China, People’s Republic

A highly efficient low-cost and environmentally friendly photocathode with long-term stability is the goal of practical solar hydrogen evolution applications. Here we found that the Cu₃BiS₃ film-based photocathode meets the abovementioned requirements. The Cu₃BiS₃-based photocathode presents a remarkable onset potential over 0.9 V_RHE with excellent photoelectrochemical current densities (~7 mA/cm² under 0 V_RHE) and appreciable 10-hour long-term stability in neutral water solutions. This high onset potential of the Cu₃BiS₃-based photocathode directly results in a good unbiased operating photocurrent of ~1.6 mA/cm² assisted by the BiVO₄ photoanode. A tandem device of Cu₃BiS₃-BiVO₄ with an unbiased solar-to-hydrogen conversion efficiency of 2.04% is presented. This tandem device also presents high stability over 20 hours. Ultimately a 5 × 5 cm² large Cu₃BiS₃-BiVO₄ tandem device module is fabricated for standalone overall solar water splitting with a long-term stability of 60 hours.

Fischer-Tropsch synthesis (FTS) is an increasingly important approach for producing liquid fuels and chemicals via syngas—that is synthesis gas a mixture of carbon monoxide and hydrogen—generated from coal natural gas or biomass. In FTS dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles which depend on the particle size morphology and crystallographic phase of the nanoparticles. In this article we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active selective and stable FTS catalysts.

Hydrogen is regarded to be one of the most promising renewable and clean energy sources. Finding a highly efficient and cost-effective catalyst to generate hydrogen via water splitting has become a research hotspot. Two-dimensional materials with exotic structural and electronic properties have been considered as economical alternatives. In this work 2D SnSe films with high quality of crystallinity were grown on a mica substrate via molecular beam epitaxy. The electronic property of the prepared SnSe thin films can be easily and accurately tuned in situ by three orders of magnitude through the controllable compensation of Sn atoms. The prepared film normally exhibited p-type conduction due to the deficiency of Sn in the film during its growth. First-principle calculations explained that Sn vacancies can introduce additional reactive sites for the hydrogen evolution reaction (HER) and enhance the HER performance by accelerating electron migration and promoting continuous hydrogen generation which was mirrored by the reduced Gibbs free energy by a factor of 2.3 as compared with the pure SnSe film. The results pave the way for synthesized 2D SnSe thin films in the applications of hydrogen production.

This work reports on H2 fuel generation from sewage water using Cu/CuO nanoporous (NP) electrodes. This is a novel concept for converting contaminated water into H2 fuel. The preparation of Cu/CuO NP was achieved using a simple thermal combustion process of Cu metallic foil at 550 ◦C for 1 h. The Cu/CuO surface consists of island-like structures with an inter-distance of 100 nm. Each island has a highly porous surface with a pore diameter of about 250 nm. X-ray diffraction (XRD) confirmed the formation of monoclinic Cu/CuO NP material with a crystallite size of 89 nm. The prepared Cu/CuO photoelectrode was applied for H2 generation from sewage water achieving an incident to photon conversion efficiency (IPCE) of 14.6%. Further the effects of light intensity and wavelength on the photoelectrode performance were assessed. The current density (Jph) value increased from 2.17 to 4.7 mA·cm−2 upon raising the light power density from 50 to 100 mW·cm−2 . Moreover the enthalpy (∆H*) and entropy (∆S*) values of Cu/CuO electrode were determined as 9.519 KJ mol−1 and 180.4 JK−1 ·mol−1 respectively. The results obtained in the present study are very promising for solving the problem of energy in far regions by converting sewage water to H2 fuel.

