Abstract
A device (OWC Oscillating Water Column) for capturing wave energy, the upper part of which contains a pressure accumulator (3) connected to the atmosphere through a unidirectional outlet turbine (4) and a vacuum accumulator (6) connected to the atmosphere through a unidirectional inlet turbine (5). The lower portion is formed by at least one block, where each block is made up of a structural column (19), which when submerged in the water gives rise to a water column (8) and an air chamber (1) in the upper portion. Each block is connected to the pressure accumulator (3) through a non-return intake valve (2), and to the vacuum accumulator (6) through a non-return exhaust valve (7), and having an inlet (16) arranged in the lower portion of each structural column (19). One of the main characteristics of the device is that the pressure (3) and vacuum (6) accumulators act as an air manifold, inhaling and exhaling through the blocks, and at the same time damping sudden changes in pressure.
Claims
1. A device for capturing wave energy, the device comprising: a lower part comprising a block that comprises: an air chamber adapted to hold a first volume of air having a first pressure; and an inlet adapted to allow water to enter the air chamber, wherein an entry of water into the air chamber affects the first pressure of the first volume of air in the air chamber; and an upper part that comprises: a pressure accumulator comprising a first air manifold, the pressure accumulator being connected directly to the air chamber via a non-return intake valve, the pressure accumulator being further connected to the atmosphere via a unidirectional outlet turbine, the pressure accumulator being adapted to hold a second volume of air having a second pressure greater than atmospheric pressure, the pressure accumulator being further adapted to transfer air from the air chamber to the unidirectional outlet turbine without use of piping; and a vacuum accumulator comprising a second air manifold, the vacuum accumulator being connected directly to the air chamber via a non-return exhaust valve, the vacuum accumulator being further connected to the atmosphere via a unidirectional inlet turbine, the vacuum accumulator being adapted to hold a third volume of air having a third pressure less than atmospheric pressure, the vacuum accumulator being further adapted to transfer air from the unidirectional inlet turbine to the air chamber without use of piping; wherein the pressure accumulator and the vacuum accumulator are adapted to inhale and exhale through the block and to dampen sudden changes in pressure.
2. The device for capturing wave energy according to claim 1, wherein the lower part comprises a plurality of blocks.
3. The device for capturing wave energy according to claim 2, wherein the plurality of blocks of the lower part are separated by respective distances.
4. The device for capturing wave energy according to claim 2, wherein each respective first block of the plurality of blocks of the lower part is in contact with a respective second block of the plurality of blocks.
5. The device for capturing wave energy according to claim 1, wherein each block has a wall disposed in the air chamber, the wall adapted to reduce wave motion inside the block.
6. The device for capturing wave energy according to claim 1, wherein the device is a floating device.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) What follows is a very brief description of a series of drawings that aid in better understanding the invention, and which are expressly related to an embodiment of said invention that is presented by way of a non-limiting example of the same.
(2) FIGS. 1A-1F illustrate different embodiments in the state of the art, or of their operating conditions.
(3) FIG. 1G shows a graph comparing overall electrical power versus time in the case of two independent devices with respect to that which is captured by a platform similar to the platform shown in FIG. 1F.
(4) FIG. 1H shows a standard configuration of a platform with several blocks connected through a pressure manifold and a vacuum manifold joined together through a unidirectional closed-circuit turbine.
(5) FIG. 1I shows a graph representing overall pneumatic power versus time in the case of two independent devices with respect to that which is captured by a platform similar to the platform shown in FIG. 1H.
(6) FIG. 2 shows a device for capturing wave energy in accordance with an embodiment.
(7) FIG. 3A shows a graph illustrating the pneumatic power of a first accumulator with volume V, with respect to the pneumatic power of a second accumulator whose volume is 7 times greater.
(8) FIG. 3B shows electrical power generated for a device with different accumulator volumes than those shown in FIG. 3A.
