China, People’s Republic

In response to increasingly stringent emission regulations low-carbon fuels have received significant attention as sustainable energy sources for internal combustion engines. This study investigates four representative low-carbon fuels methane methanol hydrogen and ammonia by systematically summarizing their combustion characteristics and emission profiles along with a review of existing after-treatment technologies tailored to each fuel type. For methane engines unburned hydrocarbon (UHC) produced during lowtemperature combustion exhibits poor oxidation reactivity necessitating integration of oxidation strategies such as diesel oxidation catalyst (DOC) particulate oxidation catalyst (POC) ozone-assisted oxidation and zoned catalyst coatings to improve purification efficiency. Methanol combustion under low-temperature conditions tends to produce formaldehyde and other UHCs. Due to the lack of dedicated after-treatment systems pollutant control currently relies on general-purpose catalysts such as three-way catalyst (TWC) DOC and POC. Although hydrogen combustion is carbon-free its high combustion temperature often leads to elevated nitrogen oxide (NOx) emissions requiring a combination of optimized hydrogen supply strategies and selective catalytic reduction (SCR)-based denitrification systems. Similarly while ammonia offers carbon-free combustion and benefits from easier storage and transportation its practical application is hindered by several challenges including low ignitability high toxicity and notable NOx emissions compared to conventional fuels. Current exhaust treatment for ammonia-fueled engines primarily depends on SCR selective catalytic reduction-coated diesel particulate filter (SDPF). Emerging NOx purification technologies such as integrated NOx reduction via hydrogen or ammonia fuel utilization still face challenges of stability and narrow effective temperatures.

Energy management in hybrid fuel cell ship systems faces the dual challenges of optimizing hydrogen consumption and ensuring power quality. This study proposes an Improved Weighted Antlion Optimization (IW-ALO) algorithm for multi-objective problems. The method incorporates a dynamic weight adjustment mechanism and an elite-guided strategy which significantly enhance global search capability and convergence performance. By integrating IW-ALO with the Equivalent Consumption Minimization Strategy (ECMS) an improved weighted ECMS (IW-ECMS) is developed enabling real-time optimization of the equivalence factor and ensuring efficient energy sharing between the fuel cell and the lithium-ion battery. To validate the proposed strategy a system simulation model is established in Matlab/Simulink 2017b. Compared with the rule-based state machine control and optimization-based ECMS methods over a representative 300 s ferry operating cycle the IW-ECMS achieves a hydrogen consumption reduction of 43.4% and 42.6% respectively corresponding to a minimum total usage of 166.6 g under the specified load profile while maintaining real-time system responsiveness. These reductions reflect the scenario tested characterized by frequent load variations. Nonetheless the results highlight the potential of IW-ECMS to enhance the economic performance of ship power systems and offer a novel approach for multi-objective cooperative optimization in complex energy systems.

As the global demand for energy increases and the transition to renewable and clean sources accelerates microgrid (MG) has emerged as a promising solution. Hydrogen fuel cell vehicles (HFCVs) offer significant advantages over gasoline vehicles in terms of reducing carbon dioxide emissions. However the development of HFCVs is hindered by the substantial up-front costs of hydrogen refueling stations (HRSs) coupled with the high cost of hydrogen transportation and the limitations of the hydrogen supply chain. This research proposes a multimicrogrid (MMG) system that integrates hydrogen energy and utilizes it as the HRS for fuel vehicle refueling. An adaptive hydrogen energy management method is employed for fuel cell vehicles to optimize the coupling between the transportation network and the power system. An integrated transportation state assessment model is developed and a smart MMG system is deployed to receive information from the transportation network. Building on this foundation an adaptive hydrogen scheduling model is developed. HFCVs are influenced by the hydrogen price adjustments leading them to travel to different MGs for refueling which in turn regulates the unit output of the MMG system. The MMG system is then integrated with the IEEE 33 bus distribution system to analyze the daily load balance. This integrated approach results in reduced traffic congestion lower MG costs and optimized power distribution network load balance.

In order to study the flow blending and transporting process of hydrogen that injects into the natural gas pipelines a three-dimensional T-pipe blending model is established and the flow characteristics are investigated systematically by the large eddy simulation (LES). Firstly the mathematical formulation of hydrogen-methane blending process is provided and the LES method is introduced and validated by a benchmark gas blending model having experimental data. Subsequently the T-pipe blending model is presented and the effects of key parameters such as the velocity of main pipe hydrogen blending ratio diameter of hydrogen injection pipeline diameter of main pipe and operating pressure on the hydrogen-methane blending process are studied systematically. The results show that under certain conditions the gas mixture will be stratified downstream of the blending point with hydrogen at the top of the pipeline and methane at the bottom of the pipeline. For the no-stratified scenarios the distance required for uniformly mixing downstream the injection point increases when the hydrogen mixing ratio decreases the diameter of the hydrogen injection pipe and the main pipe increase. Finally based on the numerical results the underlying physics of the stratification phenomenon during the blending process are explored and an indicator for stratification is proposed using the ratio between the Reynolds numbers of the natural gas and hydrogen.