A steam methane reforming reactor is a key equipment in hydrogen production and numerical analysis and process control can provide a critical insight into its reforming mechanisms and flexible operation in real engineering applications. The present paper firstly studies the transport phenomena in an industrial-scale steam methane reforming reactor by transient numerical simulations. Wall effect and local non thermal equilibrium is considered in the simulations. A temperature profile of the tube outer wall is given by user defined functions integrated into the ANSYS FLUENT software. Dynamic simulations show that the species distribution is closely related to the temperature distribution which makes the temperature of the reactor tube wall an important factor for the hydrogen production of the reformer and the thermal conductivity of the catalyst network is crucial in the heat transfer in the reactor. Besides there exists a delay of the reformer's hydrogen production when the temperature profile of the tube wall changes. Among inlet temperature inlet mass flow rate and inlet steam-to-carbon (S/C) ratio the mass flow rate is the most influencing factor for the hydrogen production. The dynamic matrix control (DMC) scheme is subsequently designed to manipulate the mole fraction of hydrogen of the outlet to the target value by setting the temperature profile trajectory of the reforming tube with time. The proportional-integral control strategy is also studied for comparison. The closed-loop simulation results show that the proposed DMC control strategy can reduce the overshoot and have a small change of the input variable. In addition the disturbances of feed disturbance can also be well rejected to assure the tracking performance indicating the superiority of the DMC controller. All the results give insight to the theoretical analysis and controller design of a steam methane reformer and demonstrate the potential of the CFD modeling in study the transport mechanism and the idea of combining CFD modelling with controller design for the real application.

Environmentally friendly and energy saving treatment of black liquor (BL) a massively produced waste in Kraft papermaking process still remains a big challenge. Here by adopting a Ni-CaO-Ca12Al14O33 bifunctional catalyst derived from hydrotalcite-like materials we demonstrate the feasibility of producing high-purity H2 (∼96%) with 0.9 mol H2 mol-1 C yield via the sorption enhanced steam reforming (SESR) of BL. The SESRBL performance in terms of H2 production maintained stable for 5 cycles but declined from the 6th cycle. XRD Raman spectroscopy elemental analysis and energy dispersive techniques were employed to rationalize the deactivation of the catalyst. It was revealed that gradual sintering and agglomeration of Ni and CaO and associated coking played important roles in catalyst deactivation and performance degradation of SESRBL while deposition of Na and K from the BL might also be responsible for the declined performance. On the other hand it was demonstrated that the SESRBL process could effectively reduce the emission of sulfur species by storing it as CaSO3. Our results highlight a promising alternative for BL treatment and H2 production thereby being beneficial for pollution control and environment governance in the context of mitigation of climate change.

Hydrogen sourced from energy recovery processes and conversion of waste materials is a method of providing both a clean fuel and a sustainable waste management alternative to landfill and incineration. The question is whether waste-to–hydrogen can become part of the zero-carbon future energy mix and serve as one of the cleaner hydrogen sources which is economically viable and environmentally friendly. This work critically assessed the potential of waste as a source of hydrogen production via various thermochemical (gasification and pyrolysis) and biochemical (fermentation and photolysis) processes. Research has shown hydrogen production yields of 33.6 mol/kg and hydrogen concentrations of 82% from mixed waste feedstock gasification. Biochemical methods such as fermentation can produce hydrogen up to 418.6 mL/g. Factors including feedstock quality process requirements and technology availability were reviewed to guide technology selection and system design. Current technology status and bottlenecks were discussed to shape future development priorities. These bottlenecks include expensive production and operation processes heterogeneous feedstock low process efficiencies inadequate management and logistics and lack of policy support. Improvements to hydrogen yields and production rates are related to feedstock processing and advanced energy efficiency processes such as torrefaction of feedstock which has shown thermal efficiency of gasification up to 4 MJ/kg. This will affect the economic feasibility and concerns around required improvements to bring the costs down to allow waste to viewed as a serious competitor for hydrogen production. Recommendations were also made for financially competitive waste-to-hydrogen development to be part of a combined solution for future energy needs.

