scholarly journals Fluid-Structure-Soil Interaction of a Moored Wave Energy Device

2019 ◽  
Author(s):  
Joe G. Tom ◽  
Dirk P. Rijnsdorp ◽  
Raffaele Ragni ◽  
David J. White
Keyword(s):  
Cyclic Loading ◽  
Wave Energy ◽  
Significant Proportion ◽  
Interdisciplinary Approach ◽  
Cost Effective ◽  
Wave Flow ◽  
Energy Device ◽  
Subsequent Increase ◽  
Operational Conditions ◽  
Energy Devices

Abstract This paper explores the response of a wave energy device during extreme and operational conditions and the effect of this response on the geotechnical stability of the associated taut moorings. The non-hydrostatic wave-flow model SWASH is used to simulate the response of a taut-moored wave energy converter. The predicted forces acting on the mooring system are used to compute the build-up of excess pore pressures in the soil around the mooring anchor and the resulting changes in strength and capacity. An initial loss of strength is followed by a subsequent increase in capacity, associated with long-term cyclic loading and hardening due to consolidation. The analyses show how cyclic loading may actually benefit and reduce anchoring requirements for wave energy devices. It demonstrates the viability of a close interdisciplinary approach towards an optimized and cost-effective design of mooring systems, which form a significant proportion of expected capital expenditures.

Life cycle comparison of a wave and tidal energy device

2011 ◽  
Vol 225 (4) ◽  
pp. 325-337 ◽  
Author(s):  
S Walker ◽  
R Howell
Keyword(s):  
Life Cycle ◽  
Wave Energy ◽  
Tidal Energy ◽  
Development Stage ◽  
Payback Period ◽  
Energy Device ◽  
Energy Mix ◽  
Energy Devices ◽  
Marine Energy ◽  
Marine Current

Tidal and wave energy devices are often discussed as a future contributor to the UK’s energy mix. Indeed, marine energy resources are said to have the potential to supply up to 20 per cent of the nation’s electricity demand. However, these technologies are currently at the development stage and make no meaningful contribution to the national grid. A number of devices have been developed, but no single method has emerged as the leading technology. This paper aims to compare two promising devices, one wave device and one tidal device, and assess the life cycle properties of each. A life cycle assessment of the Oyster wave energy device was conducted as part of this study, and a comparison of this and the SeaGen marine current turbine was undertaken. In both cases a ‘cradle-to-grave’ assessment was carried out, calculating emissions from materials, fabrication, transport, installation, lifetime maintenance, and decommissioning (including recycling). The SeaGen tidal device was calculated to have an energy payback period of 14 months, and a CO2 payback period of 8 months. The equivalent figures for the Oyster device were 12 and 8 months, respectively. The respective energy and carbon intensities for the two devices were 214 kJ/kWh and 15 gCO2/kWh for the SeaGen and 236 kJ/kWh and 25 gCO2/kWh for the Oyster. The calculated intensities and payback periods are close to those of established wind turbine technologies, and low relative to the 400–1000 g CO2/kWh of typical fossil fuel generation. With further developments in construction and deployment efficiency these intensities are expected to fall, so the devices appear to have the potential to offer a viable contribution to the UK’s future energy mix.

Floating Wave Energy Device With Two Oscillating Water Columns

2007 ◽  
Author(s):  
D. C. Hong ◽  
S. Y. Hong
Keyword(s):  
Green Function ◽  
Wave Energy ◽  
Numerical Results ◽  
The Body ◽  
Energy Device ◽  
Energy Devices ◽  
Damping Parameter ◽  
Absorbed Power ◽  
Linear Damping ◽  
Drift Force

The absorbed power, motion and drift force of a floating wave energy device with two oscillating water column (OWC) chambers are studied taking account of the interaction between two chambers within the scope of the linear wave theory. The oscillating surface-pressure in the OWC chamber is represented by a product of the air-flow velocity and an equivalent linear damping parameter. The two-dimensional potential problem is formulated as a hybrid Green integral equation using the Rankine Green function inside the chamber and the finite-depth free-surface Green function outside respectively. The present numerical method makes it possible to tune the OWC and the floating body motions to the incident waves that is essential to maximize the absorbed power. The absorbed powers are calculated by both the near-field and far-field methods for various values of the linear damping parameter in two chambers. The reflection and transmission coefficients of the body are also presented. The numerical results for one OWC devices where the OWC is placed in a backward and forward bent duct buoys (BBDB and FBDB) are also presented for comparison of the performance. The present floating wave energy devices can also be served as a good floating breakwater having small drift force. The present numerical results show that the existence of reverse time-mean horizontal wave drift force is not contradictory to the principle of wave energy conservation.

scholarly journals On Wave-Induced Elastic Deformations of a Submerged Wave Energy Device

