Ocean energy:the wave of the future

The power point presentation discussed the developing technology of ocean energy with design convergence on tidal but not on wave. Today's technologies will help solve the immediate needs, but we need to work hard nurturing tomorrow's low carbon technologies today. Ocean energy represents one of the more difficult forms of renewable energy to harness. The UK is leading internationally in the development of marine energy but further development investment is needed to move the technology forward. Marine energy could supply up to 2 GW of UK electricity demand by 2020 and significantly more than this by 2050. The development of ocean energy and promising ocean driven machines are briefly reviewed, their operating conditions and the suitability of different types of hydro turbines for use as power take off options, the recent international experience, and how the technology is developing

An Investigation into Power from Pitch-Surge Point-Absorber Wave Energy Converters.

There is a worldwide opportunity for clean renewable power. The results from the UK Government's "Marine Energy Challenge" showed that marine energy has the potential to become competitive with other forms of energy. The key to success in this lies in a low lifetime-cost of power as delivered to the user. Pitch-surge point-absorber WECs have the potential to do this with average annual powers of around 2 MW in North Atlantic conditions from relatively small devices that would be economically competitive with other technologies and would be relatively easy to install and maintain. The paper examines the factors governing the performance of such devices and outlines their underlying theory Preliminary laboratory test results from a 1/100 scale pilot design are presented. It is hoped that more extensive development work will follow these promising early results. Engineering designs for devices based on these findings are outlined

Renewable Energy Resources Impact on Clean Electrical Power by developing the North-West England Hydro Resource Model.

This paper describes the development of a sequential decision support system to promote hydroelectric power in North-West England. The system, composed of integrated models, addresses barriers to the installation of hydroelectric power schemes. Information is linked through an economic assessment which identifies different turbine options, assesses their suitability for location and demand; and combines the different types of information in a way that supports decision making. The system is structured into five components: the hydrological resource is modelled using Low Flows 2000, the turbine options are identified from hydrological, environmental and demand requirements; and the consequences of different solutions will be fed into other components so that the environmental impacts and public acceptability can be assessed and valued. A preliminary case study is presented on an old gunpowder works to illustrate how the resource model may be employed. Historical architectural structures, power uptake and educational instruction of hydro power technology are considered

Control systems for WRASPA.

The paper discusses the need for a wave energy converter (WEC) to sense and respond to its environment in order to survive and to produce its maximum useful output. Such systems are described for Wraspa, a WEC being developed at Lancaster University and first reported at ICCEP in 2007. The main control system that continually monitors and optimises the power-take-off is termed ldquoStepwise Controlrdquo and seeks to continually adjust the damping force applied to the collector to suit the wave force that drives it. The complete instrumentation and control system that will be needed is considered briefly, including the above PTO control system; direction sensing and heading control; tide level compensation; condition monitoring and provisions for access and maintenance

Numerical hydrodynamic modelling of a pitching wave energy converter

Two computational methodologies – computational fluid dynamics (CFD) and the numerical modelling using linear potential theory based boundary element method (BEM) are compared against experimental measurements of the motion response of a pitching wave energy converter. CFD is considered as relatively rigorous approach offering nonlinear incorporation of viscous and vortex phenomenon and capturing of the flow turbulence to some extent, whereas numerical approach of the BEM relies upon the linear frequency domain hydrodynamic calculations that can be further used for the time-domain analysis offering robust preliminary design analysis. This paper reports results from both approaches and concludes upon the comparison of numerical and experimental findings

Navier-stokes CFD analysis of a tidal turbine rotor in steady and planar oscillatory flow

Initial results of an ongoing Navier-Stokes Computational Fluid Dynamics study of horizontal axis tidal current turbine hydrodynamics are presented. Part of the underlying motivation is assessing the effects of the Reynolds number on turbine performance and loads in steady flow conditions and unsteady regimes. The study aims at a) providing initial verification and validation of Navier-Stokes CFD for steady and unsteady tidal turbine flows over a wide range of Reynolds numbers, and b) estimating the dependence of turbine performance and loads on this parameter, so as to enable more reliable exploitation of low-Reynolds number tank measurements for field installation analysis and design. The investigation starts from a tidal current turbine towing tank experiment conducted at the Kelvin Hydrodynamic Laboratory of Strathclyde University, compares available measured data and CFD results regarding the blade steady flow and unsteady flow due to the harmonic planar motion of the turbine, and extends the CFD analysis to the high Reynolds numbers of typical utility-scale field installations. It is found that at high (field-like) Reynolds numbers, the blade power, force and moment coefficients are about 20 percent higher than at (low) tank-like Reynolds numbers, and also that the agreement of measured and predicted loads at fairly low Reynolds numbers improves by modelling laminar-to-turbulent transition, highlighting the importance of this phenomenon in tank experiments

Fast–slow dynamic behaviors of a hydraulic generating system with multi-timescales

Hydraulic generating systems are widely modeled in the literature for investigating their stability properties by means of transfer functions representing the dynamic behavior of the reservoir, penstock, surge tank, hydro-turbine, and the generator. Traditionally, in these models the electrical load is assumed constant to simplify the modeling process. This assumption can hide interesting dynamic behaviors caused by fluctuation of the load as actually occurred. Hence, in this study, the electrical load characterized with periodic excitation is introduced into a hydraulic generating system and the responses of the system show a novel dynamic behavior called the fast–slow dynamic phenomenon. To reveal the nature of this phenomenon, the effects of the three parameters (i.e., differential adjustment coefficient, amplitude, and frequency) on the dynamic behaviors of the hydraulic generating system are investigated, and the corresponding change rules are presented. The results show that the intensity of the fast–slow dynamic behaviors varies with the change of each parameter, which provides reference for the quantification of the hydraulic generating system parameters. More importantly, these results not only present rich nonlinear phenomena induced by multi-timescales, but also provide some theoretical bases for maintaining the safe and stable operation of a hydropower station