Coke oven gas (COG) is one of the most important by-products in the steel industry and the conversion of COG to value-added products has attracted much attention from both economic and environmental views. In this work we apply the chemical looping reforming technology to produce pure H2 from COG. A series of La1-xSrxFeO3 (x = 0 0.2 0.3 0.4 0.5 0.6) perovskite oxides were prepared as oxygen carriers for this purpose. The reduction behaviours of La1-xSrxFeO3 perovskite by different reducing gases (H2 CO CH4 and the mixed gases) are investigated to discuss the competition effect of different components in COG for reacting with the oxygen carriers. The results show that reduction temperatures of H2 and CO are much lower than that of CH4 and high temperatures (>800 °C) are requested for selective oxidation of methane to syngas. The co-existence of CO and H2 shows weak effect on the equilibrium of methane conversion at high temperatures but the oxidation of methane to syngas can inhibit the consumption of CO and H2. The doping of suitable amounts of Sr in LaFeO3 perovskite (e.g. La0.5Sr0.5FeO3) significantly promotes the reactivity for selective oxidation of methane to syngas and inhibits the formation of carbon deposition obtaining both high methane conversion in the COG oxidation step and high hydrogen yield in the water splitting step. The La0.5Sr0.5FeO3 shows the highest methane conversion (67.82%) hydrogen yield (3.34 mmol·g-1) and hydrogen purity (99.85%). The hydrogen yield in water splitting step is treble as high as the hydrogen consumption in reduction step. These results reveal that chemical looping reforming of COG to produce pure H2 is feasible and an O2-assistant chemical looping reforming process can further improve the redox stability of oxygen carrier.

The extensive usage of fossil fuels has caused significant environmental pollution climate change and energy crises. The significant advantages of hydrogen such as cleanliness high efficiency and a wide range of sources make it quite promising. Hydrogen is prone to material damage which may lead to leakage. High-pressure leaking hydrogen is highly susceptible to spontaneous combustion due to its combustion characteristics which may cause jet fire or explosion accidents resulting in serious casualties and property damage. This paper presents a detailed review of the research progress on hydrogen leak diffusion characteristics leak spontaneous combustion mechanisms and material hydrogen damage mechanisms from the perspectives of theoretical analysis experiments and numerical simulations. This review points out that although a large number of research results have been obtained on the safety characteristics of hydrogen there are still some deficiencies and limitations. Further research topics are clarified such as further optimizing the kinetic mechanism of the high-pressure hydrogen leakage reaction and turbulence model exploring the expansion and dilution law of hydrogen clouds after liquid hydrogen flooding further studying the spontaneous combustion mechanism of leaked hydrogen and the interaction between mechanisms and investigating the synergistic damage effect of hydrogen and other components on materials. The leakage spontaneous combustion process in open space the development process of the bidirectional effect of hydrogen jet fuel and crack growth under the impact of high-pressure hydrogen jet fuel on the material may need to be explored next.

Fuel cell electric vehicles are generally considered to have broad development prospects due to their high efficiency and zero emissions. The governments of the United States Japan the European Union and China are taking action to promote the development of the industry. In 2020 China launched a fuel cell electric vehicle demonstration project and there will be 30∼50 thousand FCEVs included in this project by the end of 2025. How to standardize the consistency of data and develop a unified and accurate evaluation method is an important topic. The difficulty is how to keep balance among scientificity neutrality and feasibility in the evaluation method. In order to evaluate the performance of vehicles in demonstration operation projects China has issued the "Fuel Cell Electric Vehicle Test Specifications" which is an important guide for the future development of fuel cell electric vehicles in China. This paper compares the test methods for critical parameters in this specifications with those used in the United States and Japan. It explains China’s technical considerations in detail including fuel cell system rated power the volume power density of the fuel cell stack fuel cell system specific power fuel cell system sub-zero cold start and fuel cell electric vehicle range contributed by hydrogen. For the volume power density of the fuel cell stack as an example both the US Department of Energy and Japan’s New Energy and Industrial Technology Development Organization have proposed technical goals. However the lack of specific and detailed test methods has confused the industry. We propose a new test method using bipolar plate measurement based on scientificity feasibility and neutrality This is the first time to define the measuring method of the volume and specific power density of the fuel cell stack. For sub-zero cold start we put forward a feasible scheme for sub-zero cold start at the system level. For range contributed by hydrogen we propose a new test method that can distinguish the contributing of electric and hydrogen energy. Furthermore a hydrogen-to-electric conversion formula is proposed to calculate the equivalent hydrogen consumption which makes it possible to compare the energy consumption between plug-in and non-plug-in vehicles. At the same time this approach is significant in helping fuel cell-related enterprises to understand the formulation of China’s “Fuel Cell Electric Vehicle Test Specifications”. It should also be helpful for guiding product design and predicting fuel cell electric vehicle policy direction in China.

