Sweden
The Potential Role of Ammonia as Marine Fuel—Based on Energy Systems Modeling and Multi-Criteria Decision Analysis
Apr 2020
Publication
To reduce the climate impact of shipping the introduction of alternative fuels is required. There is a range of different marine fuel options but ammonia a potential zero carbon fuel has recently received a lot of attention. The purpose of this paper is to assess the prospects for ammonia as a future fuel for the shipping sector in relation to other marine fuels. The assessment is based on a synthesis of knowledge in combination with: (i) energy systems modeling including the cost-effectiveness of ammonia as marine fuel in relation to other fuels for reaching global climate targets; and (ii) a multi-criteria decision analysis (MCDA) approach ranking marine fuel options while considering estimated fuel performance and the importance of criteria based on maritime stakeholder preferences. In the long-term and to reach global GHG reduction the energy systems modeled indicate that the use of hydrogen represents a more cost-effective marine fuel option than ammonia. However in the MCDA covering more aspects we find that ammonia may be almost as interesting for shipping related stakeholders as hydrogen and various biomass-based fuels. Ammonia may to some extent be an interesting future marine fuel option but many issues remain to be solved before large-scale introduction.
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.
Investigations on Pressure Dependence of Coriolis Mass Flow Meters Used at Hydrogen Refueling Stations
Sep 2020
Publication
In the framework of the ongoing EMPIR JRP 16ENG01 ‘‘Metrology for Hydrogen Vehicles’’ a main task is to investigate the influence of pressure on the measurement accuracy of Coriolis Mass Flow Meters (CFM) used at Hydrogen Refueling Stations (HRS). At a HRS hydrogen is transferred at very high and changing pressures with simultaneously varying flow rates and temperatures. It is clearly very difficult for CFMs to achieve the current legal requirements with respect to mass flow measurement accuracy at these measurement conditions. As a result of the very dynamic filling process it was observed that the accuracy of mass flow measurement at different pressure ranges is not sufficient. At higher pressures it was found that particularly short refueling times cause significant measurement deviations. On this background it may be concluded that pressure has a great impact on the accuracy of mass flow measurement. To gain a deeper understanding of this matter RISE has built a unique high-pressure test facility. With the aid of this newly developed test rig it is possible to calibrate CFMs over a wide pressure and flow range with water or base oils as test medium. The test rig allows calibration measurements under the conditions prevailing at a 70 MPa HRS regarding mass flows (up to 3.6 kg min−1) and pressures (up to 87.5 MPa).
A Multicriteria Modeling Approach for Evaluating Power Generation Scenarios Under Uncertainty: The Case of Green Hydrogen in Greece
Oct 2023
Publication
Clean energy technological innovations are widely acknowledged as a prerequisite to achieving ambitious longterm energy and climate targets. However the optimal speed of their adoption has been parsimoniously studied in the literature. This study seeks to identify the optimal intensity of moving to a green hydrogen electricity sector in Greece using the OSeMOSYS energy modeling framework. Green hydrogen policies are evaluated first on the basis of their robustness against uncertainty and afterwards against conflicting performance criteria and for different decision-making profiles towards risk by applying the VIKOR and TOPSIS multi-criteria decision aid methods. Although our analysis focuses exclusively on the power sector and compares different rates of hydrogen penetration compared to a business-as-usual case without considering other game-changing innovations (such as other types of storage or carbon capture and storage) we find that a national transition to a green hydrogen economy can support Greece in potentially cutting at least 16 MtCO2 while stimulating investments of EUR 10–13 bn. over 2030–2050.
Design of Gravimetric Primary Standards for Field-testing of Hydrogen Refuelling Stations
Apr 2020
Publication
The Federal Institute of Metrology METAS developed a Hydrogen Field Test Standard (HFTS) that can be used for field verification and calibration of hydrogen refuelling stations. The testing method is based on the gravimetric principle. The experimental design of the HFTS as well as the description of the method are presented here.
The Cost Dynamics of Hydrogen Supply in Future Energy systems - A Techno-economic Study
Nov 2022
Publication
This work aims to investigate the time-resolved cost of electrolytic hydrogen in a future climate-neutral electricity system with high shares of variable renewable electricity generation in which hydrogen is used in the industry and transport sectors as well as for time-shifting electricity generation. The work applies a techno-economic optimization model which incorporates both exogenous (industry and transport) and endogenous (time-shifting of electricity generation) hydrogen demands to elucidate the parameters that affect the cost of hydrogen. The results highlight that several parameters influence the cost of hydrogen. The strongest influential parameter is the cost of electricity. Also important are cost-optimal dimensioning of the electrolyzer and hydrogen storage capacities as these capacities during certain periods limit hydrogen production thereby setting the marginal cost of hydrogen. Another decisive factor is the nature of the hydrogen demand whereby flexibility in the hydrogen demand can reduce the cost of supplying hydrogen given that the demand can be shifted in time. In addition the modeling shows that time-shifting electricity generation via hydrogen production with subsequent reconversion back to electricity plays an important in the climate-neutral electricity system investigated decreasing the average electricity cost by 2%–16%. Furthermore as expected the results show that the cost of hydrogen from an off-grid island-mode-operated industry is more expensive than the cost of hydrogen from all scenarios with a fully interconnected electricity system.
Review and Survey of Methods for Analysis of Impurities in Hydrogen for Fuel Cell Vehicles According to ISO 14687:2019
Feb 2021
Publication
Gaseous hydrogen for fuel cell electric vehicles must meet quality standards such as ISO 14687:2019 which contains maximal control thresholds for several impurities which could damage the fuel cells or the infrastructure. A review of analytical techniques for impurities analysis has already been carried out by Murugan et al. in 2014. Similarly this document intends to review the sampling of hydrogen and the available analytical methods together with a survey of laboratories performing the analysis of hydrogen about the techniques being used. Most impurities are addressed however some of them are challenging especially the halogenated compounds since only some halogenated compounds are covered not all of them. The analysis of impurities following ISO 14687:2019 remains expensive and complex enhancing the need for further research in this area. Novel and promising analyzers have been developed which need to be validated according to ISO 21087:2019 requirements.
