China, People’s Republic
A Review of Current Advances in Ammonia Combustion from the Fundamentals to Applications in Internal Combustion Engines
Aug 2023
Publication
The energy transition from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind solar and hydrogen is facing increasing demands. The decarbonization of global transportation could come true via applying carbon-free fuel such as ammonia especially for internal combustion engines (ICEs). Although ammonia has advantages of high hydrogen content high octane number and safety in storage it is uninflammable with low laminar burning velocity thus limiting its direct usage in ICEs. The purpose of this review paper is to provide previous studies and current research on the current technical advances emerging in assisted combustion of ammonia. The limitation of ammonia utilization in ICEs such as large minimum ignition energy lower flame speed and more NOx emission with unburned NH3 could be solved by oxygen-enriched combustion ammonia–hydrogen mixed combustion and plasma-assisted combustion (PAC). In dual-fuel or oxygen-enriched NH3 combustion accelerated flame propagation speeds are driven by abundant radicals such as H and OH; however NOx emission should be paid special attention. Furthermore dissociating NH3 in situ hydrogen by non-noble metal catalysts or plasma has the potential to replace dual-fuel systems. PAC is able to change classical ignition and extinction S-curves to monotonic stretching which makes low-temperature ignition possible while leading moderate NOx emissions. In this review the underlying fundamental mechanism under these technologies are introduced in detail providing new insight into overcoming the bottleneck of applying ammonia in ICEs. Finally the feasibility of ammonia processing as an ICE power source for transport and usage highlights it as an appealing choice for the link between carbon-free energy and power demand.
An Analysis of the Potential of Hydrogen Energy Technology on Demand Side Based on a Carbon Tax: A Case Study in Japan
Dec 2022
Publication
Hydrogen energy is considered one of the main measures of zero carbonization in energy systems but high equipment and hydrogen costs hinder the development of hydrogen energy technology. The objectives of this study are to quantify the environmental advantages of hydrogen energy through a carbon tax and study the application potential of hydrogen energy technology in a regional distributed energy system (RDES). In this study various building types in the smart community covered by Japan’s first hydrogen energy pipeline are used as an example. First ten buildings of five types are selected as the research objectives. Subsequently two comparative system models of a regional distributed hydrogen energy system (RDHES) and an RDES were established. Then by studying the optimal RDHES and RDES configuration and combining the prediction of future downward trends of fuel cell (FC) costs and energy carbon emissions the application effect of FC and hydrogen storage (HS) technologies on the demand side was analyzed. Finally the adaptability of the demand-side hydrogen energy system was studied by analyzing the load characteristics of different types of buildings. The results show that when the FC price is reduced to 1.5 times that of the internal combustion engine (ICE) the existing carbon tax system can sufficiently support the RDHES in gaining economic advantages in some regions. Notably when the carbon emissions of the urban energy system are reduced the RDHES demonstrates stronger anti-risk ability and has greater suitability for promotion in museums and shopping malls. The conclusions obtained in this study provide quantitative support for hydrogen energy promotion policies on the regional demand side and serve as a theoretical reference for the design and adaptability research of RDHESs.
Production of Hydrogen from Offshore Wind in China and Cost-competitive Supply to Japan
Nov 2021
Publication
The Japanese government has announced a commitment to net-zero greenhouse gas emissions by 2050. It envisages an important role for hydrogen in the nation’s future energy economy. This paper explores the possibility that a significant source for this hydrogen could be produced by electrolysis fueled by power generated from offshore wind in China. Hydrogen could be delivered to Japan either as liquid or bound to a chemical carrier such as toluene or as a component of ammonia. The paper presents an analysis of factors determining the ultimate cost for this hydrogen including expenses for production storage conversion transport and treatment at the destination. It concludes that the Chinese source could be delivered at a volume and cost consistent with Japan’s idealized future projections.
Design and Optimization of a Type-C Tank for Liquid Hydrogen Marine Transport
May 2023
Publication
As one of the most promising renewable energy sources hydrogen has the excellent environmental benefit of producing zero emissions. A key technical challenge in using hydrogen across sectors is placed on its storage technology. The storage temperature of liquid hydrogen (20 K or 253 C) is close to absolute zero so the storage materials and the insulation layers are subjected to extremely stringent requirements against the cryogenic behaviour of the medium. In this context this research proposed to design a large liquid hydrogen type-C tank with AISI (American Iron and Steel Institution) type 316 L stainless steel as the metal barrier using Vapor-Cooled Shield (VCS) and Rigid Polyurethane Foams (RPF) as the insulation layer. A parametric study on the design of the insulation layer was carried out by establishing a thermodynamic model. The effects of VCS location on heat ingress to the liquid hydrogen transport tank and insulation temperature distribution were investigated and the optimal location of the VCS in the insulation was identified. Research outcomes finally suggest two optimal design schemes: (1) when the thickness of the insulation layer is determined Self-evaporation Vapor-Cooled Shield (SVCS) and Forcedevaporation Vapor-Cooled Shield (FVCS) can reduce heat transfer by 47.84% and 85.86% respectively; (2) when the liquid hydrogen evaporation capacity is determined SVCS and FVCS can reduce the thickness of the insulation layer by 50% and 67.93% respectively.
Toward to Hydrogen Energy of Electric Power: Characteristics and Main Case Studies in Shenzhen
Feb 2023
Publication
China has pledged that it will strive to achieve peak carbon emission by 2030 and realize carbon neutrality by 2060 which has spurred renewed interest in hydrogen for widespread decarbonization of the economy. Hydrogen energy is an important secondary clean energy with the advantage of high density high calorific value rich reserves extensive sources and high conversion efficiency that can be widely used in power generation transportation fuel and other fields. In recent years with the guidance of policies and the progress of technology China’s hydrogen energy industry has developed rapidly. About 42% of China’s carbon emissions comes from the power system and Shenzhen has the largest urban power grid in China. Bringing the utilization of hydrogen energy into Shenzhen’s power system is an important method to achieve industry transformation achieve the “double carbon” goal and promote sustainable development. This paper outlines the domestic and international development status of hydrogen energy introduces the characteristics of Shenzhen new power system the industrial utilization of hydrogen energy and the challenges of further integrating hydrogen energy into Shenzhen new power system and finally suggests on the integration of hydrogen energy into Shenzhen new power system in different dimensions.
