WO2011024138A2

WO2011024138A2 - Solar water heating and thermal power generation apparatus

Info

Publication number: WO2011024138A2
Application number: PCT/IB2010/053841
Authority: WO
Inventors: Chia Chao Wu; Bin Chi Lu
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-08-26
Filing date: 2010-08-26
Publication date: 2011-03-03
Anticipated expiration: 2012-02-26
Also published as: WO2011024138A3; ZA200905915B

Abstract

A solar water and thermal power generating apparatus is shown. The solar water and thermal power generating apparatus includes a vacuum tube energy array, at least one thermoelectric module and a water tank. The vacuum tube energy array has at least one vacuum tube. The vacuum tube comprises a housing tube, an inner tube and a radiant energy converting device. The inner tube has a radiant energy receiving surface which absorbs radiant energy from the sun and converts the radiant energy to thermal energy, which is used to heat water. The radiant energy converting device is located within the housing tube and converts radiant energy to thermal energy. The thermoelectric module is attachable to and in thermal communication with the radiant energy converting device of the vacuum tube. The thermoelectric module receives thermal energy from at least the radiant energy converting device and converts the thermal energy to electricity. The water tank receives and stores water which has been heated.

Description

SOLAR WATER HEATING AND THERMAL POWER GENERATING APPARATUS

FIELD OF THE INVENTION

This invention relates to a solar water heating and thermal power generating apparatus which uses thermal energy from the sun to heat water and generate electricity.

BACKGROUND TO THE INVENTION

It is estimated that at least 40 percent of the world's population, mostly in developing countries, have no connection to a power grid. In South Africa, statistics show that at least 2.5 million households have no direct access to electricity for cooking, lighting or heating.

The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa. A thermoelectric unit generates electricity when there is a difference in the temperature on either side of the unit, this is known as the Seebeck Effect. In a thermoelectric unit one unit face is heated and the other unit face is cooled or is relatively cooler than the heated unit face. Furthermore, one face of the unit is electron deficient (hence having holes) and the other face of the unit is electron rich (hence having extra electrons), this difference in electron distribution, means that the extra electrons and the holes act as carriers to carry heat through a thermoelectric material. At an atomic scale, a change in temperature causes charged carriers (electrons) in the thermoelectric material to diffuse, from the heated face to the cooled or relatively cooler face, in a similar manner to that of classical gas expansion when a gas is heated. In this manner the difference in temperature between the two unit faces is converted to electricity. For example, thermoelectric units have been applied, on a pilot scale, to generate electricity using the temperature difference generated between a wooden stove and its surrounds when cooking. These systems can also be used to create temperature cycling effects. Thermoelectric units are advantageous as they are generally small and lightweight, they have precise temperature control and most notably can be used to generate an electric current. However, such systems are not applied in solar water heating systems and devices.

Solar water heating devices are also well known. These devices generally have vacuum tubes, either with or without copper inserts, which are heat conducting and function as a heating array, said heating array functioning to collect thermal energy from the sun and heat water which is then stored in a tank and dispensed from the tank. Solar water heating devices operate either through passive processes, wherein no electrically driven pumps to pump the water past the heating array are required, or active processes wherein electrical pumps are employed.

Solar water heating devices have many advantages in that they are environmentally friendly because they reduce the energy consumption that would ordinarily be associated with a geyser system. However, given that such solar water heaters are used solely for heating and storing the water in the tank, much of the solar thermal energy will not be used efficiently and is not converted to electrical energy.

OBJECT OF THE INVENTION

The object of the invention is to create an apparatus which at least in part uses thermal energy from the sun to efficiently heat water and generate electricity.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided vacuum tube, the vacuum tube including a housing tube, an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy, the thermal energy from at least the radiant energy converting device being conveyed from the radiant energy converting device into a thermoelectric unit, wherein said thermal energy is used to generate electricity. There is also provided that the radiant energy receiving surface is located on a sun receiving surface of the inner tube and is made of a selectively absorbent material that is capable of both absorbing radiant energy from the sun and converting said radiant energy to thermal energy, said thermal energy, in use, being used to heat water within the inner tube.