Centralized and Decentralized Electrolysis-based Hydrogen Supply Systems for Road Transportation - A Modeling Study of Current and Future Costs
Oct 2022
Publication
This work compares the costs of three electrolysis-based hydrogen supply systems for heavy road transportation: a decentralized off-grid system for hydrogen production from wind and solar power (Dec-Sa); a decentralized system connected to the electricity grid (Dec-Gc); and a centralized grid-connected electrolyzer with hydrogen transported to refueling stations (Cen-Gc). A cost-minimizing optimization model was developed in which the hydrogen production is designed to meet the demand at refueling stations at the lowest total cost for two timeframes: one with current electricity prices and one with estimated future prices. The results show that: For most of the studied geographical regions Dec-Gc gives the lowest costs of hydrogen delivery (2.2e3.3V/kgH2) while Dec-Sa entails higher hydrogen production costs (2.5e6.7V/kgH2). In addition the centralized system (Cen-Gc) involves lower costs for production and storage than the grid-connected decentralized system (Dec-Gc) although the additional costs for hydrogen transport increase the total cost (3.5e4.8V/kgH2).
Fuelling the Transition Podcast: How Will Hydrogen Heat and Safety in the Home?
Jan 2022
Publication
In this episode Angela Needle Director of Strategy at Cadent and John Williams Head of Hydrogen Expertise Cluster at AFRY Management Consulting join us to discuss a range of topics concerning hydrogen and the energy transition. This includes Cadent’s involvement in hydrogen through HyNet the role of hydrogen in heat safety and plans for the first hydrogen village. They also explore Angela’s role as co-founder of the Women’s Utilities Network a group focussed on helping women develop their skills within the energy space.
The podcast can be found on their website.
The podcast can be found on their website.
Balancing Electricity Supply and Demand in a Carbon-Neutral Northern Europe
Apr 2023
Publication
This work investigates how to balance the electricity supply and demand in a carbon-neutral northern Europe. Applying a cost-minimizing electricity system model including options to invest in eleven different flexibility measures and cost-efficient combinations of strategies to manage variations were identified. The results of the model were post-processed using a novel method to map the net load before and after flexibility measures were applied to reveal the contribution of each flexibility measure. The net load was mapped in the space spanned by the amplitude duration and number of occurrences. The mapping shows that depending on cost structure flexibility measures contribute to reduce the net load in three different ways; (1) by reducing variations with a long duration but low amplitude (2) by reducing variations with a high amplitude but short duration and low occurrence or (3) by reducing variations with a high amplitude short duration and high occurrence. It was found that cost-efficient variation management was achieved by combining wind and solar power and by combining strategies (1–3) to manage the variations. The cost-efficient combination of strategies depends on electricity system context where electricity trade flexible hydrogen and heat production (1) manage the majority of the variations in regions with good conditions for wind power while stationary batteries (3) were the main contributors in regions with good conditions for solar power.
An Inter-laboratory Comparison between 13 International Laboratories for Eight Components Relevant for Hydrogen Fuel Quality Assessment
Mar 2024
Publication
The quality of the hydrogen delivered by refuelling stations is critical for end-users and society. The purity of the hydrogen dispensed at hydrogen refuelling points should comply with the technical specifications included in the ISO 14687:2019 and EN 17124:2022 standards. Once laboratories have set up methods they need to verify their performances for example through participation in interlaboratory comparisons. Due to the challenge associated with the production of stable reference materials and transport of these which are produced in hydrogen at high pressure (>10 bar) interlaboratory comparisons have been organized in different steps with increasing extent. This study describes an inter-laboratory comparison exercise for hydrogen fuel involving a large number of participants (13 laboratories) completed in less than a year and included eight key contaminants of hydrogen fuel at level close to the ISO14687 threshold. These compounds were selected based on their high probability of occurrence or because they have been found in hydrogen fuel samples. For the results of the intercomparison it appeared that fully complying with ISO 21087:2019 is still challenging for many participants and highlighted the importance of organising these types of exercises. Many laboratories performed corrective actions based on their results which in turn significantly improved their performances.
A Multi-period Sustainable Hydrogen Supply Chain Model Considering Pipeline Routing and Carbon Emissions: The Case Study of Oman
Nov 2022
Publication
This paper presents a mathematical model for a multi-period hydrogen supply chain design problem considering several design features not addressed in other studies. The model is formulated as a mixed-integer program allowing the production and storage facilities to be extended over time. Pipeline and tube trailer transport modes are considered for carrying hydrogen. The model also allows finding the optimal pipeline routes and the number of transport units. The objective is to obtain an efficient supply chain design within a given time frame in a way that the demand and carbon dioxide emissions constraints are satisfied and the total cost is minimized. A computer program is developed to ease the problem-solving process. The computer program extracts the geographical information from Google Maps and solves the problem using an optimization solver. Finally the applicability of the proposed model is demonstrated in a case study from Oman.
Fuelling the Transition Podcast: Building the UK Hydrogen Backbone
Feb 2022
Publication
In this episode Tony Green Hydrogen Director at National Grid and John Williams Head of Hydrogen Expertise Cluster at AFRYManagement Consulting join us to discuss the challenges in implementing hydrogen. Tony is involved in two exciting hydrogen projects: FutureGrid andProject Union. FutureGrid involves building a facility to create a representative whole-network to trial hydrogen. Project Union will develop a UK hydrogen ‘backbone’ joining together clusters around the country potentially creating a 2000km hydrogen network.
In addition to discussing these projects this episode will explore the following issues:
♦ Managing the transition and challenges in repurposing natural gas pipelines to hydrogen
♦ The potential for blending and de-blending hydrogen
♦ The impact of hydrogen on National Grid’s regulatory approach
♦ How to take the first steps towards a hydrogen wholesale market"
The podcast can be found on their website.
In addition to discussing these projects this episode will explore the following issues:
♦ Managing the transition and challenges in repurposing natural gas pipelines to hydrogen
♦ The potential for blending and de-blending hydrogen
♦ The impact of hydrogen on National Grid’s regulatory approach
♦ How to take the first steps towards a hydrogen wholesale market"
The podcast can be found on their website.
Fuelling the Transition Podcast: Using Hydrogen to Achieve Net-zero
Jan 2021
Publication
In order to achieve the EU’s target of 55% carbon reduction by 2030 hydrogen will have to make a key contribution to the energy mix. With many applications in industrial heat mobility power and chemical refineries hydrogen can be used to decarbonise where electrification is not possible. Equinor is a broad energy company with 21000 employees developing oil gas wind and solar energy in more than 30 countries worldwide. Equinor have been at the forefront of promoting hydrogen projects in Europe and developing low-carbon hydrogen solutions. In this episode Johan Leuraers Chief Consultant - Policy and Regulatory Affairs at Equinor and John Williams Head of Hydrogen Expertise Cluster at AFRY Management Consulting join us to discuss the main barriers to the uptake of hydrogen and the next steps to kick-start the hydrogen economy.