Research on the Primary Frequency Regulation Control Strategy of a Wind Storage Hydrogen-Generating Power Station
Nov 2022
Publication
Wind curtailment and weak inertia characteristics are two factors that shackle the permeability of wind power. An electric hydrogen production device consumes electricity to produce hydrogen under normal working conditions to solve the problem of abandoning wind. When participating in frequency regulation it serves as a load reduction method to assist the system to rebuild a power balance and improve the wind power permeability. However due to its own working characteristics an electric hydrogen production device cannot undertake the high-frequency component of the frequency regulation power command; therefore an energy storage device was selected to undertake a high-frequency power command to assist the electric hydrogen production device to complete the system frequency regulation. This paper first proposes and analyzes the architecture of a wind storage hydrogen-generating station for centralized hydrogen production with a distributed energy storage and proposes the virtual inertia and droop characteristic mechanism of the wind storage hydrogen-generating station to simulate a synchronous unit. Secondly an alkaline electrolysis cell suitable for large-scale engineering applications is selected as the research object and its mathematical model is established the matching between different energy storage devices and their cooperation in power grid frequency regulation is analyzed and a super capacitor is selected. A control strategy for the wind storage hydrogen-generating power station to participate in power grid frequency regulation with a wide time scale is then proposed. Using the first-order low-pass filter the low-frequency component of the frequency regulation power command is realized by an electric hydrogen production device load reduction and a high-frequency component is realized by the energy storage device. Finally the effectiveness and rationality of the proposed control strategy are verified by establishing the simulation model of the wind storage hydrogen-generating power station with different initial wind speed states comparing the system frequency dip values under the proposed multi-energy cooperative control strategy and a single energy device control strategy.
Low-Carbon Transition Pathway Planning of Regional Power Systems with Electricity-Hydrogen Synergy
Nov 2022
Publication
Hydrogen energy leads us in an important direction in the development of clean energy and the comprehensive utilization of hydrogen energy is crucial for the low-carbon transformation of the power sector. In this paper the demand for hydrogen energy in various fields is predicted based on the support vector regression algorithm which can be converted into an equivalent electrical load when it is all produced from water electrolysis. Then the investment costs of power generators and hydrogen energy equipment are forecast considering uncertainty. Furthermore a planning model is established with the forecast data initial installed capacity and targets for carbon emission reduction as inputs and the installed capacity as well as share of various power supply and annual carbon emissions as outputs. Taking Gansu Province of China as an example the changes of power supply structure and carbon emissions under different scenarios are analysed. It can be found that hydrogen production through water electrolysis powered by renewable energy can reduce carbon emissions but will increase the demand for renewable energy generators. Appropriate planning of hydrogen storage can reduce the overall investment cost and promote a low carbon transition of the power system
International Experience of Carbon Neutrality and Prospects of Key Technologies: Lessons for China
Feb 2023
Publication
Carbon neutrality (or climate neutrality) has been a global consensus and international experience exchange is essential. Given the differences in the degree of social development resource endowment and technological level each country should build a carbon-neutral plan based on its national conditions. Compared with other major developed countries (e.g. Germany the United States and Japan) China's carbon neutrality has much bigger challenges including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels. Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon near-zero carbon and negative carbon emissions. Technological innovations associated with coal oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed. Based on integrated analysis of international experience from the world's major developed countries in-depth knowledge of the current and future technologies and China's energy and ecological resources potential five lessons for the implementation of China's carbon neutrality are proposed: (1) transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern; (2) renewable power-to-X and large-scale underground energy storage; (3) integration of green hydrogen production storage transport and utilization; (4) construction of clean energy systems based on smart sector coupling (ENSYSCO); (5) improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China. This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.
Distributionally Robust Optimal Scheduling of Integrated Energy Systems Including Hydrogen Fuel Cells Considering Uncertainties
Aug 2023
Publication
The economic operation of the integrated energy system faces the problems of coupling between energy production and conversion equipment in the system and the imbalance of various energy demands. Therefore taking system safety as the constraint and minimum economic cost as the objective function including fuel cost operation and maintenance cost this paper proposes the operation dispatching model of the integrated energy system based on hydrogen fuel cell (HFC) including HFC photovoltaic wind turbine electric boiler electric chiller absorption chiller electric energy storage and thermal energy storage equipment. On this basis a distributionally robust optimization (DRO) model is introduced to deal with the uncertainty of wind power and photovoltaic output. In the distributionally robust optimization model Kullback–Leibler (KL) divergence is used to construct an ambiguity set which is mainly used to describe the prediction errors of renewable energy output. Finally the DRO economic dispatching model of the HFC integrated energy system (HFCIES) is established. Besides based on the same load scenario the economic benefits of hybrid energy storage equipment are discussed. The dispatching results show that compared with the scenario of only electric energy storage and only thermal energy storage the economic cost of the scenario of hybrid electric and thermal storage can be reduced by 3.92% and 7.55% respectively and the use of energy supply equipment can be reduced and the stability of the energy storage equipment can be improved.
A Control Strategy Study of a Renewable CCHP Energy System Integrated Hydrogen Production Unit - A Case Study of an Industrial Park in Jiangsu Province
Aug 2023
Publication
This paper describes a renewable energy system incorporating a hydrogen production unit to address the imbalance between energy supply and demand. The system utilizes renewable energy and hydrogen production energy to release energy to fill the power gap during peak demand power supply for demand peaking and valley filling. The system is optimized by analyzing marine predator behavioral logic and optimizing the system for maximum operational efficiency and best economic value. The results of the study show that after the optimized scheduling of the hydrogen production coupled renewable energy integrated energy system using the improved marine predator optimization algorithm the energy distribution of the whole energy system is good with the primary energy saving rate maintained at 24.75% the CO2 emission reduction rate maintained at 42.32% and the cost saving rate maintained at 0.78%. In addition this paper uses the Adaboost-BP prediction model to predictively analyze the system. The results show that as the price of natural gas increases the advantages of the combined hydrogen production renewable integrated energy system proposed in this paper become more obvious and the cumulative cost over three years is better than other related systems. These research results provide an important reference for the application and development of the system.
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.
Optimal Sizing of a Stand-Alone Hybrid Power System Based on Battery/Hydrogen with an Improved Ant Colony Optimization
Sep 2016
Publication
A distributed power system with renewable energy sources is very popular in recent years due to the rapid depletion of conventional sources of energy. Reasonable sizing for such power systems could improve the power supply reliability and reduce the annual system cost. The goal of this work is to optimize the size of a stand-alone hybrid photovoltaic (PV)/wind turbine (WT)/battery (B)/hydrogen system (a hybrid system based on battery and hydrogen (HS-BH)) for reliable and economic supply. Two objectives that take the minimum annual system cost and maximum system reliability described as the loss of power supply probability (LPSP) have been addressed for sizing HS-BH from a more comprehensive perspective considering the basic demand of load the profit from hydrogen which is produced by HS-BH and an effective energy storage strategy. An improved ant colony optimization (ACO) algorithm has been presented to solve the sizing problem of HS-BH. Finally a simulation experiment has been done to demonstrate the developed results in which some comparisons have been done to emphasize the advantage of HS-BH with the aid of data from an island of Zhejiang China.