2020 ◽  
Vol 19 (3) ◽  
pp. 317-338
Author(s):  
Shuijin Li ◽  
Masoud Hayatdavoodi ◽  
R. Cengiz Ertekin
Keyword(s):  
Nonlinear Wave ◽  
Wave Energy ◽  
Structural Integrity ◽  
Accurate Determination ◽  
Elastic Response ◽  
Wave Loads ◽  
Extreme Wave ◽  
Energy Device ◽  
Energy Devices ◽  
Wave Induced

Abstract Structural integrity has remained a challenge for design and analysis of wave energy devices. A difficulty in assessment of the structural integrity is often laid in the accurate determination of the wave-induced loads on the wave energy devices and the repones of the structure. Decoupled hydroelastic response of a submerged, oscillating wave energy device to extreme nonlinear wave loads is studied here. The submerged wave energy device consists of an oscillating horizontal disc attached to a direct-drive power take-off system. The structural frame of the wave energy device is fixed on the seafloor in shallow water. Several extreme wave conditions are considered in this study. The nonlinear wave loads on members of the submerged structure are obtained by use of the level I Green-Naghdi equations and Morison’s equation for cylindrical members. Distribution of Von Mises stresses and the elastic response of the structure to the extreme wave loads are determined by use of a finite element method. The decoupled hydroelastic analysis of the structure is carried out for devices built by four different materials, namely stainless steel, concrete, aluminium alloy, and titanium alloy. The elastic response of these devices is studied and results are compared with each other. Points of maximum stress and deformations are determined and the structural integrity under the extreme conditions is assessed. It is shown that the proposed approaches provide invaluable information about the structural integrity of wave energy devices.

scholarly journals A novel wave-energy device with enhanced wave amplification and induction actuator

2020 ◽  
Vol 3 (1) ◽  
pp. 37-44
Author(s):  
Onno Bokhove ◽  
Anna Kalogirou ◽  
David Henry ◽  
Gareth P. Thomas
Keyword(s):  
Variational Principle ◽  
Numerical Model ◽  
Energy Conversion ◽  
Wave Energy ◽  
Electrical Power ◽  
Rogue Waves ◽  
Energy Device ◽  
Wave Amplification ◽  
Energy Devices ◽  
New Device

A novel wave-energy device is presented. Both a preliminary proof-of-principle of a working, scaled laboratory version of the energy device is shown as well as the derivation and analysis of a comprehensive mathematical and numerical model of the new device. The wave-energy device includes a convergence in which the waves are amplified, a constrained wave buoy with a (curved) mast and direct energy conversion of the buoy motion into electrical power via an electro-magnetic generator. The device is designed for use in breakwaters and it is possible to be taken out of action during severe weather. The new design is a deconstruction of elements of existing wave-energy devices, such as the TapChan, IP wave-buoy and the Berkeley Wedge, put together in a different manner to enhance energy conversion and, hence, efficiency. The idea of wave-focusing in a contraction emerged from our work on creating and simulating rogue waves in crossing seas, including a "bore-soliton-splash". Such crossing seas have been recreated and modelled in the laboratory and in simulations by using a geometric channel convergence. The mathematical and numerical modelling is also novel. One monolithic variational principle governs the dynamics including the combined (potential-flow) hydrodynamics, the buoy motion and the power generation, to which the dissipative elements such as the electrical resistance of the circuits, coils and loads have been added a posteriori. The numerical model is a direct and consistent discretisation of this comprehensive variational principle. Preliminary numerical calculations are shown for the case of linearised dynamics; optimisation of efficiency is a target of future work.

scholarly journals Wave Energy Converter Power Take-Off System Scaling and Physical Modelling

2020 ◽  
Vol 8 (9) ◽  
pp. 632
Author(s):  
Gianmaria Giannini ◽  
Irina Temiz ◽  
Paulo Rosa-Santos ◽  
Zahra Shahroozi ◽  
Victor Ramos ◽  
...  
Keyword(s):  
Wave Energy ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Physical Modelling ◽  
Cost Effective ◽  
Estimation Methods ◽  
Small Scale ◽  
Wave Power ◽  
Energy Converter ◽  
Energy Device

Absorbing wave power from oceans for producing a usable form of energy represents an attractive challenge, which for the most part concerns the development and integration, in a wave energy device, of a reliable, efficient and cost-effective power take-off mechanism. During the various stages of progress, for assessing a wave energy device, it is convenient to carry out experimental testing that, opportunely, takes into account the realistic behaviour of the power take-off mechanism at a small scale. To successfully replicate and assess the power take-off, good practices need to be implemented aiming to correctly scale and evaluate the power take-off mechanism and its behaviour. The present paper aims to explore and propose solutions that can be applied for reproducing and assessing the power take-off element during experimental studies, namely experimental set-ups enhancements, calibration practices, and error estimation methods. A series of recommendations on how to practically organize and carry out experiments were identified and three case studies are briefly covered. It was found that, despite specific options that can be strictly technology-dependent, various recommendations could be universally applicable.