There is further provided that the sun receiving surface of the inner tube is covered entirely by the selectively absorbent material.

There is also provided that a first end of the vacuum tube is connectable to a water tank and a second end of the vacuum tube is connectable to the thermoelectric unit.

There is further provided that the second end of the vacuum tube is sealed with a rubber stopper and a washer. There is further provided that the radiant energy converting device is located at the second end of the vacuum tube.

There is also provided that the radiant energy converting device comprises a first heat pipe which is connected to a second heat pipe, the first heat pipe being located within the housing tube and the second heat pipe protruding from the second end of the vacuum tube.

There is further provided that the first heat pipe comprises fins manufactured from aluminum and coated with a selectively absorbent material which converts radiant energy to thermal energy.

There is further provided that the thermal energy heats a heat transferring fluid in the heat pipe which heated heat transferring fluid is then conveyed into the second heat pipe which contacts the thermoelectric unit wherein said thermal energy is converted into electrical energy in said thermoelectric unit. -A-

In accordance with a second aspect of the invention there is provided a thermoelectric unit, for use in a vacuum tube energy array, comprising: a housing comprising thermoelectric material; at least one heat transmitting device located within the housing which is connectable to, and when connected, in thermal communication with, a radiant energy converting device of a vacuum tube; and a cooling device which, in use, externally cools the housing to create a temperature difference between the heat transmitting device and the cooling device, so that the thermoelectric material of the housing can convert the thermal energy in the heat transmitting device to electrical energy.

There is also provided that the heat transmitting device is a copper backbone which is connectable to a second heat pipe of the radiant energy converting device of the vacuum tube. There is further provided that multiple vacuum tubes are connectable to the heat transmitting device.

There is further provided that the heat transmitting device operatively receives thermal energy from the vacuum tube.

There is also provided that the housing comprises at least one stack structure.

There is also provided that the at least one stack structure is cooled externally by the cooling device which forms part of a water cooling system.

There is further provided that the water cooling system comprises an inlet through which cold water is received, the cold water externally cooling the at least one stack structure and an outlet which connects to a water tank inlet. There is also provided that the water cooling system comprises of at least one water pipe that abuts the at least one stack structure.

In accordance with a third aspect of the invention there is provided a vacuum tube energy array including at least one vacuum tube comprising a housing tube, an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy and at least one thermoelectric unit which is attachable to and in thermal communication with a the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity. There is also provided that where a plurality of vacuum tubes is used, said vacuum tubes are positioned parallel to each other.

In accordance with an alternate version of the third aspect of the invention there is provided a vacuum tube energy array including at least one water vacuum tube comprising a housing tube and an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water within the inner tube, at least one heat pipe energy tube comprising a housing tube, an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity.

There is further provided that a plurality of water vacuum tubes and heat pipe energy tubes is used. There is further provided that the vacuum tube energy array comprises water vacuum tubes that alternate with heat energy tubes. In accordance with a fourth aspect of the invention there is provided a solar water and thermal power generating apparatus including a vacuum tube energy array comprising at least one vacuum tube comprising a housing tube, an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, said thermal energy being used to heat water and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of converting said radiant energy to thermal energy and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity and a water tank, which receives and stores water which has been heated by contact with the vacuum tube energy array.

In accordance with an alternative version of the fourth aspect of the invention there is provided a solar water and thermal power generating apparatus including a vacuum tube energy array comprising at least one water vacuum tube comprising a housing tube and an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water, at least one heat energy tube comprising a housing tube, an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity and a water tank, which receives and stores water which has been heated by contact with the vacuum tube energy array. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a sectioned view of a vacuum tube, for use in a solar water heating and thermal power generating apparatus, in accordance with a first aspect of the invention;

Figure 2 is a top view of a thermoelectric unit, for use in a solar water heating and thermal power generating apparatus, in accordance with a second aspect of the invention;