Fuel cells as clean power sources are very attractive for the maritime sector which is committed to sustainability and reducing greenhouse gas and atmospheric pollutant emissions from ships. This paper presents a technological review on fuel cell power systems for maritime applications from the past two decades. The available fuels including hydrogen ammonia renewable methane and methanol for fuel cells under the context of sustainable maritime transportation and their pre-processing technologies are analyzed. Proton exchange membrane molten carbonate and solid oxide fuel cells are found to be the most promising options for maritime applications once energy efficiency power capacity and sensitivity to fuel impurities are considered. The types layouts and characteristics of fuel cell modules are summarized based on the existing applications in particular industrial or residential sectors. The various research and demonstration projects of fuel cell power systems in the maritime industry are reviewed and the challenges with regard to power capacity safety reliability durability operability and costs are analyzed. Currently power capacity costs and lifetime of the fuel cell stack are the primary barriers. Coupling with batteries modularization mass production and optimized operating and control strategies are all important pathways to improve the performance of fuel cell power systems.

Owing to their extremely high energy density single-bonded polymeric nitrogen and atomic metallic hydrogen are generally regarded as the ultimate energetic materials. Although their syntheses normally require ultrahigh pressures of several hundred gigapascals (GPa) which prohibit direct materials application research on their stability metastability and fundamental properties are valuable for seeking extreme energetic materials through alternative synthetic routes. Various crystalline and amorphous polymeric nitrogens have been discovered between 100 and 200 GPa. Metastability at ambient conditions has been demonstrated for some of these phases. Cubic-gauche and black-phosphorus polymorphs of single-bonded nitrogen are two particularly interesting phases. Their large hystereses warrant further application-inspired basic research of nitrogen. In contrast although metallic hydrogen contains the highest-estimated energy density its picosecond lifetime and picogram quantity make its practical material application impossible at present. “Metallic hydrogen” remains a curiosity-driven basic research pursuit focusing on the pressure-induced evolution of the molecular hydrogen crystal and its electronic band structure from a low-density insulator with a very wide electronic band gap to a semiconductor with a narrow gap to a dense molecular metal and atomic metal and eventually to a previously unknown exotic state of matter. This great experimental challenge is driving relentless advancement in ultrahigh-pressure science and technology.

Under the dual pressure of energy conservation and environmental protection the internal combustion engine industry is facing huge challenges and it is imperative to find new clean energy. Hydrogen energy is expected to replace traditional fossil fuels as an excellent fuel for internal combustion engines because of its clean continuous regeneration and good combustion performance. This review article focuses on the research and development of blended hydrogen-fuel internal combustion engines in China since the beginning of this century. The main achievements gained by Chinese researchers in performing research on the effects of the addition of hydrogen into engines which predominantly include many types of hydrogen-blended engines such as gasoline diesel natural gas and alcohol engines rotary engines are discussed and analyzed in these areas of the engine’s performance and the combustion and emission characteristics etc. The merits and demerits of blended hydrogen-fuel internal combustion engines could be concluded and summarized after discussion. Finally the development trend and direction of exploration on hydrogen-fuel internal combustion engines could also be forecasted for relevant researchers.

