China, People’s Republic

Hydrogen as one of the most promising renewable clean energy sources holds significant strategic importance and vast application potential. However as a high-energy combustible gas hydrogen poses risks of fire and explosion in the event of a leakage. Hydrogen production plants typically feature large spatial volumes and complex obstacles which can significantly influence the diffusion pathways and localized accumulation of hydrogen during a short-term high-volume release further increasing the risk of accidents. Implementing effective hydrogen leakage monitoring measures can mitigate these risks ensuring the safety of personnel and the environment to the greatest extent possible. Therefore this paper uses CFD methods to simulate the hydrogen leakage process in a hydrogen production plant. The study examines the molar fraction distribution characteristics of hydrogen in the presence of obstacles by varying the ventilation speed of the plant and the directions of leakage. The main conclusions are as follows: enhancing ventilation can effectively prevent the rapid increase in hydrogen concentration with higher ventilation speeds yielding better suppression. After a hydrogen leak in a confined space hydrogen tends to diffuse along the walls and accumulate in corner areas indicating that hydrogen monitoring equipment should be placed in corner locations.

In response to the growing significance of hydrogen as a clean energy carrier this study investigates the advanced rectifier technologies employed in electrolytic hydrogen production. First the topologies of three rectifiers typically employed in industry—24-pulse thyristor rectifiers insulated gate bipolar transistor (IGBT) rectifiers and 24-pulse diode rectifiers with multi-phase choppers—are described in detail. Subsequently at a constant 5 MW power level the three rectifiers are compared in terms of rectifier efficiency gridside power quality power factor and overall investment cost. The results indicate that in comparison to the other two rectifiers the thyristor rectifier provides superior efficiency and cost advantages thereby maintaining a dominant market share. Additionally case studies of rectifier power supplies from three real-world industrial projects are presented along with actual grid-side power quality data. Finally the challenges potential applications and future prospects of rectifiers in renewable energy-based hydrogen production are discussed and summarized.

As the main body of resource aggregation Virtual Power Plant (VPP) not only needs to participate in the external energy market but also needs to optimize the management of internal resources. Different from other energy storage hydrogen energy storage systems can participate in the hydrogen market in addition to assuming the backup supplementary function of electric energy. For the Virtual Power Plant Operator (VPPO) it needs to optimize the scheduling of internal resources and formulate bidding strategies for the electric-hydrogen market based on external market information. In this study a two-stage model is constructed considering the internal and external interaction mechanism. The first stage model optimizes the operation of renewable energy flexible load extraction storage and hydrogen energy storage system based on the complementary characteristics of internal resources; the second stage model optimizes the bidding strategy to maximize the total revenue of the electricity energy market auxiliary service market and hydrogen market. Finally a typical scenario is constructed and the rationality and effectiveness of the strategy are verified. The results show that the hybrid VPP with hydrogen storage has better economic benefits resource benefits and reliability.

A 3.5 tonne forklift containing proton exchange membrane fuel cells (PEMFCs) and lithium-ion batteries was manufactured and tested in a real factory. The work efficiency and economic applicability of the PEMFC forklift were compared with that of a lithium-ion battery-powered forklift. The results showed that the back-pressure of air was closely related to the power density of the stack whose stability could be improved by a reasonable control strategy and membrane electrode assemblies (MEAs) with high consistency. The PEMFC powered forklift displayed 40.6% higher work efficiency than the lithium-ion battery-powered forklift. Its lower use-cost compared to internal engine-powered forklifts is beneficial to the commercialization of this product.

With the massive use of traditional fossil fuels greenhouse gas emissions are increasing and environmental pollution is becoming an increasingly serious problem which led to an imminent energy transition. Therefore the development and application of renewable energy are particularly important. This paper reviews a wide range of issues associated with hybrid renewable energy systems (HRESs). The issues concerning system configurations energy storage options simulation and optimization with artificial intelligence are discussed in detail. Storage technology options are introduced for stand-alone (off-grid) and grid-connected (on-grid) HRESs. Different optimization methodologies including classical techniques intelligent techniques hybrid techniques and software tools for sizing system components are presented. Besides the artificial intelligence methods for optimizing the solar/wind HRESs are discussed in detail.

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation demand-side mitigation or mitigation technologies. Additionally there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo future vision and key actions of the low-carbon development of the world and China’s ISI. First this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency shifting to Scrap/EAF route promoting material efficiency strategy and deploying radical innovation technologies.