Figure 3 is a side view of the thermoelectric unit of Figure 2 connected to a vacuum tube energy array comprising a plurality of vacuum tubes of the type shown in

Figure 1 ;

Figure 4 a is a side view of a vacuum tube energy array, for use in a solar water heating and thermal power generating apparatus, in accordance with a third aspect of the invention; Figure 4 b is a side view of an alternating vacuum tube energy array, for use in solar water heating and thermal power energy generation, in accordance with an alternate version of the third aspect of the invention; and

Figure 5 is a perspective view of a solar water and thermal power generating apparatus in accordance with a fourth aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION In Figure 1 a vacuum tube (10), for use in a vacuum energy array, in accordance with a first aspect of the invention is shown. The vacuum tube (10) has a housing tube (12), an inner tube (14) and a radiant energy converting device (18). The vacuum tube (10) has a first end (20) and a second end (22). The first end (20) is connectable to and can receive water to be heated from a water tank. The water tank is not shown in Figure 1 but will be described further below with reference to Figure 5.

A vacuum (1 1) is defined between the housing tube (12) and the inner tube (14). The vacuum (1 1) is created, when the vacuum tube (10) is manufactured, using a flash getter, more particularly a barium flash getter (13). After the vacuum tube (10), containing the barium flash getter (13), has been manufactured and sealed the barium flash getter (13) is heated by induction this heating causes the barium to evaporate and react with any residual gas in the vacuum tube (10).

The inner tube (14) has a radiant energy receiving surface (16) which is made of a selectively absorbent material which is capable of absorbing radiant energy from the sun and converting this radiant energy to thermal energy, the thermal energy is then used to heat water, this water can be stored in a water tank, as will be described further below. The radiant energy receiving surface (16) is located on a sun receiving surface of the inner tube (14). The selectively absorbent material of radiant energy receiving surface (16) will generally cover the entire upper surface of the inner tube (14) on the sun receiving surface of the inner tube (14). It is however, envisaged that only parts of the sun receiving surface of the inner tube (14) may be coated with the selectively absorbent material.

The radiant energy converting device (18) is located at the second end (22) of the vacuum tube (10) within the housing tube (12) and is capable of receiving radiant energy and converting the received radiant energy to thermal energy. The thermal energy produced in the radiant energy converting device (18) is then conveyed into a thermoelectric unit, which is connectable to the second end (22) of the vacuum tube (10). The thermoelectric unit is not shown in Figure 1 but will be described in more detail below with reference to Figures 2 and 3. The thermoelectric unit uses the thermal energy produced in the radiant energy converting device (18) to generate electricity, electricity being generated by a thermoelectric process, more particularly the Seebeck Effect.

The radiant energy converting device (18) comprises a first heat pipe (28) and a second heat pipe (30). The first heat pipe (28) is located within the radiant energy converting device (18) and is connected to the second heat pipe (30). The second heat pipe (28) protrudes from the second end (22) of the vacuum tube. In particular, the second end (22) of the vacuum tube is sealed with a rubber stopper (24), more particularly a silicon stopper, and a washer (26), more particularly an aluminum washer. The second heat pipe (30) is fitted such that it protrudes through the washer (26) and the rubber stopper (24). The connection of the thermoelectric unit to the second end (22) of the vacuum tube (10) is made via the second heat pipe (30). The first heat pipe (28) has fins (34) which are manufactured from aluminum and are coated with a selectively absorbent material. The selectively absorbent material converts radiant energy to thermal energy. The thermal energy causes a heat transferring fluid (not shown) in the heat pipe (28) to heat up. This heat transferring fluid acts as a conveying fluid wherein heat (thermal energy) is transferred from the first heat pipe (28) to the second heat pipe (30).

The thermal energy produced in the radiant energy converting device (18) is conveyed into a thermoelectric unit (not shown) via the second heat pipe (30) said thermal energy being converted into electrical energy in said thermoelectric unit.

