China, People’s Republic

Power-to-gas (P2G) facilities use surplus electricity to convert to natural gas in integrated energy systems (IES) increasing the capacity of wind power to be consumed. However the capacity limitation of P2G and the antipeaking characteristic of wind power make the wind abandonment problem still exist. Meanwhile the oxygen generated by P2G electrolysis is not fully utilized. Therefore this study proposes a low-carbon economic dispatch model considering the utilization of hydrogen and oxygen energy. First the two-stage reaction model of P2G is established and the energy utilization paths of hydrogen blending and oxygen-rich deep peaking are proposed. Specifically hydrogen energy is blended into the gas grid to supply gas-fired units and oxygen assists oxygenrich units into deep peaking. Subsequently the stochastic optimization is used to deal with the uncertainty of the system and the objective function and constraints of the IES are given to establish a low-carbon dispatch model under the energy utilization model. Finally the effectiveness of the proposed method is verified based on the modified IEEE 39-node electric network 20-node gas network and 6-node heat network models.

Using photovoltaic (PV) energy to produce hydrogen through water electrolysis is an environmentally friendly approach that results in no contamination making hydrogen a completely clean energy source. Alkaline water electrolysis (AWE) is an excellent method of hydrogen production due to its long service life low cost and high reliability. However the fast fluctuations of photovoltaic power cannot integrate well with alkaline water electrolyzers. As a solution to the issues caused by the fluctuating power a hydrogen production system comprising a photovoltaic array a battery and an alkaline electrolyzer along with an electrical control strategy and energy management strategy is proposed. The energy management strategy takes into account the predicted PV power for the upcoming hour and determines the power flow accordingly. By analyzing the characteristics of PV panels and alkaline water electrolyzers and imposing the proposed strategy this system offers an effective means of producing hydrogen while minimizing energy consumption and reducing damage to the electrolyzer. The proposed strategy has been validated under various scenarios through simulations. In addition the system’s robustness was demonstrated by its ability to perform well despite inaccuracies in the predicted PV power.

For commercial applications the durability and economy of the fuel cell hybrid system have become obstacles to be overcome which are not only affected by the performance of core materials and components but also closely related to the energy management strategy (EMS). This paper takes the 7.9 t fuel cell logistics vehicle as the research object and designed the EMS from two levels of qualitative and quantitative analysis which are the composite fuzzy control strategy optimized by genetic algorithm and Pontryagin’s minimum principle (PMP) optimized by objective function respectively. The cost function was constructed and used as the optimization objective to prolong the life of the power system as much as possible on the premise of ensuring the fuel economy. The results indicate that the optimized PMP showed a comprehensive optimal performance the hydrogen consumption was 3.481 kg/100 km and the cost was 13.042 $/h. The major contribution lies in that this paper presents a method to evaluate the effect of different strategies on vehicle performance including fuel economy and durability of the fuel cell and battery. The comparison between the two totally different strategies helps to find a better and effective solution to reduce the lifetime cost.

Power to hydrogen (P2H) provides a promising solution to the geographic mismatch between sources of renewable energy and the market due to its technological maturity flexibility and the availability of technical and economic data from a range of active demonstration projects. In this review we aim to provide an overview of the status of P2H analyze its technical barriers and solutions and propose potential opportunities for future research and industrial demonstrations. We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification. Strong evidence shows that an addition of about 10% hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances and may therefore extend the asset value of the pipelines after natural gas is depleted. To obtain pure hydrogen from hydrogen-enriched natural gas (HENG) mixtures end-user separation is inevitable and can be achieved through membranes adsorption and other promising separation technologies. However novel materials with high selectivity and capacity will be the key to the development of industrial processes and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG. It is also worth investigating the feasibility of electrochemical separation (hydrogen pumping) at a large scale and its energy analysis. Cryogenics may only be feasible when liquefied natural gas (LNG) is one of the major products. A range of other technological and operational barriers and opportunities such as water availability byproduct (oxygen) utilization and environmental impacts are also discussed. This review will advance readers’ understanding of P2H and foster the development of the hydrogen economy.

The hot electron transition of noble materials to catalysis accelerated by localized surface plasmon resonances (LSPRs) was detected by in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) in this article. This paper synthesized an Ag Nanowire (AgNW) @ WS₂ core-shell structure with an ultra-thin shell of WS₂(3 ∼ 7 nm) and characterized its photocatalytic properties. The AgNW@WS₂ core-shell structure exhibited different surface-enhanced Raman spectroscopy (SERS) effects by changing shell thickness indicating that the effect of AgNW could be controlled by WS₂ shell. Furthermore the hydrogen production of AgNW@WS₂ could reach to 356% of that of pure WS₂. The hot electrons arising from the LSPRs effect broke through the Schottky barrier between WS2 and AgNW and transferred to the WS₂ shell whose photocatalytic effect was thus enhanced. In addition when the LSPRs effect was intensified by reducing the shell thickness the hot electron transition of noble materials to catalysis was accelerated.