Real-Time Energy Management Strategy of Hydrogen Fuel Cell Hybrid Electric Vehicles Based on Power Following Strategy–Fuzzy Logic Control Strategy Hybrid Control
Nov 2023
Publication
Fuel cell hybrid electric vehicles have the advantages of zero emission high efficiency and fast refuelling etc. and are one of the key directions for vehicle development. The energy management problem of fuel cell hybrid electric vehicles is the key technology for power distribution. The traditional power following strategy has the advantage of a real-time operation but the power correction is usually based only on the state of charge of a lithium battery which causes the operating point of the fuel cell to be in the region of a low efficiency. To solve this problem this paper proposes a hybrid power-following-fuzzy control strategy where a fuzzy logic control strategy is used to optimise the correction module based on the power following strategy which regulates the state of charge while correcting the output power of the fuel cell towards the efficient operating point. The results of the joint simulation with Matlab + Advisor under the Globally Harmonised Light Vehicle Test Cycle Conditions show that the proposed strategy still ensures the advantages of real-time energy management and for the hydrogen fuel cell the hydrogen consumption is reduced by 13.5% and 4.1% compared with the power following strategy and the fuzzy logic control strategy and the average output power variability is reduced by 14.6% and 5.1% respectively which is important for improving the economy of the whole vehicle and prolonging the lifetime of fuel cell.
A Review on the Research Progress and Application of Compressed Hydrogen in the Marine Hydrogen Fuel Cell Power System
Jan 2024
Publication
The urgency to mitigate greenhouse gas emissions from maritime vessels has intensified due to the increasingly stringent directives set forth by the International Maritime Organization (IMO). These directives specifically address energy efficiency enhancements and emissions reduction within the shipping industry. In this context hydrogen is the much sought after fuel for all the global economies and its applications for transportation and propulsion in particular is crucial for cutting down carbon emissions. Nevertheless the realization of hydrogen-powered vessels is confronted by substantial technical hurdles that necessitate thorough examination. This study undertakes a comprehensive analysis encompassing diverse facets including distinct variations of hydrogen fuel cells hydrogen internal combustion engines safety protocols associated with energy storage as well as the array of policies and commercialization endeavors undertaken globally for the advancement of hydrogen-propelled ships. By amalgamating insights from these multifaceted dimensions this paper adeptly encapsulates the myriad challenges intrinsic to the evolution of hydrogen-fueled maritime vessels while concurrently casting a forward-looking gaze on their prospective trajectory.
Research on the Adaptability of Proton Exchange Membrane Electrolysis in Green Hydrogen-Electric Coupling System Under Multi-operating Conditions
Mar 2023
Publication
The green hydrogen–electric coupling system can consume locally generated renewable energy thereby improving energy utilization and enabling zero-carbon power supply within a certain range. This study focuses on a green hydrogen–electric coupling system that integrates photovoltaic energy storage and proton exchange membrane electrolysis (PEME). Firstly the impact of operating temperature power quality and grid auxiliary services on the characteristics of the electrolysis cell is analyzed and a voltage model and energy model for the cell are established. Secondly a multi-operating conditions adaptability experiment for PEME grid-connected operation is designed. A test platform consisting of a grid simulator simulated photovoltaic power generation system lithium battery energy storage system PEME and measurement and acquisition device is then built. Finally experiments are conducted to simulate multi-operating conditions such as temperature changes voltage fluctuations frequency offsets harmonic pollution and current adjustment speed. The energy efficiency and consumption is calculated based on the recorded data and the results are helpful to guide the operation of the system.
Study on Enhancing Hydrogen Production Potential from Renewable Energy in Multi-terminal DC System
Aug 2021
Publication
Renewable energy complementary hydrogen production can enhance the full consumption of renewable energy and reduce the abandonment of wind and solar power. The integration of renewable energy and hydrogen production equipment through existing multi-terminal DC systems can reduce new power lines construction and save investment in distribution equipment. For integrated renewable energy/hydrogen energy in an existing multi-terminal DC system this paper investigates its potential of hydrogen production based on renewable energy while ensuring the normal performance of the existing system being not affected. The typical structure and control strategy of the integrated renewable energy/hydrogen energy in multi-terminal DC system are firstly described. Then the state space model of the system is constructed and the key parameters affecting the hydrogen production capacity are studied by using the eigenvalues analysis method. Finally the corresponding system simulation model and test platform are built and the theoretical analysis results are verified and the potential of using multi-terminal DC system to enhance hydrogen production is quantitatively analyzed. The proposed scheme can enhance the hydrogen production potential from renewable energy meanwhile the normal performance of the existing system is not affected.
Distributional Trends in the Generation and End-Use Sector of Low-Carbon Hydrogen Plants
Mar 2023
Publication
This paper uses established and recently introduced methods from the applied mathematics and statistics literature to study trends in the end-use sector and the capacity of low-carbon hydrogen projects in recent and upcoming decades. First we examine distributions in plants over time for various end-use sectors and classify them according to metric discrepancy observing clear similarity across all industry sectors. Next we compare the distribution of usage sectors between different continents and examine the changes in sector distribution over time. Finally we judiciously apply several regression models to analyse the association between various predictors and the capacity of global hydrogen projects. Across our experiments we see a welcome exponential growth in the capacity of zero-carbon hydrogen plants and significant growth of new and planned hydrogen plants in the 2020’s across every sector.
Life Cycle Assessment of Electric Vehicles and Hydrogen Fuel Cell Vehicles Using the GREET Model—A Comparative Study
Apr 2021
Publication
Facing global warming and recent bans on the use of diesel in vehicles there is a growing need to develop vehicles powered by renewable energy sources to mitigate greenhouse gas and pollutant emissions. Among the various forms of non-fossil energy for vehicles hydrogen fuel is emerging as a promising way to combat global warming. To date most studies on vehicle carbon emissions have focused on diesel and electric vehicles (EVs). Emission assessment methodologies are usually developed for fast-moving consumer goods (FMCG) which are non-durable household goods such as packaged foods beverages and toiletries instead of vehicle products. There is an increase in the number of articles addressing the product carbon footprint (PCF) of hydrogen fuel cell vehicles in the recent years while relatively little research focuses on both vehicle PCF and fuel cycle. Zero-emission vehicles initiative has also brought the importance of investigating the emission throughout the fuel cycle of hydrogen fuel cell and its environmental impact. To address these gaps this study uses the life-cycle assessment (LCA) process of GREET (greenhouse gases regulated emissions and energy use in transportation) to compare the PCF of an EV (Tesla Model 3) and a hydrogen fuel cell car (Toyota MIRAI). According to the GREET results the fuel cycle contributes significantly to the PCF of both vehicles. The findings also reveal the need for greater transparency in the disclosure of relevant information on the PCF methodology adopted by vehicle manufacturers to enable comparison of their vehicles’ emissions. Future work will include examining the best practices of PCF reporting for vehicles powered by renewable energy sources as well as examining the carbon footprints of hydrogen production technologies based on different methodologies.