In Figure 2 and 3 a thermoelectric unit (1 10), for use in a vacuum tube energy array that may comprise a plurality of vacuum tubes of the type shown in Figure 1 , is shown. The thermoelectric unit (1 10) has a housing (112), at least one heat transmitting device (1 14), located within the housing (112) and cooling device (1 16). The heat transmitting device (1 14) is a copper backbone which is connectable to a second heat pipe (122) of a radiant energy converting device (1 18) of the vacuum tube (120). It is envisaged that multiple vacuum tubes may be connected to the heat transmitting device (1 14). The second heat pipe (122), the radiant energy converting device (1 18) and the vacuum tube (120) described here are similar to the second heat pipe (30), the radiant energy converting device (18) and the vacuum tube (10) as described above with reference to Figure 1. The heat transmitting device (1 14) operatively receives thermal energy from the vacuum tube (120), more specifically from the second heat pipe (122) of the radiant energy converting device (1 18), and as a result the heat transmitting device (114), which, in use, is in thermal communication with the second heat pipe (122), heats up.

The second heat pipe (122) contains a heat transfer liquid (not shown) which heats up when thermal energy is received from a first heat pipe (133) of the radiant energy converting device (1 18). The first heat pipe (133) in this instance being similar to the first heat pipe (28) as shown in Figure 1. The second heat pipe (122) comprises a first end (131 ) and a second end (132), the first end (131 ) being in thermal communication with the first heat pipe (133) and the second end abutting the heat transmitting device (1 14). The first end (131 ) receives thermal energy from the first heat pipe (133). The thermal energy heats the heat transfer liquid and the heat transfer liquid evaporates. When the heat transfer liquid evaporates it is converted to a heat transfer vapour (not shown) which expands and moves towards the second end (132) of the second heat pipe (122). The second end (132) of the second heat pipe (122) is relatively cooler than the first end (131 ) of the second heat pipe (122) and due to this difference in temperature the heat transfer vapour condenses at the second end (132) of the second heat pipe (122). Thermal energy is thereby transferred from the heat transfer vapour, when the vapour is converted back to a heat transfer liquid by condensation, to the second end (132) of the second heat pipe (122). The second end (132) of the second heat pipe (122) abuts the heat transmitting device (114) and thermal energy received from the second end (132) of the second heat pipe (122) causes the heat transmitting device (1 14) to heat up. The heat transfer liquid then collects at the second end (132) of the second heat pipe (122) and is then transferred back to the first end (131 ) of the second heat pipe (122) in a capillary tube (not shown), which is located within the second heat pipe, by capillary action. The heat transfer liquid is generally water or ethanol but it is envisaged that other liquids may be used.

It is envisaged that more than one vacuum tube (120) may be connectable to the heat transmitting device (1 14) and where this is the case the heat transmitting device (1 14) will receive thermal energy from all of the vacuum tubes (120) simultaneously. The cooling device (116) externally cools the housing (1 12) so that the temperature of the housing (1 12) is lower than the temperature of the heat transmitting device (1 14) thereby allowing for electricity to be generated. Generally, electricity is generated by the Seebeck Effect however it is envisaged that other processes may be employed. The housing (1 12) is made up of at least one stack structure (124), which abuts the heat transmitting device (1 14). Although the housing may comprise only one stack structure (124), generally more than one stack structure (124) is used. When more than one stack structure (124) is used, the stack structures (124) are arranged such that they effectively sandwich the copper backbone. The stack structures (124) are made of thermoelectric material such as Bismuth Telluride (Bi₂Te₃) or Lead Telluride (PbTe) or another thermoelectric material such as Zinc Antimony (Zn₄Sb₃) or Antimony Telluride (Sb₂Te₃), which converts the heat energy into electrical energy when a temperature difference is created between the stack structures (124) and the copper backbone. The stack structures (124) are cooled on an external surface (121 ) by a water cooling system (126) and are in thermal communication with the copper back bone at an internal surface (123) hence a temperature gradient between said external (121 ) and internal surface (123) is created and this gradient allows for electricity generation, generally via the Seebeck Effect, to occur. It is envisaged that a process other than the Seebeck Effect may be used to generate electricity. The electricity generated is stored in a battery (not shown) and can then be used as the primary energy source for households which are not connected to a electricity grid, thereby providing electricity for lighting, air cooling and other domestic use, such electricity would not otherwise be available. The water cooling system (126) comprises at least one water pipe (127) which has an inlet (128) through which cold water is received and an outlet (130) which connects to a water tank inlet. The water tank inlet is not shown but is discussed in more detail below with reference to Figure 5. It is envisaged that more than one stack structure (124) may be used, as described above, and as such more than one water pipe (127) would be used. Where more than one water pipe (127) is used the water pipes (127) are positioned parallel to each other and are located to abut each of the stacks (124) on the external surfaces (121 ) of each of the stacks (124) so that the water pipes (127) of the water cooling system (126) effectively sandwich the stacks (124). The water exiting the outlet (130) will be fed into a water tank and from the water tank into a heating process whereby a vacuum tube energy array, as described below with reference to Figures 4a and 4 b, is used to heat the water. The water tank is not shown in Figure 3, but will be discussed in more detail below with reference to Figure 5.

