The present invention relates to a submersible wave energy conversion unit as defined in the preamble of claim 1.
The wave energy conversion unit according to the invention is suited very well for instance to be used in connection with a panel or wing element hinged with its lower edge to make a reciprocating movement caused by wave energy or tidal energy of seawater. The wave energy or tidal energy collected is further converted underwater with the remote controlled conversion unit for instance to electric energy and/or fresh water, hydrogen, pressurized water, pressurized air or chemicals. For the sake of simplicity, only the term wave energy is later mentioned and then both the wave energy and the tidal energy of seawater is meant.
According to the prior art there are various types of wave energy conversion units where the arrangements include a base and, for instance, one or more panels or wings of plate type pivotally connected to the base to make a reciprocating or oscillating movement about a rotation axis in response to wave forces or tidal forces. The oscillating movement is then converted for example to electric energy with the help of a generator or alike.
Typically a part of the components of the prior art wave energy conversion units such as hydraulic cylinders or pumps working as collecting means and a machinery room are situated separately in the neighborhood of the reciprocating panel, or the machinery room is installed on the shore where it is out of water. One typical solution of the prior art is shown in WO2004007953A1. When the hydraulic cylinders and a machinery room are in the water close to the panel arrangement they need a separate room and are subject to all harmful influences of seawater. Whereas if the machinery room is on the shore and the collecting means are far at the sea the pressurized water being as transmitter media has to be transferred at first to the shore and only then it is possible to convert the collected wave energy for instance to electric energy. This kind of transmission path is long and large and also very expensive.
The object of the present invention is to eliminate the drawbacks described above and to achieve a reliable, compact and efficient submersible wave energy conversion unit in order to be able to capture a maximum amount of available wave energy with the unit where the natural space of the unit is utilized for placement of the wave energy collecting means such as hydraulic cylinders or pumps and a machinery and control units. One object of the present invention is also to protect the wave energy collecting means such as hydraulic cylinders or pumps and the machinery and control units against the harmful influences of seawater. Yet one object of the present invention is to make the installation and maintenance of the submersible wave energy conversion unit easy and fast. The wave energy conversion unit according to the invention is characterized by what is presented in the characterization part of claim 1. Other embodiments of the invention are characterized by what is presented in the other claims.
The solution of the invention has the advantage that thanks to the large size of the panel of this size category the natural free space inside the panel can be utilized to place the wave energy collecting means such as hydraulic cylinders or pumps and the machinery and control units inside the panel unit where they are protected against harmful influences of salty seawater. Another advantage is the fact that a separate machine room is not needed at all. This saves room and installation work at the installation location because all the machinery for wave energy recovery is already installed in the panel. A further advantage is that the maintenance work is easy and fast, and can be done in fairly good conditions. All the components for the maintenance are inside the panel and can be taken with at the same time when the panel is transferred to the maintenance location. A part of the maintenance work can also be done inside the panel at the sea when the panel has been lifted onto the surface of the sea. Yet a further advantage is the easy and economical transmission path of the collected wave energy. Because all the machinery needed for the energy conversion is inside the panel only an electric cable is needed to transfer the electricity directly eligible for consumer use to further usage. If the conversion unit is purposed for other use, for example for producing fresh water, pressurized water, hydrogen, pressurized air or chemicals, the same degree of readiness is possible.
In the following, the invention will be described in detail by the aid of an example by referring to the attached simplified and diagrammatic drawings, wherein
The basic idea of the present invention is to place the machine room with all of its main components inside the reciprocating panel or wing. In this case the whole power-take-off machinery (PTO) including a wave energy collecting means and a wave energy conversion means is thus situated inside the reciprocating panel of the wave energy conversion unit according to the invention.
An electric cable 4 is equipped to transfer the converted seawater energy as electricity to further use, and/or other transmission means such as a pipe 5 for fresh water, pressurized water, hydrogen, pressurized air or chemicals are also connected to the wave energy conversion unit according to the invention. In connection with the electric cable 4 the wave energy conversion unit has an optical cable for controlling the system. The quality of electricity produced by the wave energy conversion unit according to the present invention is so good that the produced electricity can be connected directly into a commercial electricity network.
The panel 1 of the wave energy conversion unit according to the example of the present invention comprises at least two essentially horizontal tubular and essentially hollow capture elements 6, the first capture element 6 on the top and the second capture element 6 below the first one. There is a narrow cap between the first and second capture elements 6. The cap is covered by a covering element 6a that prevents water running through the cap between the capture elements 6. Below the capture elements 6 there is a third essentially horizontal and essentially hollow tubular capture element 7 that has a short distance to the second capture element 6. The three capture elements 6 and 7 are mutually in the same straight line in relation to each other and form together a capture surface for capturing the kinetic energy of the movement of seawater. The size category of the panel 1 is such that the diameter of the capture elements 6 and 7 is about 2 to 4 meters and the total length is about 20 to 40 meters. Thus the height of the capture surface of the panel 1 in the vertical position is about 7 to 14 meters.