The podcast can be found on their website.
The podcast can be found on their website.
Deep Decarbonisation Pathways of the Energy System in Times of Unprecedented Uncertainty in the Energy Sector
May 2023
Publication
Unprecedented investments in clean energy technology are required for a net-zero carbon energy system before temperatures breach the Paris Agreement goals. By performing a Monte-Carlo Analysis with the detailed ETSAPTIAM Integrated Assessment Model and by generating 4000 scenarios of the world’s energy system climate and economy we find that the uncertainty surrounding technology costs resource potentials climate sensitivity and the level of decoupling between energy demands and economic growth influence the efficiency of climate policies and accentuate investment risks in clean energy technologies. Contrary to other studies relying on exploring the uncertainty space via model intercomparison we find that the CO2 emissions and CO2 prices vary convexly and nonlinearly with the discount rate and climate sensitivity over time. Accounting for this uncertainty is important for designing climate policies and carbon prices to accelerate the transition. In 70% of the scenarios a 1.5 ◦C temperature overshoot was within this decade calling for immediate policy action. Delaying this action by ten years may result in 2 ◦C mitigation costs being similar to those required to reach the 1.5 ◦C target if started today with an immediate peak in emissions a larger uncertainty in the medium-term horizon and a higher effort for net-zero emissions.
Hydrogen Fuel Quality from Two Main Production Processes: Steam Methane Reforming and Proton Exchange Membrane Water Electrolysis
Oct 2019
Publication
Thomas Bacquart,
Karine Arrhenius,
Stefan Persijn,
Andrés Rojo,
Fabien Auprêtre,
Bruno Gozlan,
Abigail Morris,
Andreas Fischer,
Arul Murugan,
Sam Bartlett,
Niamh Moore,
Guillaume Doucet,
François Laridant,
Eric Gernot,
Teresa E. Fernandez,
Concepcion Gomez,
Martine Carré,
Guy De Reals and
Frédérique Haloua
The absence of contaminants in the hydrogen delivered at the hydrogen refuelling station is critical to ensure the length life of FCEV. Hydrogen quality has to be ensured according to the two international standards ISO 14687–2:2012 and ISO/DIS 19880-8. Amount fraction of contaminants from the two hydrogen production processes steam methane reforming and PEM water electrolyser is not clearly documented. Twenty five different hydrogen samples were taken and analysed for all contaminants listed in ISO 14687-2. The first results of hydrogen quality from production processes: PEM water electrolysis with TSA and SMR with PSA are presented. The results on more than 16 different plants or occasions demonstrated that in all cases the 13 compounds listed in ISO 14687 were below the threshold of the international standards. Several contaminated hydrogen samples demonstrated the needs for validated and standardised sampling system and procedure. The results validated the probability of contaminants presence proposed in ISO/DIS 19880-8. It will support the implementation of ISO/ DIS 19880-8 and the development of hydrogen quality control monitoring plan. It is recommended to extend the study to other production method (i.e. alkaline electrolysis) the HRS supply chain (i.e. compressor) to support the technology growth.
Feasibility and Impact of a Swedish Fuel Cell-powered Rescue Boat
Jun 2021
Publication
With the increasing interest for zero-emission vehicles electric boats represent a growing area. Weight is a limiting factor for battery-powered boats therefore the use of fuel cell/battery systems is investigated. The present study examines the power requirements the energy-storage solutions and the sustainability assessment of a light and fast rescue boat operating in the Swedish lake Barken. A weight-optimized hybrid fuel cell/battery system is presented. The results show that if the hydrogen storage is wisely selected the weight of the hybrid system is significantly less than that of a battery system and can compete with an internal combustion engine system. The sustainability assessment highlights and compares the impact in terms of cost and emissions of the different energy storage solutions. The quantification of the emissions for the different energy systems under several scenarios shows a clear advantage for the electric solutions.
How do Variations in Ship Operation Impact the Techno-economic Feasibility and Environmental Performance of Fossil-free Fuels? A Life Cycle Study
Aug 2023
Publication
Identifying an obvious non-fossil fuel solution for all ship types for meeting the greenhouse gas reduction target in shipping is challenging. This paper evaluates the technical viability environmental impacts and economic feasibility of different energy carriers for three case vessels of different ship types: a RoPax ferry a tanker and a service vessel. The energy carriers examined include battery-electric and three electro-fuels (hydrogen methanol and ammonia) which are used in combination with engines and fuel cells. Three methods are used: preliminary ship design feasibility life cycle assessment and life cycle costing. The results showed that battery-electric and compressed hydrogen options are not viable for some ships due to insufficient available onboard space for energy storage needed for the vessel's operational range. The global warming reduction potential is shown to depend on the ship type. This reduction potential of assessed options changes also with changes in the carbon intensity of the electricity mix. Life cycle costing results shows that the use of ammonia and methanol in engines has the lowest life cycle cost for all studied case vessels. However the higher energy conversion losses of these systems make them more vulnerable to fluctuations in the price of electricity. Also these options have higher environmental impacts on categories like human toxicity resource use (minerals and metals) and water use. Fuel cells and batteries are not as cost-competitive for the case vessels because of their higher upfront costs and shorter lifetimes. However these alternatives are less expensive than alternatives with internal combustion engines in the case of higher utilization rates and fuel costs.
Renewable Marine Fuel Production for Decarbonised Maritime Shipping: Pathways, Policy Measures and Transition Dynamics
Jun 2023
Publication
This article investigates the potential of renewable and low-carbon fuel production for the maritime shipping sector using Sweden as a case in focus. Techno-economic modelling and socio-technical transition studies are combined to explore the conditions opportunities and barriers to decarbonising the maritime shipping industry. A set of scenarios have been developed considering demand assumptions and potential instruments such as carbon price energy tax and blending mandate. The study finds that there are opportunities for decarbonising the maritime shipping industry by using renewable marine fuels such as advanced biofuels (e.g. biomethanol) electrofuels (e.g. e-methanol) and hydrogen. Sweden has tremendous resource potential for bio-based and hydrogen-based renewable liquid fuel production. In the evaluated system boundary biomethanol presents the cheapest technology option while e-ammonia is the most expensive one. Green electricity plays an important role in the decarbonisation of the maritime sector. The results of the supply chain optimisation identify the location sites and technology in Sweden as well as the trade flows to bring the fuels to where the bunker facilities are potentially located. Biomethanol and hydrogen-based marine fuels are cost-effective at a carbon price beyond 100 €/tCO2 and 200 €/tCO2 respectively. Linking back to the socio-technical transition pathways the study finds that some shipping companies are in the process of transitioning towards using renewable marine fuels thereby enabling niche innovations to break through the carbon lock-in and eventually alter the socio-technical regime while other shipping companies are more resistant. Overall there is increasing pressure from (inter)national energy and climate policy-making to decarbonise the maritime shipping industry.