To maximize the utilization of renewable energy (RE) as much as possible in cold areas while reducing traditional energy use and carbon dioxide emissions a three-layer configuration optimization and scheduling model considering a multi-park integrated energy system (MPIES) a shared energy storage power station (SESPS) and a hydrogen refueling station (HRS) cooperation based on the Wasserstein generative adversarial networks the simultaneous backward reduction technique and the Quantity-Contour (WGAN-SBR_QC) method is proposed. Firstly the WGAN-SBR_QC method is used to generate typical scenarios of RE output. Secondly a three-layer configuration and schedule optimization model is constructed using MPIES SESPS and HRS. Finally the model’s validity is investigated by selecting a multi-park in Eastern Mongolia. The results show that: (1) the typical scenario of RE output improved the overall robustness of the system. (2) The profits of the MPIES and HRS increased by 1.84% and 52.68% respectively and the SESPS profit increased considerably. (3) The proposed approach increased RE utilization to 99.47% while reducing carbon emissions by 32.67%. Thus this model is a reference for complex energy system configuration and scheduling as well as a means of encouraging RE use.

Hydrogen energy represents a crucial pathway towards achieving carbon neutrality and is a pivotal facet of future strategic emerging industries. The safe and efficient transportation of hydrogen is a key link in the entire chain development of the hydrogen energy industry’s “production storage and transportation”. Mixing hydrogen into natural gas pipelines for transportation is the potential best way to achieve large-scale long-distance safe and efficient hydrogen transportation. Welds are identified as the vulnerable points in natural gas pipelines and compatibility between hydrogen-doped natural gas and existing pipeline welds is a critical technical challenge that affects the global-scale transportation of hydrogen energy. Therefore this article systematically discusses the construction and weld characteristics of hydrogen-doped natural gas pipelines the research status of hydrogen damage mechanism and mechanical property strengthening methods of hydrogen-doped natural gas pipeline welds and points out the future development direction of hydrogen damage mechanism research in hydrogen-doped natural gas pipeline welds. The research results show that: 1 Currently there is a need for comprehensive research on the degradation of mechanical properties in welds made from typical pipe materials on a global scale. It is imperative to systematically elucidate the mechanism of mechanical property degradation due to conventional and hydrogeninduced damage in welds of high-pressure hydrogen-doped natural gas pipelines worldwide. 2 The deterioration of mechanical properties in welds of hydrogen-doped natural gas pipelines is influenced by various components including hydrogen carbon dioxide and nitrogen. It is necessary to reveal the mechanism of mechanical property deterioration of pipeline welds under the joint participation of multiple damage mechanisms under multi-component gas conditions. 3 Establishing a fundamental database of mechanical properties for typical pipeline steel materials under hydrogen-doped natural gas conditions globally is imperative to form a method for strengthening the mechanical properties of typical high-pressure hydrogen-doped natural gas pipeline welds. 4 It is essential to promptly develop relevant standards for hydrogen blending transportation welding technology as well as weld evaluation testing and repair procedures for natural gas pipelines.

Hydrogen energy is regarded as an important way to achieve carbon emission reduction. This paper focuses on the combination of the design of the hydrogen supply chain network and the location of hydrogen refueling stations on the expressway. Based on the cost analysis of the hydrogen supply chain a multi-objective model is developed to determine the optimal scale and location of hydrogen refueling stations on the hydrogen expressway. The proposed model considers the hydrogen demand forecast hydrogen source selection hydrogen production and storage and transportation hydrogen station refueling mode etc. Taking Dalian City China as an example with offshore wind power as a reliable green hydrogen supply to select the location and capacity of hydrogen refueling stations for the hydrogen energy demonstration section of a certain expressway under multiple scenarios. The results of the case show that 4 and 5 stations are optimized on the expressway section respectively and the unit hydrogen cost is $14.3 /kg H2 and $11.8 /kg H2 respectively which are equal to the average hydrogen price in the international range. The optimization results verify the feasibility and effectiveness of the model.

The increasingly severe energy crisis has strengthened the determination todevelop environmentally friendly energy. And hydrogen has emerged as a candi-date for clean energy. Among many hydrogen generation methods biohydrogenstands out due to its environmental sustainability simple operating environ-ment and cost advantages. This review focuses on the rational design of catalystsfor fermentative hydrogen production. The principles of microbial dark fermen-tation and photo-fermentation are elucidated exhaustively. Various strategiesto increase the efficiency of fermentative hydrogen production are summa-rized and some recent representative works from microbial dark fermentationand photo-fermentation are described. Meanwhile perspectives and discussionson the rational design of catalysts for fermentative hydrogen production areprovided.