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Drakoo Wave Energy Converter

Hann-Ocean has developed a novel technology for wave energy conversion, named “Drakoo.” Its namesake, Drakoo wave energy converter, is the company’s flagship product. It is capable of absorbing, transforming and converting wave energy into electricity while reactively cancelling or reducing reflective wave energy in the ocean. Kinetic energy from the waves drives a hydro-turbine generator to produce electricity in a wide range of wave heights and periods.

The Working Principle

Drakoo works by transforming ocean waves into a stream of continuous water flow which drives a hydro-turbine generator.

This is accomplished in two steps:

Firstly: an incoming wave crest increases the inlet chamber’s water level. Simultaneously, water is partly directed from the inlet to the outlet through a hydro-turbine set within the hull.

Secondly: as the wave crest passes inward and the water level outside falls with the incoming trough, so do the levels in both the chambers of the device, leading to a flow from the inlet chamber to the outlet chamber via the turbine, followed by flow from the outlet chamber to the outside environment.

Drakoo is able to synchronize this two-step action of its water columns continuously with waves by using passive, one-way checkerboard valves to regulate the flow between itself and the environment. Within the device, the flow is kept constant and unidirectional which enables a smooth operation of the hydro turbine. These mechanisms make Drakoo an incredibly potent wave energy converter

Performance

Verified by National Renewable Energy Center (Narec, UK), Drakoo has consistently achieved a wave to hydro power conversion efficiency (a.k.a. Capture Width Ratio (CWR)), of over 80% at peak and 50% on average in regular waves over broad wave spectrums. The Drakoo-B0010 model (10kWp) has been proven to achieve peak conversion efficiency (waves to electricity) of close to 50%.

Key elements

Drakoo WEC comprises three key features:
Twin-chamber Body
Checkerboard Valves
Power Take-off System
Hann-Ocean has devised a unique method of integrating these three factors, allowing the system to be customized for different Drakoo models which use various wave conditions. Designed for simplicity, the system employs a specially designed composite material for the checkerboard valves, a proven permanent magnetic generator, mature technology for the hydro turbine and cost effective materials in the overall design. When taken in conjunction with its highly efficient working principle, Drakoo’s modular configuration and simplicity give it an unassailable edge over its competitors.

Advantages

Drakoo is the world’s first WEC that works efficiently under very small wave condtions. The main advantages include:

specifications

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Applications

Fixed Modular Drakoo WEC Array

Drakoo-B series works in fixed mode, verified by Narec UK. It is also a modular concept which is well suited for the construction of arrays where the units are installed side by side. In sea waters with little tidal level changes, Drakoo-B can be fixed on the shore, seabed or on a rigid breakwater as long as sufficient draft is available for the device to operate.

Floating Modular Drakoo WEC Array

Drakoo-B models also work in floating mode, which has been verified repeatedly in sea trials of prototypes. In floating mode, as in fixed, their modular design enables the construction of large scale arrays in which the units are connected to each other using the company’s proprietary Rigid Pontoon Connectors (RPC) or by simply welding them together. These self-buoyant devices can float on their own or be tethered to existing floating structures such as floating wind turbines, semi-submersibles, floating jetties and floating breakwaters. Additionally, they can also be integrated with offshore production platforms or ships, to power those installations. In areas prone to large tidal changes, Drakoo-B models work more efficiently in floating mode which enables the device to maintain a constant draft.

Floating Stand-alone Drakoo WEC

Hann-Ocean is actively engaged in the research and development of a stand-alone device which is capable of generating mega-watt scale (utility) electricity. Named “Drakoo-R”, the WEC is round in shape and is designed to operate in large waves (2.5m – 5.5m high) of any heading.

Wave Absorbers

Drakoo technology extracts wave energy when used as a static (fixed) or semi-static system (floating anchored). When Drakoo-B WECs are integrated into fixed breakwaters, they absorb incident wave energy rather than reflecting the waves. This also prevents the waves from propagating behind the devices which greatly reduces wave-breaking damage caused to the breakwater structure.