that need closure to enable future commercial electrolyzer plant projects to develop an economically viable and plant design and layout more efficiently and cost-effectively.
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