Abstract:
The method is for using solar power in an efficient manner. A solar concentrator is provided in operative engagement with a storage unit. The storage unit has at least one glass rod disposed therein and at least one sheet enclosing the storage unit. The solar concentrator receives solar power as sunrays and conveys the solar power to the glass rod disposed in the storage unit. The solar power is in the glass rod is converted to heat to heat to the storage unit. Gas flows between the storage unit and the sheets. The storage unit heats the gas. The gas flows to a heat exchanger to exchange heat with steam.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a method for using concentrated solar power. 
       BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    Solar power or solar energy has been used for many decades for heating dwellings and water and for generating electricity. Because solar power is a renewable energy source much effort has been made to develop systems to use such energy. The costs have been high and the storage of energy has not been very effective. It has been particularly difficult and expensive to store energy at very high temperatures (900-1000° C.) due to large heat losses. However, the efficiency of conventional systems has been low and there is a need for a more efficient and cost effective system. 
         [0003]    The method of the present invention provides a solution to the above-outlined problems. More particularly, the method is for using solar power in an efficient manner. A solar concentrator is provided that is in operative engagement with a storage unit. The storage unit has at least one glass rod disposed therein and at least one sheet enclosing the storage unit. The solar concentrator receives solar power, concentrates the solar power before conveying the solar power as light to the glass rod disposed in the storage unit. The glass rod emits light and the light is converted to heat upon impact with the storage unit to heat the storage unit. Gas or water steam flows between the storage unit and the sheets. The storage unit heats the gas. The gas or water steam flows to a heat exchanger to continuously exchange heat with steam. 
         [0004]    In another embodiment, the solar concentrator is connected to a fiber optic cable that is connected to the glass rod disposed inside the storage unit. 
         [0005]    In another embodiment, the glass rod could be formed into a spiral shape. 
         [0006]    In yet another embodiment, a plurality of sheets as sheet layers enclose the storage unit and gas flows between each sheet layer. 
         [0007]    In another embodiment, the fiber optic cable guides the solar power as light at different wave lengths towards a center of the fiber optic cable. 
         [0008]    In yet another embodiment, the fiber optic cable transmits the centered solar power to the glass rod. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a schematic view of a solar power system of the present invention; 
           [0010]      FIG. 2  is a cross-sectional side view of a first embodiment of the storage unit; 
           [0011]      FIG. 3  is a detailed cross-sectional view of the storage system; 
           [0012]      FIG. 4  is a cross-sectional view of a second embodiment of the storage unit; 
           [0013]      FIG. 5  is a schematic view of an alternative embodiment of the present invention; 
           [0014]      FIG. 6  is a cross-sectional view along line A-A of  FIG. 5 ; 
           [0015]      FIG. 7  is a schematic view of an alternative embodiment of the present invention; and 
           [0016]      FIG. 8  is a cross-sectional view along line A-A of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  is a schematic overview of the solar power system  100  of the present invention. It has a solar concentrator  102  that concentrates beams or rays  107  received from the sun  105  and conveys the light beams to a fiber-optic cable  104 . The solar concentrator  102  has suitable lenses, such as Fresnel lenses or a solar guiding system, to concentrate the sunrays to a focal point. In one preferred embodiment, if the lens is about one square meter then the focal point, after the concentration of the sun rays by the lens, has a diameter of about 18 millimeters or less. It is desirable to further concentrate the sun rays so that the focal point is about 2 square millimeters which is about the same as the size of each fiber. It is possible to use many fibers in each cable so that a plurality of lenses in the solar concentrator may be used also to increase the amount of energy conveyed by the cable. For example, if the total area of all the lenses is about 25 square meters in the solar concentrator then about 25 fibers may be included in the cable. 
         [0018]    The cable  104  may be made of doped glass that includes a carbon pattern that can handle all the visible wave-lengths of the sun light or sun rays received by the concentrator  102 . In general, the visible wave-lengths have the most energy and are the most desirable to convey. The carbon pattern may have hollow rods of different sizes around a central opening of the fiber that extend along the fiber that act as reflection surfaces and guide the sun rays or light towards the central opening of each fiber in the cable  104 . For example, each fiber may contain seven hollow rods and each rod is about 1.7 micrometers. Other dimensions may also be used. In this way, it is possible to effectively transport the sun rays or light of different wave-lengths via the cable  104 . The cable  104  may be bendable (or non-bendable) and carries the light at a range of visible (and non-visible) wave-lengths. Instead of using the cable  104  it is also possible to use solid glass in the fibers although the energy losses are greater, the range of wave-lengths that can be carried is more limited and it may be necessary to use relatively thick glass rods which are difficult or impossible to bend without breaking the rods. 
         [0019]    The concentrator  102  is connected to a high-temperature storage system  103  via the fiber-optic cable  104  that carries the conveyed light energy to the storage system  103  where it is converted to heat. The storage system  103  may be made of any suitable material such as concrete, sand or any other material that is suitable for storing heat in a range of 300-1000° C. Preferably, the temperatures are higher than 300 C in order to make electricity. Gas  106 , such as argon, circulates in conduits  108  the storage system  102  and heat is exchanged in a heat exchanger  110  to heat steam  112  flowing in a circulation conduit  114 . Pumps  116 ,  118  may be used to drive the gas  106  and steam  112 , respectively. A steam turbine  120  is connected to the conduit  114  and to a capacitor  122 . It is also possible to place the heat exchanger  110  inside storage  103  to eliminate the need for the gas  106  and the circulation line and pump  116 . 
         [0020]      FIG. 2  is a cross-sectional side view of a first embodiment of the storage unit  103 . The fiber cable  104  is connected to relatively long spiral-formed glass-rods  132  disposed inside the storage unit  103 . It is also possible to direct the light directly from the solar concentrator  102  via the air to the ends of the glass-rods that extend out of the storage unit  103 . One drawback of the latter design is that the solar concentrator  102  should be relatively close to the storage unit and that the storage unit  103  must be unobstructed and visible from the solar concentrator. Another option is to use the solar power to heat gas that, in turn, is circulated into the storage unit  103  to heat the glass rods disposed in the unit. 
         [0021]    The hot glass-rods  132  convert the light energy, carried in the fiber cable  104 , to heat which is used to heat the storage unit  103 . More particularly, as the rods  132  emit light inside the storage unit  103  the light energy is converted into heat. When the rods are substantially straight the light is reflected on the inside walls of the fiber cable and no or very little light is emitted. However, when the fiber cable is sufficiently bent or curved then light escapes from the fiber. In other words, the light energy is mostly emitted where the rods are bent and this light energy is converted into heat. The spiral shape of the rods  132  increases the contact surface area against the storage unit  103  to improve the transfer of heat from the glass-rods  132  to the storage unit  103 . At the end  133  of the rods  132  very little light energy remains so the end does not create much heat. As mentioned above, it is also possible to transfer the light energy from the solar concentrator  102  directly to the storage  103  by directly directing or reflecting the light energy to the glass-rods  132  that are sticking out of the storage unit  124 . In this way, the glass rods  132  are heated. A straight rod, shaped like a cone, also works but makes it more difficult to accomplish an even energy distribution in the storage unit. 
         [0022]      FIG. 3  is a schematic cross-sectional view of the storage system  103  that includes a storage unit  124  and several layers of sheets  126   a - 126   e  completely enclosing and surrounding the storage unit  124 . Only a portion of the sheets are shown in  FIG. 3 . The system  103  of the present invention may use more or fewer sheets as necessary. Gas  106  flows between the sheets  126   a - 126   e . The circulating gas is heated by the hot storage unit  124  and may be used to produce electricity, as described below. Each sheet reflects back heat to the gas flowing between the sheets. The first sheet  126   a  may reduce the heat emitted from the unit  124  with up to 50%. Sheets  126   b - 126   e  continue reducing the heat emitted by reflecting in back to heat the gas flowing between the sheets. The gas thus cools down the sheets  126   a - 126   e . Preferably, the gases from each layer are mixed before they enter the heat exchanger  109 . 
         [0023]    High temperature insulation  128  is preferably used between the outer sheet  126   e  and low temperature insulation  130 . The temperature at the outer sheet  126   e  may be about 100-600° C. and the temperature between the high temperature insulation  128  and the low temperature insulation  130  may be about 50-300° C. or any other suitable temperature. The temperature outside insulation layer  130  may be ambient or about 20° C. Because the circulating gas  106  cools the storage unit  124 , it is possible to use less expensive insulation layers  128 ,  130  that are designed for insulating temperatures in the range of 100-600 C. It was surprisingly discovered that the gases reduce the temperature so much that virtually no insulation layers  128 ,  130  are necessary. An important feature of the present invention is thus to use the heat losses from storage unit  124  for further use such as making electricity. Another important aspect is that the heat losses are continuously being recovered although the sun may not be out to provide the solar power. The storage unit should be designed so that it stores energy for up to 4-6 months so that heat generated during the summer months can be used during the winter months. 
