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Exploring Decarbonization Priorities for Sustainable Shipping: A Natural Language Processing-based Experiment
Oct 2024
Publication
The shipping industry is currently the sixth largest contributor to global emissions responsible for one billion tons of greenhouse gas emissions. Urgent action is needed to achieve carbon neutrality in the shipping industry for sustainability. In this paper we use natural language processing techniques to analyze policies announcements and position papers from national and international organizations related to the decarbonization of shipping. In particular we perform the analysis using a novel matrix-based corpus and a fine-tuned machine learning model BERTopic. Our research suggests that the top four priorities for decarbonizing shipping are preventing emissions from methane leaks promoting non-carbon-based hydrogen implementing reusable modular containers to reduce packaging waste in container shipping and protecting Arctic biodiversity while promoting the Arctic shipping route to reduce costs. Our study highlights the validity of NLP techniques in quantitatively extracting critical information related to the decarbonization of the shipping industry.
Analysing the Prospects of Grid-connected Green Hydrogen Production in Predominantly Fossil-based Countries - A Case Study of South Africa
Aug 2024
Publication
Importing substantial amount of green hydrogen from countries like South Africa which have abundant solar and wind potentials to replace fossil fuels has attracted interest in developed regions. This study analyses South African strategies for improving and decarbonizing the power sector while also producing hydrogen for export. These strategies include the Integrated Resource Plan the Transmission Development Plan Just Energy Transition and Hydrogen Society Roadmap for grid connected hydrogen production in 2030. Results based on an hourly resolution optimisation in Plexos indicate that annual grid-connected hydrogen production of 500 kt can lead to a 20–25% increase in the cost of electricity in scenarios with lower renewable energy penetration due to South African emission constraints by 2030. While the price of electricity is still in acceptable range and the price of hydrogen can be competitive on the international market (2–3 USD/kgH2 for production) the emission factor of this hydrogen is higher than the one of grey hydrogen ranging from 13 to 24 kgCO2/kgh2. When attempting to reach emission factors based on EU directives the three policy roadmaps become unfeasible and free capacity expansion results in significant sixteen-fold increase of wind and seven-fold increase in solar installations compared to 2023 levels by 2030 in South Africa.
Experimental Study of the Mitigation of Hydrogen-Air Explosions by Inhibiting Powder
Sep 2023
Publication
The development of hydrogen production technologies and new uses represents an opportunity to accelerate the ecological transition and create a new industrial sector. However the risks associated with the use of hydrogen must be considered. Mitigation of a hydrogen explosion in an enclosure is partly based on prevention strategies such as detection and ventilation and protection strategies such as explosion venting. Even if applications involving hydrogen probably are most interesting for vented explosions in weak structures the extreme reactivity of hydrogen-air mixtures often excludes the use of regular venting devices such as in highly constrained urban environments. Thus having alternative mitigation solutions can make the effects of the explosion acceptable by reducing the flame speed and the overpressure loading or suppressing the secondary explosion. The objective of this paper is to present experimental studies of the mitigation of hydrogen-air deflagration in a 4 m3 vented enclosure by injection of inhibiting powder (NaHCO₃). After describing the experimental set-up the main experimental results are presented for several trial configurations showing the influence of inhibiting powder in the flammable cloud on flame propagation. An interpretation of the mitigating effect of inhibiting powder on the explosion effects is proposed based on the work of Proust et al.
Regime-driven Niches and Institutional Entrepreneurs: Adding Hydrogen to Regional Energy Systems in Germany
Nov 2023
Publication
In recent years production and supply of hydrogen has gained significant attention within the German energy transition. This is due to increasingly urgent pressures to mitigate climate change and geopolitical imperatives to substitute natural gas. Hydrogen is seen as an important cross-sectoral energy carrier serving multiple functions including heat production for industry and households fuel for transportation and energy storage for stabilization of electricity supply. In the context of various funding mechanisms on several administrative levels regional value chains for green hydrogen supply are emerging. To date however few studies analyzing regional hydrogen systems exist. Due to its high projected demand of energy sources for heating industrial processes and mobility Germany appears to be a very relevant research area in this emerging field. Situated within the concept of the multi-level perspective this article examines the way how regional “niches” of green hydrogen evolve and how they are organized. The study takes an evolutionary perspective in analyzing processes of embedding green hydrogen infrastructures in regional energy regimes which entered “re-configuration”-pathways. It argues that the congruence of available resources for renewable electricity established networks of institutional entrepreneurs and access to higher level funding are conditions which put incumbent regime-actors in favorable positions to implement green hydrogen niches. Conversely the embedding of green hydrogen infrastructures in regional energy systems is a case in point of how the attributes of niches in particular technological domains can be used to explain the transition pathway entered by a surrounding energy regime.