In this paper the composition function and structure of the catalyst layer (CL) of a proton exchange membrane fuel cell (PEMFC) are summarized. The hydrogen reduction reaction (HOR) and oxygen reduction reaction (ORR) processes and their mechanisms and the main interfaces of CL (PEM|CL and CL|MPL) are described briefly. The process of mass transfer (hydrogen oxygen and water) proton and electron transfer in MEA are described in detail including their influencing factors. The failure mechanism of CL (Pt particles CL crack CL flooding etc.) and the degradation mechanism of the main components in CL are studied. On the basis of the existing problems a structure optimization strategy for a high‐performance CL is proposed. The commonly used preparation processes of CL are introduced. Based on the classical drying theory the drying process of a wet CL is explained. Finally the research direction and future challenges of CL are pointed out hoping to provide a new perspective for the design and selection of CL materials and preparation equipment.

Power to gas (PTG) refers to the technology of converting power into energy-storage gas which can absorb excess power when there is excess power and release energy-storage gas when needed. Based on the carbon dioxide (CO2 ) emission of Karamay City in Northwest China this study designed a process flow of the CO2 absorption process and the hydrogen and CO2 methanation process in PTG technology. The results show that the efficiency of the CO2 absorption process was 91.5% and the methanation efficiency was 77.5%. The heat recovery module was set during the process and the total heat recovered was 17.85 MW. The cost of producing synthetic natural gas (SNG) in the PTG factory was 1782 USD/ton. In terms of cost the cost of hydrogen production from electrolyzed water accounted for the largest proportion. In terms of product profit the sale of pure oxygen was the largest part of the profit. At present the carbon emission reduction index profit brought by SNG production accounted for a small proportion. In the future with technological progress industrial upgrading and the improvement in the carbon trading market PTG technology is expected to become one of the ways to achieve carbon-emission-reduction targets.

As a promising alternative to petroleum fossil energy polymer electrolyte membrane fuel cell has drawn considerable attention due to its low pollution emission high energy density portability and long operation times. Proton exchange membrane (PEM) like Nafion plays an essential role as the core of fuel cell. A good PEM must have satisfactory performance such as high proton conductivity excellent mechanical strength electrochemical stability and suitable for making membrane electrode assemblies (MEA). However performance degradation and high permeability remain the main shortcomings of Nafion. Therefore the development of a new PEM with better performance in some special conditions is greatly desired. In this review we aim to summarize the latest achievements in improving the Nafion performance that works well under elevated temperature or methanol-fueled systems. The methods described in this article can be divided into some categories utilizing hydrophilic inorganic material metal-organic frameworks nanocomposites and ionic liquids. In addition the mechanism of proton conduction in Nafion membranes is discussed. These composite membranes exhibit some desirable characteristics but the development is still at an early stage. In the future revolutionary approaches are needed to accelerate the application of fuel cells and promote the renewal of energy structure.

In recent years hydrogen is rapidly developing because it is environmentally friendly and sustainable. In this case hydrogen energy storage systems (HESSs) can be widely used in the distribution network. The application of hybrid electric-hydrogen energy storage systems can solve the adverse effects caused by renewable energy access to the distribution network. In order to ensure the rationality and effectiveness of energy storage systems (ESSs) configuration economic indicators of battery energy storage systems (BESSs) and hydrogen energy storage systems power loss and voltage fluctuation are chosen as the fitness function in this paper. Meanwhile multi-objective particle swarm optimization (MOPSO) is used to solve Pareto non-dominated set of energy storage systems’ optimal configuration scheme in which the technique for order preference by similarity to ideal solution (TOPSIS) based on information entropy weight (IEW) is used select the optimal solution in Pareto non-dominated solution set. Based on the extended IEEE-33 system and IEEE-69 system the rationality of energy storage systems configuration scheme under 20% and 35% renewable energy penetration rate is analyzed. The simulation results show that the power loss can be reduced by 7.9%–22.8% and the voltage fluctuation can be reduced by 40.0%–71% when the renewable energy penetration rate is 20% and 35% respectively in IEEE-33 and 69 nodes systems. Therefore it can be concluded that the locations and capacities of energy storage systems obtained by multi-objective particle swarm optimization can improve the distribution network stability and economy after accessing renewable generation.

