Patent Document

FIELD OF THE INVENTION 
       [0001]    The present invention relates to an apparatus and method for converting potential energy stored as water under pressure in submarine aquifers and converting that energy to kinetic and/or electrical energy. 
       BACKGROUND OF THE INVENTION 
       [0002]    Submarine aquifer discharge is a common, naturally occurring feature along most coastlines, lakes and rivers. It also occurs in deep ocean waters. 
         [0003]    Typically, aquifer discharge comprises freshwater flowing into sea water. If flows are large enough a “pool” of freshwater appears on the sea water surface. Flowing freshwater is not easily mixed with salt water. 
         [0004]    Aquifers are porous, permeable layers of sediments such as sandstone, silt or limestone, sandwiched between non-permeable rock and clays. They are fed by rainfall from the land or supplied from a source rock and may be confined or unconfined. 
         [0005]    Aquifers that occur in sediment under bodies of sea water, can be connected to that sea water, by natural features such as faults, volcanic action, physical or chemical erosion, earthquakes, glacial activity, sea level movement, sedimentation etc. Water is forced by gravity from the aquifer into the lake or ocean above it. The aquifer is “squeezed” by the overburden and water rises where possible. 
         [0006]    Aquifers may be connected to a local coastline following an old river bed, seabed or flood plain, or confined within older sediments at great depth. Typically this happens during times of lower ocean depths such as an active glacial period or ice age. As the glaciers recede the freshwater in rivers becomes confined in a sedimentary aquifer under the ocean. 
         [0007]    This also occurs in very deep water. Trapped water in a confined aquifer can be millions of years old before it finally is naturally exposed and leaks under great pressure. The velocity of escaping leakage is reduced by friction. However, the pressure is generally maintained. 
         [0008]    What each aquifer type has in common is some naturally occurring discharge area from the ocean or lake floor. This leakage may occur over a small or very large area. Large volume, small area, leakage points are often well known and may appear as “named” features on ocean charts. 
         [0009]    The potential energy contained in a submarine aquifer is significant. Friction reduces the discharge velocity as it flows through permeable sediments to the sea or lake, floor. By diverting the aquifer discharge flow into a specially shaped membrane connected to an exit pipeline, water can be accelerated to a much higher velocity. 
         [0010]    This potential energy may be harvested with little or no emission of pollutants or carbon dioxide. 
         [0011]    Where the discharge water quality is suitable, it can also provide a huge source of untapped irrigation or drinking water. 
         [0012]    Large flows can often be seen on the ocean or lake surface with the naked eye. Most often the discharge is of a different temperature and the discharge flow area can be detected using satellite or aircraft with infra-red photography. Such flows are usually many thousands of years old, and may even be millions of years old. 
         [0013]    The suitability of a seep can be easily assessed by using well known measuring techniques used by hydro-geologists and oceanographers. Such techniques are used to obtain the flow rate, discharge quality and age, ocean or lake depth, location of required piping etc. 
       DISCLOSURE OF THE INVENTION 
       [0014]    The invention provides a method of driving an apparatus, comprising, piping water derived from an underwater seep under such conditions that the piped water is arranged to flow under its own pressure to the apparatus to drive the apparatus. 
         [0015]    By saying that the piped water is arranged to flow under its own pressure, we mean pressure resulting from the difference in density of saline water overlying the seep and the density of the water emanating from the seep, plus pressure if any of water emanating from the underwater seep. Generally speaking, it is expected that the major difference in density will be caused by the difference in salinity of the overlying water and the water from the seep. However, other factors such as temperature differences may also come into play. 