Enabling Industrial Decarbonization: A MILP Optimization Model for Low-carbon Hydrogen Supply Chains
Jun 2024
Publication
This study develops a an optimization model focused on the layout and dispatch of a low-carbon hydrogen supply chain. The objective is to identify the lowest Levelized Cost of Hydrogen for a given demand. The model considers various elements including electricity supply from the local grid and renewable sources (photovoltaic and wind) alongside hydrogen production compression storage and transportation to end users. Applied to an industrial case study in Sweden the findings indicate that the major cost components are linked to electricity generation and investment in electrolyzers with the LCOH reaching 5.2 EUR/kgH2 under typical demand conditions. Under scenarios with higher peak demands and greater demand volatility the LCOH increases to 6.8 EUR/kgH2 due to the need for additional renewable energy capacity. These results highlight the critical impact of electricity availability and demand fluctuations on the LCOH emphasizing the complex interdependencies within the hydrogen supply chain. This study provides valuable insights into the feasibility and cost-effectiveness of adopting hydrogen as an energy carrier for renewable electricity in the context of decarbonizing industrial processes in the energy system.
Multi-option Analytical Modeling of Levelised Costs Across Various Hydrogen Supply Chain Nodes
May 2024
Publication
Hydrogen is envisioned to become a fundamental energy vector for the decarbonization of energy systems. Two key factors that will define the success of hydrogen are its sustainability and competitiveness with alternative solutions. One of the many challenges for the proliferation of hydrogen is the creation of a sustainable supply chain. In this study a methodology aimed at assessing the economic feasibility of holistic hydrogen supply chains is developed. Based on the designed methodology a tool which calculates the levelized cost of hydrogen for the different stages of its supply chain: production transmission & distribution storage and conversion is proposed. Each stage is evaluated individually combining relevant technical and economic notions such as learning curves and scaling factors. Subsequently the findings from each stage are combined to assess the entire supply chain as a whole. The tool is then applied to evaluate case studies of various supply chains including large-scale remote and small-scale distributed green hydrogen supply chains as well as conventional steam methane reforming coupled with carbon capture and storage technologies. The results show that both green hydrogen supply chains and conventional methods can achieve a competitive LCOH of around €4/kg in 2030. However the key contribution of this study is the development of the tool which provides a foundation for a comprehensive evaluation of hydrogen supply chains that can be continuously improved through the inputs of additional users and further research on one or more of the interconnected stages.
Techno-economic Analysis for Advanced Methods of Green Hydrogen Production
May 2024
Publication
In the ongoing effort to reduce carbon emissions on a worldwide scale green hydrogen which is generated through environmentally responsible processes has emerged as a significant driving force. As the demand for clean energy continues to rise it is becoming increasingly important to have a solid understanding of the technological and economic elements of modern techniques of producing green hydrogen. In the context of green hydrogen generation understanding green hydrogen production's techno-economic features is necessary to reduce carbon emissions and transition to a low-carbon economy. associated with breakthroughs in technology the present study examines the most fascinating and relevant aspects of techno-economic analysis. Despite challenges green hydrogen can help the world move to a cleaner more sustainable energy future with solid analytical frameworks and legislation.
On the Green Transformation of the Iron and Steel Industry: Market and Competition Aspects of Hydrogen Biomass Options
Feb 2024
Publication
The iron and steel industry is a major emitter of carbon dioxide globally. To reduce their carbon footprint the iron and steel industry pursue different decarbonization strategies including deploying bio-based materials and energy carriers for reduction carburisation and/or energy purposes along their value-chains. In this study two potential roles for biomass were analysed: (a) substituting for fossil fuels in iron-ore pellets induration and (b) carburisation of DRI (direct reduced iron) produced via fully hydrogen-based reduction. The purpose of the study was to analyse the regional demand-driven price and allocative effects of biomass assortments under different biomass demand scenarios for the Swedish iron and steel industry. Economic modelling was used in combination with spatial biomass supply assessments to predict the changes on relevant biomass markets. The results showed that the estimated demand increases for forest biomass will have significant regional price effects. Depending on scenario the biomass demand will increase up to 25 percent causing regional prices to more than doubling. In general the magnitude of the price effects was driven by the volumes and types of biomasses needed in the different scenarios with larger price effects for harvesting residues and industrial by-products compared to those of roundwood. A small price effect of roundwood means that the incentives for forest-owners to increase their harvests and thus also the availability of harvest residues are small. Flexibility in the feedstock sourcing (both regarding quality and geographic origin) will thus be important if forest biomass is to satisfy demands in iron and steel industry.
Low Platinum Fuel Cell as Enabler for the Hydrogen Fuel Cell Vehicle
Feb 2024
Publication
In this work the design and modeling of a fuel cell vehicle using low-loading platinum catalysts were investigated. Data from single fuel cells with low Pt-loading cathode catalysts were scaled up to fuel cell stacks and systems implemented in a vehicle and then compared to a commercial fuel cell vehicle. The low-loading Pt systems have shown lower efficiency at high loads compared to the commercial systems suggesting less stable materials. However the analysis showed that the vehicle comprising low-loading Pt catalysts achieves similar or higher efficiency compared to the commercial fuel cell vehicle when being scaled up for the same number of cells. When the systems were scaled up for the same maximum power as the commercial fuel cell vehicle all the low-loading Pt fuel cell systems showed higher efficiencies. In this case more cells are needed but still the amount of Pt is significantly reduced compared to the commercial one. The high-efficiency results can be associated with the vehicle’s power range operation that meets the region where the low-loading Pt fuel cells have high performance. The results suggested a positive direction towards the reduction of Pt in commercial fuel cell vehicles supporting a cost-competitive clean energy transition based on hydrogen.