The Role of Hydrogen Storage in an Electricity System with Large Hydropower Resources
Feb 2024
Publication
Hydrogen is considered one of the key pillars of an effective decarbonization strategy of the energy sector; however the potential of hydrogen as an electricity storage medium is debated. This paper investigates the role of hydrogen as an electricity storage medium in an electricity system with large hydropower resources focusing on the Swiss electricity sector. Several techno-economic and climate scenarios are considered. Findings suggest that hydrogen storage plays no major role under most conditions because of the large hydropower resources. More specifically no hydrogen storage is installed in Switzerland if today’s values of net-transfer capacities and low load-shedding costs are assumed. This applies even to hydrogen-favorable climate scenarios (dry years with low precipitation and dam inflows) and economic assumptions (high learning rates for hydrogen technologies). In contrast hydrogen storage is installed when net-transfer capacities between countries are reduced below 30% of current values and load-shedding costs are above 1000 EUR/MWh. When installed hydrogen is deployed in a few large-scale installations near the national borders.
Equivalent Minimum Hydrogen Consumption of Fuzzy Control-Based Fuel Cells: Exploration of Energy Management Strategies for Ships
Feb 2024
Publication
Aiming to solve the problems of insufficient dynamic responses the large loss of energy storage life of a single power cell and the large fluctuation in DC (direct current) bus voltage in fuel cell vessels this study takes a certain type of fuel cell ferry as the research object and proposes an improved equivalent minimum hydrogen consumption energy management strategy based on fuzzy logic control. First a hybrid power system including a fuel cell a lithium–iron–phosphate battery and a supercapacitor is proposed with the simulation of the power system of the modified mother ship. Second a power system simulation model and a double-closed-loop PI (proportion integration) control model are established in MATLAB/Simulink to design the equivalent hydrogen consumption model and fuzzy logic control strategy. The simulation results show that under the premise of meeting the load requirements the control strategy designed in this paper improves the Li-ion battery’s power the Li-ion battery’s SOC (state of charge) the bus voltage stability and the equivalent hydrogen consumption significantly compared with those before optimization which improves the stability and economy of the power system and has certain practical engineering value.
A Review of Hydrogen Storage and Transportation: Progresses and Challenges
Aug 2024
Publication
This review aims to summarize the recent advancements and prevailing challenges within the realm of hydrogen storage and transportation thereby providing guidance and impetus for future research and practical applications in this domain. Through a systematic selection and analysis of the latest literature this study highlights the strengths limitations and technological progress of various hydrogen storage methods including compressed gaseous hydrogen cryogenic liquid hydrogen organic liquid hydrogen and solid material hydrogen storage as well as the feasibility efficiency and infrastructure requirements of different transportation modes such as pipeline road and seaborne transportation. The findings reveal that challenges such as low storage density high costs and inadequate infrastructure persist despite progress in high-pressure storage and cryogenic liquefaction. This review also underscores the potential of emerging technologies and innovative concepts including metal–organic frameworks nanomaterials and underground storage along with the potential synergies with renewable energy integration and hydrogen production facilities. In conclusion interdisciplinary collaboration policy support and ongoing research are essential in harnessing hydrogen’s full potential as a clean energy carrier. This review concludes that research in hydrogen storage and transportation is vital to global energy transformation and climate change mitigation.
