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巨大。英国政府和其他国家应对气候变化的承诺需要扩大可再生技术的开发和部署，人们普遍认为海浪能将在实现未来碳排放减少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，旨在生产强大的和经济上可行的波浪能转换器（WECs）方面取得了重大进展，但对未来WECs的设计和操作方向仍然没有明确的共识。除了支持现有的概念外，重要的是继续探索有前途的波浪能转换新想法。人们普遍认为，成功的WEC设计有两个关键要素。首先，设计应该由波能吸收的基本理论原理驱动，因为这些原理最终决定了功率转换的能力。第二，预期设计必须考虑在恶劣海洋环境中操作时出现的重大工程挑战。在最近的论文“A summered cylinder wave energy converter”中，Crowley，Porter & Evans，Journal of Fluid Mechanics，2013，vol 716，（以下简称CPE）提出了一种寻求解决这两个需求的WEC设计。特别是，该设计假定使用内部动力输出系统，该系统由在水平轴上旋转的摆锤组成，该摆锤的旋转被阻尼以产生动力。这种设计的好处是与海洋环境隔离，依靠很少的运动部件，机械坚固，并且没有与设备过激励相关的端部停止问题。理论和数值计算结果表明，CPE装置在能量密集的波浪周期的广泛范围内提取显著的功率。实际上，平均捕获因子是任何现有WEC类型的两倍以上。由WITT有限公司开发的WITT与CPE工作中设想的设备密切相关，WITT有限公司正在领导TSB拨款。WITT是一种专为浮标设计的设备，而不是一种在长圆柱体内以纵荡/纵摇运动模式工作的线性设备。它不仅能在纵荡和俯仰模式下转换动力，还能在横摇和横滚模式下转换动力。威特由齿轮传动系统专家开发，已被证明在动能到电能的转换中具有高效率。该项目由威特牵头，合作伙伴包括专门从事系泊系统和海上部署、动力输出装置设计和制造以及实验方法（包括波浪水槽测试）的专业人员。在布里斯托，该项目将开发一个理论模型，用于研究威特WEC装置作为浮式或水下球形浮标的运行，包括系泊缆的影响，该装置及其与模型海况和内部动力输出系统的相互作用。该工作将基于CPE的早期工作，并进行更改以考虑修改后的转换器几何形状、系泊线配置和动力输出系统。验证测试完成后，将采用优化方法确定威特设备在各种物理规模下的最佳功率转换参数。这项工作将与项目的其他合作伙伴一起开展，特别是在开发最佳系泊系统方面，并通过在南安普顿进行的实验工作验证理论预测。该项目的成功完成将导致一组实验验证的理论结果为WEC designwith的潜力被开发一个更大的规模，并最终全面商业化。

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.