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Accurate Predictions of the Effect of Hydrogen Composition on the Thermodynamics and Transport Properties of Natural Gas
Mar 2024
Publication
This work demonstrates the need for accurate thermodynamic models to reliably quantify changes in the thermophysical properties of natural gas when blended with hydrogen. For this purpose a systematic evaluation was carried out on the predictive accuracy of three well-known models the Peng−Robinson equation of state (EoS) the multiparameter empirical GERG-2008 model and the molecular-based polar softSAFT EoS in describing the thermodynamic behavior of mixtures of hydrogen with commonly found components in natural gas. Deviations between the calculated properties and experimental data for phase equilibria critical loci second-order derivative properties and viscosities are used to determine the accuracy of the models with polar soft-SAFT performing either equally or better than the other two examined models. The evaluation for the effect of H2 content on the properties of methane simulated as natural gas at conditions for transportation reveals higher changes in blend density and speed of sound with increasing H2 content within 5% change per 5 mol % H2 added while viscosity is the least affected property changing by 0.4% for every 5 mol % H2.
A Multi-Criteria Decision-Making Framework for Zero Emission Vehicle Fleet Renewal Considering Lifecycle and Scenario Uncertainty
Mar 2024
Publication
: In the last decade with the increased concerns about the global environment attempts have been made to promote the replacement of fossil fuels with sustainable sources. For transport which accounts for around a quarter of total greenhouse gas emissions meeting climate neutrality goals will require replacing existing fleets with electric or hydrogen-propelled vehicles. However the lack of adequate decision support approach makes the introduction of new propulsion technologies in the transportation sector a complex strategic decision problem where distorted non-optimal decisions may easily result in long-term negative effects on the performance of logistic operators. This research addresses the problem of transport fleet renewal by proposing a multi-criteria decision-making approach and takes into account the multiple propulsion technologies currently available and the objectives of the EU Green Deal as well as the inherent scenario uncertainty. The proposed approach based on the TOPSIS model involves a novel decision framework referred to as a generalized life cycle evaluation of the environmental and cost objectives which is necessary when comparing green and traditional propulsion systems in a long-term perspective to avoid distorted decisions. Since the objective of the study is to provide a practical methodology to support strategic decisions the framework proposed has been validated against a practical case referred to the strategic fleet renewal decision process. The results obtained demonstrate how the decision maker’s perception of the technological evolution of the propulsion technologies influences the decision process thus leading to different optimal choices.
Hydrogen Safety Challenges: A Comprehensive Review on Production, Storage, Transport, Utilization, and CFD-Based Consequence and Risk Assessment
Mar 2024
Publication
This review examines the central role of hydrogen particularly green hydrogen from renewable sources in the global search for energy solutions that are sustainable and safe by design. Using the hydrogen square safety measures across the hydrogen value chain—production storage transport and utilisation—are discussed thereby highlighting the need for a balanced approach to ensure a sustainable and efficient hydrogen economy. The review also underlines the challenges in safety assessments points to past incidents and argues for a comprehensive risk assessment that uses empirical modelling simulation-based computational fluid dynamics (CFDs) for hydrogen dispersion and quantitative risk assessments. It also highlights the activities carried out by our research group SaRAH (Safety Risk Analysis and Hydrogen) relative to a more rigorous risk assessment of hydrogenrelated systems through the use of a combined approach of CFD simulations and the appropriate risk assessment tools. Our research activities are currently focused on underground hydrogen storage and hydrogen transport as hythane.
Research on the Sealing Mechanism of Split-Liner High-Pressure Hydrogen Storage Cylinders
Mar 2024
Publication
Hydrogen storage is a crucial factor that limits the development of hydrogen energy. This paper proposes using a split liner for the inner structure of a hydrogen storage cylinder. A self-tightening seal is employed to address the sealing problem between the head and the barrel. The feasibility of this structure is demonstrated through hydraulic pressure experiments. The influence laws of the O-ring compression rate the distance from the straight edge section of the head to the sealing groove and the thickness of the head on the sealing performance of gas cylinders in this sealing structure are revealed using finite elements analysis. The results show that when the gas cylinder is subjected to medium internal pressure the maximum contact stress on the O-ring extrusion deformation sealing surface is greater than the medium pressure. There is sufficient contact width that is the arc length of the part where the stress on the O-ring contact surface is greater than the medium pressure so that it can form a good sealing condition. At the same time increasing the compression ratio of the O-ring and the head’s thickness will help improve the sealing performance and reducing the distance from the straight edge section of the head to the sealing groove will also improve the sealing performance.