In Figure 4a, a vacuum tube energy array (210), in accordance with a third aspect of the invention, is shown. The vacuum tube energy array (210) has at least one vacuum tube (212) and at least one thermoelectric unit (214). The at least one vacuum tube (212) is similar to the vacuum tube (10 and 120) described above and the thermoelectric unit (214) is similar to the thermoelectric unit (1 10) described above. It is envisaged that more than one vacuum tube (212) will be used in the vacuum tube energy array (210) and where more than one vacuum tube (212) is used the vacuum tubes (212) are connected parallel to each other.

The thermoelectric unit (214) is attachable to and in thermal communication with a radiant energy converting device (216), which radiant energy converting device (216) is similar to the radiant energy converting device (1 18) described above, of the at least one vacuum tube (212). The thermoelectric unit (214), in use, receives thermal energy and converts the thermal energy to electricity. More particularly the thermoelectric unit (214) is attached to the radiant energy converting device (216) via a second heat pipe (217), which is similar to the second heat pipe (30) described above, which second heat pipe (217) forms part of the radiant energy converting device (216). As described above, the conversion of thermal energy to electrical energy generally takes place by the Seebeck Effect.

The radiant energy converting device (216) of each vacuum tube (212) is connectable to a single thermoelectric unit (214). It is envisaged however, that each vacuum tube (212) may be connected to a separate thermoelectric unit.

In Figure 4 b an alternative embodiment of the vacuum tube energy array (410) is shown, with this embodiment being referred to as an alternating vacuum tube energy array. In this embodiment, although only one is shown, every second vacuum tube is a heat pipe vacuum tube (412) which has a radiant energy converting device (416) which is connectable to the thermoelectric unit (414). The radiant energy converting device (416) comprises a first heat pipe (411 ) which spans the length of the heat pipe vacuum tube (412) and a second heat pipe (417). The second heat pipe (417) is connected to the first heat pipe (41 1) and receives thermal energy from the first heat pipe (41 1 ). The heat pipe vacuum tube (412) operates in a similar manner to the radiant energy converting device (18), as described above with reference to Figure 1 , in that fins (419) located adjacent to the second heat pipe (417) receive radiant energy from the sun and convert this radiant energy to thermal energy. The thermal energy heats up a heat transferring fluid (not shown) in the first heat pipe (41 1) and this heat transferring fluid conveys heat (thermal energy) to the second heat pipe (417).

