China, People’s Republic

Solid-state hydrogen storage technology has emerged as a disruptive solution to the “last mile” challenge in large-scale hydrogen energy applications garnering significant global research attention. This paper systematically reviews the Chinese research progress in solid-state hydrogen storage material systems thermodynamic mechanisms and system integration. It also quantitatively assesses the market potential of solid-state hydrogen storage across four major application scenarios: on-board hydrogen storage hydrogen refueling stations backup power supplies and power grid peak shaving. Furthermore it analyzes the bottlenecks and challenges in industrialization related to key materials testing standards and innovation platforms. While acknowledging that the cost and performance of solid-state hydrogen storage are not yet fully competitive the paper highlights its unique advantages of high safety energy density and potentially lower costs showing promise in new energy vehicles and distributed energy fields. Breakthroughs in new hydrogen storage materials like magnesium-based and vanadium-based materials coupled with improved standards specifications and innovation mechanisms are expected to propel solid-state hydrogen storage into a mainstream technology within 10–15 years with a market scale exceeding USD 14.3 billion. To accelerate the leapfrog development of China’s solid-state hydrogen storage industry increased investment in basic research focused efforts on key core technologies and streamlining the industry chain from materials to systems are recommended. This includes addressing challenges in passenger vehicles commercial vehicles and hydrogen refueling stations and building a collaborative innovation ecosystem involving government industry academia research finance and intermediary entities to support the achievement of carbon peak and neutrality goals and foster a clean low-carbon safe and efficient modern energy system.

With the increasing concern about global energy crisis and environmental pollution the integrated renewable energy system has gradually become one of the most important ways to achieve energy transition. In the context of the rapid development of hydrogen energy industry the proportion of hydrogen energy in the energy system has gradually increased. The conversion between various energy sources has also become more complicated which poses challenges to the planning and construction of park-level integrated energy systems (PIES). To solve this problem we propose a bi-level planning model for an integrated energy system with hydrogen energy considering multi-stage investment and carbon trading mechanism. First the mathematical models of each energy source and energy storage in the park are established respectively and the independent operation of the equipment is analyzed. Second considering the operation state of multi-energy coordination a bi-level planning optimization model is established. The upper level is the capacity configuration model considering the variable installation time of energy facilities while the lower level is the operation optimization model considering several typical daily operations. Third considering the coupling relationship between upper and lower models the bi-level model is transformed into a solvable single-level mixed integer linear programming (MILP) model by using Karush–Kuhn–Tucker (KKT) condition and big-M method. Finally the proposed model and solution methods are verified by comprehensive case studies. Simulation results show that the proposed model can reduce the operational cost and carbon emission of PIES in the planning horizon and provide insights for the multi-stage investment of PIES.

Arguably one of the most important issues the world is facing currently is climate change. At the current rate of fossil fuel consumption the world is heading towards extreme levels of global temperature rise if immediate actions are not taken. Transforming the current energy system from one largely based on fossil fuels to a carbon-neutral one requires unprecedented speed. Based on the current state of development direct electrification of the future energy system alone is technically challenging and not enough especially in hard-to-abate sectors like heavy industry road trucking international shipping and aviation. This leaves a considerable demand for alternative carbon-neutral fuels such as green ammonia and hydrogen and renewable methanol. From this perspective we discuss the overarching roles of each fuel in reaching net zero emission within the next three decades. The challenges and future directions associated with the fuels conclude the current perspective paper.

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.

Amidst the growing imperative to address carbon emissions aiming to improve energy utilization efficiency optimize equipment operation flexibility and further reduce costs and carbon emissions of regional integrated energy systems (RIESs) this paper proposes a low-carbon economic operation strategy for RIESs. Firstly on the energy supply side energy conversion devices are utilized to enhance multi-energy complementary capabilities. Then an integrated demand response model is established on the demand side to smooth the load curve. Finally consideration is given to the RIES’s participation in the green certificate–carbon trading market to reduce system carbon emissions. With the objective of minimizing the sum of system operating costs and green certificate–carbon trading costs an integrated energy system optimization model that considers electricity gas heat and cold coupling is established and the CPLEX solver toolbox is used for model solving. The results show that the coordinated optimization of supply and demand sides of regional integrated energy systems while considering multi-energy coupling and complementarity effectively reduces carbon emissions while further enhancing the economic efficiency of system operations.

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.