In the horizontal direction the panel 1 is divided symmetrically into three separate sections by two shaft elements 8 that are essentially perpendicular to the capture elements 6 and 7, and extend from the top of the panel 1 to underneath of the panel 1 when the panel 1 is in its neutral vertical position. The lowermost part of each shaft element 8 has a housing 11 for closing the lower end of the shaft element 8 and protecting the wave energy collecting elements of the wave energy conversion unit. Whereas on top of each shaft element 8 there is a manhole with a watertight lid 9 for accessing the shaft element 8 for example when the maintenance of the machinery is needed. The inside of the shaft element 8 forms a dry space inside the panel 1. Likewise at least part of the insides of the capture elements 6 and 7 have been arranged to form a dry space inside the panel 1, and all the dry spaces inside the panel 1 can be connected to each other.
Essentially tubular hydraulic oil tanks 10 are situated horizontally at the side of the panel 1 between the second capture element 6 and the third capture element 7 and between the shafts elements 8. The hydraulic oil of the tanks 10 is used for the machinery of the wave energy conversion unit to convert wave energy to electricity or to some other suitable form.
When the bigger maintenance is needed the panel 1 is disconnected from the stands 2 by loosening the shaft securing elements 14a and the panel 1 is lifted with its shafts 14 onto the surface of the sea so that a part of the panel 1 remains under the surface whereas another part is above the surface. The panel 1 has been balanced so that when it is freely floating it keeps well balanced in its upright position. After lifting the panel 1 onto the surface the maintenance can be done at that location or the panel 1 can be towed to the shore for the maintenance.
In
In a dry space inside the lower part of each shaft element 8 there are wave energy collecting means 15 such as hydraulic cylinders or hydraulic pumps that resist or attenuate the reciprocating movement of the panel 1 and by doing so create pressure and flow in the hydraulic circuit of the wave energy conversion unit. The achieved pressure and flow are directed to the hydraulic conversion unit 17 in the machinery space 16 in which conversion unit 17 a hydraulic motor rotates a hydraulic generator.
Ladders 18 are installed in a dry space inside the shaft element 8 in order to make it possible for the service people to descent down to the wave energy collecting means 15 and to the hydraulic conversion unit 17 for repair and maintenance purposes. A support base 19 is fastened inside the shaft element 8 in order to give a steady support and fastening place for the upper end of the wave energy collecting means 15.
The machinery space 16 is situated in a dry space inside the second end of the third capture element 7 and is connected to the dry space of the shaft element 8 through the opening 20. In addition of the conversion unit 17 the machinery space 16 contains also a control unit 21 of the hydraulic conversion unit 17 and a control unit 22 of the whole wave energy conversion unit. At least the wave energy collecting means 15, the hydraulic conversion unit 17 and the control unit 21 form together the power-take-off machinery (PTO) according to the invention.
The panel 1 is mounted onto the stationary support shaft 14 by the help of bearings 24 that are placed in bearing housings 24a fastened to the sidewalls of the shaft elements 8. So the panel 1 can make reciprocating movement around the central axis of the support shaft 14. The support base 19 has in addition a manhole 19a to facilitate the access to the lower parts of the shaft element 8.
The support shaft 14 and the support assembly 23 remain non-rotary when the panel 1 reciprocates and therefore only the length of the hydraulic cylinders 25 and 28 changes. This change causes pressure and flow in the hydraulic circuit of the hydraulic system of the wave energy conversion unit, which pressure and flow are converted in the machinery space 16 inside the panel 1 to electricity and/or other suitable forms such as fresh water, pressurized water, hydrogen, pressurized air or chemicals.
The form and size of the apertures 8b corresponds to the cross-section of the capture element module 6b, 7b that is for instance an elongated tubular object with a circular cross-section. In addition the capture element module 6b, 7b comprises advantageously one or more apertures 19c that are arranged to be aligned with the apertures 19b of the shaft element module 8a in order to facilitate a connection from the top of the shaft element module 8a to the bottom of the shaft element module 8a. The capture element module 6b, 7b may also have other apertures.
In
The capture element modules 6b, 7b can be mutually different. Some of them can be only hollow pipes without apertures 19c and some of them can contain apertures 19c. In one panel 1, for instance, one or more uppermost capture element modules 6b can be empty and only inside the lowermost capture element module 7b there is the machinery space 16 with or without the power-take-off (PTO) machinery and/or the hydraulic conversion unit 17 and/or the control unit 21, and/or other components needed. If one capture element module 6b, 7b breaks down it can fast and easily be replaced with a new one.
All the dry spaces inside the panel 1 have been sealed against seawater with seals. In that case there are seals at least between the support shaft 14 and the sidewalls of the shaft element 8, between the lids 9 of the manholes and the roof plates of the shaft elements 8, and around through holes of the electric cable 4 and water pipe 5, or around corresponding pipes or hoses.
It is obvious to the person skilled in the art that the invention is not restricted to the example described above but that it may be varied within the scope of the claims presented below. Thus, for example, the structure of the wave energy recovery unit can vary.
Filing Document | Filing Date | Country | Kind |
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PCT/FI2013/050376 | 4/5/2013 | WO | 00 |