Conceptual Design of OWC Wave Energy Converters Combined With Breakwater Structures

2010 ◽  
Author(s):  
Vallam Sundar ◽  
Torgeir Moan ◽  
Jo̸rgen Hals
Keyword(s):  
Wave Energy ◽  
Ocean Waves ◽  
Floating Bodies ◽  
Energy Device ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Caisson Breakwater ◽  
Perforated Caisson ◽  
Energy Converters

Ocean wave energy is one of several renewable sources of energy found in the ocean. The energy in the oscillatory ocean waves can be used to drive a machinery that converts the energy to other forms. Depending on the type and their location with respect the coast and offshore, a number of devices have been and are being developed to extract the wave energy for conversion into electricity. The most common devices are referred to as the oscillating water column (OWC), hinged contour device, buoyant moored device, hinged flap and overtopping device. Particularly popular are OWCs and moored floating bodies. The idea of integrating breakwater and wave energy converters emerged in the Indian wave energy program. Graw (1996) discussed this idea and pointed out the advantage of shared costs between the breakwater and the wave energy device. Because long waves are usually experience stronger reflection at coasts and breakwaters, they provide good conditions for the operation wave energy devices which work efficiently when the reflection is high. There are examples that OWC devices have been installed in water as shallow as 3 m. This paper reviews the options of integrating OWCs with different kinds of breakwaters like the perforated or non-perforated caisson breakwater, and non-gravity piled and floating types. The purpose of each of the concepts will also be highlighted.

scholarly journals A Nonlinear Extension for Linear Boundary Element Methods in Wave Energy Device Modelling

2012 ◽  
Author(s):  
Alexis Merigaud ◽  
Jean-Christophe Gilloteaux ◽  
John V. Ringwood
Keyword(s):  
Boundary Element ◽  
Wave Energy ◽  
Linear Models ◽  
Boundary Element Methods ◽  
Hydrodynamic Models ◽  
Energy Device ◽  
Energy Capture ◽  
Energy Devices ◽  
Higher Order Terms ◽  
Device Modelling

To date, mathematical models for wave energy devices typically follow Cummins equation, with hydrodynamic parameters determined using boundary element methods. The resulting models are, for the vast majority of cases, linear, which has advantages for ease of computation and a basis for control design to maximise energy capture. While these linear models have attractive properties, the assumptions under which linearity is valid are restrictive. In particular, the assumption of small movements about an equilibrium point, so that higher order terms are not significant, needs some scrutiny. While this assumption is reasonable in many applications, in wave energy the main objective is to exaggerate the movement of the device through resonance, so that energy capture can be maximised. This paper examines the value of adding specific nonlinear terms to hydrodynamic models for wave energy devices, to improve the validity of such models across the full operational spectrum.

scholarly journals Multi-Country Scale Assessment of Available Energy Recovery Potential Using Micro-Hydropower in Drinking, Pressurised Irrigation and Wastewater Networks, Covering Part of the EU

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 899
Author(s):  
Djordje Mitrovic ◽  
Miguel Crespo Chacón ◽  
Aida Mérida García ◽  
Jorge García Morillo ◽  
Juan Antonio Rodríguez Diaz ◽  
...  
Keyword(s):  
Drinking Water ◽  
Northern Ireland ◽  
Energy Recovery ◽  
Large Scale ◽  
Significant Proportion ◽  
Value Added ◽  
Cost Effective ◽  
Net Energy ◽  
Water Networks ◽  
Scale Assessment

Studies have shown micro-hydropower (MHP) opportunities for energy recovery and CO2 reductions in the water sector. This paper conducts a large-scale assessment of this potential using a dataset amassed across six EU countries (Ireland, Northern Ireland, Scotland, Wales, Spain, and Portugal) for the drinking water, irrigation, and wastewater sectors. Extrapolating the collected data, the total annual MHP potential was estimated between 482.3 and 821.6 GWh, depending on the assumptions, divided among Ireland (15.5–32.2 GWh), Scotland (17.8–139.7 GWh), Northern Ireland (5.9–8.2 GWh), Wales (10.2–8.1 GWh), Spain (375.3–539.9 GWh), and Portugal (57.6–93.5 GWh) and distributed across the drinking water (43–67%), irrigation (51–30%), and wastewater (6–3%) sectors. The findings demonstrated reductions in energy consumption in water networks between 1.7 and 13.0%. Forty-five percent of the energy estimated from the analysed sites was associated with just 3% of their number, having a power output capacity >15 kW. This demonstrated that a significant proportion of energy could be exploited at a small number of sites, with a valuable contribution to net energy efficiency gains and CO2 emission reductions. This also demonstrates cost-effective, value-added, multi-country benefits to policy makers, establishing the case to incentivise MHP in water networks to help achieve the desired CO2 emissions reductions targets.

Sign in / Sign up

Export Citation Format

Share Document