Wave power offers an incredible potential as a source of large scale renewable energy. Wave power is much more levelised (less fluctuations) than wind and solar offering a superior supply quality and minimising the requirements for electrical storage.

The base for AMOG's design is a 25m floating vessel with a damped pendulum, the latter based on the principles of Dynamic Vibration Absorbers (DVAs, also known as Tuned Mass Dampers) which have been used in many technologies since ~1900, including car engines, bridges, cable structures, and even hand-held electrical shavers. In the case of AMOG's WEC, the system is tuned to maximise power from incoming waves, extracting energy from the the pendulum damping via electromotive force (EMF).

AMOG is currently planning a 1/3 scale (approx) technology demonstration of the AMOG WEC. This is planned to occur during Summer 2019 at FaBTest, Falmouth, Cornwall, in the UK. More information on each phase of research can be found using the drop down menu.

For more technical information on AMOG's WEC, you may like to refer to AMOG's peer-reviewed technical paper, "A New Class of Wave Energy Converter - the Floating Pendulum Dynamic Vibration Absorber," published as part of the proceedings of 36th International Conference on Ocean, Offshore and Arctic Engineering.

Core Technology

The WEC technology concept consists of the following key elements:

  • A floating body with tunable natural roll period through shifting ballast water
  • An in-air pendulum with tunable natural period by controlling pendulum length (winching a mass up or down), mutually reacting against the vessel
  • A compliant passive mooring system
    • This can take the form of drag embedment anchors with simple chain and wire rope at the fore and aft of the vessel, allowing a limited degree of weathervaning control
    • The mooring would be capable of being installed from a small workboat with a low day rate, thus aiming for a low cost installation
  • Maximum pendulum excitation achieved through following the principles of DVAs
  • Energy extraction from a variable EMF damper on the pendulum
Dynamic Vibration Absorbers Theory

The WEC concept utilises the theory of a DVA first presented by Den Hartog. Considering a primary mass (floating body) undergoing an alternating force of steady frequency (waves), a DVA can be used to suppress the primary mass motions (e.g. roll motions).

In the WEC concept the DVA is implemented using a pendulum. The resulting motion suppression can then be used to translate wave energy into mechanical energy. The figure below presents a schematic for a damped DVA with an undamped primary mass. The DVA comprises a mass, spring, and damper. Controlling the mass (M2), spring stiffness (k2) and damping (c2) of the DVA system, enables tuning of the primary mass motion suppression, or in the WEC application, energy extraction at the damper (c2).

S WEC application

AMOG's WEC technology is being progressed along a technology readiness level (TRL) path, with a carefully planned development path. The current status of the technology is shown in the figure below.

S WEC TRL

 

Wave power into electrical energy - a case study

The illustrations below show prime example location for a wave power array, off the coast of South Australia/South West Victoria. Determining how much power is in the incident wave field, can be calculated from a matrix of seastates. Wave power is proportional to wave period and the square of the wave height. The second figure below shows the probability of occurrence of each combination of seastates, courtesy of the ARENA wave energy atlas.

Different devices respond differently to sea-states and a complete picture of the power generated is estimated from wave field. It’s probability, device efficiency are shown as a function of wave height and period; limiting seastates for the operation of the device, and availability of the device. AMOG has performed detailed simulations of these cases, based on experience from parallel industries. We have estimated very favourable and attractive levelised costs of electricity for our WEC technology.

S WEC SA1S WEC SA2