JournalTOCs

Clean Energy
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This is an Open Access Journal

Open Access journal
ISSN (Print) 2515-4230 - ISSN (Online) 2515-396X
Published by Oxford University Press

[424 journals]

Forward perspective on the development and strategic pathway of green
hydrogen in China
- Pages: 1 - 7
  Abstract: Fundamental transformations are taking place in the areas of energy structure on the supply side and on the energy-consumption side towards clean, low-carbon and safe energy. Furthermore, a new energy system is being constructed with renewable energy as its core in China with energy transition and ‘carbon peak and carbon neutral’ as the overall goal. China’s hydrogen-industry plan, ‘Mid-to-long term hydrogen industry development plan (2021–2035)’, has an emphasis on hydrogen generation by using renewable energies as the centre piece, which points in the right direction for hydrogen’s green development. In this paper, the current status of China’s hydrogen industry is analysed; strategic needs for green hydrogen’s development and its hurdles in its paths are sorted out. Integrated demonstration at provincial levels, development of a ‘great hydrogen base’ and the green-hydrogen development path by gradual substitution with renewable hydrogen are proposed. Scaled-up hydrogen production, expanded consumer hydrogen usage and established hydrogen commodity exchange are recommended to safeguard its development and promote its high-quality development in China.
  PubDate: Wed, 01 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac094
  Issue No: Vol. 7, No. 1 (2023)
Wind energy as a source of green hydrogen production in the USA
- Pages: 8 - 22
  Abstract: The study incorporates an overview of the green hydrogen-production potential from wind energy in the USA, its application in power generation and the scope of substituting grey and blue hydrogen for industrial usage. Over 10 million metric tons of grey and blue hydrogen is produced in the USA annually to fulfil the industrial demand, whereas, for 1 million metric tons of hydrogen generated, 13 million metric tons of CO2 are released into the atmosphere. The research aims to provide a state-of-the-art review of the green hydrogen technology value chain and a case study on the production of green hydrogen from an 8-MW wind turbine installed in the southern plain region of Texas. This research estimates that the wind-farm capacity of 130 gigawatt-hours is required to substitute grey and blue hydrogen for fulfilling the current US annual industrial hydrogen demand of 10 million metric tons. The study investigates hydrogen-storage methods and the scope of green hydrogen-based storage facilities for energy produced from a wind turbine. This research focuses on the USA’s potential to meet all its industrial and other hydrogen application requirements through green hydrogen.
  PubDate: Tue, 07 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac075
  Issue No: Vol. 7, No. 1 (2023)
Development of fuelling protocols for gaseous hydrogen vehicles: a key
component for efficient and safe hydrogen mobility infrastructures
- Pages: 23 - 29
  Abstract: Large-scale applications of fuel-cell vehicles (FCVs) are of vital importance to reduce emissions of greenhouse gases in the transportation sector, especially in the heavy-duty and long-distance scenarios. Efficient fuelling for the on-board gaseous hydrogen cylinders of an FCV is essential to achieve a fuelling experience that is comparable to that of traditional fossil-fuel-powered vehicles. However, the heating effect during refuelling leads to potential safety issues when the hydrogen temperature in the cylinder exceeds 85°C. Therefore, fuelling protocols are critical to ensure the efficiency and safety of the hydrogen mobility infrastructure. In this paper, the fuelling protocols for FCV vans and buses with type III cylinders were developed and the pre-cooling temperatures were optimized to minimize the energy consumption. Their performance was demonstrated with a 35-MPa hydrogen fuelling station. We found that FCV vans and buses can be safely refuelled in 3 or 5 minutes at a minimum, respectively, demonstrating a fuelling experience that is similar to that of traditional vehicles.
  PubDate: Thu, 09 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac087
  Issue No: Vol. 7, No. 1 (2023)
Economic analysis of hydrogen production from China’s province-level
power grid considering carbon emissions
- Pages: 30 - 40
  Abstract: Hydrogen energy contributes to China’s carbon peaking and carbon neutralization by serving as an important energy carrier. However, the calculation of the cost of hydrogen production by the power grid ignores the current cost of carbon emissions. To measure the cost of hydrogen-production projects in various provinces more comprehensively and accurately, this study incorporates the carbon-emission cost into the traditional levelized cost of hydrogen model. An analysis of the energy structure of the power supply is conducted in each province of China to calculate carbon-emission costs, which are then subjected to a sensitivity test. Based on the results, the carbon-emission costs for hydrogen in each province are between 0.198 and 1.307 CNY/kg, and the levelized cost of hydrogen based on carbon-emission costs varies from 24.813 to 48.020 CNY/kg; in addition, carbon-emission costs range from 0.61% to 3.4% of the total costs. The results also show that the levelized cost of hydrogen considering carbon-emission costs in the Shanghai municipality specifically is most sensitive to the carbon-emission price, changing by 0.131 CNY/kg for every 10% fluctuation in the carbon-emission price.