Hydrogen has emerged as a new energy vector beyond its usual role as an industrial feedstock primarily for the production of ammonia methanol and petroleum refining. In addition to environmental sustainability issues energy-scarce developed countries such as Japan and Korea are also facing an energy security issue and hydrogen or hydrogen carriers such as ammonia and methylcyclohexane seem to be options to address these long-term energy availability issues. China has been eagerly developing renewable energy and hydrogen infrastructure to meet their sustainability goals and the growing energy demand. In this review we focus on hydrogen electrification through proton-exchange membrane fuel cells (PEMFCs) which are widely believed to be commercially suitable for automotive applications particularly for vehicles requiring minimal hydrogen infrastructure support such as fleets of taxies buses and logistic vehicles. This review covers all the key components of PEMFCs thermal and water management and related characterization techniques. A special consideration of PEMFCs in automotive applications is the highlight of this work leading to the infrastructure development for hydrogen generation storage and transportation. Furthermore national strategies toward the use of hydrogen are reviewed thereby setting the rationale for the hydrogen economy.

With the development of energy integration technology demand response (DR) has gradually evolved into integrated demand response (IDR). In this study for the integrated energy system (IES) on the distribution grid side with electricity heat natural gas network and hydrogen energy equipment the analogy relationship between the thermal and mobile hydrogen energy storage networks is proposed. Moreover a unified model that reflects network commonalities across different energy forms is established. Then considering the time delay of the IES in the nontransient network a time-domain two-port model of the IES considering the time delay is established. This model shows the joint effect of time and space on system parameters. Finally this study validates the model in the application of DR. The verification results show that in DR the time-domain two-port model can accurately “cut peaks and fill valleys” for the IES and effectively reduce the operating cost of the IES system.

As a high-quality secondary energy hydrogen energy has great potential in energy storage and utilization. The development of power-to-hydrogen (P2H) technology has alleviated the problem of wind curtailment and improved the coupling between the power grid and the natural gas grid. Under the premise of ensuring safety using P2H technology to mix the produced hydrogen into the natural gas network for long-distance transmission and power generation can not only promote the development of hydrogen energy but also reduce carbon emissions. This paper presents a new model for incorporating hydrogen into natural gas pipelines. To minimize the sum of wind curtailment cost operation cost and carbon emission cost an electric–gas integrated energy system (EGIES) model of hydrogen-compressed natural gas (HCNG) containing P2H for power generation is constructed. Aiming at the problem of global warming caused by a lot of abandoned wind and carbon emissions the economy and environmental protection of the system model are analyzed. The results show that the model of EGIES considering HCNG can not only absorb excess wind power but also reduce carbon emission costs and system costs which can reduce the total cost of the environmental economic dispatch of the EGIES by about 34.1%. In the context of the EGIES the proposal of this model is of great significance to the economical and environmentally friendly operation of the system.

The development of hydrogen-blended natural gas (HBNG) increases the risk of gas transportation and presents challenges for pipeline security in utility tunnels. The objective of this study is to investigate the diffusion properties of HBNG in utility tunnels and evaluate the effectiveness of various ventilation mechanisms. The numerical simulation software Fluent 2023 R1 is applied to simulate and analyze the leakage of small holes in a HBNG pipeline in the natural gas compartment. By examining the leaking behavior of HBNG through small holes in different circumstances we aimed to identify the most unfavorable operational situation for leakage. Subsequently we analyzed the ventilation strategy for sub-high-pressure pipes at various pressure levels in this unfavorable condition. This study’s findings demonstrate that blending hydrogen improves the gas diffusion capacity and increases the likelihood of explosion. The primary factors that influence the pattern of leakage are the size of the leaking holes and the pressure of the pipeline. The gas compartment experiences the most unfavorable working conditions for natural gas pipeline leaks when there are higher pressures wider leak openings higher hydrogen blending ratios (HBRs) and leaks in close proximity to an air inlet. When the HBR is 20% the minimum accident ventilation rates for pressures of 0.4 MPa and 0.8 MPa are 15 air changes per hour and 21 air changes per hour respectively. The maximum allowable wind speed for accident ventilation is 5 m/s as regulated by China’s national standard GB 50838-2015. This regulation makes it difficult to minimize the risk of leakage in a 1.6 MPa gas pipeline. It is recommended to install a safety interlock device to quickly shut off the pipeline in the event of a leak in order to facilitate the dispersion of the substance.