Breaking the Hard-to-abate Bottleneck in China’s Path to Carbon Neutrality with Clean Hydrogen
Sep 2022
Publication
Countries such as China are facing a bottleneck in their paths to carbon neutrality: abating emissions in heavy industries and heavy-duty transport. There are few in-depth studies of the prospective role for clean hydrogen in these ‘hard-to-abate’ (HTA) sectors. Here we carry out an integrated dynamic least-cost modelling analysis. Results show that first clean hydrogen can be both a major energy carrier and feedstock that can significantly reduce carbon emissions of heavy industry. It can also fuel up to 50% of China’s heavy-duty truck and bus fleets by 2060 and significant shares of shipping. Second a realistic clean hydrogen scenario that reaches 65.7 Mt of production in 2060 could avoid US$1.72 trillion of new investment compared with a no-hydrogen scenario. This study provides evidence of the value of clean hydrogen in HTA sectors for China and countries facing similar challenges in reducing emissions to achieve net-zero goals.
Modeling of Hydrogen Production System for Photovoltaic Power Generation and Capacity Optimization of Energy Storage System
Sep 2022
Publication
Hydrogen production using solar energy is an important way to obtain hydrogen energy. However the inherent intermittent and random characteristics of solar energy reduce the efficiency of hydrogen production. Therefore it is necessary to add an energy storage system to the photovoltaic power hydrogen production system. This paper establishes a model of a photovoltaic power generation hydrogen system and optimizes the capacity configuration. Firstly the mathematical model is modeled and analyzed and the system is modeled using Matlab/Simulink; secondly the principle of optimal configuration of energy storage capacity is analyzed to determine the optimization strategy we propose the storage capacity configuration algorithm based on the low-pass filtering principle and optimal time constant selection; finally a case study is conducted whose photovoltaic installed capacity of 30 MW verifying the effectiveness of the proposed algorithm analyzing the relationship between energy storage capacity and smoothing effect. The results show that as the cut-off frequency decreases the energy storage capacity increases and the smoothing effect is more obvious. The proposed algorithm can effectively reduce the 1 h maximum power variation of PV power generation. In which the maximum power variation of PV generation 1 h before smoothing is 4.31 MW. We set four different sets of time constants the maximum power variation of PV generation 1 h after smoothing is reduced to 0.751 0.389 0.078 and 0.04 MW respectively.
Coordinated Control of a Wind-Methanol-Fuel Cell System with Hydrogen Storage
Dec 2017
Publication
This paper presents a wind-methanol-fuel cell system with hydrogen storage. It can manage various energy flow to provide stable wind power supply produce constant methanol and reduce CO2 emissions. Firstly this study establishes the theoretical basis and formulation algorithms. And then computational experiments are developed with MATLAB/Simulink (R2016a MathWorks Natick MA USA). Real data are used to fit the developed models in the study. From the test results the developed system can generate maximum electricity whilst maintaining a stable production of methanol with the aid of a hybrid energy storage system (HESS). A sophisticated control scheme is also developed to coordinate these actions to achieve satisfactory system performance.
Electrocatalysts for the Generation of Hydrogen, Oxygen and Synthesis Gas
Sep 2016
Publication
Water electrolysis is the most promising method for efficient production of high purity hydrogen (and oxygen) while the required power input for the electrolysis process can be provided by renewable sources (e.g. solar or wind). The thus produced hydrogen can be used either directly as a fuel or as a reducing agent in chemical processes such as in Fischer–Tropsch synthesis. Water splitting can be realized both at low temperatures (typically below 100 °C) and at high temperatures (steam water electrolysis at 500– 1000 °C) while different ionic agents can be electrochemically transferred during the electrolysis process (OH− H+ O2− ). Singular requirements apply in each of the electrolysis technologies (alkaline polymer electrolyte membrane and solid oxide electrolysis) for ensuring high electrocatalytic activity and long-term stability. The aim of the present article is to provide a brief overview on the effect of the nature and structure of the catalyst–electrode materials on the electrolyzer’s performance. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The current trends limitations and perspectives for future developments are summarized for the diverse electrolysis technologies of water splitting while the case of CO2/H2O co-electrolysis (for synthesis gas production) is also discussed.
Emission Reduction and Cost-benefit Analysis of the Use of Ammonia and Green Hydrogen as Fuel for Marine Applications
Dec 2023
Publication
Increasingly stringent emission standards have led shippers and port operators to consider alternative energy sources which can reduce emissions while minimizing capital investment. It is essential to understand whether there is a certain economic investment gap for alternative energy. The present work mainly focuses on the simulation study of ships using ammonia and hydrogen fuels arriving at Guangzhou Port to investigate the emission advantages and cost-benefit analysis of ammonia and hydrogen as alternative fuels. By collecting actual data and fuel consumption emissions of ships arriving at Guangzhou Port the present study calculated the pollutant emissions and cost of ammonia and hydrogen fuels substitution. As expected it is shown that with the increase of NH3 in fuel mixed fuels will effectively reduce CO and CO2 emissions. Compared to conventional fuel the injection of NH3 increases the NOx emission. However the cost savings of ammonia fuel for CO2 SOx and PM10 reduction are higher than that for NOx. In terms of pollutants ammonia is less expensive than conventional fuels when applied to the Guangzhou Port. However the cost of fuel supply is still higher than conventional energy as ammonia has not yet formed a complete fuel supply and storage system for ships. On the other hand hydrogen is quite expensive to store and transport resulting in higher overall costs than ammonia and conventional fuels even if no pollutants are produced. At present conventional fuels still have advantage in terms of cost. With the promotion of ammonia fuel technology and application the cost of supply will be reduced. It is predicted that by 2035 ammonia will not only have emission reduction benefits but also will have a lower overall economic cost than conventional fuels. Hydrogen energy will need longer development and technological breakthroughs due to the limitation of storage conditions.
Evaluation of Hydrogen Addition on Combustion and Emission Characteristics of Dual-Fuel Diesel Engines with Different Compression Ratios
Sep 2023
Publication
In this paper a computational fluid dynamics (CFD) model was established and verified on the basis of experimental results and then the effect of hydrogenation addition on combustion and emission characteristics of a diesel–hydrogen dual-fuel engine fueled with hydrogenation addition (0% 5% and 10%) under different hydrogenation energy shares (HESs) and compression ratios (CRs) were investigated using CONVERGE3.0 software. And this work assumed that the hydrogen and air were premixed uniformly. The correctness of the simulation model was verified by experimental data. The values of HES are in the range of 0% 5% 10% and 15%. And the values of CR are in the range of 14 16 18 and 20. The results of this study showed that the addition of hydrogen to diesel fuel has a significant effect on the combustion characteristics and the emission characteristics of diesel engines. When the HES was 15% the in-cylinder pressure increased by 10.54%. The in-cylinder temperature increased by 15.11%. When the CR was 20 the in-cylinder pressure and the in-cylinder temperature increased by 66.10% and 13.09% respectively. In all cases HC CO CO2 and soot emissions decreased as the HES increased. But NOx emission increased.
Genesis and Energy Significance of Natural Hydrogen
Jan 2023
Publication
H2 is clean energy and an important component of natural gas. Moreover it plays an irreplaceable role in improving the hydrocarbon generation rate of organic matter and activating ancient source rocks to generate hydrocarbon in Fischer-Tropsch (FT) synthesis and catalytic hydrogenation. Compared with hydrocarbon reservoir system a complete hydrogen (H2) accumulation system consists of H2 source,reservoirs and seal. In nature the four main sources of H2 are hydrolysis organic matter degradation the decomposition of substances such as methane and ammonia and deep mantle degassing. Because the complex tectonic activities the H2 produced in a geological environment is generally a mixture of various sources. Compared with the genetic mechanisms of H2 the migration and preservation of H2 especially the H2 trapping are rarely studied. A necessary condition for large-scale H2 accumulation is that the speed of H2 charge is much faster than diffusion loss. Dense cap rock and continuous H2 supply are favorable for H2 accumulation. Moreover H2O in the cap rock pores may provide favorable conditions for short-term H2 accumulation.
Industrial Development Status and Prospects of the Marine Fuel Cell: A Review
Jan 2023
Publication
In the context of the increasingly strict pollutant emission regulations and carbon emission reduction targets proposed by the International Maritime Organization the shipping industry is seeking new types of marine power plants with the advantages of high efficiency and low emissions. Among the possible alternatives the fuel cell is considered to be the most practical technology as it provides an efficient means to generate electricity with low pollutant emissions and carbon emissions. Very few comprehensive reviews focus on the maritime applications of the fuel cell. Thus news reports and literature on the maritime applications of the fuel cell in the past sixty years were collected and the industrial development status and prospects of the marine fuel cell were summarized as follows. Some countries in Europe North America and Asia have invested heavily in researching and developing the marine fuel cell and a series of research projects have achieved concrete results such as the industrialized marine fuel cell system or practical demonstration applications. At present the worldwide research of the marine fuel cell focuses more on the proton exchange membrane fuel cell (PEMFC). However the power demand of the marine fuel cell in the future will show steady growth and thus the solid oxide fuel cell (SOFC) with the advantages of higher power and fuel diversity will be the mainstream in the next research stage. Although some challenges exist the SOFC can certainly lead the upgrading and updating of the marine power system with the cooperative efforts of the whole world.
Experimental Investigations of the Hydrogen Injectors on the Combustion Characteristics and Performance of a Hydrogen Internal Combustion Engine
Feb 2024
Publication
Hydrogen is regarded as an ideal zero-carbon fuel for an internal combustion engine. However the low mass flow rate of the hydrogen injector and the low volume heat value of the hydrogen strongly restrict the enhancement of the hydrogen engine performance. This experimental study compared the effects of single-injectors and double-injectors on the engine performance combustion pressure heat release rate and the coefficient of variation (CoVIMEP) based on a singlecylinder 0.5 L port fuel injection hydrogen engine. The results indicated that the number of hydrogen injectors significantly influences the engine performance. The maximum brake power is improved from 4.3 kW to 6.12 kW when adding the injector. The test demonstrates that the utilization of the double-injector leads to a reduction in hydrogen obstruction in the intake manifold consequently minimizing the pumping losses. The pump mean effective pressure decreased from −0.049 MPa in the single-injector condition to −0.029 MPa in the double-injector condition with the medium loads. Furthermore the double-injector exhibits excellent performance in reducing the coefficient of variation. The maximum CoVIMEP decreased from 2.18% in the single-injector configuration to 1.92% in the double-injector configuration. This result provides new insights for optimizing hydrogen engine injector design and optimizing the combustion process.
Optimal Capacity Configuration of Wind–Solar Hydrogen Storage Microgrid Based on IDW-PSO
Aug 2023
Publication
Because the new energy is intermittent and uncertain it has an influence on the system’s output power stability. A hydrogen energy storage system is added to the system to create a wind light and hydrogen integrated energy system which increases the utilization rate of renewable energy while encouraging the consumption of renewable energy and lowering the rate of abandoning wind and light. Considering the system’s comprehensive operation cost economy power fluctuation and power shortage as the goal considering the relationship between power generation and load assigning charging and discharging commands to storage batteries and hydrogen energy storage and constructing a model for optimal capacity allocation of wind–hydrogen microgrid system. The optimal configuration model of the wind solar and hydrogen microgrid system capacity is constructed. A particle swarm optimization with dynamic adjustment of inertial weight (IDW-PSO) is proposed to solve the optimal allocation scheme of the model in order to achieve the optimal allocation of energy storage capacity in a wind–hydrogen storage microgrid. Finally a microgrid system in Beijing is taken as an example for simulation and solution and the results demonstrate that the proposed approach has the characteristics to optimize the economy and improve the capacity of renewable energy consumption realize the inhibition of the fluctuations of power reduce system power shortage and accelerate the convergence speed.
Research on Hydrogen Production System Technology Based on Photovoltaic-Photothermal Coupling Electrolyzer
Dec 2023
Publication
Solar hydrogen production technology is a key technology for building a clean low-carbon safe and efficient energy system. At present the intermittency and volatility of renewable energy have caused a lot of “wind and light.” By combining renewable energy with electrolytic water technology to produce high-purity hydrogen and oxygen which can be converted into electricity the utilization rate of renewable energy can be effectively improved while helping to improve the solar hydrogen production system. This paper summarizes and analyzes the research status and development direction of solar hydrogen production technology from three aspects. Energy supply mode: the role of solar PV systems and PT systems in this technology is analyzed. System control: the key technology and system structure of different types of electrolytic cells are introduced in detail. System economy: the economy and improvement measures of electrolytic cells are analyzed from the perspectives of cost consumption efficiency and durability. Finally the development prospects of solar hydrogen production systems in China are summarized and anticipated. This article reviews the current research status of photovoltaic-photothermal coupled electrolysis cell systems fills the current research gap and provides theoretical reference for the further development of solar hydrogen production systems.
Prediction of Mixing Uniformity of Hydrogen Injection in Natural Gas Pipeline Based on a Deep Learning Model
Nov 2022
Publication
It is economical and efficient to use existing natural gas pipelines to transport hydrogen. The fast and accurate prediction of mixing uniformity of hydrogen injection in natural gas pipelines is important for the safety of pipeline transportation and downstream end users. In this study the computational fluid dynamics (CFD) method was used to investigate the hydrogen injection process in a T-junction natural gas pipeline. The coefficient of variation (COV) of a hydrogen concentration on a pipeline cross section was used to quantitatively characterize the mixing uniformity of hydrogen and natural gas. To quickly and accurately predict the COV a deep neural network (DNN) model was constructed based on CFD simulation data and the main influencing factors of the COV including flow velocity hydrogen blending ratio gas temperature flow distance and pipeline diameter ratio were taken as input nodes of the DNN model. In the model training process the effects of various parameters on the prediction accuracy of the DNN model were studied and an accurate DNN architecture was constructed with an average error of 4.53% for predicting the COV. The computational efficiency of the established DNN model was also at least two orders of magnitude faster than that of the CFD simulations for predicting the COV.