Entropy Production and Filling Time in Hydrogen Refueling Stations: An Economic Assessment
Aug 2024
Publication
A multi-objective optimization is performed to obtain fueling conditions in hydrogen stations leading to improved filling times and thermodynamic efficiency (entropy production) of the de facto standard of operation which is defined by the protocol SAE J2601. After finding the Pareto frontier between filling time and total entropy production it was found that SAE J2601 is suboptimal in terms of these process variables. Specifically reductions of filling time from 47 to 77% are possible in the analyzed range of ambient temperatures (from 10 to 40 °C) with higher saving potential the hotter the weather conditions. Maximum entropy production savings with respect to SAE J2601 (7% for 10 °C 1% for 40 °C) demand a longer filling time that increases with ambient temperature (264% for 10 °C 350% for 40 °C). Considering average electricity prices in California USA the operating cost of the filling process can be reduced between 8 and 28% without increasing the expected filling time.
Performance Assessment and Optimization of the Ultra-High Speed Air Compressor in Hydrogen Fuel Cell Vehicles
Feb 2024
Publication
Air compressors in hydrogen fuel cell vehicles play a crucial role in ensuring the stability of the cathode air system. However they currently face challenges related to low efficiency and poor stability. To address these issues the experimental setup for the pneumatic performance of air compressors is established. The effects of operational parameters on energy consumption efficiency and mass flow rate of the air compressor are revealed based on a Morris global sensitivity analysis. Considering a higher flow rate larger efficiency and lower energy consumption simultaneously the optimal operating combination of the air compressor is determined based on grey relational multi-objective optimization. The optimal combination of operational parameters consisted of a speed of 80000 rpm a pressure ratio of 1.8 and an inlet temperature of 18.3 °C. Compared to the average values the isentropic efficiency achieved a 48.23% increase and the mass flow rate rose by 78.88% under the optimal operational combination. These findings hold significant value in guiding the efficient and stable operation of air compressors. The comprehensive methodology employed in this study is applicable further to investigate air compressors for hydrogen fuel cell vehicles.
Strategic Public Relations Policy for Accelerating Hydrogen Acceptance: Insights from an Expert Survey in South Korea
Aug 2024
Publication
Hydrogen has great growth potential due to its green carbon-neutral nature but public acceptance is low due to negative perceptions of the dangers associated with hydrogen energy. Safety concerns particularly related to its flammability and explosiveness are an obstacle to hydrogen energy policy. In South Korea recent hydrogen-related explosions have exacerbated these concerns undermining public confidence. This study developed public relations (PR) strategies to manage risk perception and promote hydrogen energy acceptance by analyzing the opinions of government officials and experts using SWOT factors the TOWS matrix and the analytic hierarchy process. The findings highlight the importance of addressing weaknesses and threats in PR efforts. Key weaknesses include Korea’s technological lag and the low localization of core hydrogen technologies both of which hinder competitiveness and negatively impact public perception of hydrogen energy. Notable threats include deteriorating energy dependency and expanding global carbon regulations. This information can be used to influence attitudes and foster public acceptance of hydrogen energy policies. Emphasizing weaknesses and threats may result in more effective PR strategies even if they do not directly address the primary concerns of scientific experts. The persuasive insights identified in this study can support future policy communication and PR strategies.
Total Cost of Ownership Analysis for Hydrogen and Battery Powertrains: A Comparative Study in Finnish Heavy-duty Transport
Sep 2024
Publication
The road transport sector is one of the major contributors to greenhouse gas emissions as it still largely relies on traditional powertrain solutions. While some progress has been made in the passenger car sector with the diffusion of battery electric vehicles heavy-duty transport remains predominantly dependent on diesel internal combustion engines. This research aims to evaluate and compare three potential solutions for the decarbonisation of heavy-duty freight transport from an economic perspective: Battery Electric Trucks (BETs) Fuel Cell Electric Trucks (FCETs) and Hydrogen-fuelled Internal Combustion Engine Trucks (H2ICETs). The study focuses on the Finnish market and road network where affordable and low-carbon electricity creates an ideal environment for the development of alternative powertrain vehicles. The analysis employs the Total Cost of Ownership (TCO) method which allows for a comprehensive assessment of all cost components associated with the vehicles throughout their entire lifecycle encompassing both initial expenses and operational costs. Among the several factors affecting the results the impact of the three powertrain technologies on the admissible payloads has been taken into account. The study specifically focuses on the costs directly incurred by the truck owner. Additionally to evaluate the cost effectiveness of the proposed powertrain technologies under different scenarios a sensitivity analysis on electricity and hydrogen prices is conducted. The outcomes of this study reveal that no single powertrain solution emerges as universally optimal as the most cost-effective choice depends strongly on the truck type and its use (i.e. daily mileage). For relatively small trucks (18 t) covering short driving distances (approximately 100 to 200 km/day) BETs prove to be the best solution due to their higher efficiency and lower vehicle costs compared to FCETs. Conversely for larger trucks (42 and 76 t) engaged in longer hauls (>300 km/day) H2ICETs exhibit larger cost benefits due to their lower vehicle costs among the three options under investigation. Finally for small trucks (18 t) travelling long distances (200 km/day or more) FCETs represent a competitive choice due to their high efficiency and costeffective energy storage system. Considering future advancements in FCETs and BETs in terms of improved performance and reduced investment cost the fuel cell-based solution is expected to emerge as the best option across various combinations of truck sizes and daily mileages.
