Wind-assisted propulsion system (WAPS) is one of the important energy-saving measures for shipping decarbonization. The optimal design and operation control of wind-assisted ships can efficiently harvest and utilize wind energy, and thus further tapping the potential of improving the ship energy efficiency. However, there remains a shortage of the comprehensive analysis of the wind-assisted technologies to provide references for further study and practical applications of the WAPS. Thus, the present progress achieved in the key techniques, including the aerodynamics analysis for different sails, the optimal design and operation control of the ship adopting WAPS, as well as the comprehensive analysis of the sail-diesel hybrid propulsion system (SDHPS), are systematically analyzed. Additionally, the challenges encountered in the development of the WAPS are proposed, and prospective research directions are suggested to boost advancement of the WAPS for the shipping decarbonization. The investigation results indicate that the optimal design of sails and hybrid power systems, along with the applications of energy efficiency optimization strategies, can fully use the wind energy resources and reduce fuel usage of the ship equipped with WAPS. Additionally, it is anticipated that the wind-assisted technology incorporating complicated sea conditions can contribute to a further optimization of ship energy utilization, thereby promoting the low-carbon development of the shipping industry.

In this work, the electrochemical behavior of zirconium was studied on an inert molybdenum electrode at 550 °C in a LiCl-KCl-K₂ZrF₆ molten salt system, which is considered as an ideal electrolyte for the zirconium electrorefining process. Several transient electrochemical techniques were used such as cyclic voltammetry, chronopotentiometry, square wave voltammetry, and open circuit chronopotentiometry. The reduction of Zr (IV) was determined to follow a two-step mechanism of Zr (IV)/Zr (II) and Zr (II)/Zr. The diffusion coefficient of Zr (IV) was investigated with cyclic voltammetry and chronopotentiometry, and the results turned out to be in fair agreement from the both methods, as to be 4.26×10^-5 and 4.98×10^-5 cm²/s, respectively. The present study aims to provide a theoretical reference for the Zr electrorefining process.

In the present paper, a detailed study of the redox behavior of zirconium in the eutectic LiF-NaF system was carried out on an inert molybdenum electrode at 750 °C. Several transient electrochemical methods were used such as cyclic voltammetry, square wave voltammetry, chronopotentiometry, and open circuit voltammetry. The reduction of Zr (IV) was found to follow a two-step mechanism of Zr (IV)/Zr (II) and Zr (II)/Zr at the potentials of about −1.10 and −1.50 V versus Pt, respectively. The theoretical evaluations of the number of transferred electrons according to both cyclic voltammetry and square wave voltammetry further confirmed the Zr reduction mechanism. The estimations of Zr (IV) diffusion coefficient in the LiF-NaF eutectic melt at 750 °C through cyclic voltammetry and chronopotentiometry are in fair agreement, as to be approximately 1.13E-5 and 2.42E-5 cm²/s, respectively.

In this paper, a detailed study of the electrochemical behavior of zirconium in the molten LiF-KF-ZrF₄ system on an inert molybdenum electrode was carried out at 600 °C. Several electrochemical techniques were employed such as cyclic voltammetry, chronoamperometry and square wave voltammetry. The reduction of zirconium was found to be a multi-step process that at the potentials of 1.15, 1.50 and 1.62 V versus Pt, the corresponding cathodic reactions of Zr⁴⁺/Zr²⁺, Zr²⁺/Zr⁺ and Zr⁺/Zr occurred. The result was further confirmed by the theoretical calculation of the number of transferred electrons according to the cyclic voltammetry and square wave voltammetry analysis. Moreover, based on the cyclic voltammograms, the diffusion coefficient of Zr⁴⁺ ions in the eutectic LiF-KF containing 1 wt% ZrF₄ at 600 °C was estimated to be about 8.31 × 10^-6 cm² s^-1. The present electrochemical study on zirconium in the molten fluoride system will be a theoretical reference for future zirconium electrorefining from Zr alloy or scraps.