  PubDate: Fri, 17 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac091
  Issue No: Vol. 7, No. 1 (2023)
Announcing the 2021 Best Paper Prize Winners
- Pages: 41 - 41
  Abstract: Clean Energy, with the support of the China Energy Group, is pleased to announce the Clean Energy Best Paper Prizes for 2021. The editors recognize that Clean Energy has been growing. Therefore in 2021, we presented three prize winners that cover important and forward-looking research to support a clean and low-carbon energy future.
  PubDate: Fri, 24 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac093
  Issue No: Vol. 7, No. 1 (2023)
Research on cooling-temperature control strategy of fuel-cell engine test
bench
- Pages: 42 - 52
  Abstract: As one of the important ways to utilize hydrogen energy, fuel cells are receiving more and more attention and research from countries and institutions. To meet the practical needs of testing the performance of high-power fuel-cell systems and simulate the actual application environment as much as possible, a fuel-cell system test bench is usually used to test the system performance, in which the cooling-temperature control of the test bench has a great impact on the results of the performance of the fuel-cell system. This paper studies the cooling-temperature control strategy of a 150-kW-class fuel-cell engine test platform, proposes a new test-bench cooling-system structure with a thermostat and heat exchanger as the main heat-dissipation components, and compares and analyzes the impact of coordinated thermostat and heat-exchanger control on the fuel-cell system test performance. The test results show that the control strategy of the coordinated operation of a thermostat and heat exchanger can maintain the steady-state error to within ±0.3℃ and maintain the temperature variation to within ±1.5℃ during the loading-condition test, so as to avoid the limitation of system output performance due to excessive cooling-temperature fluctuation and ensure that the fuel-cell engine performance-test process is carried out smoothly and efficiently.
  PubDate: Fri, 24 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkad001
  Issue No: Vol. 7, No. 1 (2023)
Design of GH4169 diaphragm for combined improvements of yield strength and
surface roughness
- Pages: 53 - 58
  Abstract: Diaphragm compressors have become the primary source of on-site hydrogen compression for hydrogen fuelling stations around the world. The most common hydrogen-compressor-failure mechanism has been identified as diaphragm fracture due to low tensile strength and poor surface properties. In this study, a new type of GH4169 diaphragm with high yield strength and low surface roughness was fabricated. Microstructures, tensile behaviours and surface properties of the specimens were characterized by using scanning electron microscopy, an electronic universal testing machine and atomic force microscopy, respectively. The evolution of the γ′′ and γ′ phases with temperature has been examined. Both γ′′ and γ′ phases were precipitant-strengthened phases for GH4169 and the volume and size of γ′′ and γ′ phases increase with ageing time. In addition, the γ′′ phase is the main strengthening phase and γ′ is the supportive strengthening phase. Tensile strength was increased due to the strengthening phases at the cost of ductility. The roughness of the diaphragm could reach an arithmetic average roughness (Ra) of 0.1 μ m by applying a cooling-assisted polishing process. This work improves the reliability and reduces the auxiliary steps and down-time for diaphragm compressors.
  PubDate: Fri, 24 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac090
  Issue No: Vol. 7, No. 1 (2023)
A review on the sealing structure and materials of fuel-cell stacks
- Pages: 59 - 69
  Abstract: Proton-exchange-membrane fuel cells (PEMFCs) have the characteristics of zero emissions, a low operating temperature and high power density, and have great potential in improving energy-utilization efficiency. However, fuel cells are still quite expensive as a result of the cost of key components, including the membranes, catalysts and bipolar plates of PEMFCs. As a result of the cost and importance of these items, most researchers have focused on improving the lifetime and performance of fuel-cell stacks in recent years. In contrast, seals, sealants and adhesives play a more mundane role in the overall performance of a fuel cell, but failure of these materials can lead to reduced system efficiency, system failure and even safety issues. Little attention has been paid to the performance and durability of these products but as other fuel-cell components improve, these seals are becoming an even more critical link in the long-term performance of fuel cells. This article highlights the importance and background of fuel-cell seals. The latest research progress on the mechanical properties and structural optimization of different sealing materials is reviewed.
