Underwater compressed air energy storage was developed from its terrestrial counterpart. It has also evolved to underwater compressed natural gas and hydrogen energy storage in recent years. UWCGES is a promising energy storage technology for the marine environment and subsequently of recent significant interest attention. However, it is still immature. In this study, the latest progress in both academic and industrial fields is summarized. Additionally, challenges facing this emerging technology are analyzed. The pros and cons of UWCGES are provided and are differentiated from the terrestrial variant. Technical, economic, environmental, and policy challenges are examined. In particular, the critical issues for developing artificial large and ultra-large underwater gas storage accumulators and effective underwater gas transportation are comprehensively analyzed. Finally, the demand for marine energy storage technology is briefly summarized, and the potential application scenarios and application modes of underwater compressed gas energy storage technology are prospected. This study aims to highlight the current state of the UWCGES sector and provide some guidance and reference for theoretical research and industrial development.

Exhausted air reuse is one of the most important energy-saving methods for pneumatic actuation systems. However, traditional exhausted air storage tanks have the disadvantages of unstable pressure and low energy density. To solve these problems, this paper presents an energy-saving method by exhausted air reuse for industrial pneumatic actuation systems based on a constant pressure elastic accumulator. Employing the hyperelastic mechanical properties of rubber, a constant pressure energy storage accumulator is designed and applied to a pneumatic circuit for exhausted air recovery and energy saving. In the circuit, the accumulator recovers exhausted air from a primary cylinder and supplies it to another secondary cylinder. Then the secondary cylinder no longer needs air supply from the air compressor to achieve the purpose of energy saving. The energy-saving mathematical model of the circuit is established using air consumption, and the system operation test bed is built to verify the energy-saving efficiency. Results show that the maximum energy-saving efficiency of the system is 54.1% under given working conditions, and the stability of the cylinder can be improved.

To solve the problem that small rescue vessels are seriously affected by waves when working at sea, which causes damage to the crew and equipment, a catamaran with a suspended and articulated cabin is designed. The multi-body dynamic model of the whole vessel based on SimMechanics is built, and the prototype is tested on the water. The correctness of the model is verified based on the three aspects of the roll motion, pitch motion, and heave motion of the rescue platform. The motion of the rescue platform is simulated under the conditions of bow waves and large heave waves, and the RMS value of the vertical acceleration of the rescue platform is taken as the response target to analyze the influence of the suspension system parameters of the whole vessel. The suspension system has good buffering and motion reduction effects under various working conditions, and it has an obvious reduction effect on the vertical acceleration at the rescue platform. The larger the amplitude of the wave impact, the more obvious the effect. The articulated system reduces the roll angle and the heave amplitude under the conditions of bow waves.