Technology

How Aqua Power Technologies Wave Energy Convertor Works

Overview

Aqua Power Technologies wave device is a semi-submersible multi axis wave energy converter, specifically designed to generate in ocean waves. The design has the unique ability to absorb forces from the peaks and troughs of the waves in any given direction. The multi axis structure’s test results highlighted the increased potential and efficiency to convert external movements into hydraulic pressure, compared to conventional linear devices.

The design has undergone multiple simulations, CAD iterations, and a 40th scale fully functional prototype, RWP001. Testing at Lancaster University’s wave tank proved the multi axis structures principles while displaying promising results for energy generation using the new and unique structure. The hydraulic power take-off system is a proven design capable of reacting and changing valve states in respect of the sea state. This variable setup allows the maximum energy to be harvested from the ocean in any given sea condition.

 

Aqua Power Technologies Slide 2

 

Wave data recorded from a data buoy in the Orkneys was scaled and propagated down the wave tank to provide scaled wave heights and wave lengths in which to test the structure. The three dimensional nature of a wave front is not to be approached in a two dimensional manor. Any attempts to resist the movements of a wave will after time end up with a stress, leading to a fracture and eventually failure. With this in mind, Aqua Power Technologies wave energy convertor absorbs a wave’s three dimensional movement.

The hydraulic cylinders on the device absorb any movements that the structure encounters and effectively pumps up and pressurizes the closed loop hydraulic system. High pressure accumulators contain the pressure and adapt to the sea conditions to modify the pressures in realtime, allowing for optimized performance from the structure. As the high pressure accumulator reaches its variable pre-determined limit, hydraulic fluid is released under pressure through a hydraulic motor mated to a generator and, as a result, energy is created.

Whether the unit is cresting a wave or sitting in the trough of a wave, the cylinders are capable of pumping fluid around the system. The setup allows rotary motion to be converted via linear hydraulic cylinders into fluid pressure. The pressure within the system is stored in accumulators, which at a capped pressure allows fluid to be released through a hydraulic motor. This action generates rotary motion on the hydraulic motors output shaft which is mated to a generator. The fluid that has travelled through the hydraulic motor is fed into a low pressure accumulator reservoir. Consequently, redraw of the hydraulic cylinder draws fluid from the low pressure reservoir and the closed loop cycle continues.

X Y Z

The multi axis nature of Aqua Power Technologies wave energy convertor absorbs any wave’s 3D movement into energy.

Semi-Submersible

A fast grid connection and an easily accessible and serviceable wave energy convertor reduce costs and increase generation time.

Efficient

Any wave from any direction within the wave energy convertors capture width is absorbed by the structure and converted into energy.

Hydraulic Power Take Off

Wave energy conversion can be considered a very suitable application for hydraulics. Waves apply large forces at slow speeds and hydraulic systems are suited to absorbing energy under this regime.

The use of hydraulics within Aqua Power Technologies wave energy convertor for extracting the power within waves is suitable for a variety of reasons. The full power of a hydraulic system can be delivered regardless of the hydraulic cylinder’s stroke position. Furthermore, the power outputs capable are far cheaper than other similar mechanical variants and the control and flexibility of a hydraulic system means the system can always be controlled. With regards to the environmental aspects, the noise levels generated by hydraulic systems is extremely low, especially when the power transfers are taken into account. Low noise levels ultimately results in minimum disruption to the environment within which the device is situated. Hydraulic systems have many favorable characteristics and many wave energy convertor proposals have incorporated a hydraulic power take off in their design. However, Aqua Power Technologies device is unique in it’s ability to absorb the energy in the waves from any direction. This multi axis approach to absorbing energy sets the device aside from traditional wave energy convertors.

The novel hydraulic system incorporated into the wave energy convertor is a self contained, closed loop system. The autonomous system is capable of monitoring and adjusting its parameters with regards to the current sea state. This autonomy allows the device to refine the system to the optimum energy generating setup.