  PubDate: Sat, 25 Feb 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac096
  Issue No: Vol. 7, No. 1 (2023)
Improved cell performance and sulphur tolerance using A-site substituted
Sr2Fe1.4Ni0.1Mo0.5O6–δ anodes for solid-oxide fuel cells
- Pages: 70 - 83
  Abstract: Solid-oxide fuel cells (SOFCs) offer great promise for producing electricity using a wide variety of fuels such as natural gas, coal gas and gasified carbonaceous solids; however, conventional nickel-based anodes face great challenges due to contaminants in readily available fuels, especially sulphur-containing compounds. Thus, the development of new anode materials that can suppress sulphur poisoning is crucial to the realization of fuel-flexible and cost-effective SOFCs. In this work, La0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (LSFNM) and Pr0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (PSFNM) materials have been synthesized using a sol-gel method in air and investigated as anode materials for SOFCs. Metallic nanoparticle-decorated ceramic anodes were obtained by the reduction of LSFNM and PSFNM in H2 at 850°C, forming a Ruddlesden–Popper oxide with exsolved FeNi3 bimetallic nanoparticles. The electrochemical performance of the Sr2Fe1.4Ni0.1Mo0.5O6–δ ceramic anode was greatly enhanced by La doping of A-sites, resulting in a 44% decrease in the polarization resistance in reducing atmosphere. The maximum power densities of Sr- and Mg-doped LaGaO3 (LSGM) (300 μm) electrolyte-supported single cells with LSFNM as the anode reached 1.371 W cm −2 in H2 and 1.306 W cm–2 in 50 ppm H2S–H2 at 850°C. Meanwhile, PSFNM showed improved sulphur tolerance, which could be fully recovered after six cycles from H2 to 50 ppm H2S–H2 operation. This study indicates that LSFNM and PSFNM are promising high-performance anodes for SOFCs.
  PubDate: Thu, 02 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac089
  Issue No: Vol. 7, No. 1 (2023)
Techno-economic analysis of green hydrogen as an energy-storage medium for
commercial buildings
- Pages: 84 - 98
  Abstract: Green-hydrogen production is vital in mitigating carbon emissions and is being adopted globally. In its transition to a more diverse energy mix with a bigger share for renewable energy, United Arab Emirates (UAE) has committed to investing billions of dollars in the production of green hydrogen. This study presents the results of the techno-economic assessment of a green-hydrogen-based commercial-building microgrid design in the UAE. The microgrid has been designed based on the building load demand, green-hydrogen production potential utilizing solar photovoltaic (PV) energy and discrete stack reversible fuel cell electricity generation during non-PV hours. Given the current market conditions and the hot humid climate of the UAE, a performance analysis is derived to evaluate the technical and economic feasibility of this microgrid. The study aims at maximizing both the building microgrid’s independence from the main grid and its renewable fraction. Simulation results indicate that the designed system is capable of meeting three-quarters of its load demand independently from the main grid and is supported by a 78% renewable-energy fraction. The economic analysis demonstrates a 3.117-$/kg levelized cost of hydrogen production and a 0.248-$/kWh levelized cost for storing hydrogen as electricity. Additionally, the levelized cost of system energy was found to be less than the current utility costs in the UAE. Sensitivity analysis shows the significant impact of the capital cost and discount rate on the levelized cost of hydrogen generation and storage.