Hydrogen-Powered Vehicles: Comparing the Powertrain Efficiency and Sustainability of Fuel Cell versus Internal Combustion Engine Cars
Feb 2024
Publication
Due to the large quantities of carbon emissions generated by the transportation sector cleaner automotive technologies are needed aiming at a green energy transition. In this scenario hydrogen is pointed out as a promising fuel that can be employed as the fuel of either a fuel cell or an internal combustion engine vehicle. Therefore in this work we propose the design and modeling of a fuel cell versus an internal combustion engine passenger car for a driving cycle. The simulation was carried out using the quasistatic simulation toolbox tool in Simulink considering the main powertrain components for each vehicle. Furthermore a brief analysis of the carbon emissions associated with the hydrogen production method is addressed to assess the clean potential of hydrogen-powered vehicles compared to conventional fossil fuel-fueled cars. The resulting analysis has shown that the hydrogen fuel cell vehicle is almost twice as efficient compared to internal combustion engines resulting in a lower fuel consumption of 1.05 kg-H2/100 km in the WLTP driving cycle for the fuel cell vehicle while the combustion vehicle consumed about 1.79 kg-H2/100 km. Regarding using different hydrogen colors to fuel the vehicle hydrogen-powered vehicles fueled with blue and grey hydrogen presented higher carbon emissions compared to petrol-powered vehicles reaching up to 2–3 times higher in the case of grey hydrogen. Thus green hydrogen is needed as fuel to keep carbon emissions lower than conventional petrol-powered vehicles.
Towards a Sustainable Future: Bio-hydrogen Production from Food Waste for Clean Energy Generation
Jan 2024
Publication
To address climate change energy security and waste management new sustainable energy sources must be developed. This study uses Aspen Plus software to extract bio-H2 from food waste with the goal of efficiency and environmental sustainability. Anaerobic digestion optimised to operate at 20-25°C and keep ammonia at 3% greatly boosted biogas production. The solvent [Emim][FAP] which is based on imidazolium had excellent performance in purifying biogas. It achieved a high level of methane purity while consuming a minimal amount of energy with a solvent flow rate of 13.415 m³/h. Moreover the utilization of higher temperatures (600-700°C) during the bio-H2 generation phase significantly enhanced both the amount and quality of hydrogen produced. Parametric and sensitivity assessments were methodically performed at every stage. This integrated method was practicable and environmentally friendly according to the economic assessment. H2 generation using steam reforming results in a TCC of 1.92×106 USD. The CO2 separation step has higher costs (TCC of 2.15×107 USD) due to ionic liquid washing and CO2 liquefaction. Compressor electricity consumption significantly impacts total operating cost (TOC) totaling 4.73×108 USD. showing its ability to reduce greenhouse gas emissions optimize resource utilization and promote energy sustainability. This study presents a sustainable energy solution that addresses climate and waste challenges.
Tapping the Conversation on the Meaning of Decarbonization: Discourses and Discursive Agency in EU Politics on Low-Carbon Fuels for Maritime Shipping
Jun 2024
Publication
EU politics on decarbonizing shipping is an argumentative endeavor where different policy actors strive try to influence others to see problems and policy solutions according to their perspectives to gain monopoly on the framing and design of policies. This article critically analyzes by means of argumentative discourse analysis the politics and policy process related to the recent adoption of the FuelEU Maritime regulation the world’s first legislation to set requirements for decarbonizing maritime shipping. Complementing previous research focusing on the roles and agency of policy entrepreneurs and beliefs of advocacy coalitions active in the policy process this paper dives deeper into the politics of the new legislation. It aims to explore and explain the discursive framing and politics of meaning-making. By analyzing the political and social meaning-making of the concept “decarbonizing maritime shipping” this paper helps us understand why the legislation was designed in the way it was. Different narratives storylines and discourses defining different meanings of decarbonization are analyzed. So is the agency of policy actors trying to mutate the different meanings into a new meaning. Two discourses developed in dialectic conversation framed the policy proposals and subsequent debates in the policy process focusing on (i) incremental change and technology neutrality to meet moderate emission reductions and maintain competitiveness and (ii) transformative change and technology specificity to meet zero emissions and gain competitiveness and global leadership in the transition towards a hydrogen economy. Policy actors successfully used discursive agency strategies such as multiple functionality and vagueness to navigate between and resolve conflicts between the two discourses. Both discourses are associated with the overarching ecological modernization discourse and failed to include issue of climate justice and a just transition. The heritage of the ecological modernization discourse creates lock-ins for a broader decarbonization discourse thus stalling a just transition.
Overview of International Activities in Hydrogen System Safety in IEA Hydrogen TCP Task 43
Sep 2023
Publication
Safety and reliability have long been recognized as key issues for the development commercialization and implementation of new technologies and infrastructure and hydrogen systems are no exception to this rule. Reliability engineering quantitative risk assessment (QRA) and knowledge exchange each play a key role in proactive addressing safety – before problems happen – and help us learn from problems if they happen. Many international research activities are focusing on both reliability and risk assessment for hydrogen systems. However the element of knowledge exchange is sometimes less visible. To support international collaboration and knowledge exchange the International Energy Agency (IEA) convened a new Technology Collaboration Program “Task 43: Safety and Regulatory Aspects of Emerging Large Scale Hydrogen Energy Applications” started in June 2022. Within Task 43 Subtask E focuses on Hydrogen Systems Safety. This paper discusses the structure of the Hydrogen Systems Safety subtask and the aligned activities and introduces opportunities for future work.
IEA TCP Task 43 - Subtask Safety Distances: State of the Art
Sep 2023
Publication
The large deployment of hydrogen technologies for new applications such as heat power mobility and other emerging industrial utilizations is essential to meet targets for CO2 reduction. This will lead to an increase in the number of hydrogen installations nearby local populations that will handle hydrogen technologies. Local regulations differ and provide different safety and/or separation distances in different geographies. The purpose of this work is to give an insight on different methodologies and recommendations developed for hydrogen (mainly) risk management and consequences assessment of accidental scenarios. The first objective is to review available methodologies and to identify the divergent points on the methodology. For this purpose a survey has been launched to obtain the needed inputs from the subtask participants. The current work presents the outcomes of this survey highlighting the gaps and suggesting the prioritization of the actions to take to bridge these gaps.