As an important energy source to achieve carbon neutrality green hydrogen has always faced the problems of high use cost and unsatisfactory environmental benefits due to its remote production areas. Therefore a liquid-gaseous cascade green hydrogen delivery scheme is proposed in this article. In this scheme green hydrogen is liquefied into high-density and low-pressure liquid hydrogen to enable the transport of large quantities of green hydrogen over long distances. After longdistance transport the liquid hydrogen is stored and then gasified at transfer stations and converted into high-pressure hydrogen for distribution to the nearby hydrogen facilities in cities. In addition this study conducted a detailed model evaluation of the scheme around the actual case of hydrogen energy demand in Chengdu City in China and compared it with conventional hydrogen delivery methods. The results show that the unit hydrogen cost of the liquid-gaseous cascade green hydrogen delivery scheme is only 51.58 CNY/kgH2 and the dynamic payback periods of long- and short-distance transportation stages are 13.61 years and 7.02 years respectively. In terms of carbon emissions this scheme only generates indirect carbon emissions of 2.98 kgCO2/kgH2 without using utility electricity. In sum both the economic and carbon emission analyses demonstrate the advantages of the liquidgaseous cascade green hydrogen delivery scheme. With further reductions in electricity prices and liquefication costs this scheme has the potential to provide an economically/environmentally superior solution for future large-scale green hydrogen applications.

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.

With the rapid development of hydrogen pipelines their safety issues have become increasingly prominent. In order to evaluate the properties of pipeline materials under a highpressure hydrogen environment this study investigates the hydrogen embrittlement sensitivity of X70 welded pipe in a 10 MPa high-pressure hydrogen environment using slow strain rate testing (SSRT) and low-cycle fatigue (LCF) analysis. The microstructure slow tensile and fatigue fracture morphology of base metal (BM) and weld metal (WM) were characterized and analyzed by means of ultra-depth microscope scanning electron microscope (SEM) electron backscattering diffraction (EBSD) and transmission electron microscope (TEM). Results indicate that while the high-pressure hydrogen environment has minimal impact on ultimate tensile strength (UTS) for both BM and WM it significantly decreases reduction of area (RA) and elongation (EL) with RA reduction in WM exceeding that in BM. Under the nitrogen environment the slow tensile fracture of X70 pipeline steel BM and WM is a typical ductile fracture while under the high-pressure hydrogen environment the unevenness of the slow tensile fracture increased and a large number of microcracks appeared on the fracture surface and edges with the fracture mode changing to ductile fracture + quasicleavage fracture. In addition the high-pressure hydrogen environment reduces the fatigue life of the BM and WM of X70 pipeline steel and the fatigue life of the WM decreases more than that of the BM as well. Compared to the nitrogen environment the fatigue fracture specimens of BM and WM in the hydrogen environment showed quasi-cleavage fracture patterns and the fracture area in the instantaneous fracture zone (IFZ) was significantly reduced. Compared with the BM of X70 pipeline steel although the effective grain size of the WM is smaller WM’s microstructure with larger Martensite/austenite (M/A) constituents and MnS and Al-rich oxides contributes to a heightened embrittlement sensitivity. In contrast the second-phase precipitation of nanosized Nb V and Ti composite carbon-nitride in the BM acts as an effective irreversible hydrogen trap which can significantly reduce the hydrogen embrittlement sensitivity

A reliable and sustainable energy source is essential for human survival and progress. Hydrogen energy is both clean and environmentally friendly which highlights the need for the development of effective photocatalysts to enhance the efficiency of photocatalytic hydrogen production. Near-infrared (NIR) light makes up a significant part of the solar spectrum and possesses strong penetration capabilities. Therefore it is important to enhance research on photocatalysis that utilizes both NIR and visible light. Metal-organic frameworks (MOFs) possess outstanding photocatalytic characteristics and are utilized in various applications for the photocatalytic generation of hydrogen. Consequently this minireview examines the fundamental characteristics of MOFs focusing on their classification the mechanisms of hydrogen production and the use of MOFs composites in photocatalytic hydrogen production. It discusses MOFs materials that feature type I II III Z and S heterojunctions along with strategies for modifying MOFs through elemental doping and the addition of co-catalysts. The study investigates methods to expand the photo-response range through up-conversion reduce the band gap of photocatalyst materials and utilize plasmon resonance and photothermal effects. This minireview lays the groundwork for achieving photocatalysis that responds to near-infrared and visible light thereby enhancing photocatalytic efficiency for hydrogen production. Finally the guidance and obstacles for upcoming studies on MOFs materials in the context of photocatalytic hydrogen production are examined.