The Paris Agreement has set the goal of carbon neutrality to cope with global climate change. China has pledged to achieve carbon neutrality by 2060 which will strategically change everything in our society. As the main source of carbon emissions the consumption of fossil energy is the most profoundly affected by carbon neutrality. This work presents an analysis of how China can achieve its goal of carbon neutrality based on its status of fossil energy utilization. The significance of transforming fossils from energy to resource utilization in the future is addressed while the development direction and key technologies are discussed.

This paper proposes a current decoupling controller for a Doubly-fed Induction Generator (DFIG) based on floating offshore wind turbine and power to gas. The proposed controller realizes Maximum Power Point Tracking (MPPT) through integral sliding mode compensation. By using the internal model control strategy an open-loop controller is designed to ensure that the system has good dynamic performance. Furthermore using the integral Sliding Mode Control (SMC) strategy a compensator is designed to eliminate the parameter perturbation and external disturbance of the open-loop control. The parameters of the designed controller are designed through Grey Wolf Optimization (GWO). Simulation results show that the proposed control strategy has better response speed and smaller steady-state error than the traditional control strategy. This research is expected to be applied to the field of hydrogen production by floating offshore wind power.

The aeroderivative gas turbine is widely used as it demonstrates many advantages. Adding hydrogen to natural gas fuels can improve the performance of combustion. Following this the effects of hydrogen enrichment on combustion characteristics were analyzed in an aeroderivative gas turbine combustor using CFD simulations. The numerical model was validated with experimental results. The conditions of the constant mass flow rate and the constant energy input were studied. The results indicate that adding hydrogen reduced the fuel residues significantly (fuel mass at the combustion chamber outlet was reduced up to 60.9%). In addition the discharge of C2H2 and other pollutants was reduced. Increasing the volume fraction of hydrogen in the fuel also reduced CO emissions at the constant energy input while increasing CO emissions at the constant fuel mass flow rate. An excess in the volume fraction of added hydrogen changed the combustion mode in the combustion chamber resulting in fuel-rich combustion (at constant mass flow rate) and diffusion combustion (at constant input power). Hydrogen addition increased the pattern factor and NOx emissions at the outlet of the combustion chamber.

Facing the challenge that the single-motor electric drive powertrain cannot meet the continuous uphill requirements in the cold mountainous area of the 2022 Beijing Winter Olympics the manuscript adopted a dual-motor coupling technology. Then according to the operating characteristics and performance indicators of the fuel cell (FC)–traction battery hybrid power system the structure design and parameter matching of the vehicle power system architecture were carried out to improve the vehicle’s dynamic performance. Furthermore considering the extremely cold conditions in the Winter Olympics competition area and the poor low-temperature tolerance of core components of fuel cell electric vehicles (FCEV) under extremely cold conditions such as the reduced capacity and service life of traction batteries caused by the rapid deterioration of charging and discharging characteristics the manuscript proposed a fuzzy logic control-based energy management strategy (EMS) optimization method for the proton exchange membrane fuel cell (PEMFC) to reduce the power fluctuation hydrogen consumption and battery charging/discharging times and at the same time to ensure the hybrid power system meets the varying demand under different conditions. In addition the performance of the proposed approach was investigated and validated in an intercity coach in real-world driving conditions. The experimental results show that the proposed powertrain with an optimal control strategy successfully alleviated the fluctuation of vehicle power demand reduced the battery charging/discharging times of traction battery and improved the energy efficiency by 20.7%. The research results of this manuscript are of great significance for the future promotion and application of fuel cell electric coaches in all climate environments especially in an extremely cold mountain area.

The thermal efficiency and combustion of conventional hydrogen engines cannot be optimized and improved by its symmetric reciprocating. This article introduces an asymmetric motion hydrogen engine (AHE) and investigates its combustion characteristics using diesel pilot ignition. A dynamic model is firstly proposed to describe the asymmetric motion of the AHE and then it is coupled into a multidimensional model for combustion simulation. The effect of asymmetric motion on the AHE combustion is also analyzed by comparing with a corresponding conventional symmetric hydrogen engine (SHE). The results show that the AHE moves slower in compression and faster in expansion than the SHE which brings about higher hydrogen-air mixing level for combustion. The asymmetric motion delays diesel injection to ignite the AHE and its combustion appears later than the SHE which leads to lower pressure and temperature for reducing NO formation. However the AHE faster expansion has a more severe post-combustion effect to reduce isovolumetric heat release level and decrease the energy efficiency.