Current Status and Economic Analysis of Green Hydrogen Energy Industry Chain
Feb 2024
Publication
Under the background of the power system profoundly reforming hydrogen energy from renewable energy as an important carrier for constructing a clean low-carbon safe and efficient energy system is a necessary way to realize the objectives of carbon peaking and carbon neutrality. As a strategic energy source hydrogen plays a significant role in accelerating the clean energy transition and promoting renewable energy. However the cost and technology are the two main constraints to green hydrogen energy development. Herein the technological development status and economy of the whole industrial chain for green hydrogen energy “production-storage-transportation-use” are discussed and reviewed. After analysis the electricity price and equipment cost are key factors to limiting the development of alkaline and proton exchange membrane hydrogen production technology; the quantity scale and distance of transportation are key to controlling the costs of hydrogen storage and transportation. The application of hydrogen energy is mainly concentrated in the traditional industries. With the gradual upgrading and progress of the top-level design and technology the application of hydrogen energy mainly including traffic transportation industrial engineering energy storage power to gas and microgrid will show a diversified development trend. And the bottleneck problems and development trends of the hydrogen energy industry chain are also summarized and viewed.
An Exploration of Safety Measures in Hydrogen Refueling Stations: Delving into Hydrogen Equipment and Technical Performance
Feb 2024
Publication
The present paper offers a thorough examination of the safety measures enforced at hydrogen filling stations emphasizing their crucial significance in the wider endeavor to advocate for hydrogen as a sustainable and reliable substitute for conventional fuels. The analysis reveals a wide range of crucial safety aspects in hydrogen refueling stations including regulated hydrogen dispensing leak detection accurate hydrogen flow measurement emergency shutdown systems fire-suppression mechanisms hydrogen distribution and pressure management and appropriate hydrogen storage and cooling for secure refueling operations. The paper therefore explores several aspects including the sophisticated architecture of hydrogen dispensers reliable leak-detection systems emergency shut-off mechanisms and the implementation of fire-suppression tactics. Furthermore it emphasizes that the safety and effectiveness of hydrogen filling stations are closely connected to the accuracy in the creation and upkeep of hydrogen dispensers. It highlights the need for materials and systems that can endure severe circumstances of elevated pressure and temperature while maintaining safety. The use of sophisticated leak-detection technology is crucial for rapidly detecting and reducing possible threats therefore improving the overall safety of these facilities. Moreover the research elucidates the complexities of emergency shut-off systems and fire-suppression tactics. These components are crucial not just for promptly managing hazards but also for maintaining the station’s structural soundness in unanticipated circumstances. In addition the study provides observations about recent technical progress in the industry. These advances effectively tackle current safety obstacles and provide the foundation for future breakthroughs in hydrogen fueling infrastructure. The integration of cutting-edge technology and materials together with the development of upgraded safety measures suggests a positive trajectory towards improved efficiency dependability and safety in hydrogen refueling stations.