(9) FIG. 4 is a graph representing pneumatic power versus time for a device with multiple blocks according to the invention presented herein (with two unidirectional turbines connected to the atmosphere) and the output of a device with multiple blocks with a unidirectional turbine connecting the pressure and vacuum accumulators in a closed circuit.
(10) FIG. 5 compares the performance of the OWC, the performance of the turbine, the cost of the energy and the cost of the device, with the volume of the accumulators.
(11) FIG. 6 shows a platform with different options for the opening of the column inlets.
(12) FIG. 7 shows a block of the device in isolation, with the elements that make it up.
(13) FIG. 8A shows device for capturing wave energy that has two blocks.
(14) FIG. 8B shows a device for capturing wave energy that has several blocks separated by short distances.
(15) FIG. 8C shows a device for capturing wave energy that has several blocks wherein each respective block is in contact with one or more other blocks.
(16) In the detailed description of the invention, specific dimensions for the various chambers of the device are shown solely for illustrative purposes. It shall fall upon the designer to, given the needs of a specific project not limited to a target power to produce, a geographic location, budget or cost, seek the right sizes in order to achieve the best energy cost and the optimum return on their investment.
DETAILED DESCRIPTION OF THE INVENTION
(17) FIG. 1 shows the known state of the art, where, specifically:
(18) FIG. 1A shows a standard OWC device where (8) is the water column, (1) is the air chamber, (24) is the bidirectional turbine and (23) is the atmosphere.
(19) FIG. 1B shows an OWC device with a unidirectional rectified airflow turbine with four non-return valves.
(20) FIG. 1C shows an OWC device with a unidirectional rectified airflow turbine with two non-return valves.
(21) FIG. 1D shows an OWC device with a unidirectional, rectified airflow, closed-circuit turbine with two non-return valves.
(22) FIG. 1E shows a standard oversize OWC device with an arrow indicating the direction of the wave (33), wherein outside the device there is a crest (31) and a trough (32), meaning that the flow (Q) collected by the turbine is almost null.
(23) FIG. 1F shows two platform options with several standard OWC devices joined together by a rigid structure (41).
(24) FIG. 1G is a graph comparing overall electrical power versus time in the case of two independent devices (dotted line) with respect to that which is captured by a platform like the one in FIG. 1F (solid line). One can see that the statistical trend is to reduce the peaks and troughs of the electricity output.
(25) FIG. 1H shows a standard configuration of a platform with several blocks connected through a pressure manifold and a vacuum manifold joined together through a unidirectional closed-circuit turbine.
(26) FIG. 1I is a graph representing overall pneumatic power versus time in the case of two independent devices (dotted line) with respect to that which is captured by a platform like the one in FIG. 1H (solid line). One can see that the delivered pneumatic power is more stable when the devices are joined together, along with an increase in the average power.
(27) The arrangement of the oscillating water column device (OWC) that is the subject matter of the present patent application, and more specifically, of the column and its corresponding inner chambers and accumulators that house the turbines actuated by the energy captured from the waves, is as shown in FIG. 2. The wave (22) has an up and down movement that causes the water column (8) to move up and down, represented by the solid and dashed lines, respectively. When the water column (8) rises, the pressure created in the air chamber (1) creates an airflow that passes through the non-return intake valve (2) and enters the pneumatic pressure accumulator (3), resulting in overpressure. There, the concentrated air has enough pressure to move the corresponding unidirectional outlet turbine (4) and being exhausted to the atmosphere (23). Once this process is completed, when the water column (8) begins to decrease, the atmospheric air flows through the unidirectional inlet turbine (5) to fill the vacuum accumulator (6), and from there it is sent through the non-return exhaust valve (7) into the air chamber (1). The non-return intake (2) and exhaust valves (7) open and close alternately on each accumulator, making pressure/vacuum possible in the accumulators.
(28) FIG. 3A analyzes the influence of volume on the accumulators. The dashed line shows the pneumatic power of an accumulator with volume V, with respect to the solid line showing the pneumatic power of an accumulator whose volume is 7 times greater (7V). It may be observed that the greater the volume, the more constant the rate and the better the performance of the turbine, although the average power is, however, lower and the manufacturing costs are higher. FIG. 3B shows electrical power generated for a device with different accumulator volumes than those shown in FIG. 3A. The dashed line shows a device with a small accumulator volume and a higher-power air turbine, while the solid line shows a device with larger accumulator volumes and a turbine having lower nominal power but higher performance. In this case it can be seen how the electrical production of the complete device is higher. It shall fall upon the designer to seek out ideal intermediate dimensions with the lowest cost for the energy produced.
(29) Above, it was mentioned that there is an arrangement whereby the pressure (3) and vacuum (6) accumulator chambers each have their own unidirectional turbine (4 and 5) directed towards the atmosphere, instead of a single turbine between the two pressure (3) and vacuum (6) accumulator chambers. FIG. 4 uses a solid line to show the behavior of the solution with two unidirectional turbines directed towards the atmosphere, with respect to the dashed line showing a single unidirectional turbine between the two chambers.
(30) The key characteristic of the accumulator (3 or 6) is its volume. The bigger it is, the more it dampers variations in pneumatic pressure at the intake of the accumulator (3 or 6), making the pressure at the outlet more constant. This damping improves the performance of the turbine and the alternator, as both are higher the more stable the pressure at the inlet. However, increasing the volume leads to a reduction in the pneumatic energy available for the turbine, and increases manufacturing costs. For this reason, finding the right size for the accumulators involves seeking a volume at which the reduction in pneumatic performance and the increase in manufacturing costs are compensated by the increase in turbine performance. This is the point at which the cost of the energy will be at its lowest, as is shown in FIG. 5, where the x-axis is the volume of the accumulators and the y-axis is performance and cost. The solid line is pneumatic performance (12), the dashed line is the performance of the turbine (13) and the solid line is the cost of the device (15). The curve at the top is the cost of the energy generated (14), and its lowest point indicates the ideal volume for the accumulator design.
(31) FIG. 6 shows the embodiment of a device whose lower portion is formed by joining together various blocks, where each block is connected to the pressure (3) and vacuum (6) accumulators, from which the corresponding outlet (4) and inlet (5) turbines protrude. The entire assembly forms a floating platform that includes mooring and orientation systems to position itself with respect to the wave (22). The lower portion of the structural columns (19) is equipped with inlets (16). Said inlets may have different heights and/or inclinations to optimize wave (22) capturing and reduce shielding between blocks. The common orientation of the inlets (16) is against the waves, although in some implementations the opposite orientation may be chosen, as in the case of devices situated on the shoreline.
(32) FIG. 7 shows a block in isolation, wherein one can see the elements that make it up: a structural column (19), which when submerged inside the wave (22) forms a water column (8) and an air chamber (1). The block is completed by two non-return valves (2 and 7), the intake (16), and in some setups one or several intermediate walls (18) to minimize wave turbulence inside the structural column, and to provide the block with greater rigidity.
(33) FIG. 8 shows other embodiments with the same device, showing a pressure accumulator (3) and a vacuum accumulator (6), from which the corresponding outlet (4) and inlet (5) turbines protrude. The difference resides in the number of blocks that each device incorporates. Option (a) is the one already discussed in FIG. 6; option (b) is similar to the previous option, but with still more blocks having the same structural column (19) dimensions inserted to reduce the intervening gap; and lastly, option (c) is the one that incorporates so many blocks that they cover the entire surface of the device that is the subject matter of the invention. In this way, there may be several possible configurations for a device with the same overall dimensions, where the number of blocks, and therefore the distance between them, may vary, such that said distance may even be null. The system indicated may acceptably be applied in floating and fixed devices (usually near the coast, on the shoreline, or on breakwaters).