In the present study a numerical model was established to investigate the thermal dynamic behavior of liquid hydrogen in a 40-foot ISO tank. The volume of fluids (VOF) method was applied to capture the liquid surface and a phase change model was used to describe the evaporation phenomenon of hydrogen. The mesh independence analysis and the experimental validation have been made. Under different filling levels motion statuses and heat leakage conditions the variations in pressure and temperature of the tank were investigated. The pressure of 90% filling level case was reduced by 12.09% compared to the 50% case. Besides the pressure of the sloshing condition has increased twofold contrasted with the stationary one and thermal stratification disappeared. Additionally 16.67 minutes were taken for the ullage pressure to reach around 1MPa in emergencies of being extremely heated. Some valuable conclusions and suggestions for the transportation of liquid hydrogen arrived. Those could be the references to predict the release time of boil-off hydrogen and primarily support for gas-releasing control strategies.

In order to achieve carbon neutrality in a few decades the clean energy proportion in power mix of China will significantly rise to over 90%. A consensus has been reached recently that it will be of great significance to promote hydrogen energy that is produced by variable renewable energy power generation as a mainstay energy form in view of its potential value on achieving carbon neutrality. This is because hydrogen energy is capable of complementing the power system and realizing further electrification especially in the section that cannot be easily replaced by electric energy. Power system related planning model is commonly used for mid-term and long-term planning implemented through power installation and interconnection capacity expansion optimization. In consideration of the high importance of hydrogen and its close relationship with electricity an inclusive perspective which contains both kinds of the foresaid energy is required to deal with planning problems. In this study a joint model is established by coupling hydrogen energy model in the chronological operation power planning model to realize coordinated optimization on energy production transportation and storage. By taking the carbon neutrality scenario of China as an example the author applies this joint model to deploy a scheme research on power generation and hydrogen production inter-regional energy transportation capacity and hydrogen storage among various regions. Next by taking the technology progress and cost decrease prediction uncertainty into account the main technical– economic parameters are employed as variables to carry out sensitivity analysis research with a hope that the quantitative calculation and results discussion could provide suggestion and reference to energy-related companies policy-makers and institute researchers in formulating strategies on related energy development.

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.

Reducing the carbon emissions from trucks is critical to achieving the carbon peak of road freight. Based on the prediction of truck population and well-to-wheel (WTW) emission analysis of traditional diesel trucks and potential clean trucks including natural gas battery-electric plug-in hybrid electric and hydrogen fuel cell the paper analyzed the total greenhouse gas (GHG) emissions of China's road freight under four scenarios including baseline policy facilitation (PF) technology breakthrough (TB) and PF-TB. The truck population from 2021 to 2035 is predicted based on regression analysis by selecting the data from 2002 to 2020 of the main variables such as the GDP scale road freight turnover road freight volume and the number of trucks. The study forecasts the truck population of different segments such as mini-duty trucks (MiDT) light-duty trucks (LDT) medium-duty trucks (MDT) and heavy-duty trucks (HDT). Relevant WTW emissions data are collected and adopted based on the popular truck in China's market PHEVs have better emission intensity especially in the HDT field which reduces by 51% compared with ICEVs. Results show that the scenario of TB and PF-TB can reach the carbon peak with 0.13% and 1.5% total GHG emissions reduction per year. In contrast the baseline and PF scenario fail the carbon peak due to only focusing on the number of clean trucks while lacking the restrictions on the GHG emission factors of energy and ignoring the improvement of trucks' energy efficiency and the total emissions increased by 29.76% and 16.69% respectively compared with 2020. As the insights adopting clean trucks has an important but limited effect which should coordinate with the transition to low carbon energy and the melioration of clean trucks to reach the carbon peak of road freight in China.