Towards Safer Hydrogen Refuelling Stations: Insights from Computational Fluid Dynamics LH2 Leakage
May 2024
Publication
The transition to a sustainable future with hydrogen as a key energy carrier necessitates a comprehensive understanding of the safety aspects of hydrogen including liquid hydrogen (LH₂). Hence this study presents a detailed computational fluid mechanics analysis to explore accidental LH₂ leakage and dispersion in a hydrogen refuelling station under varied conditions which is essential to prevent fire and explosion. The correlated impact of influential parameters including wind direction wind velocity leak direction and leak rate were analysed. The study shows that hydrogen dispersion is significantly impacted by the combined effect of wind direction and surrounding structures. Additionally the leak rate and leak direction have a significant effect on the development of the flammable cloud volume (FCV) which is critical for estimating the explosion hazards. Increasing wind velocity from 2 to 4 m/s at a constant leak rate of 0.06 kg/s results in an 82% reduction in FCV. The minimum FCV occurs when leak and wind directions oppose at 4 m/s. The most critical situation concerning FCV arises when the leak and wind directions are perpendicular with a leak rate of 0.06 kg/s and a wind velocity of 2 m/s. These findings can aid in the development of optimised sensing and monitoring systems and operational strategies to reduce the risk of catastrophic fire and explosion consequences.
A Review of Life Cycle Assessment (LCA) Studies for Hydrogen Production Technologies through Water Electrolysis: Recent Advances
Aug 2024
Publication
Climate change is a major concern for the sustainable development of global energy systems. Hydrogen produced through water electrolysis offers a crucial solution by storing and generating renewable energy with minimal environmental impact thereby reducing carbon emissions in the energy sector. Our research evaluates current hydrogen production technologies such as alkaline water electrolysis (AWE) proton exchange membrane water electrolysis (PEMWE) solid oxide electrolysis (SOEC) and anion exchange membrane water electrolysis (AEMWE). We systematically review life cycle assessments (LCA) for these technologies analyzing their environmental impacts and recent technological advancements. This study fills essential gaps by providing detailed LCAs for emerging technologies and evaluating their scalability and environmental footprints. Our analysis outlines the strengths and weaknesses of each technology guiding future research and assisting stakeholders in making informed decisions about integrating hydrogen production into the global energy mix. Our approach highlights operational efficiencies and potential sustainability enhancements by employing comparative analyses and reviewing advancements in membrane technology and electrocatalysts. A significant finding is that PEMWE when integrated with renewable energy sources offers rapid response capabilities that are vital for adaptive energy systems and reducing carbon footprints.
Small-Scale High-Pressure Hydrogen Storage Vessels: A Review
Feb 2024
Publication
Nowadays high-pressure hydrogen storage is the most commercially used technology owing to its high hydrogen purity rapid charging/discharging of hydrogen and low-cost manufacturing. Despite numerous reviews on hydrogen storage technologies there is a relative scarcity of comprehensive examinations specifically focused on high-pressure gaseous hydrogen storage and its associated materials. This article systematically presents the manufacturing processes and materials used for a variety of high-pressure hydrogen storage containers including metal cylinders carbon fiber composite cylinders and emerging glass material-based hydrogen storage containers. Furthermore it introduces the relevant principles and theoretical studies showcasing their advantages and disadvantages compared to conventional high-pressure hydrogen storage containers. Finally this article provides an outlook on the future development of high-pressure hydrogen storage containers.
Can an Energy Only Market Enable Resource Adequacy in a Decarbonized Power System? A Co-simulation with Two Agent-based-models
Feb 2024
Publication
Future power systems in which generation will come almost entirely from variable Renewable Energy Sources (vRES) will be characterized by weather-driven supply and flexible demand. In a simulation of the future Dutch power system we analyze whether there are sufficient incentives for market-driven investors to provide a sufficient level of security of supply considering the profit-seeking and myopic behavior of investors. We cosimulate two agent-based models (ABM) one for generation expansion and one for the operational time scale. The results suggest that in a system with a high share of vRES and flexibility prices will be set predominantly by the demand’s willingness to pay particularly by the opportunity cost of flexible hydrogen electrolyzers. The demand for electric heating could double the price of electricity in winter compared to summer and in years with low vRES could cause shortages. Simulations with stochastic weather profiles increase the year-to-year variability of cost recovery by more than threefold and the year-to-year price variability by more than tenfold compared to a scenario with no weather uncertainty. Dispatchable technologies have the most volatile annual returns due to high scarcity rents during years of low vRES production and diminished returns during years with high vRES production. We conclude that in a highly renewable EOM investors would not have sufficient incentives to ensure the reliability of the system. If they invested in such a way to ensure that demand could be met in a year with the lowest vRES yield they would not recover their fixed costs in the majority of years.
