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。尽管在过去35年中，在开发旨在生产坚固耐用和经济可行的波能转换器(WEC)的新想法方面取得了重大进展，但对于WEC未来的设计和运行方向仍未达成明确的共识。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：第一，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，设计采用了一个内部动力输出系统，该系统由一个在水平轴上旋转的钟摆组成，它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，依靠很少的运动部件在机械上坚固，并且没有与设备过激励相关的末端停止问题。理论和数值结果的结合表明，CPE装置在能量密集的波周期内提取了大量的功率。实际上，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工作中构思的装置密切相关。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。它具有可伸缩性和健壮性。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槽测试在内的实验方法的合作伙伴。在布里斯托尔，该项目将为WITTWEC装置作为漂浮或潜水的球形浮标的运行开发一个理论模型，以包括系泊绳索的影响、该装置及其与模型海况和内部动力输出系统的相互作用。这项工作将在CPE早期工作的基础上进行修改，以考虑到修订后的变流器几何结构、系泊绳索配置和动力输出系统。在完成验证测试后，将应用优化方法来确定WITT WEC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，并通过在南安普顿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设计带来一系列经过实验验证的理论结果，并有可能开发出更大规模的产品，最终实现全面商业化。

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 existingconcepts, it is important that promising new ideas for wave energy conversion continue to be explored. It is widelyaccepted that there are two key elements to a successful WEC design.First, the design should be driven by fundamental theoretical principles of wave energy absorption as these ultimatelydetermine the capacity for power conversion. Second, prospective designs must take account of the significantengineering challenges that arise when 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 whoserotation was damped to produce power.Such a design benefits by its isolation from the marine environment, mechanically robust by relying on few moving partsand free from end-stop problems associated with over-excitation of the device. A combination of theoretical and numericalresults demonstrated that the device of CPE extracts significant power over a broad range of energy-dense wave periods.Indeed, a mean capture factor more than double any existing WEC of its type was 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 partnersspecialising in mooring systems and marine deployment, power take-off design and manufacture and experimentalmethods including wave tank testing. In Bristol, the project will develop a theoretical model for the operation of the WITTWEC device as a spherical buoy either floating or submerged, to include effect of the mooring lines, the device and itsinteraction with a model sea state and the internal power take-off system. The work will be based on the earlier work ofCPE, with changes implemented to account for the revised converter geometry, mooring line configuration and power take-off system.After verification tests have been completed, an optimisation method will be applied to determine parameters for optimalpower conversion for WITT WEC devices over a range of physical scales. The work will develop in tandem with otherpartners on the project, in particular in developing the optimal mooring system and through the validation of theoreticalpredictions by the experimental work performed in Southampton. The successful completion of this project will result in aset of experimentally-validated theoretical results for a WEC design with the potential to be developed a larger scale andeventually to full scale commercialisation.