The Effect of Explosions on the Protective Wall of a Containerized Hydrogen Fuel Cell System
Jun 2023
Publication
With the development of hydrogen energy containerized hydrogen fuel cell systems are being used in distributed energy-supply systems. Hydrogen pipelines and electronic equipment of fuel cell containers can trigger hydrogen-explosion accidents. In the present study Computational Fluid Dynamics (CFD) software was used to calculate the affected areas of hydrogen fuel cell container-explosion accidents with and without protective walls. The protective effects were studied for protective walls at various distances and heights. The results show that strategically placing protective walls can effectively block the propagation of shock waves and flames. However the protective wall has a limited effect on the reduction of overpressure and temperature behind the wall when the protective wall is insufficiently high. Reflected explosion shock waves and flames will cause damage to the area inside the wall when the protective wall is too close to the container. In this study a protective wall that is 5 m away from the container and 3 m high can effectively protect the area behind the wall and prevent damage to the container due to the reflection of shock waves and flame. This paper presents a suitable protective wall setting scheme for hydrogen fuel cell containers.
Design of Long-Life Wireless Near-Field Hydrogen Gas Sensor
Feb 2024
Publication
A compact wireless near-field hydrogen gas sensor is proposed which detects leaking hydrogen near its source to achieve fast responses and high reliability. A semiconductor-type sensing element is implemented in the sensor which can provide a significant response in 100 ms when stimulated by pure hydrogen. The overall response time is shortened by orders of magnitude compared to conventional sensors according to simulation results which will be within 200 ms compared with over 25 s for spatial concentration sensors under the worst conditions. Over 1 year maintenance intervals are enabled by wireless design based on the Bluetooth low energy protocol. The average energy consumption during a single alarm process is 153 µJ/s. The whole sensor is integrated on a 20 × 26 mm circuit board for compact use.
Research on the Technical Scheme of Multi-stack Common Rail Fuel Cell Engine Based on the Demand of Commercial Vehicle
Feb 2024
Publication
At present most fuel cell engines are single-stack systems and high-power single-stack systems have bottlenecks in meeting the power requirements of heavy-duty trucks mainly because the increase in the single active area and the excessive number of cells will lead to poor distribution uniformity of water gas and heat in the stack which will cause local attenuation and reduce the performance of the stack. This paper introduces the design concept of internal combustion engine takes three-stack fuel cell engine as an example designs multi-stack fuel cell system scheme and serialized high-voltage scheme. Through Intelligent control technology of independent hydrogen injection based on multi-stack coupling the hydrogen injection inflow of each stack is controlled online according to the real-time anode pressure to achieve accurate fuel injection of a single stack and ensure the consistency between multiple stacks. proves the performance advantage of multi-stack fuel cell engine through theoretical designintelligent control and test verification and focuses on analyzing the key technical problems that may exist in multi-stack consistency. The research results provide a reference for the design of multi-stack fuel cell engines and have important reference value for the powertrain design of long-distance heavy-duty and high-power fuel cell trucks.
Hydrogen as a Transition Tool in a Fossil Fuel Resource Region: Taking China’s Coal Capital Shanxi as an Example
Aug 2023
Publication
Because of the pressure to meet carbon neutrality targets carbon reduction has become a challenge for fossil fuel resource-based regions. Even though China has become the most active country in carbon reduction its extensive energy supply and security demand make it difficult to turn away from its dependence on coal-based fossil energy. This paper analyzes the Chinese coal capital—Shanxi Province—to determine whether the green low-carbon energy transition should be focused on coal resource areas. In these locations the selection and effect of transition tools are key to ensuring that China meets its carbon reduction goal. Due to the time window of clean coal utilization the pressure of local governments and the survival demands of local high energy consuming enterprises Shanxi Province chose hydrogen as its important transition tool. A path for developing hydrogen resources has been established through lobbying and corporative influence on local and provincial governments. Based on such policy guidance Shanxi has realized hydrogen applications in large-scale industrial parks regional public transport and the iron and steel industry. This paper distinguishes between the development strategies of gray and green hydrogen. It shows that hydrogen can be an effective development model for resource-based regions as it balances economic stability and energy transition.
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.
A Model for Assessing the Potential Impact Radius of Hydrogen Pipelines Based on Jet Fire Radiation
Jan 2024
Publication
The accurate determination of the potential impact radius is crucial for the design and risk assessment of hydrogen pipelines. The existing methodologies employ a single point source model to estimate radiation and the potential impact radius. However these approaches overlook the jet fire shape resulting from high-pressure leaks leading to discrepancies between the calculated values and real-world incidents. This study proposes models that account for both the mass release rate while considering the pressure drop during hydrogen pipeline leakage and the radiation while incorporating the flame shape. The analysis encompasses 60 cases that are representative of hydrogen pipeline scenarios. A simplified model for the potential impact radius is subsequently correlated and its validity is confirmed through comparison with actual cases. The proposed model for the potential impact radius of hydrogen pipelines serves as a valuable reference for the enhancement of the precision of hydrogen pipeline design and risk assessment.
Study on the Application of a Multi-Energy Complementary Distributed Energy System Integrating Waste Heat and Surplus Electricity for Hydrogen Production
Feb 2024
Publication
To improve the recovery of waste heat and avoid the problem of abandoning wind and solar energy a multi-energy complementary distributed energy system (MECDES) is proposed integrating waste heat and surplus electricity for hydrogen storage. The system comprises a combined cooling heating and power (CCHP) system with a gas engine (GE) solar and wind power generation and miniaturized natural gas hydrogen production equipment (MNGHPE). In this novel system the GE’s waste heat is recycled as water vapor for hydrogen production in the waste heat boiler while surplus electricity from renewable sources powers the MNGHPE. A mathematical model was developed to simulate hydrogen production in three building types: offices hotels and hospitals. Simulation results demonstrate the system’s ability to store waste heat and surplus electricity as hydrogen thereby providing economic benefit energy savings and carbon reduction. Compared with traditional energy supply methods the integrated system achieves maximum energy savings and carbon emission reduction in office buildings with an annual primary energy reduction rate of 49.42–85.10% and an annual carbon emission reduction rate of 34.88–47.00%. The hydrogen production’s profit rate is approximately 70%. If the produced hydrogen is supplied to building through a hydrogen fuel cell the primary energy reduction rate is further decreased by 2.86–3.04% and the carbon emission reduction rate is further decreased by 12.67–14.26%. This research solves the problem of waste heat and surplus energy in MECDESs by the method of hydrogen storage and system integration. The economic benefits energy savings and carbon reduction effects of different building types and different energy allocation scenarios were compared as well as the profitability of hydrogen production and the factors affecting it. This has a positive technical guidance role for the practical application of MECDESs.