Evaluating Reservoir Suitability for Large-scale Hydrogen Storage: A Preliminary Assesment Considering Reservoir Properties
May 2024
Publication
With rising demand for clean energy global focus turns to finding ideal sites for large-scale underground hydrogen storage (UHS) in depleted petroleum reservoirs. A thorough preliminary reservoir evaluation before hydrogen (H2) injection is crucial for UHS success and safety. Recent criteria for UHS often emphasize economics and chemistry neglecting key reservoir attributes. This study introduces a comprehensive framework for the reservoir-scale preliminary assessment specifically tailored for long-term H2 storage within depleted gas reservoirs. The evaluation criteria encompass critical components including reservoir geometry petrophysical properties tectonics and formation fluids. To illustrate the practical application of this approach we assess the Barnett shale play reservoir parameters. The assessment unfolds through three key stages: (1) A systematic evaluation of the reservoir's properties against our comprehensive screening criteria determines its suitability for H2 storage. (2) Using both homogeneous and multilayered gas reservoir models we explore the feasibility and efficiency of H2 storage. This phase involves an in-depth examination of reservoir behavior during the injection stage. (3) To enhance understanding of UHS performance sensitivity analyses investigate the impact of varying reservoir dimensions and injection/production pressures. The findings reveal the following: (a) Despite potential challenges associated with reservoir compaction and aquifer support the reservoir exhibits substantial promise as an H2 storage site. (b) Notably a pronounced increase in reservoir pressure manifests during the injection stage particularly in homogeneous reservoirs. (c) Furthermore optimizing injection-extraction cycle efficiency can be achieved by augmenting reservoir dimensions while maintaining a consistent thickness. To ensure a smooth transition to implementation further comprehensive investigations are advised including experimental and numerical studies to address injectivity concerns and explore storage site development. This evaluation framework is a valuable tool for assessing the potential of depleted gas reservoirs for large-scale hydrogen storage advancing global eco-friendly energy systems.
Blending Hydrogen in Existing Natural Gas Pipelines: Integrity Consequences from a Fitness for Service Perspective
Jun 2023
Publication
Blending hydrogen in existing natural gas pipelines compromises steel integrity because it increases fatigue crack growth promotes subcritical cracking and decreases fracture toughness. In this regard several laboratories reported that the fracture toughness measured in a hydrogen containing gaseous atmosphere KIH can be 50% or less than KIC the fracture toughness measured in air. From a pipeline integrity perspective fracture mechanics predicts that injecting hydrogen in a natural gas pipeline decreases the failure pressure and the size of the critical flaw at a given pressure level. For a pipeline with a given flaw size as shown in this work the effect of hydrogen embrittlement (HE) in the predicted failure pressure is largest when failure occurs by brittle fracture. The HE effect on failure pressure diminishes with a decreasing crack size or increasing fracture toughness. The safety margin after a successful hydrostatic test is reduced and therefore the time between hydrotests should be decreased. In this work all those effects were quantified using a crack assessment methodology (level 2 API 579-ASME FFS) considering literature values for KIH and KIC reported for an API 5L X52 pipeline steel. To characterize different scenarios various crack sizes were assumed including a small crack with a size close to the detection limit of current in-line inspection techniques and a larger crack that represents the largest crack size that could survive a hydrotest to 100% of the steel specified minimum yield stress. The implications of a smaller failure pressure and smaller critical crack size on pipeline integrity are discussed in this paper.
Hydrogen Energy in Electrical Power Systems: A Review and Future Outlook
Aug 2024
Publication
Hydrogen energy as a zero-carbon emission type of energy is playing a significant role in the development of future electricity power systems. Coordinated operation of hydrogen and electricity will change the direction and shape of energy utilization in the power grid. To address the evolving power system and promote sustainable hydrogen energy development this paper initially examines hydrogen preparation and storage techniques summarizes current research and development challenges and introduces several key technologies for hydrogen energy application in power systems. These include hydrogen electrification technology hydrogen-based medium- and long-term energy storage and hydrogen auxiliary services. This paper also analyzes several typical modes of hydrogen–electricity coupling. Finally the future development direction of hydrogen energy in power systems is discussed focusing on key issues such as cost storage and optimization.
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