  PubDate: Wed, 08 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac083
  Issue No: Vol. 7, No. 1 (2023)
Overview of hydrogen-resistant alloys for high-pressure hydrogen
environment: on the hydrogen energy structural materials
- Pages: 99 - 115
  Abstract: With the progressive expansion of hydrogen fuel demand, hydrogen pipelines, hydrogen storage cylinders and hydrogen refuelling stations (HRSs) are the primary components of hydrogen energy systems that face high-pressure hydrogen environments. Hydrogen embrittlement (HE) is a typical phenomenon in metallic materials, particularly in the high-pressure hydrogen environment, that causes loss of ductility and potentially catastrophic failure. HE is associated with materials, the service environment and stress. The primary mechanisms for explaining the HE of materials are hydrogen-enhanced decohesion, hydrogen-induced phase transformation, hydrogen-enhanced local plasticity, adsorption-induced dislocation emission and hydrogen-enhanced strain-induced vacancy. To reduce the risk of HE for metallic structural materials used in hydrogen energy systems, it is crucial to reasonably select hydrogen-resistant materials for high-pressure hydrogen environments. This paper summarizes HE phenomena, mechanisms and current problems for the metallic structural materials of hydrogen energy systems. A research perspective is also proposed, mainly focusing on metal structural materials for hydrogen pipelines, hydrogen storage cylinders and hydrogen compressors in HRSs from an application perspective.
  PubDate: Sat, 04 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkad009
  Issue No: Vol. 7, No. 1 (2023)
Research progress in green synthesis of ammonia as hydrogen-storage
carrier under ‘hydrogen 2.0 economy’
- Pages: 116 - 131
  Abstract: Hydrogen energy is characterized by its environmental friendliness, high efficiency, lack of carbon emissions and wide range of applications. However, its transportation and storage are challenges that limit further development of the hydrogen-energy industry. Ammonia is a carbon-free hydrogen-rich carrier. The storage of hydrogen in ammonia has unique advantages of high energy density, easy storage and transportation, reliable safety, a mature industrial foundation and no tail-end carbon emissions. However, industrial ammonia synthesis still heavily relies on the Haber–Bosch process, which accounts for significant energy consumption and greenhouse gas emissions. Therefore, the development of green and sustainable ammonia-synthesis methods is extremely important and urgent. Recently, ammonia-synthesis technologies such as electrocatalysis, photocatalysis, photoelectrocatalysis and biocatalysis have successfully produced ammonia from nitrogen and water, resulting in lower costs. The nitrogen-reduction-reaction conditions of these methods are mild and can be carried out under ambient temperatures and atmospheric pressure with low energy consumptions. Meanwhile, these methods bypass the traditional hydrogen-production section and their routes are simpler. Therefore, these technologies can be used to flexibly integrate renewable energy, including intermittent renewable energy, to achieve distributed ammonia synthesis. These benefits contribute to both global energy and environmental sustainability goals. In this study, the mechanisms of ammonia synthesis under ambient conditions are reviewed and the technical difficulties of various catalysts for ammonia synthesis are summarized. Based on the optimization strategies reported for various catalysts, the high-performing catalysts reported for ammonia synthesis are reviewed and the developmental trend of this field has been forecasted.
  PubDate: Thu, 09 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac095
  Issue No: Vol. 7, No. 1 (2023)
Integrated energy corridor: a comprehensive proposal of the low-carbon
transition for China Energy Group
- Pages: 132 - 138
  Abstract: New energy is considered to be an indispensable means to significantly reduce carbon emissions and to achieve the temperature-control goals defined by the Paris Climate Accord. Despite the bright future, the inherent characteristics, including volatility, intermittency and uneven seasonal and geographical distributions, and the rapid growth of installations make it increasingly difficult to connect green electricity to grids. This becomes a dominating bottleneck for the low-carbon transition of China Energy Group (CE). This paper aims to help with the implementation of the new-energy development plan and to define the low-carbon energy-transition path for CE. Based on the current industry structure of CE, Shenhua Engineering Technology Co., Ltd proposes the concept of an ‘integrated energy corridor’. The integrated energy corridor represents a comprehensive energy-transmission channel with coal, green electricity, green hydrogen, green oxygen and other green energy products such as transmission media, railways, pipelines and power grids as transmission means and thermal power, coal chemical plants, cities, etc. along the route as new-energy consumers and regulators. The integrated energy corridor can support the rapid development of new-energy assets and the low-carbon transition of CE.