Low-carbon Economy Dispatching of Integrated Energy System with P2G-HGT Coupling Wind Power Absorption Based on Stepped Carbon Emission Trading
Aug 2023
Publication
To improve the renewable energy consumption capacity of integrated energy system (IES) and reduce the carbon emission level of the system a low-carbon economic dispatch model of IES with coupled power-to-gas (P2G) and hydrogen-doped gas units (HGT) under the stepped carbon trading mechanism is proposed. On the premise of wind power output uncertainty the operating characteristics of the coupled electricity-to-gas equipment in the system are used to improve the wind abandonment problem of IES and increase its renewable energy consumption capacity; HGT is introduced to replace the traditional combustion engine for energy supply and on the basis of refined P2G a part of the volume fraction of hydrogen obtained from the production is extracted and mixed with methane to form a gas mixture for HGT combustion so as to improve the low-carbon economy of the system. The ladder type carbon trading mechanism is introduced into IES to guide the system to control carbon emission behavior and reduce the carbon emission level of IES. Based on this an optimal dispatching strategy is constructed with the economic goal of minimizing the sum of system operation cost wind abandonment cost carbon trading cost and energy purchase cost. After linearization of the established model and comparison analysis by setting different scenarios the wind power utilization rate of the proposed model is increased by 24.5% and the wind abandonment cost and CO2 emission are reduced by 86.3% and 10.5% respectively compared with the traditional IES system which achieves the improvement of renewable energy consumption level and low carbon economy.
Two-stage Optimization of Hydrogen and Storage Coordination for a Multi-region Flexible Intermodal Multi-energy Port System
Jan 2024
Publication
To address the issue of imbalanced electricity and hydrogen supply and demand in the flexible multi-energy port area system a multi-regional operational optimization and energy storage capacity allocation strategy considering the working status of flexible multi-status switches is proposed. Firstly based on the characteristics of the port area system models for system operating costs generation equipment energy storage devices flexible multi-status switches and others are established. Secondly the system is subjected to a first-stage optimization where different regions are optimized individually. The working periods of flexible multi-status switches are determined based on the results of this first-stage optimization targeting the minimization of the overall daily operating costs while ensuring 100% integration of renewable energy in periods with electricity supply-demand imbalances. Subsequently additional constraints are imposed based on the results of the first-stage optimization to optimize the entire system obtaining power allocation during system operation as well as power and capacity requirements for energy storage devices and flexible multi-status switches. Finally the proposed approach is validated through simulation examples demonstrating its advantages in terms of economic efficiency reduced power and capacity requirements for energy storage devices and carbon reduction.
Process Path for Reducing Carbon Emissions from Steel Industry—Combined Electrification and Hydrogen Reduction
Jan 2024
Publication
This review focuses on the energy structure of iron and steel production and a feasible development path for carbon reduction. The process path and feasible development direction of carbon emission reduction in the iron and steel industry have been analyzed from the perspective of the carbon–electricity–hydrogen ternary relationship. Frontier technologies such as “hydrogen replacing carbon” are being developed worldwide. Combining the high efficiency of microwave electric-thermal conversion with the high efficiency and pollution-free advantages of hydrogen-reducing agents may drive future developments. In this review a process path for “microwave + hydrogen” synergistic metallurgy is proposed. The reduction of magnetite powder by H2 (CO) in a microwave field versus in a conventional field is compared. The driving effect of the microwave field is found to be significant and the synergistic reduction effect of microwaves with H2 is far greater than that of CO.
How Would Structural Change in Electricity and Hydrogen End Use Impact Low-Carbon Transition of an Energy System? A Case Study of China
Feb 2024
Publication
Driven by global targets to reduce greenhouse gas emissions energy systems are expected to undergo fundamental changes. In light of carbon neutrality policies China is expected to significantly increase the proportion of hydrogen and electricity in its energy system in the future. Nevertheless the future trajectory remains shrouded in uncertainty. To explore the potential ramifications of varying growth scenarios pertaining to hydrogen and electricity on the energy landscape this study employs a meticulously designed bottom-up model. Through comprehensive scenario calculations the research aims to unravel the implications of such expansions and provide a nuanced analysis of their effects on the energy system. Results show that with an increase in electrification rates cumulative carbon dioxide emissions over a certain planning horizon could be reduced at the price of increased unit reduction costs. By increasing the share of end-use electricity and hydrogen from 71% to 80% in 2060 the unit carbon reduction cost will rise by 17%. Increasing shares of hydrogen could shorten the carbon emission peak time by approximately five years but it also brings an increase in peak shaving demand.
Anion Exchange Membrane Water Electrolyzer: Electrode Design, Lab-scaled Testing System and Performance Evaluation
Aug 2022
Publication
Green hydrogen produced by water electrolysis is one of the most promising technologies to realize the efficient utilization of intermittent renewable energy and the decarbonizing future. Among various electrolysis technologies the emerging anion-exchange membrane water electrolysis (AEMWE) shows the most potential for producing green hydrogen at a competitive price. In this review we demonstrate a comprehensive introduction to AEMWE including the advanced electrode design the lab-scaled testing system establishment and the electrochemical performance evaluation. Specifically recent progress in developing high activity transition metal-based powder electrocatalysts and self-supporting electrodes for AEMWE is summarized. To improve the synergistic transfer behaviors between electron charge water and gas inside the gas diffusion electrode (GDE) two optimizing strategies are concluded by regulating the pore structure and interfacial chemistry. Moreover we provide a detailed guideline for establishing the AEMWE testing system and selecting the electrolyzer components. The influences of the membrane electrode assembly (MEA) technologies and operation conditions on cell performance are also discussed. Besides diverse electrochemical methods to evaluate the activity and stability implement the failure analyses and realize the in-situ characterizations are elaborated. In end some perspectives about the optimization of interfacial environment and cost assessments have been proposed for the development of advanced and durable AEMWE.
Numerical Investigation on the Liquid Hydrogen Leakage and Protection Strategy
Apr 2023
Publication
One of China’s ambitious hydrogen strategies over the past few years has been to promote fuel cells. A number of hydrogen refueling stations (HRSs) are currently being built in China to refuel hydrogen-powered automobiles. In this context it is crucial to assess the dangers of hydrogen leaking in HRSs. The present work simulated the liquid hydrogen (LH2) leakage with the goal of undertaking an extensive consequence evaluation of the LH2 leakage on an LH2 refueling station (LHRS). Furthermore the utilization of an air curtain to prevent the diffusion of the LH2 leakage is proposed and the defending effect is studied accordingly. The results reveal that the Richardson number effectively explained the variation of plume morphology. Furthermore different facilities have great influence on the gas cloud diffusion trajectory with the consideration of different leakage directions. The air curtain shows satisfactory prevention of the diffusion of the hydrogen plume. Studies show that with the increase in air volume (equivalent to wind speed) and the narrowing of the air curtain width (other factors remain unchanged) the maximum flammable distance of hydrogen was shortened.