         [0016]    Seeps which flow with aged water, are likely to substantially maintain their flow rate even in times of drought, as the water may have been deposited many years before the drought occurred. In choosing seeps, it is preferable to perform the invention in relation to seeps which are likely to maintain their water flow ie. choosing seeps with water which is aged will generally be preferred. Typically one would prefer to have seeps supplying water which is aged by at least 5 years, more preferably 10 or 20 years. 
         [0017]    The apparatus of the invention is most suitably used to generate electricity, although it is to be appreciated that the energy supplied by the piped water can be used to drive mechanical arrangements other than electricity generating apparatus. 
         [0018]    After water from the seep has been used to drive the apparatus, it may be returned to a marine environment or alternatively, it may be sent to a storage reservoir for purposes such as irrigation or drinking water. 
         [0019]    The water from the seep may be collected under a flexible diaphragm. The flexible diaphragm may be arranged so that it has a broader end covering the seep. The diaphragm may taper to a narrower opening for an offtake pipe. The offtake pipe may also be formed of a flexible material. 
         [0020]    The flexible material used to collect water from the seep to direct it to the offtake pipe may suitably be formed in the shape of a generally conical member with the base of the cone sitting against the floor of an ocean or lake in communication with the seep. The edges of the cone may be covered with material to hold the cone down. Suitable material may comprise aggregate and/or rocks. 
         [0021]    A float may be used to hold the top of the cone upright. It may be connected to the top of the cone by a cable and may be arranged to sit below the surface of the overlying water by a distance which is chosen having regard to disturbance by wave action on the surface. The depth of the float may vary between different environments. However, in most circumstances, it is expected that ensuring that the float remains 10 metres below the surface more preferably 12 metres will suffice. In this way it should be possible to reduce disturbance by wave action. 
         [0022]    The surface of the diaphragm forming the cone may be treated with a material resistant to being fouled by marine flora and fauna or it may itself be resistant in this regard. It has been found that polymeric materials are generally resistant in such circumstances. The flexible piping material may also be treated in the same fashion. 
         [0023]    The cone may be reinforced by a plurality of battens. Battens may also be used to reinforce the flexible pipe. 
         [0024]    Electricity may be generated by using conventional means such as a pelton wheel and/or francis turbine driving a generator or alternator. 
         [0025]    As it is anticipated that the major driving force for the piped water will be the difference in density between the water emanating from the seep and surrounding water, it is preferred that saline content of the surrounding water be at least 50% of the average salt content of the earth&#39;s oceans. Of course, the greater the difference in density, the greater pressure exerted per metre of depth on the emanating seep water. 
         [0026]    Where the seep is located in an ocean, given the difference in density between fresh water and the saline water, the depth of the seep below the surface of the saline water should preferably be at least 15 metres. 
         [0027]    Where there is more than one seep in a region, or where a single seep covers a large area, multiple cones or other collecting members may be used to collect water from the seep. Water from the multiple collecting members may be joined in series or in parallel and may be sent off to one or more systems for driving electrical generating apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  illustrates a schematic view of a construction according to the invention; 
           [0029]      FIG. 2  shows a schematic view of an arrangement for collecting water from a seep; 
           [0030]      FIGS. 3A ,  3 B and  3 C show outlines of typical membrane shapes for collecting water from a seep; 
           [0031]      FIG. 4  shows a schematic view of more than one collection point for a seep; and 
           [0032]      FIG. 5  shows schematically steps taken in erecting a seep collection point. 
       