The Heat Transfer Potential of Compressor Vanes on a Hydrogen Fueled Turbofan Engine
Sep 2023
Publication
Hydrogen is a promising fuel for future aviation due to its CO2-free combustion. In addition its excellent cooling properties as it is heated from cryogenic conditions to the appropriate combustion temperatures provides a multitude of opportunities. This paper investigates the heat transfer potential of stator surfaces in a modern high-speed low-pressure compressor by incorporating cooling channels within the stator vane surfaces where hydrogen is allowed to flow and cool the engine core air. Computational Fluid Dynamics simulations were carried out to assess the aerothermal performance of this cooled compressor and were compared to heat transfer correlations. A core air temperature drop of 9.5 K was observed for this cooling channel design while being relatively insensitive to the thermal conductivity of the vane and cooling channel wall thickness. The thermal resistance was dominated by the air-side convective heat transfer and more surface area on the air-side would therefore be required in order to increase overall heat flow. While good agreement with established heat transfer correlations was found for both turbulent and transitional flow the correlation for the transitional case yielded decent accuracy only as long as the flow remains attached and while transition was dominated by the bypass mode. A system level analysis indicated a limited but favorable impact at engine performance level amounting to a specific fuel consumption improvement of up to 0.8% in cruise and an estimated reduction of 3.6% in cruise NOx. The results clearly show that although it is possible to achieve high heat transfer rate per unit area in compressor vanes the impact on cycle performance is constrained by the limited available wetted area in the low-pressure compressor.
Hydrogen Sampling Systems Adapted to Heavy-duty Refuelling Stations' Current and Future Specifications - A Review
Sep 2024
Publication
To meet the new regulation for the deployment of alternative fuels infrastructure which sets targets for electric recharging and hydrogen refuelling infrastructure by 2025 or 2030 a large infrastructure comprising trucksuitable hydrogen refuelling stations will soon be required. However further standardisation is required to support the uptake of hydrogen for heavy-duty transport for Europe’s green energy future. Hydrogen-powered vehicles require pure hydrogen as some contaminants can reduce the performance of the fuel cell even at very low levels. Even if previous projects have paved the way for the development of the European quality infrastructure for hydrogen conformity assessment sampling systems and methods have yet to be developed for heavy-duty hydrogen refuelling stations (HD-HRS). This study reviews different aspects of the sampling of hydrogen at heavy-duty hydrogen refuelling stations for purity assessment with a focus on the current and future specifications and operations at HD-HRS. This study describes the state-of-the art of sampling systems currently under development for use at HD-HRS and highlights a number of aspects which must be taken into consideration to ensure safe and accurate sampling: risk assessment for the whole sampling exercise selection of cylinders methods to prepare cylinders before the sampling filling pressure and venting of the sampling systems.
Gas Storage in Geological Formations: A Comparative Review on Carbon Dioxide and Hydrogen Storage
Feb 2024
Publication
Carbon dioxide and hydrogen storage in geological formations at Gt scale are two promising strategies toward net-zero carbon emissions. To date investigations into underground hydrogen storage (UHS) remain relatively limited in comparison to the more established knowledge body of underground carbon dioxide storage (UCS). Despite their analogous physical processes can be used for accelerating the advancements in UHS technology the existing distinctions possibly may hinder direct applicability. This review therefore contributes to advancing our fundamental understanding on the key differences between UCS and UHS through multi-scale comparisons. These comparisons encompass key factors influencing underground gas storage including storage media trapping mechanisms and respective fluid properties geochemical and biochemical reactions and injection scenarios. They provide guidance for the conversion of our existing knowledge from UCS to UHS emphasizing the necessity of incorporating these factors relevant to their trapping and loss mechanisms. The article also outlines future directions to address the crucial knowledge gaps identified aiming to enhance the utilisation of geological formations for hydrogen and carbon dioxide storage.
An Artificial Neural Network-Based Fault Diagnostics Approach for Hydrogen-Fueled Micro Gas Turbines
Feb 2024
Publication
The utilization of hydrogen fuel in gas turbines brings significant changes to the thermophysical properties of flue gas including higher specific heat capacities and an enhanced steam content. Therefore hydrogen-fueled gas turbines are susceptible to health degradation in the form of steam-induced corrosion and erosion in the hot gas path. In this context the fault diagnosis of hydrogen-fueled gas turbines becomes indispensable. To the authors’ knowledge there is a scarcity of fault diagnosis studies for retrofitted gas turbines considering hydrogen as a potential fuel. The present study however develops an artificial neural network (ANN)-based fault diagnosis model using the MATLAB environment. Prior to the fault detection isolation and identification modules physics-based performance data of a 100 kW micro gas turbine (MGT) were synthesized using the GasTurb tool. An ANN-based classification algorithm showed a 96.2% classification accuracy for the fault detection and isolation. Moreover the feedforward neural network-based regression algorithm showed quite good training testing and validation accuracies in terms of the root mean square error (RMSE). The study revealed that the presence of hydrogen-induced corrosion faults (both as a single corrosion fault or as simultaneous fouling and corrosion) led to false alarms thereby prompting other incorrect faults during the fault detection and isolation modules. Additionally the performance of the fault identification module for the hydrogen fuel scenario was found to be marginally lower than that of the natural gas case due to assumption of small magnitudes of faults arising from hydrogen-induced corrosion.
Energy Efficiency of Hydrogen for Vehicle Propulsion: On- or Off-board H2 to Electricity Conversion?
Nov 2024
Publication
If hydrogen fuel is available to support the transportation sector decarbonization its usage can be placed either directly onboard in a fuel cell vehicle or indirectly off-board by using a fuel cell power station to produce electricity to charge a battery electric vehicle. Therefore in this work the direct and indirect conversion scenarios of hydrogen to vehicle propulsion were investigated regarding energy efficiency. Thus in the first scenario hydrogen is the fuel for the onboard electricity production to propel a fuel cell vehicle while in the second hydrogen is the electricity source to charge the battery electric vehicle. When simulated for a drive cycle results have shown that the scenario with the onboard fuel cell consumed about 20% less hydrogen demonstrating higher energy efficiency in terms of driving range. However energy efficiency depends on the outside temperature when heat loss utilization is considered. For outside temperatures of − 5 ◦C or higher the system composed of the battery electric vehicle fueled with electricity from the off-board fuel cell was shown to be more energyefficient. For lower temperatures the system composed of the onboard fuel cell again presented higher total (heat + electricity) efficiency. Therefore the results provide valuable insights into how hydrogen fuel can be used for vehicle propulsion supporting the hydrogen economy development.
