Abstract Ocean waves contain one of the world's largest untapped and predictable renewable energy sources that can be used to fulfil the energy demand in the present energy crises situation. There are many devices that have been proposed and prototyped in different countries all around the world to harness wave energy based on different power take-off (PTO) systems. The aim of this article is to review the power take-off (PTO) systems of the wave energy converters (WEC). The review starts with a brief introduction and background of wave energy. Following this, a novel classification of WEC systems is introduced. Then, the WECs based on the different working methods of their power take off systems are briefly reviewed. This includes an analysis and comparison of advantages and challenges of the power take off systems. Aspects of current international research and development activities and networks for wave energy is also discussed. The current market of wave energy technologies is also assessed, showing that the mechanical direct drive system is the most popular. Hybrid PTO systems are seen as an important development for the future.

中文翻译：

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基于动力输出 (PTO) 系统的波浪能转换器的进展：综述

摘要 海浪包含世界上最大的未开发和可预测的可再生能源之一，可用于满足当前能源危机形势下的能源需求。世界各地的不同国家已经提出并制作了许多装置，以利用基于不同动力输出 (PTO) 系统的波浪能。本文的目的是回顾波浪能转换器 (WEC) 的动力输出 (PTO) 系统。回顾首先简要介绍了波浪能的背景和背景。在此之后，引入了 WEC 系统的新分类。然后，简要回顾了基于其取力器系统不同工作方法的 WEC。这包括对取力器系统的优势和挑战的分析和比较。还讨论了当前国际波浪能研究和开发活动和网络的各个方面。还评估了当前的波浪能技术市场，表明机械直接驱动系统最受欢迎。混合动力输出系统被视为未来的重要发展。