Wave Energy Converter

Abstract: - Wave Energy Converter :- 

The Wave Energy Converter - WEC is a new, highly efficient technology that harnesses the immense, renewable energy contained in ocean waves. Its unique ability to extract and convert energy from both the rising and falling of waves, represents a technological breakthrough.

A wave energy conversion apparatus comprises at least two devices , each comprising a surface float , at least one of the surface floats being rigidly attached to a submerged body . The movement between the at least two devices preferably effects an energy generation which is harnessed by the linkages.

The apparatus may also include mooring systems that maintain the complete apparatus in a position that is consistent with statutory requirements and not significantly inhibit its efficient operation.

Machine Configuration

Rotor

Two types of magnet fixation methods, surface mounting and burying magnets between pole efficiency and low material usage is desired. The electromagnetic efficiency includes hysteresis losses, eddy current losses and resistive losses. Furthermore, a low load angle is desired. A machine with inherently low load angle has better performance at both normal and transient conditions and is less affected by changing loads and varying frequencies. The four rotor concepts are simulated for different magnet dimensions and various pole widths. Output power, voltage and stator width are held constant in the simulation and the vertical length of the rotor is iterated to fulfill these conditions, usage such as total magnet volume, stator steel.

Magnet Dimensions

Different heights to width relations of the magnets have been investigated in order to see if there is an optimum. The magnet volume of single magnet is kept constant and the electromagnetic efficiency and total magnet weight is plotted for different height to width relations of the magnets. As can be seen the electromagnetic efficiency is steadily increasing and the total magnet weight is decreasing with increasing magnet width for the surface mounted magnets. The pole width limits the magnet width and no optimum is reach for the surface mounted magnets. 

Floating Wave Energy Extractor 

Another variation of a wave energy converter, which uses the vertically exerted force of a wave, is a Floating wave energy extractor.

About the technology

The floating wave energy extractor is also a method for the maximum exploitation of the wave energy and it is designed for distant offshore with very unstable sea surface. The system is consists of a rectangular shaped huge mass floating body supported by a large number of floating air columns. The air column’s extensions are connected to pistons. The pistons are placed its own cylinders and it can move up and down through the cylinders when the floating air columns moves with the up-down movements of the waves. The upper side of the cylinders has two valves. One to a high-pressure fluid pipe and it will open when the floating air column on crest. One valve is to the low-pressure fluid pipe and it will open when the floating air column on the trough. The whole system is anchored to the sea bottom.  

Working

When the wave moves through the floating air columns, it to oscillate the floating air columns. When some of the air columns (air columns that on the crest) move upward, the whole weight of the floating system will be supported through that air columns. Also, now some floating air columns (the air columns that on the trough) will move downward. As some of the air columns move upward, the pistons of those air columns to pressurize its corresponding cylinders and the hydraulic fluid inside of the cylinders rush to the high-pressure fluid pipe with high pressure (now the valves to the low-pressure fluid pipe will be closed). Since the whole of the high-pressure fluid pipes are interconnected, the net pressure will focus on the turbine and the turbine will rotate. As the floating air columns that on the trough move down ward because of the gravity, the valves to the high-pressure fluid pipe will be closed and the valves to the low-pressure fluid pipe (the low-pressure fluid pipes are also interconnected) will be open. Now the low-pressure fluid will enter to the cylinders and will be filled. As the turbine rotate, the generator connected to the turbine generate electricity. 

Difficulties

•      moorings – long-term fatigue of lines and connections; 

•      standard couplings for quick-release and re-attachment of moorings and cables; 

•      reduced-cost production of cables, construction and laying offshore;