  PubDate: Thu, 09 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkad005
  Issue No: Vol. 7, No. 1 (2023)
Effect of hydrogen impurities on hydrogen oxidation activity of Pt/C
catalyst in proton exchange membrane fuel cells
- Pages: 139 - 147
  Abstract: High-purity of hydrogen is vital to the guarantee of end usage in proton exchange membrane fuel cell (PEMFC) electric vehicles (EVs) with superior durability and low expense. However, the currently employed hydrogen, primarily from fossil fuel, still contains some poisoning impurities that significantly affect the durability of PEMFCs. Here, we investigate the poisoning effect of several typical hydrogen impurities (S2–, Cl–, HCOO– and CO32–) on the hydrogen oxidation reaction (HOR) of the state-of-the-art carbon-supported platinum (Pt/C) catalyst used in the PEMFC anode. Electrochemical results indicate that the electrochemically active surface area of Pt/C is hampered by these hydrogen impurities with reduced effective Pt reactive sites due to the competitive adsorption against hydrogen at Pt sites showing the extent of the poisoning on Pt sites in the order: S2– > Cl– > HCOO– > CO32–. Density functional theory calculations reveal that the adsorption energy of S2– on Pt (111) is greater than that of Cl–, HCOO– and CO2, and the electronic structure of Pt is found to be changed due to the adsorption of impurities showing the downshift of the d-band centre of Pt that weakens the adsorption of hydrogen on the Pt sites. This work provides valuable guidance for future optimization of hydrogen quality and also emphasizes the importance of anti-poisoning anode catalyst development, especially towards H2S impurities that seriously affect the durability of PEMFCs.
  PubDate: Thu, 09 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkac085
  Issue No: Vol. 7, No. 1 (2023)
Design and implementation of China Hydrogen Price Index system
- Pages: 148 - 156
  Abstract: Hydrogen will be an important part of China’s energy system in the future and an important carrier for energy-using terminals to realize green and low-carbon transformation. It is important to establish a nationwide hydrogen market to promote the healthy and orderly development of the hydrogen industry chain. The core is to form a complete hydrogen price mechanism and play a decisive role in the process of resource allocation by the market. In this paper, we have developed the framework of the ‘China Hydrogen Price Index’ system by establishing the ‘Assessment + Collection’ model, which covers four types of hydrogen: hydrogen, clean hydrogen, renewable hydrogen and high-purity hydrogen. The model considers the raw materials required for hydrogen production, fixed equipment, engineering construction costs and carbon prices, and conducts sensitivity analysis on the trends and influencing factors of national and regional hydrogen prices of multiple categories since 2018. The results show that, with respect to the level of hydrogen prices, fossil-energy-rich and renewable-energy-rich areas have more advantages than other regions. The price of raw materials is the main factor of the hydrogen price change, and the utilization hours of renewable energy and hydrogen production equipment have a key influence on the price of renewable hydrogen. Next, by establishing an index update mechanism, improving the standard system and building a trading platform, we can further exert the role of price signals and continue to promote the efficient and smooth expansion of the domestic hydrogen market.
  PubDate: Thu, 09 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkad008
  Issue No: Vol. 7, No. 1 (2023)
Wind-farm and hydrogen-storage co-location system optimization for dynamic
frequency response in the UK
- Pages: 157 - 173
  Abstract: The continuous development of hydrogen-electrolyser and fuel-cell technologies not only reduces their investment and operating costs but also improves their technical performance to meet fast-acting requirements of electrical grid balancing services such as frequency-response services. In order to project the feasibility of co-locating a hydrogen-storage system with a wind farm for the dynamic regulation frequency-response provision in Great Britain, this paper develops a modelling framework to coordinate the wind export and frequency responses to the main grid and manage the interaction of the electrolyser, compressor, storage tank and fuel cell within the hydrogen-storage system by respecting the market mechanisms and the balance and conversion of power and hydrogen flows. Then the revenue of frequency-response service provision and a variety of costs induced by the hydrogen-storage system are translated into the net profit of the co-location system, which is maximized by optimizing the capacities of hydrogen-storage-system components, hydrogen-storage levels that guide the hydrogen restoration via operational baselines and the power interchange between a wind-farm and hydrogen-storage system, as well as the capacities tendered for low- and high-frequency dynamic regulation services. The developed modelling framework is tested based on a particular 432-MW offshore wind farm in Great Britain combined with the techno-economics of electrolysers and fuel cells projected for 2030 and 2050 scenarios. The optimized system configuration and operation are compared between different operating scenarios and discussed alongside the prospect of applying hydrogen-storage systems for frequency-response provision.
  PubDate: Fri, 10 Mar 2023 00:00:00 GMT
  DOI: 10.1093/ce/zkad006
  Issue No: Vol. 7, No. 1 (2023)