Abstract:
The present invention pertains to a new method and system for producing electricity from tidal energy. In one embodiment the system employs at least one underground region for collecting water percolating at a higher tide level and at least another underground region capable of fluid communication with the first underground region. The system is configured to release water at separate times from the underground regions to operate hydro turbines and generators to produce electricity.

Description:
FIELD OF THE INVENTION 
     Embodiments disclosed herein relate to a power system operated by changing water levels, e.g., tidal, and related methods. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Although not yet widely used, generating power from changing water levels such as tides has potential for future electricity generation. Tides are more predictable than both wind energy and solar power. What is needed then are effective, lower cost tidal power electrical generating systems and methods. 
     Advantageously, the present invention pertains to efficient and cost-effective new methods and systems for generating power from tidal energy. In one embodiment, a hydropower generation method utilizes changing water levels. The method comprises collecting water percolating through a permeable substance into a first underground region as a water level is increased. The collected water is released from the first underground region into a second underground region. In this manner a first hydro turbine and generator operatively coupled therebetween can generate power. Water may be released from the second underground region as water level is decreased. This can operate a second hydro turbine and generator operatively coupled therebetween to also generate power. 
     In another embodiment the present invention pertains to a tidal power system. The system comprises a first underground region for collecting water percolating through a coastal area medium at a higher tide level and a second underground region capable of fluid communication with the first underground region. Water is released from the first underground region to the second underground region through an inflow pipe. The inflow pipe further comprises a first hydro turbine and generator operatively coupled thereto to generate power. The system has an outflow pipe through which water is released from the second underground region. The outflow pipe further comprises a second hydro turbine and generator operatively coupled thereto to generate power. The system is configured to release water at separate times from the first underground region and the second underground regions to operate the hydro turbines and generators and thereby produce electricity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an embodiment of a tidal power system. 
         FIG. 2  illustrates filling a seepage region of the tidal power system at or near high tide. 
         FIG. 3  illustrates a power generating state of the tidal power system at or near high tide. 
         FIG. 4  illustrates a steady state of the tidal power system. 
         FIG. 5  illustrates a power generating state of the tidal power system at or near low tide. 
     
    
    