Low-Carbon Economic Dispatch of Integrated Energy Systems in Industrial Parks Considering Comprehensive Demand Response and Multi-Hydrogen Supply
Mar 2024
Publication
To address the increasing hydrogen demand and carbon emissions of industrial parks this paper proposes an integrated energy system dispatch strategy considering multi-hydrogen supply and comprehensive demand response. This model adopts power-to-gas technology to produce green hydrogen replacing a portion of gray hydrogen and incorporates a carbon capture system to effectively reduce the overall carbon emissions of the industrial park. Meanwhile incentive-based and price-based demand response strategies are implemented to optimize the load curve. A scheduling model is established targeting the minimization of procurement operation carbon emission and wind curtailment costs. The case study of a northern industrial park in China demonstrates that the joint supply of green and gray hydrogen reduces carbon emissions by 40.98% and costs by 17.93% compared to solely using gray hydrogen. The proposed approach successfully coordinates the economic and environmental performance of the integrated energy system. This study provides an effective scheduling strategy for industrial parks to accommodate high shares of renewables while meeting hydrogen needs and carbon reduction targets.
Studies Concerning Electrical Repowering of a Training Airplane Using Hydrogen Fuel Cells
Mar 2024
Publication
The increase in greenhouse gas emissions as well as the risk of fossil fuel depletion has prompted a transition to electric transportation. The European Union aims to substantially reduce pollutant emissions by 2035 through the use of renewable energies. In aviation this transition is particularly challenging mainly due to the weight of onboard equipment. Traditional electric motors with radial magnetic flux have been replaced by axial magnetic flux motors with reduced weight and volume high efficiency power and torque. These motors were initially developed for electric vehicles with in-wheel motors but have been adapted for aviation without modifications. Worldwide there are already companies developing propulsion systems for various aircraft categories using such electric motors. One category of aircraft that could benefit from this electric motor development is traditionally constructed training aircraft with significant remaining flight resource. Electric repowering would allow their continued use for pilot training preparing them for future electrically powered aircraft. This article presents a study on the feasibility of repowering a classic training aircraft with an electric propulsion system. The possibilities of using either a battery or a hybrid source composed of a battery and a fuel cell as an energy source are explored. The goal is to utilize components already in production to eliminate the research phase for specific aircraft components.
Identifying and Analysing Important Model Assumptions: Combining Techno-economic and Political Feasibility of Deep Decarbonisation Pathways in Norway
Mar 2024
Publication
Understanding the political feasibility of transition pathways is a key issue in energy transitions. Policy changes are a significant source of uncertainty in energy system optimisation modelling. Energy system models are nevertheless continuously being updated to reflect policy signals as realistically as possible. Using the concept of transition pathways as a starting point this cross-disciplinary study combines energy system optimization modelling with political feasibility of different transition pathways. This combination generates insights into key political decision points in the ongoing energy transition. Resting on actor support structure and political feasibility of four main pathway categories (electrification hydrogen biomass and energy efficiency) we identify critical model assumptions that are politically significant and impact model outcome. Then by replacing the critical assumptions with technical limitations we model a scenario that is unrestrained by assumptions about policy we identify areas where political choices are key to model outcomes. The combination of actor preferences and modelled energy system consequences enables the identification of future key decision points. We find that there is considerable support for electrification as the main pathway to net-zero. The implications of widespread electrification in terms of energy production and grid capacity lead us to identify challenging policy decisions with implications for the energy transition.
Assessing Fluctuating Wind to Hydrogen Production via Long-term Testing of Solid Oxide Electrolysis Stacks
Mar 2024
Publication
The Danish government plans two energy islands to collect offshore wind power for power distribution and green fuel production. Wind power is often criticized for lacking stability which challenges downstream fuel synthesis processes. Solid oxide electrolysis cells (SOEC) are promising for green hydrogen production on a commercial scale but the impact of fluctuating power on SOEC remains uncertain. This paper explores the feasibility of a Wind-SOEC coupled system by conducting a 2104-h durability test with the state-of-the-art Topsoe TSP-1 stack. Three periods of steady operation and two periods of dynamic operation were conducted. Wind power fluctuation was simulated during the dynamic period and two control strategies were used to handle it. The constant flow (CF) and constant conversion (CC) strategies maintain the feedstock flow rate and conversion ratio of steamto‑hydrogen respectively. Compared to steady operation the stack shows no signs of additional degradation in dynamic operation. Thus the TSP-1 stack has been proven robust and flexible enough to handle fluctuating wind power supplies under both operation strategies. Further stack performance during dynamic periods was compared and analyzed by removing degradation effects. Accordingly SOEC stacks with CC control will consume less external heat than CF to maintain a heat balance. Nevertheless SOEC systems with CF and CC control strategies may have different efficiency or hydrogen production costs. Tech-economic analyses will be needed to investigate control strategies at the system level.