Alternative Power Options for Improvement of the Environmental Friendliness of Fishing Trawlers
Dec 2022
Publication
The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency environmental performance and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy i.e. by analyzing ship technical data and assuming its operative profile or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea including three phases of the Life-Cycle Assessment (manufacturing Well-to-Pump (WTP) and Pump-to-Wake (PTW)). Based on the data on fuel consumption the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy due to their high price and complex application in an obsolete fleet they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers.
Parametric Study and Optimization of Hydrogen Production Systems Based on Solar/Wind Hybrid Renewable Energies: A Case Study in Kuqa, China
Jan 2024
Publication
Based on the concept of sustainable development to promote the development and application of renewable energy and enhance the capacity of renewable energy consumption this paper studies the design and optimization of renewable energy hydrogen production systems. For this paper six different scenarios for grid-connected and off-grid renewable energy hydrogen production systems were designed and analyzed economically and technically and the optimal grid-connected and off-grid systems were selected. Subsequently the optimal system solution was optimized by analyzing the impact of the load data and component capacity on the grid dependency of the grid-connected hydrogen production system and the excess power rate of the off-grid hydrogen production system. Based on the simulation results the most matched load data and component capacity of different systems after optimization were determined. The grid-supplied power of the optimized grid-connected hydrogen production system decreased by 3347 kWh and the excess power rate of the off-grid hydrogen production system decreased from 38.6% to 10.3% resulting in a significant improvement in the technical and economic performance of the system.
Coal Decarbonization: A State-of-the-art Review of Enhanced Hydrogen Production in Underground Coal Gasification
Aug 2022
Publication
The world is endowed with a tremendous amount of coal resources which are unevenly distributed in a few nations. While sustainable energy resources are being developed and deployed fossil fuels dominate the current world energy consumption. Thus low-carbon clean technologies like underground coal gasification (UCG) ought to play a vital role in energy supply and ensuring energy security in the foreseeable future. This paper provides a state-of-the-art review of the world's development of UCG for enhanced hydrogen production. It is revealed that the world has an active interest in decarbonizing the coal industry for hydrogen-oriented research in the context of UCG. While research is ongoing in multiple coal-rich nations China dominates the world's efforts in both industrial-scale UCG pilots and laboratory experiments. A variety of coal ranks were tested in UCG for enhanced hydrogen output and the possibilities of linking UCG with other prospective technologies had been proposed and critically scrutinized. Moreover it is found that transborder collaborations are in dire need to propel a faster commercialization of UCG in an ever-more carbon-conscious world. Furthermore governmental and financial support is necessary to incentivize further UCG development for large-scale hydrogen production.
Green Hydrogen Credit Subsidized Renewable Energy-hydrogen Business Models for Achieving the Carbon Netural Future
Feb 2024
Publication
The global resurgence of hydrogen as a clean energy source particularly green hydrogen derived from renewable energy is pivotal for achieving a carbon-neutral future. However scalability poses a significant challenge. This research proposes innovative business models leveraging the low-emission property of green hydrogen to reduce its financial costs thereby fostering its widespread adoption. Key components of the business workflow are elaborated mathematical formulations of market parameters are derived and case studies are presented to demonstrate the feasibility and efficiency of these models. Results demonstrate that the substantial costs associated with the current hydrogen industry can be effectively subsidized via the implementation of proposed business models. When the carbon emission price falls within the range of approximately 86–105 USD/ton free access to hydrogen becomes a viable option for end-users. This highlights the significance and promising potential of the proposed business models within the green hydrogen credit framework.
Data-driven Scheme for Optimal Day-ahead Operation of a Wind/hydrogen System Under Multiple Uncertainties
Nov 2022
Publication
Hydrogen is believed as a promising energy carrier that contributes to deep decarbonization especially for the sectors hard to be directly electrified. A grid-connected wind/hydrogen system is a typical configuration for hydrogen production. For such a system a critical barrier lies in the poor cost-competitiveness of the produced hydrogen. Researchers have found that flexible operation of a wind/hydrogen system is possible thanks to the excellent dynamic properties of electrolysis. This finding implies the system owner can strategically participate in day-ahead power markets to reduce the hydrogen production cost. However the uncertainties from imperfect prediction of the fluctuating market price and wind power reduce the effectiveness of the offering strategy in the market. In this paper we proposed a decision-making framework which is based on data-driven robust chance constrained programming (DRCCP). This framework also includes multi-layer perception neural network (MLPNN) for wind power and spot electricity price prediction. Such a DRCCP-based decision framework (DDF) is then applied to make the day-ahead decision for a wind/hydrogen system. It can effectively handle the uncertainties manage the risks and reduce the operation cost. The results show that for the daily operation in the selected 30 days offering strategy based on the framework reduces the overall operation cost by 24.36% compared to the strategy based on imperfect prediction. Besides we elaborate the parameter selections of the DRCCP to reveal the best parameter combination to obtain better optimization performance. The efficacy of the DRCCP method is also highlighted by the comparison with the chance-constrained programming method.
Off-grid Wind/Hydrogen Systems with Multi-electrolyzers: Optimized Operational Strategies
Sep 2023
Publication
Optimized operation of wind/hydrogen systems can increase the system efficiency and further reduce the hydrogen production cost. In this regard extensive research has been done but there is a lack of detailed electrolyzer models and effective management of multiple electrolyzers considering their physical restrictions. This work proposes electrolyzer models that integrate the efficiency variation caused by load level change start–stop cycle (including hot and cold start) thermal management and degradation caused by frequent starts. Based on the proposed models three operational strategies are considered in this paper: two traditionally utilized methods simple start–stop and cycle rotation strategies and a newly proposed rolling optimizationbased strategy. The results from daily operation show that the new strategy results in a more balanced load level among the electrolyzers and a more stable temperature. Besides from a yearly operation perspective it is found that the proposed rolling optimization method results in more hydrogen production higher system efficiency and lower LCOH. The new method leads to hydrogen production of 311297 kg compared to 289278 kg and 303758 kg for simple start–stop and cycle rotation methods. Correspondingly the system efficiencies for the new simple start–stop and cycle rotation methods are 0.613 0.572 and 0.587. The resulting LCOH from the new method is 3.89 e/kg decreasing by 0.35 e/kg and 0.21 e/kg compared to the simple start–stop and cycle rotation methods. Finally the proposed model is compared with two conventional models to show its effectiveness in revealing more operational details and reliable results.
Efficient Combustion of Low Calorific Industrial Gases: Opportunities and Challenges
Dec 2022
Publication
It is becoming increasingly important to develop effective combustion technologies for low calorific industrial gases (LCIG) because of the rising energy demand and environmental issues caused by the extensive use of fossil fuels. In this review the prospect of these opportunity fuels in China is discussed. Then the recent fundamental and engineering studies of LCIG combustion are summarized. Specifically the differences between LCIG and traditional fuels in the composition and fundamental combustion characteristics are described. The state-of-the-art combustion strategies for burning LCIG are reviewed including porous media combustion flameless combustion oxy-fuel combustion and dual-fuel combustion. The technical challenges and further development needs for efficient LCIG combustion are also discussed.
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