     DETAILED DESCRIPTION 
     A power system and method is disclosed. The power system and method may be configured to effectively capture energy from changing water levels such as tides using water percolation through a permeable substance. The specific permeable substance is not particularly important so long as water is capable of being collected through it. Examples of permeable substances include those substances often found on or near coastal waters or beaches. For example, the permeable substance may comprise sand, gravel, rock, and mixtures thereof. In this manner as tides vary between, for example, a low tide and a high tide power may be generated. 
     In one embodiment a tidal power system may include two parts: at least one seepage region and at least one water storage region. The invention is described herein with respect to one seepage region and one water storage region. However, if desired the system may include two, three, or even four or more seepage regions. Similarly, the system may include two, three, or even four or more water storage regions coupled to the one or more seepage regions. In addition, two or more systems may be coupled together. In this manner, if desired the systems may share a power storage, transmission, and/or distribution system. 
     The seepage region may be constructed in any convenient manner which manner may differ depending upon, for example, the specific application, available materials, and other components. Generally, the seepage region may comprise an underground region or space which may have one or more structured supports. If desired, the seepage region may employ a filter-like material configured to, for example, block a majority of sand, dirt and other undesirable materials while allowing water to infiltrate the space as it percolates through a permeable substance, e.g., sand, on or near the coastal water. The specific filter-like material to be employed is not particularly critical and, if employed, it may conveniently be selected from a mesh, screen, net, or some combination thereof. 
     In practice, the water level of the collected water in the seepage region varies by application. In some embodiments the water level generally corresponds with current tide levels. In this manner the collected water may serve as the water source for the tidal power system and hydraulic head during power generation. 
     The water storage region, like the seepage region, may be constructed in any convenient manner which manner may differ depending upon, for example, the specific application, available materials, and other components. Generally, the water storage region is near the seepage region and located at a similar elevation. The elevation of both regions is generally at or near sea level. The water storage region usually comprises a space or tank that is substantially sealed off or insulated from undesired water infiltration through percolation or otherwise. In practice water may enter the water storage region at a desired time when a water inflow pipe or other connection is opened between the seepage region and the water storage region. For efficiency, the desired time to open the connection to release at least a partial amount up to all of the water may be at or near high tide and/or sometimes during absolute high tide. 
     As the water storage region fills, water may travel through the water inflow pipe and, if desired, operates a hydro turbine and generator operatively coupled to the water inflow pipe. The type of hydro turbine and generator are not particularly critical and may be selected from any of those known or hereinafter discovered. Generally, the water flow encounters and rotates one more turbines comprising one or more blades, which in turn, rotates a shaft member of a generator for generating electricity. 
     Once the water storage region is filled to its desired capacity, the water is held in the storage region until it is desired to be released. For efficiency, at least a partial amount up to all of the water may be released at or near low tide and/or sometimes during absolute low tide. When the outflow pipe is opened, water flows out of the water storage region, usually directly into the local body of water adjacent the system. Advantageously, at least some up to all of the water flowing from the water storage region through the outflow pipe may be used to operate a hydro turbine and generator operatively coupled to the water outflow pipe. Generally, the water flow encounters and rotates one or more turbines comprising one or more blades, which in turn rotates a shaft member of a generator for generating electricity. 
       FIG. 1  illustrates an embodiment of a tidal power system. The tidal power system may be installed in a coastal beach  50  or any other location bordering a body of water  52  experiencing tides or similar water energy. A deeper portion of the beach  50  may be sand  54  that is constantly saturated with water (“saturated sand”), and which generally corresponds with low tide levels. The tidal power system may be positioned at a level in the beach  50  just at or above the saturated sand  54 . The tidal power system includes a seepage region  102  for collecting water percolating through the beach  50 . The seepage region  102  may be an underground space of any suitable size, dimension, or shape within the beach  50 . In one embodiment, the seepage region  102  may be enclosed by wire or plastic mesh or screen, which effectively defines the seepage region  102 . The mesh or screen may completely or partially enclose the seepage region  102 . Any available mesh or screen sizes may be used which are suitable for blocking and preventing a deleterious amount of dirt or sand or other unwanted particles or objects from entering the seepage region while still allowing water to enter the seepage region. The tidal power system further includes a water storage region  106 . 
     In one embodiment, the water storage region  106  may be a storage tank or any type of enclosure that is sealed off from any unwanted water infiltration. The water storage region  106  may be an suitable size or shape. The water storage region  106  may be positioned directly adjacent the seepage region  102 , or at a suitable distance from the seepage region  102 . 
     The tidal power system includes an inflow pipe  108  of any suitable size or type that allows fluid communication between the seepage region  102  and the water storage region  106 . The inflow pipe  108  may be disposed as low as possible near a bottom of the seepage region  102  and water storage region  106 . In this manner any use of the hydraulic head when the seepage region is filled may be maximized as will be explained below. 
     The inflow pipe  108  may include one or more pipe valves  110  of any type configured to control fluid communication between the seepage region  102  and the water storage region  106 . The pipe valves may be manually or automatically operated, including but not limited to, electrically, hydraulically, or pneumatically. The tidal power system further includes an inflow hydro turbine and generator  112  which is operated by flow of water from the seepage region  102  to the water storage region  106  as described below. 
     The tidal power system further includes an outflow pipe  114  of any suitable size or type that allows fluid communication between the water storage region  106  and a body of water  52 . The outflow pipe  114  may be disposed as low as possible near a bottom of the water storage region  106 . The outflow pipe  114  includes a first pipe valve  116  of any type disposed at a first end or near the water storage tank  106 , and a second pipe valve  118  of any type disposed at a second or distal end of the outflow pipe  114 . The pipe valves may be manually or automatically operated, including but not limited to, electrically, hydraulically, or pneumatically. The outflow pipe  114  further includes a hydro turbine and generator  120  which is operated by flow of water from the water storage region  106  to the body of water  52  as described below. 
     Methods of using the tidal power system are described as follows in accordance with  FIGS. 2-5 .  FIG. 2  illustrates a current tide level higher than low tide (e.g., at or near high tide). Pipe valves of the outflow pipe  114 , particularly distal pipe valve  118 , are closed to prevent water from entering the outflow pipe  114 . A pipe valve  110  in the inflow pipe  112  is closed to prevent water from entering the water storage region  106 . Water percolating through the porous material of the beach passes through mesh or screen layer and is collected in the seepage region  102 . Water continues to collect in the seepage region  102  until a water level within the seepage region  102  is substantially equal to the current tide level. 
       FIG. 3  illustrates a power generating state of the tidal power system, that is, a height differential exists between the tide level and corresponding water level in the seepage region  102 , and water level (or lack thereof) in the water storage region  106 . In a first electrical generation stage, water is released or transferred from the seepage region  102  to the water storage region  106 . At or near high tide, sometimes absolute high tide, the pipe valve  110  in the inflow pipe  108  is opened (outflow pipe valve  116  remains closed), and the water storage region  106  is filled with water from the seepage region  102  through the inflow pipe  108  until water levels between the two regions are substantially equal. Water release from the seepage region to the water storage region operates the hydro turbine and generator  112  operatively coupled to the inflow pipe, which generates electricity.  FIG. 3  illustrates a lighthouse  56  being powered by electricity generated by the generator  112  during the first electrical generation stage. However, electricity generated may be stored locally and/or transmitted to any device or location needing electricity, whether for consumption or storage. 
       FIG. 4  illustrates a steady state of the tidal power system in which no electricity is being generated. That is, there is substantially no water level difference between the seepage region  102  and the water storage tank  106 , and therefore there is little or no potential energy to drive water flow between the two regions. However, the water storage region  106  is filled with water in anticipation of a low tide when electricity may again be generated as described below. 
       FIG. 5  illustrates a power generating state of the tidal power system, that is, a height differential exists between the water level in the water storage region  106  and the tide level, which is at or near low tide. In a second electrical generation stage, water is released from the water storage region  106 . At or near low tide, or sometimes absolute low tide, outflow pipe valves  116 ,  118  are opened, and water is released from the water storage region  106  through the outflow pipe  114 . Generally, water released from the water storage region  106  through the outflow pipe  114  flows directly into the local body of water adjacent to the beach, which is at a lower tide. Water release from the water storage region  106  through the outflow pipe  114  operates the hydro turbine and generator  120  coupled to the outflow pipe, which generates electricity.  FIG. 5  again illustrates a lighthouse  56  being powered by electricity generated by the generator  112  during the second electrical generation stage. However, electricity generated may be stored locally and/or transmitted to any device or location needing electricity, whether for consumption or storage. In one embodiment, electricity generated during the first and second electrical generation stages may be transmitted to different locations or devices. 
     Advantageously, the tidal power system disclosed has little to no interaction with marine life, does not substantially interfere with established and/or navigable waterways, and generally does not come into contact with most floating debris. Moreover, the tidal power system is underground and mostly hidden from sight by land and water. Still further, the tidal power system may have the potential to reduce seepage-induced erosion of coastal beaches. These advantages and more will be apparent to the skilled person upon reading the instant specification. 
     The claimed subject matter is not to be limited in scope by the specific embodiments described herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims.