The capability of the WITT Wave Energy Converter to generate megawatts of offshore power at a competitive LCOE

从海浪中利用大量清洁可再生能源的潜力是巨大的。英国政府和其他国家为应对气候变化做出的承诺要求扩大可再生技术的开发和部署，人们普遍认识到，海浪能将在实现未来碳减排目标方面发挥重要作用。虽然在过去的35年里，在开发新的想法以生产坚固和经济可行的波能转换器(WEC)方面取得了重大进展，但对于WEC未来的设计和运行方向仍没有明确的共识。除了支持现有的概念外，重要的是继续探索有前途的波能转换的新想法。人们普遍认为，成功的WEC设计有两个关键要素。首先，设计应遵循波能吸收的基本理论原理，因为这些原理最终决定了功率转换的能力。其次，未来的设计必须考虑到在恶劣的海洋环境中运行时出现的重大工程挑战。在最近的一篇论文中，Crowley，Porter&Evans，《流体力学杂志》，2013年，第716卷，(以下简称CPE)倡导WEC设计，试图满足这两个要求。特别是，设计采用了内部动力输出系统，该系统由一个在水平轴上旋转的钟摆组成，该摆的旋转被抑制以产生动力。这种设计的好处是它与海洋环境隔绝，机械上坚固耐用，依靠很少的移动部件，并且没有与设备过激励相关的末端停止问题。理论和数值结果相结合的结果表明，CPE装置在大范围的能量密集波周期内提取了相当大的功率。事实上，预测的平均捕获系数是现有同类WEC的两倍以上。由Witt Limited开发的WITT与CPE工作中构思的设备密切相关。WITT不是工作在长长圆柱体内的浪涌/俯仰运动模式下的线性装置，而是一种设计用于浮标的装置。它不仅可以在喘振和俯仰模式下转换功率，还可以在摇摆和滚动模式下转换功率。WITT是由齿轮传动系统专家开发的，已被证明在动能到电能的转换方面具有高效率。WITT领导的项目包括专门从事系泊系统和海上部署、动力输出设计和制造以及包括波浪水箱测试在内的实验方法的合作伙伴。在布里斯托尔，该项目将开发一个理论模型，用于WITT WEC装置作为球形浮标的操作，无论是漂浮还是潜水，包括系泊绳索、装置及其与模型海况和内部动力输出系统的相互作用。这项工作将以CPE以前的工作为基础，并进行了修改，以考虑到修订后的转炉几何形状、系泊绳索配置和动力输出系统。在验证测试完成后，将应用优化方法来确定WITT设备在一系列物理规模上的最佳功率转换参数。这项工作将与该项目的其他合作伙伴共同开展，特别是在开发最佳系泊系统方面，并通过在南安普敦进行的实验工作对理论预测进行验证。该项目的成功完成将为WEC设计带来一套经过实验验证的理论结果，具有大规模开发并最终实现全面商业化的潜力。

The potential for harnessing significant amounts of clean renewable energy from ocean waves is vast. Commitments madeby the UK government and others to tackle climate change require an expansion in development and deployment ofrenewable technologies and it is widely recognised that ocean wave energy will play an important role in meeting futuretargets for the reduction of carbon emissions. Whilst significant advances have been made over the last 35 years indeveloping new ideas aimed towards producing robust and economically viable wave energy converters (WECs) thereremains no clear consensus on future direction of design and operation of WECs.In addition to supporting existing concepts, it is important that promising new ideas for wave energy conversion continue tobe explored. It is widely accepted that there are two key elements to a successful WEC design. First, the design should bedriven by fundamental theoretical principles of wave energy absorption as these ultimately determine the capacity forpower conversion. Second, prospective designs must take account of the significant engineering challenges that arisewhen operating in harsh marine environments.In a recent paper "A submerged cylinder wave energy converter" Crowley, Porter & Evans, Journal of Fluid Mechanics,2013, vol 716, (hereafter CPE) advocated a WEC design which sought to address these two demands. In particular, thedesign was assumed to use an internal power take-off system consisting of a pendulum rotating on a horizontal axis whose rotation was damped to produce power. Such a design benefits by its isolation from the marine environment, mechanicallyrobust by relying on few moving parts and free from end-stop problems associated with over-excitation of the device. Acombination of theoretical and numerical results demonstrated that the device of CPE extracts significant power over abroad range of energy-dense wave periods. Indeed, a mean capture factor more than double any existing WEC of its typewas predicted.The WITT developed by WITT Limited under whom this TSB grant is being led is closely related to the device conceived inthe work of CPE. Instead of a linear device working in surge/pitch modes of motion enclosed within a long cylinder, theWITT is a device designed for use in buoys. It not only converts power in surge and pitch modes but also in sway and roll.The WITT has been developed by specialists in gear transmission systems and has been shown to have high efficiency inconversion of kinetic to electric power. It is scalable and robust.The project being led by WITT includes partners specialising in mooring systems and marine deployment, power take-offdesign and manufacture and experimental methods including wave tank testing.In Bristol, the project will develop a theoretical model for the operation of the WITT WEC device as a spherical buoy eitherfloating or submerged, to include effect of the mooring lines, the device and its interaction with a model sea state and theinternal power take-off system. The work will be based on the earlier work of CPE, with changes implementated to accountfor the revised converter geometry, mooring line configuration and power take-off system. After verification tests have beencompleted, an optimisation method will be applied to determine parameters for optimal power conversion for WITT devicesover a range of physical scales.The work will develop in tandem with other partners on the project, in particular in developing the optimal mooring systemand through the validation of theoretical predictions by the experimental work performed in Southampton.The successful completion of this project will result in a set of experimentally-validated theoretical results for a WEC designwith the potential to be developed a larger scale and eventually to full scale commercialisation.