    
    
       [0033]    The various elements identified by numerals in the drawings are listed in the following integer list. 
       INTEGER LIST 
       [0000]    
       
         
           
               1  Generating system 
               3  Conical collecting member 
               4  Base 
               5  Sea floor 
               6  Upper portion 
               7  Sloping floor 
               9  Shore 
               11  Float 
               12  Cable 
               13  Seep 
               15  Water flow 
               17  Surface 
               19  Relief valve 
               21  Join 
               23  Flexible pipe 
               25  Solid pipe 
               27  Electrical generator 
               29  Offtake pipe 
               31  Aggregate 
               33  Conical collecting member 
               35  Circular base 
               37  Apex 
               39  Batten 
               40  Offtake water 
               41  Conical member 
               43  Square base 
               45  Offtake water 
               47  Collecting member 
               49  Offtake water 
               51  Multiple system 
               53  Conical member 
               54  Seep water 
               55  Flexible pipe 
               57  Flexible membrane 
               59  Pole 
               61  Float 
               63  Surface 
               65  Seep water flow 
               67  Weight 
               69  Wire 
               71  Weight 
               73  Wire 
               75  Relief valve 
               77  Cable 
               79  Offtake pipe 
               81  Pulley 
           
         
       
     
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0080]    Referring to  FIG. 1 , there is shown a generating system for generating electricity which is indicated by the reference numeral  1 . 
         [0081]    The generating system  1  comprises a conical member  3  made of a flexible material such as polyethylene or polypropylene or even carbon fibre. It may be a woven or sheet material. If the flexible material is prone to be fouled by marine organisms, it is preferred that at least the outer surface of the flexible material be covered by an anti-fouling agent or a material which resists fouling such as polyethylene. 
         [0082]    The base  4  of the conical member  3  sits on the sea floor  5  and will be held down by appropriate means some of which are described hereinafter. The base  4  sits over a seep  13  from which there is a water flow  15 . The upper portion  6  of the conical member  3  is provided with a join  21  connecting the narrower end of the conical member to a flexible pipe  23 . The flexible pipe may be made of any material which may be sufficiently strong to resist the pressure of water inside the flexible pipe and it may also incorporate or be composed of a material which resists fouling by marine organisms. It may be formed of the same material as the material forming the conical member. 
         [0083]    A float  11  joined by a cable  12  to a relief valve  19  provided at the top of the conical member holds the conical member upright at a level beneath the surface  17  of the sea. In this way, it is possible to maintain the top of the conical member at a depth below which it is not likely to be unduly disturbed by ocean waves. 
         [0084]    A solid pipe  25  joined to the end of the flexible pipe  23  at a region where the flexible pipe abuts the sloping floor of the sea floor sits along the sloping floor and directs water flowing through the pipe to the shore 9. 
         [0085]    An electrical generator  27  sitting on the shore 9 is driven by water from the pipe  25 . An offtake pipe  29  takes water exiting the electrical generator and returns it to the sea or pipes it for ongoing use such as irrigation or domestic use. 
         [0086]    In  FIG. 2 , it can be seen that the conical member  3  has its edges covered by an aggregate  31  to hold the conical member down on the sea floor in a manner that the water flow  15  from the seep is not in communication with the water of the sea. In such an arrangement, any pressure inherent in the water flow  15  is additive to the pressure derived from the difference in density between the water flow  15  and the sea water. 
         [0087]    In  FIG. 3A , it can be seen that the conical collecting member having a circular base  35  and an apex  37  is reinforced with battens  39 . Offtake water  40  is bled off from near the apex of the conical collecting member  33  as per the description with reference to  FIG. 1 . 
         [0088]    In  FIG. 3B , the conical member  41  has a square base  43 . It may also optionally be reinforced with battens and offtake water  45  is again taken near the apex of the conical member. 
         [0089]    The collecting member  47  shown with reference to  FIG. 3C  shows that a range of alternative shapes of collecting members may be used provided that offtake water  49  is taken from a high point along the collecting member and provided the cross-sectional area of the connection for taking the offtake water  49  is less than the cross-sectional area of the seep over which the collecting member is placed. This is to ensure that there is sufficient water flow and pressure to drive machinery which is piped from the seep. It is to be appreciated that all types of different shapes and sizes of collecting member may be used depending upon the particular dimensions of the seep, the depth of the water, topography and rate of water flow. 
         [0090]    In this regard, referring to  FIG. 4 , which shows a multiple system generally designated  51 , it can be seen that two or more collecting members such as the two conical members  53  may be placed over one or more seeps providing seep water  54  and may be joined in series by flexible pipes  55  which can direct water from the seep to one or more locations. Whilst the illustration in  FIG. 4  shows two collecting members  53  in series, it is to be appreciated that, series, parallel and combination series/parallel systems may also be employed. 
         [0091]    Referring to  FIG. 5 , the illustration on the left hand of  FIG. 5  shows one of the first stages of deployment of a conical member over a seep water flow  65  prior to the conical member being fully erected. 
         [0092]    Initially, a flexible membrane  57  wrapped on a pole  59  is suspended beneath the ocean surface  63  by a float  61 . The pole  59  is held down by a weight  71  and wires  73  secure the bottom of the, flexible membrane, to a plurality of weights  67 . The wires  73  extend under pulleys  81  and extend upwardly as wires  69  to one or more vessels on the surface  63  of the water during deployment. By pulling on wires  69 , the flexible membrane is extended to the conical shape shown on the right side of the drawing of  FIG. 5 . A cable  77  extends into and attaches to the relief valve. The float  61  suspends the top of the flexible membrane  57  at a predetermined depth and maintains it in a conical shape. Subsequently, the offtake pipe  79  may be fitted to the top of the conical member in the region of the pressure relief valve and aggregate may be placed over the edges of the bottom of the conical member to hold it on to the ocean floor. 
         [0093]    Whilst the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention. 
         [0094]    It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features. 
         [0095]    The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

Technology Category: f