Research on Multi-Objective Energy Management of Renewable Energy Power Plant with Electrolytic Hydrogen Production
Mar 2024
Publication
This study focuses on a renewable energy power plant equipped with electrolytic hydrogen production system aiming to optimize energy management to smooth renewable energy generation fluctuations participate in peak shaving auxiliary services and increase the absorption space for renewable energy. A multi-objective energy management model and corresponding algorithms were developed incorporating considerations of cost pricing and the operational constraints of a renewable energy generating unit and electrolytic hydrogen production system. By introducing uncertain programming the uncertainty issues associated with renewable energy output were successfully addressed and an improved particle swarm optimization algorithm was employed for solving. A simulation system established on the Matlab platform verified the effectiveness of the model and algorithms demonstrating that this approach can effectively meet the demands of the electricity market while enhancing the utilization rate of renewable energies.
Optimal Configuration of Multi-Energy Storage in an Electric–Thermal–Hydrogen Integrated Energy System Considering Extreme Disaster Scenarios
Mar 2024
Publication
Extreme disasters have become increasingly common in recent years and pose significant dangers to the integrated energy system’s secure and dependable energy supply. As a vital part of an integrated energy system the energy storage system can help with emergency rescue and recovery during major disasters. In addition it can improve energy utilization rates and regulate fluctuations in renewable energy under normal conditions. In this study the sizing scheme of multienergy storage equipment in the electric–thermal–hydrogen integrated energy system is optimized; economic optimization in the regular operating scenario and resilience enhancement in extreme disaster scenarios are also considered. A refined model of multi-energy storage is constructed and a two-layer capacity configuration optimization model is proposed. This model is further enhanced by the integration of a Markov two-state fault transmission model which simulates equipment defects and improves system resilience. The optimization process is solved using the tabu chaotic quantum particle swarm optimization (TCQPSO) algorithm to provide reliable and accurate optimization results. The results indicate that addressing severe disaster situations in a capacity configuration fully leverages the reserve energy function of energy storage and enhances system resilience while maintaining economic efficiency; furthermore adjusting the load loss penalty coefficients offers a more targeted approach to the balancing of the system economy and resilience. Thus new algorithmic choices and planning strategies for future research on enhancing the resilience of integrated energy systems under extreme disaster scenarios are provided.
Optimized Design of a H2-Powered Moped for Urban Mobility
Mar 2024
Publication
Micro-mobility plays an increasingly important role in the current energy transition thanks to its low energy consumption and reduced contribution to urban congestion. In this scenario fuel cell hybrid electric vehicles have several advantages over state-of-the-art battery electric vehicles such as increased driving ranges and reduced recharge times. In this paper we study the conversion of a commercial electric moped (Askoll eS3 ®) into a fuel cell hybrid electric vehicle by finding the optimal design of the components through an optimization methodology based on backward dynamic programming. This optimal design and operation strategy can also be implemented with a rulesbased approach. The results show that a system composed of a 1 kW proton exchange membrane fuel cell a 2000 Sl metal hydride hydrogen tank and a 240 Wh buffer battery can cover the same driving range as the batteries in an electric moped (119 km). Such a hybrid system occupies considerably less volume (almost 40 L) and has a negligibly higher mass. The free volume can be used to extend the driving range up to almost three times the nominal value. Moreover by using a high-pressure composite tank it is possible to increase the mass energy density of the onboard energy storage (although compression can require up to 10% of the hydrogen’s chemical energy). The fuel cell hybrid electric vehicle can be recharged with green hydrogen that is locally produced. In detail we analyze a residential scenario and a shared mobility scenario in the small Italian city of Viterbo.
Impact of Depth on Underground Hydrogen Storage Operations in Deep Aquifers
Mar 2024
Publication
Underground hydrogen storage in geological structures is considered appropriate for storing large amounts of hydrogen. Using the geological Konary structure in the deep saline aquifers an analysis of the influence of depth on hydrogen storage was carried out. Hydrogen injection and withdrawal modeling was performed using TOUGH2 software assuming different structure depths. Changes in the relevant parameters for the operation of an underground hydrogen storage facility including the amount of H2 injected in the initial filling period cushion gas working gas and average amount of extracted water are presented. The results showed that increasing the depth to approximately 1500 m positively affects hydrogen storage (flow rate of injected hydrogen total capacity and working gas). Below this depth the trend was reversed. The cushion gas-to-working gas ratio did not significantly change with increasing depth. Its magnitude depends on the length of the initial hydrogen filling period. An increase in the depth of hydrogen storage is associated with a greater amount of extracted water. Increasing the duration of the initial hydrogen filling period will reduce the water production but increase the cushion gas volume.
An Analysis of Emerging Renewable Hydrogen Policy through an Energy Democracy Lens: The Case of Australia
Mar 2024
Publication
As part of reducing carbon emissions governments across the world are working on measures to transition sectors of the economy away from fossil fuels. The socio-technical regimes being constructed around the energy transition can encourage energy centralisation and constrain actor engagement without proper policy and planning. The energy transition is liable to have significant impacts across all of society but less attention has been given to the role of democratic participation and decision-making in the energy system during this time. Using the energy democracy framework developed by Kacper Szulecki we employ content analysis to investigate how Australia’s renewable hydrogen strategies at the Commonwealth and state levels engage with the broader objective of democratising energy systems. Based on our findings we recommend ways to support a renewable hydrogen regime in Australia in line with the principles of energy democracy such as community engagement built-in participation popular sovereignty community-level agency and civic ownership. This study provides a perspective on the energy transition that is often overlooked and a reminder to policymakers that the topology of an energy transition can take many forms.
Optimal Scheduling of Electricity-Hydrogen Coupling Virtual Power Plant Considering Hydrogen Load Response
Mar 2024
Publication
With the rapid development of hydrogen production by water electrolysis the coupling between the electricity-hydrogen system has become closer providing an effective way to consume surplus new energy generation. As a form of centralized management of distributed energy resources virtual power plants can aggregate the integrated energy production and consumption segments in a certain region and participate in electricity market transactions as a single entity to enhance overall revenue. Based on this this paper proposes an optimal scheduling model of an electricity-hydrogen coupling virtual power plant (EHC-VPP) considering hydrogen load response relying on hydrogen to ammonia as a flexibly adjustable load-side resource in the EHC-VPP to enable the VPP to participate in the day-ahead energy market to maximize benefits. In addition this paper also considers the impact of the carbon emission penalty to practice the green development concept of energy saving and emission reduction. To validate the economy of the proposed optimization scheduling method in this paper the optimization scheduling results under three different operation scenarios are compared and analyzed. The results show that considering the hydrogen load response and fully exploiting the flexibility resources of the EHC-VPP can further reduce the system operating cost and improve the overall operating efficiency.
Labour Implications of the Net-zero Transition and Clean Energy Exports in Australia
Mar 2024
Publication
We examine the employment implications of a domestic net-zero transition and establishment of clean energy export systems for an historically significant energy exporting country through a case study of Australia. The labour impacts of a multi-decadal transition are simulated across both the domestic and export energy systems considering a wide range of energy technologies resources and activities with assessment according to occupation lifecycle stage education and skill requirements. Across all net-zero scenario pathways by mid-century the total gross employment created for the domestic and export sectors comprises 210–490 thousand jobs and 350–510 thousand jobs respectively. This represents a significant expansion of energy sector employment from the current total of 120 thousand across domestic and export sectors an increase from less than 1 % of the total Australian workforce in 2020 to 3–4 % by 2060. The need to build out energy system infrastructure at large-scale over a number of decades results in construction jobs continuing over that timeframe and a subsequent need for a large ongoing operations and maintenance workforce for new energy system assets. Those employed in domestic energy markets work primarily in utility solar PV onshore wind batteries and electricity transmission and distribution activities while export market jobs are dominated by clean hydrogen production and shipping supply chains. Crucially these export jobs are unevenly distributed across the country in regions of highest quality solar resource. All states and territories experience net job growth across each decade to 2060. However in a few sub-state regions net job losses occur in the short-term.
Comparative Technical and Economic Analyses of Hydrogen-Based Steel and Power Sectors
Mar 2024
Publication
Decarbonizing the current steel and power sectors through the development of the hydrogen direct-reduction iron ore–electric arc furnace route and the 100% hydrogen-fired gas turbine cycle is crucial. The current study focuses on three clusters of research works. The first cluster covers the investigation of the mass and energy balance of the route and the subsequent application of these values in experiments to optimize the reduction yield of iron ore. In the second cluster the existing gas turbine unit was selected for the complete replacement of natural gas with hydrogen and for finding the most optimal mass and energy balance in the cycle through an Aspen HYSYS model. In addition the chemical kinetics in the hydrogen combustion process were simulated using Ansys Chemkin Pro to research the emissions. In the last cluster a comparative economic analysis was conducted to identify the levelized cost of production of the route and the levelized cost of electricity of the cycle. The findings in the economic analysis provided good insight into the details of the capital and operational expenditures of each industrial sector in understanding the impact of each kg of hydrogen consumed in the plants. These findings provide a good basis for future research on reducing the cost of hydrogen-based steel and power sectors. Moreover the outcomes of this study can also assist ongoing large-scale hydrogen and ammonia projects in Uzbekistan in terms of designing novel hydrogen-based industries with cost-effective solutions.
Navigating Algeria Towards a Sustainable Green Hydrogen Future to Empower North Africa and Europe's Clean Hydrogen Transition
Mar 2024
Publication
Algeria richly-endowed with renewable resources is well-positioned to become a vital green hydrogen provider to Europe. Aiming to aid policymakers stakeholders and energy sector participants this study embodies the first effort in literature to investigate the viability and cost-effectiveness of implementing green hydrogen production projects destined for exports to Europe via existing pipelines. A land suitability analysis utilizing multi-criteria decision making (MCDM) coupled with geographical information system (GIS) identified that over 43.55% of Algeria is highly-suitable for hydrogen production. Five optimal locations were investigated utilizing Hybrid Optimization of Multiple Electric Renewables (HOMER) with solar-hydrogen proving the most cost-effective option. Wind-based production offering higher output volumes reaching 968 kg/h requires turbine cost reductions of 17.50% (Ain Salah) to 54.50% (Djanet) to achieve a competitive levelized cost of hydrogen (LCOH) of $3.85/kg with PV systems. A techno-economic sensitivity analysis was conducted identifying Djanet as the most promising location for a 100 MW solar-hydrogen plant with a competitive LCOH ranging from $1.96/kg to $4.85/kg.
Synergistic Hybrid Marine Renewable Energy Harvest System
Mar 2024
Publication
This paper proposes a novel hybrid marine renewable energy-harvesting system to increase energy production reduce levelized costs of energy and promote renewable marine energy. Firstly various marine renewable energy resources and state-of-art technologies for energy exploitation and storage were reviewed. The site selection criteria for each energy-harvesting approach were identified and a scoring matrix for site selection was proposed to screen suitable locations for the hybrid system. The Triton Knoll wind farm was used to demonstrate the effectiveness of the scoring matrix. An integrated energy system was designed and FE modeling was performed to assess the effects of additional energy devices on the structural stability of the main wind turbine structure. It has been proven that the additional energy structures have a negligible influence on foundation/structure deflection.
Electrochemical Devices to Power a Sustainable Energy Transition—An Overview of Green Hydrogen Contribution
Mar 2024
Publication
This work discusses the current scenario and future growth of electrochemical energy devices such as water electrolyzers and fuel cells. It is based on the pivotal role that hydrogen can play as an energy carrier to replace fossil fuels. Moreover it is envisaged that the scaled-up and broader deployment of the technologies can hold the potential to address the challenges associated with intermittent renewable energy generation. From a sustainability perspective this synergy between hydrogen and electricity from renewable sources is particularly attractive: electrolyzers convert the excess energy from renewables into green hydrogen and fuel cells use this hydrogen to convert it back into electricity when it is needed. Although this transition endorses the ambitious goal to supply greener energy for all it also entails increased demand for the materials that are essential for developing such cleaner energy technologies. Herein several economic and environmental issues are highlighted besides a critical overview regarding each technology. The aim is to raise awareness and provide the reader (a non-specialist in the field) with useful resources regarding the challenges that need to be overcome so that a green hydrogen energy transition and a better life can be fully achieved.
Hydrogen Fuel Cell Aircraft for the Nordic Market
Mar 2024
Publication
A model for a fuel cell propelled 50 PAX hydrogen aircraft is developed. In terms of year 2045 Nordic air travel demand this aircraft is expected to cover 97% of travel distances and 58% of daily passenger volume. Using an ATR 42 as a baseline cryogenic tanks and fuel cell stacks are sized and propulsion system masses updated. Fuselage and wing resizing are required which increases mass and wetted area. Sizing methods for the multi-stack fuel cell and the cryogenic tanks are implemented. The dynamic aircraft model is updated with models for hydrogen consumption and tank pressure control. For the Multi-layer insulation (MLI) tank a trade study is performed. A ventilation pressure of 1.76 bar and 15 MLI layers are found to be optimal for the design mission. A return-without-refuel mission is explored where for a 10-hour ground hold 38.4% of the design range is retained out of the theoretically achievable 50%.
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