A proton exchange membrane electrolyzer can effectively utilize the electricity generated by intermittent solar power. Different methods of generating electricity may have different efficiencies and hydrogen production rates. Two coupled systems namely PV/T- and CPV/T-coupling PEMEC respectively are presented and compared in this study. A maximum power point tracking algorithm for the photovoltaic system is employed and simulations are conducted based on the solar irradiation intensity and ambient temperature of a specific location on a particular day. The simulation results indicate that the hydrogen production is relatively high between 11:00 and 16:00 with a peak between 12:00 and 13:00. The maximum hydrogen production rate is 99.11 g/s and 29.02 g/s for the CPV/T-PEM and PV/T-PEM systems. The maximum energy efficiency of hydrogen production in CPV/T-PEM and PV/T-PEM systems is 66.7% and 70.6%. Under conditions of high solar irradiation intensity and ambient temperature the system demonstrates higher total efficiency and greater hydrogen production. The CPV/T-PEM system achieves a maximum hydrogen production rate of 2240.41 kg/d with a standard coal saving rate of 15.5 tons/day and a CO2 reduction rate of 38.0 tons/day. Compared to the PV/T-PEM system the CPV/T-PEM system exhibits a higher hydrogen production rate. These findings provide valuable insights into the engineering application of photovoltaic/thermal-coupled hydrogen production technology and contribute to the advancement of this field.

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.

As a key link in the application of hydrogen energy hydrogen refueling stations are significant for their safe operation. This paper established a three-dimensional 1:1 model for a seaport hydrogen refueling station in Ningbo City. In this work the CFD software FLUENT was used to study the influence of leakage angles on the leakage of high-pressure hydrogen through a small hole. Considering the calculation accuracy and efficiency this paper adopted the pseudo-diameter model. When the obstacle was far from the leakage hole it had almost no obstructive effect on the jet's main body. Still it affected the hydrogen whose momentum in the outer layer of the jet has been significantly decayed. In this condition there would be more hydrogen in stagnation. Thus the volume of the flammable hydrogen cloud was hardly affected while there was a significant increase in the volume of the hazardous hydrogen cloud. When the obstacle was close to the leakage hole it directly affected the jet's main body. Therefore the volume of the flammable hydrogen cloud increased. However the air impeded the hydrogen jet relatively less because the hydrogen jet contacted the obstacle more quickly. The hydrogen jet blocked by the obstacle still has some momentum. Therefore there was no more hydrogen in stagnation and no significant increase in the volume of the hazardous hydrogen cloud.

To reduce carbon dioxide emissions from the steel industry efforts are made to introduce a steelmaking route based on hydrogen reduction of iron ore instead of the commonly used cokebased reduction in a blast furnace. Changing fundamental pieces of steelworks affects the functions of most every system unit involved and thus warrants the question of how such a transition could optimally take place over time and no rigorous attempts have until now been made to tackle this problem mathematically. This article presents a steel plant optimization model written as a mixed-integer non-linear programming problem where aging blast furnaces and basic oxygen furnaces could potentially be replaced with shaft furnaces and electric arc furnaces minimizing costs or emissions over a long-term time horizon to identify possible transition pathways. Example cases show how various parameters affect optimal investment pathways stressing the necessity of appropriate planning tools for analyzing diverse cases.

Carbon capture utilization and storage (CCUS) technology plays a pivotal role in China’s “Carbon Peak” and “Carbon Neutrality” goals. This approach offers low-carbon zero-carbon and even negative-carbon solutions. This paper employs bibliometric analysis using the Web of Science to comprehensively review global CCUS progress and discuss future development prospects in China. The findings underscore it as a prominent research focus attracting scholars from both domestic and international arenas. China notably leads the global landscape in terms of research paper output with the Chinese Academy of Sciences holding a prominent position in total published papers. The research predominantly centers on refining geological storage techniques and optimizing oil and gas recovery rates. Among the CCUS pathways enhanced oil recovery technology stands out due to its relative maturity and commercial applicability particularly within the conventional oil and gas reservoirs. The application potential of enhanced gas recovery technology especially in the Sichuan and Ordos Basins in China necessitates robust research and demonstration efforts. Within China’s current energy landscape “Blue Hydrogen” emerges as the primary solution for hydrogen production in conjunction with CCUS technology. The underground coal gasification approach holds significant promise as a hydrogen production avenue albeit with inherent ecological and environmental challenges tied to geological storage that require meticulous consideration. The establishment of effective risk identification and evaluation methodologies for geological storage is imperative. The trajectory ahead involves a strategic convergence of policy technology and market dynamics to enhance China’s CCUS policy framework legislative framework standardization initiatives and pioneering technological advancements. These collective efforts converge to outline an exclusive development pathway in China. This study assumes a pivotal role in accelerating CCUS technology research and deployment enhancing oil and gas recovery efficiency and ultimately realizing the overarching goals of a “Dual Carbon” future.

In order to realize carbon mitigation and the efficient utilization of waste biogas the biogas-to-methanol process is an important method. The syngas produced by the conventional biogas reforming technology is rich in CO2 and CO whereas it is poor in hydrogen. Therefore additional H2 is introduced into the system to adjusted the syngas ratio promoting the efficient conversion of the biogas. However the use of traditional H2 production technologies generally results in considerable carbon emissions. Given these points low-carbon H2 production technologies namely methane pyrolysis technology and chemical looping reforming technology are integrated with the biogas-to-methanol process to enhance carbon conversion carbon reduction and cost-saving potentials. Comprehensive technical and economic comparisons of the integrated processes are conducted. The process coupled with chemical looping reforming technology has a higher carbon conversion efficiency (73.52%) and energy efficiency (70.41%) and lower unit carbon emissions (0.73 t CO2/t methanol). Additionally the process coupled with methane pyrolysis technology has higher product revenue whereas that including chemical looping reforming technology has a lower net production cost (571.33 USD/t methanol). In summary the novel chemical looping reforming technology provides a cleaner and more sustainable pathway with which to promote the efficient conversion of biogas into methanol.