         [0024]      FIG. 4  is a cross-sectional side view of a second embodiment of the storage unit  134  that includes a plurality of relatively short glass rods  136  that release or transfer much more energy at each bend  138  compared to the energy transferred at each bend of the glass-rods  136  mainly because the rods are bent more. This is to illustrate that the emission of light energy varies depending on the shape or form of the glass rods. In general, the larger the radius (r) of the curvature of the glass rods, the less energy is emitted from the glass rods. 
         [0025]      FIG. 5  is a schematic view of an alternative embodiment of a system  200  of the present invention. Storage  103 ′ is connected to concentrator  102  as described in  FIG. 1  and insulation layers  128 , 130  encapsulate the storage unit  103 ′. Water comes in via tube  202 , pumped by pump  203 , and is split up between vertical tubes  204  and  206  so that the water is heated to steam by storage unit  103 ′ and steam flows away from unit  103 ′ via conduit  208 . A re-circulation loop  210  may be connected to a switch valve  212  to use heat from the inside of the storage unit  103 ′ when the outside of the storage unit  103 ′ is not hot enough. 
         [0026]      FIG. 6  is a top cross-section view of tube  206  along line A-A of  FIG. 5 . Preferably, tube  206  has an outer manifold ring  214  and an inner manifold ring  216 . Each manifold ring includes a plurality of small tubes  218 ,  220 , respectively. 
         [0027]      FIGS. 7-8  are a schematic view of an alternative embodiment  300 . A liquid, such water, flows in conduit  302  and is pumped by pump  304  via a valve  306  into conduit  308  that extends to an inner water manifold  310  or into conduit  309  that extends to a round peripheral water manifold  311 . The pressure at pump  304  may be about 1 bar or any other suitable pressure. The valve  306  may be used to control the flow of water between conduit  308  and  309 . A plurality of inner tubes  312   a - c , are in fluid communication with manifold  310  to carry the water through the heated storage system  314  that is substantially similar to storage system  103 . The tubes  312   a - c  extend through storage system  314  to a steam manifold  316  and then flows as steam into a common conduit  318 . The pressure of the steam in steam manifold  316  may be 20 bars or a pressure substantially higher than the pressure at pump  304 . As best seen in  FIG. 8 , there are more inner tubes used and only inner tubes  312   a - c  are shown in  FIG. 7 . The storage system  314  heats the water to steam. Peripheral tubes  313   a - b  extend between water manifold  311  to steam manifold  316  outside storage system  314 . As best shown in  FIG. 8 , there are more peripheral tubes than tubes  313   a - b  that are shown in  FIG. 7 . Radiation shield  322  is disposed outside storage system  314  to act as a heat shield and preferably, tubes  313   a - b  and all the other peripheral tubes connected to water manifold  311  are immediately adjacent to or in contact with the radiation shield  322 . In this way, heat losses from the storage system  314  are transferred to the water flowing in the peripheral tubes  313   a - b  and the other peripheral tubes connected to water manifold  311 . The water in tubes  313  is heated to steam. Conduit  318  extends from steam manifold  316  to a steam engine  320 , to generate power such as electricity, and then further to a condenser  321  where the pressure and temperature are reduced so that the steam is condensed to water again. Preferably, the temperature of the over-heated pressurized steam when it enters the steam engine  320  should be several hundred degrees Celsius such as about 200-225 C. After the condenser  321 , the water flows to pump  304  to be re-circulated into the storage system  314  again in the same way as described above. When there is not enough heat in storage system  314  then the water is directed via conduit  308  by switching valve  306  to open the flow into conduit  308 . When the storage system  314  is hot enough, such as when the temperature in the storage system  314  is between 200-225 C, then the valve  306  may be used to direct water via conduit  309  into water manifold  311  to flow in the peripheral tubes  313  into steam manifold  316 . It is also possible to successively open the valve  306  so that there is flow in both conduit  308  and  309  and the exact flow in the conduits  308 ,  309  may be set by valve  306 . In this way, the flow in conduit  308  may be higher than conduit  309  or vice versa. 
         [0028]    While the present invention has been described in accordance with preferred compositions and embodiments, it is to be understood that certain substitutions and alterations may be made thereto without departing from the spirit and scope of the following claims.