Whole System Impacts of Decarbonising Transport with Hydrogen: A Swedish Case Study
Oct 2024
Publication
This study aims to carry out a techno-economic analysis of different hydrogen supply chain designs coupled with the Swedish electricity system to study the inter-dependencies between them. Both the hydrogen supply chain designs and the electricity system were parameterized with data for 2030. The supply chain designs comprehend centralised production decentralised production a combination of both and with/without seasonal variation in hydrogen demand. The supply chain design is modelled to minimize the overall cost while meeting the hydrogen demands. The outputs of the supply chain model include the hydrogen refuelling stations’ locations the electrolyser’s locations and their respective sizes as well as the operational schedule. The electricity system model shows that the average electricity prices in Sweden for zones SE1 SE2 SE3 and SE4 will be 4.28 1.88 8.21 and 8.19 €/MWh respectively. The electricity is mainly generated from wind and hydropower (around 42% each) followed by nuclear (14%) solar (2%) and then bio-energy (0.3%). In addition the hydrogen supply chain design that leads to a lower overall cost is the decentralised design with a cost of 1.48 and 1.68 €/kgH2 in scenarios without and with seasonal variation respectively. The seasonal variation in hydrogen demand increases the cost of hydrogen regardless of the supply chain design.
Development of Various Photovoltaic-Driven Water Electrolysis Technologies for Green Solar Hydrogen Generation
Sep 2021
Publication
Sonya Calnan,
Rory Bagacki,
Fuxi Bao,
Iris Dorbandt,
Erno Kemppainen,
Christian Schary,
Rutger Schlatmann,
Marco Leonardi,
Salvatore A. Lombardo,
R. Gabriella Milazzo,
Stefania M. S. Privitera,
Fabrizio Bizzarri,
Carmelo Connelli,
Daniele Consoli,
Cosimo Gerardi,
Pierenrico Zani,
Marcelo Carmo,
Stefan Haas,
Minoh Lee,
Martin Mueller,
Walter Zwaygardt,
Johan Oscarsson,
Lars Stolt,
Marika Edoff,
Tomas Edvinsson and
Ilknur Bayrak Pehlivan
Direct solar hydrogen generation via a combination of photovoltaics (PV) andwater electrolysis can potentially ensure a sustainable energy supply whileminimizing greenhouse emissions. The PECSYS project aims at demonstrating asolar-driven electrochemical hydrogen generation system with an area >10 m 2with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers(ECs) using thin-film silicon undoped and silver-doped Cu(InGa)Se 2 and siliconheterojunction PV combined with alkaline electrolysis to form one unit aredeveloped on a prototype level with solar collection areas in the range from 64 to2600 cm 2 with the solar-to-hydrogen (StH) efficiency ranging from 4 to 13%.Electrical direct coupling of PV modules to a proton exchange membrane EC totest the effects of bifaciality (730 cm 2 solar collection area) and to study the long-term operation under outdoor conditions (10 m 2 collection area) is also inves-tigated. In both cases StH efficiencies exceeding 10% can be maintained over thetest periods used. All the StH efficiencies reported are based on measured gasoutflow using mass flow meters.
Anion Exchange Membrane Water Electrolysis using Aemion™ Membranes and Nickel Electrodes
Jul 2022
Publication
Anion exchange membrane water electrolysis (AEMWE) is a potentially low-cost and sustainable technology for hydrogen production that combines the advantages of proton exchange membrane water electrolysis and traditional alkaline water electrolysis systems. Despite considerable research efforts in recent years the medium-term (100 h) stability of Aemion™ membranes needs further investigation. This work explores the chemical and electrochemical durability (>100 h) of Aemion™ anion exchange membranes in a flow cell using nickel felt as the electrode material on the anode and cathode sides. Remixing the electrolytes between the AEMWE galvanostatic tests was very important to enhance electrolyte refreshment and the voltage stability of the system. The membranes were analyzed by NMR spectroscopy after the AEMWE tests and the results showed no sign of severe chemical degradation. In a separate experiment the chemical stability and mechanical integrity of the membranes were studied by soaking them in a strongly alkaline electrolyte for a month (>700 h) at 90 C followed by NMR analysis. A certain extent of ionic loss was observed due to chemical degradation and the membranes disintegrated into small pieces.
Hydrogen Embrittlement as a Conspicuous Material Challenge - Comprehensive Review and Future Directions
May 2024
Publication
Hydrogen is considered a clean and efficient energy carrier crucial for shapingthe net-zero future. Large-scale production transportation storage and use of greenhydrogen are expected to be undertaken in the coming decades. As the smallest element inthe universe however hydrogen can adsorb on diffuse into and interact with many metallicmaterials degrading their mechanical properties. This multifaceted phenomenon isgenerically categorized as hydrogen embrittlement (HE). HE is one of the most complexmaterial problems that arises as an outcome of the intricate interplay across specific spatialand temporal scales between the mechanical driving force and the material resistancefingerprinted by the microstructures and subsequently weakened by the presence of hydrogen. Based on recent developments in thefield as well as our collective understanding this Review is devoted to treating HE as a whole and providing a constructive andsystematic discussion on hydrogen entry diffusion trapping hydrogen−microstructure interaction mechanisms and consequencesof HE in steels nickel alloys and aluminum alloys used for energy transport and storage. HE in emerging material systems such ashigh entropy alloys and additively manufactured materials is also discussed. Priority has been particularly given to these lessunderstood aspects. Combining perspectives of materials chemistry materials science mechanics and artificial intelligence thisReview aspires to present a comprehensive and impartial viewpoint on the existing knowledge and conclude with our forecasts ofvarious paths forward meant to fuel the exploration of future research regarding hydrogen-induced material challenges.
Zero-emission Propulsion System Featuring, Flettner Rotors, Batteries and Fuel Cells, for a Merchant Ship
Jul 2024
Publication
To meet the International Maritime Organization’s (IMO) goal of decarbonising the shipping sector by 2050 zero-emission ship propulsion systems should be developed to replace conventional fossil fuel-based ones. In this study we propose a zero-emission hybrid hydrogen-wind-powered propulsion system to be retrofitted to a benchmark merchant ship with a conventional propulsion system. The ship and its propulsion systems are modelled using an in-house platform. We analyse power and energy requirements for the ship over a realistic route and one-year schedule factoring in actual sea and weather conditions. Initially we examine the battery-powered propulsion system which proves impractical even with a reduction in the ship’s speed and the addition of a charging station. This retrofitted battery-powered propulsion system will occupy a significant portion of the existing ship’s deadweight due to its substantial weight consequently reducing the ship’s cargo capacity. To address this we evaluate integrating a hydrogen-powered fuel cell system with power equal to the non-propulsive constant load in the ship. We demonstrate that under these conditions and with four Flettner rotors and the charging station positioned mid-port on the ship’s route the size of the zero-emission propulsion system can be approximately 20% of the deadweight rendering such a system feasible.
Hydrogen as Fuel in the Maritime Sector: From Production to Propulsion
Nov 2024
Publication
The maritime sector plays a crucial role in global trade yet its contribution to greenhouse gas emissions remains significant. The adoption of hydrogen as a clean energy solution is gaining traction to address this. This review paper delves into the opportunities and challenges of integrating hydrogen as a marine fuel. The entire hydrogen supply chain is investigated from production to end use highlighting advancements limitations and potential safety risks. Key findings reveal that while hydrogen offers promise for reducing emissions its widespread adoption requires a well-established production storage and distribution infrastructure. Challenges persist in large-scale storage transportation and bunkering particularly in addressing space limitations and ensuring safety protocols. Propulsion systems such as internal combustion engines gas turbines and fuel cells show po tential for hydrogen adoption yet further research is needed to optimize efficiency and address technical con straints. Safety considerations also appear prominently necessitating comprehensive bunkering operations and hazard management protocols. Addressing knowledge gaps is imperative for successfully integrating hydrogen as a marine fuel. Future research should focus on optimizing storage methods developing efficient propulsion systems and enhancing safety measures to enhance hydrogen utilization in the maritime sector.
Compact Heat Exchangers for Hydrogen-fueled Aero Engine Intercooling and Recuperation
Jan 2024
Publication
This study investigates the application of compact heat exchangers for the purpose of intercooling and recuperation systems for short-to-medium range aircraft equipped with hydrogen-fueled turbofan engines. The primary objective is to assess the potential effects of engine-integrated compact heat exchangers on fuel consumption and emissions. The paper encompasses the conceptual design of integrated heat exchangers and associated ducts followed by aerodynamic optimization studies to identify suitable designs that minimize air-side pressure losses and ensure flow uniformity at the inlet of the high-pressure compressor. Pressure drop correlations are then established for selected duct designs and incorporated into a system-level performance model allowing for a comparison of their impact on specific fuel consumption NOx emissions and fuel burn against an uncooled baseline engine. The intercooled-recuperated engine resulted in the most significant improvement in take-off specific fuel consumption with a reduction of up to 7.7% compared to the baseline uncooled engine whereas the best intercooled engine resulted in an improvement of about 4%. Furthermore the best configuration demonstrated a decrease in NOx emissions by up to 37% at take-off and a reduction in mission fuel burn by 5.5%. These enhancements were attributed to reduced compression work pre-heating of the hydrogen fuel and lower high-pressure compressor outlet temperatures.
Hydrogen from Waste Gasification
Feb 2024
Publication
Hydrogen is a versatile energy vector for a plethora of applications; nevertheless its production from waste/residues is often overlooked. Gasification and subsequent conversion of the raw synthesis gas to hydrogen are an attractive alternative to produce renewable hydrogen. In this paper recent developments in R&D on waste gasification (municipal solid waste tires plastic waste) are summarised and an overview about suitable gasification processes is given. A literature survey indicated that a broad span of hydrogen relates to productivity depending on the feedstock ranging from 15 to 300 g H2/kg of feedstock. Suitable gas treatment (upgrading and separation) is also covered presenting both direct and indirect (chemical looping) concepts. Hydrogen production via gasification offers a high productivity potential. However regulations like frame conditions or subsidies are necessary to bring the technology into the market.
Modelling of a "Hydrogen Valley" to Investigate the Impact of a Regional Pipeline for Hydrogen Supply
Jul 2024
Publication
Introduction: The transition towards electrolysis-produced hydrogen in refineries and chemical industries is expected to have a potent impact on the local energy system of which these industries are part. In this study three urban areas with hydrogen-intense industries are studied regarding how the energy system configuration is affected if the expected future hydrogen demand is met in each node individually as compared to forming a “Hydrogen Valley” in which a pipeline can be used to trade hydrogen between the nodes.<br/>Method: A technoeconomic mixed-integer linear optimization model is used to study the investments in and dispatch of the included technologies with an hourly time resolution while minimizing the total system cost. Four cases are investigated based on the availability of offshore wind power and the possibility to invest in a pipeline.<br/>Results: The results show that investments in a pipeline reduces by 4%–7% the total system cost of meeting the demands for electricity heating and hydrogen in the cases investigated. Furthermore investments in a pipeline result in greater utilization of local variable renewable electricity resources as compared to the cases without the possibility to invest in a pipeline.<br/>Discussion: The different characteristics of the local energy systems of the three nodes in local availability of variable renewable electricity grid capacity and available storage options compared to local demands of electricity heating and hydrogen are found to be the driving forces for forming a Hydrogen Valley.
A Multi-Zone Model for Hydrogen Accumulation and Ventilation in Enclosures
Sep 2023
Publication
Due to the small characteristic molecular size of hydrogen small leaks are more common in hydrogen systems compared to similar systems with hydrocarbons. This together with the high reactivity makes an efficient ventilation system very important in hydrogen applications. There are several models available for ventilation sizing that are based on either a well-mixed assumption or a fully stratified situation. However experiments show that many realistic releases will be neither and therefore additional models are needed. One possibility is to use CFD-models but the small release sizes for pinhole releases (<<1 mm) make it difficult to find an appropriate mesh without excessive computational time (especially since the simulations need to be iterated to find the optimum ventilation size). An alternative approach which is described and benchmarked in the current paper is to use a multi-zone model where the domain is divided into several large cells where the mass exchange is simplified compared to CFD and thus simulation time is reduced. The flow in the model is governed by mass conservation and density differences due to concentration gradients using the Bernoulli equation. The release of gas generates a plume which is modelled based on an empirical plume model which gives the entrainment and hydrogen source term for each cell. The model has a short run time and will therefore allow optimization in a short time frame. The model is benchmarked against five experiments with helium at the Canadian Nuclear Laboratories (CNL) in Canada and one hydrogen experiment performed at Lodz University of Technology in Poland. The result shows that the model can reasonably well reproduce accumulation in the experiments with small release without ventilation but appears to slightly underestimate the level of stratification and the interface height for ventilated cases where the source is elevated from the floor level.
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