The alternate vacuum tubes, being the vacuum tubes between the heat pipe vacuum tubes (412), are not connected to the thermoelectric unit (414) but act as water vacuum tubes (412 b). The water vacuum tubes (412b) do not have heat pipes but merely comprise a housing tube (421 ) and an inner tube (423) with a vacuum (425) defined between the housing tube (421) and the inner tube (423). A barium getter (427), as described above, with reference to Figure 1 , is used to remove any excess gas from the vacuum (425). The water vacuum tubes (412b) are only involved in receiving radiant energy and converting this radiant energy to thermal energy which will be used in the solar water heating process. The water to be heated flows from a water tank into a water receiving end (429) of the water vacuum tube (412 b). Both the process by which the water is heated and the water tank will be discussed further below with reference to Figure 5. Figure 5 shows a solar water and thermal power generating apparatus (310) in accordance with a fourth aspect of the invention. The solar water and thermal power generating apparatus (310) consists of a vacuum tube energy array (314), as described above and as shown in Figure 4a or an alternating vacuum tube energy array as described above with reference to Figure 4b, and a water tank (312). The solar water and thermal power generating apparatus (310) has a number of vacuum tubes (31 1) which are connected parallel to each other and which connect to the water tank (312) at a first end (313) and to a thermoelectric unit (315) at a second end (317). It is envisaged that more than one thermoelectric unit (315) may be used in the solar water and thermal power generating apparatus (310).

Each vacuum tube (311 ) of vacuum tube energy array (314) operatively receives water from the water tank (312). The water flows from the water tank (312) into an inner tube (319) of the vacuum tube (31 1). The inner tube (319), operates in a similar manner to the inner tube (14) described with reference to Figure 1 , in that the sun receiving surface (321) of the inner tube (319) receives radiant energy from the sun and converts this radiant energy to thermal energy. The thermal energy causes the inner tube (319) to become heated. In the inner tube (319) the water molecules heat up, due to exposure to the heated inner tube (319) and this causes the water molecules to move upwards via a process of convection. As the water moves upwards in the inner tube (319) it is continually exposed to the heated inner tube and so heats up further before re-entering the water tank (312). This process of solar water heating is known as thermosiphon but it is envisaged that other processes of solar water heating may be employed. The water tank (312) receives water from the water cooling system (126), as described above and as referred to in Figure 2. Water is received from the water cooling system at a water tank inlet (333) and this water is then fed into the water heating process. The thermoelectric unit (315) generates electricity, generally via the Seebeck Effect, by using the excess thermal energy generated by a water heating process. The process by which electricity is generated is explained further above with reference to the second aspect of the invention and Figures 2 and 3. The excess thermal energy generated by the solar heating device is used to produce electrical energy which can be used in households which are not connected to an electricity grid. It is possible that an apparatus of this kind can be manufactured on a large scale and then be widely distributed to millions of households around the world which have no access to power grids.

Claims

1. A vacuum tube comprising: a housing tube; an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy; and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy, the thermal energy from at leas the radiant energy converting device being conveyed from the radiant energy converting device into a thermoelectric unit, wherein said thermal energy is used to generate electricity.

2. The vacuum tube, as claimed in claim 1 , wherein the radiant energy receiving surface is located on a sun receiving surface of the inner tube and is made of a selectively absorbent material that is capable of both absorbing radiant energy from the sun and converting said radiant energy to thermal energy, said thermal energy, in use, being used to heat water within the inner tube.

3. The vacuum tube, as claimed in claim 2, wherein the sun receiving surface of the inner tube is covered entirely by the selectively absorbent material.

4. The vacuum tube, as claimed in claim 1 , wherein a first end of the vacuum tube is connectable to a water tank and a second end of the vacuum tube is connectable to the thermoelectric unit.

5. The vacuum tube, as claimed in claim 4, wherein the second end of the vacuum tube is sealed with a rubber stopper and a washer.

6. The vacuum tube, as claimed in claim 4, wherein the radiant energy converting device is located at the second end of the vacuum tube.

7. The vacuum tube, as claimed in claim 4, wherein the radiant energy converting device comprises a first heat pipe which is connected to a second heat pipe, the first heat pipe being located within the housing tube and the second heat pipe protruding from the second end of the vacuum tube.

8. The vacuum tube, as claimed in claim 7, wherein the first heat pipe comprises fins coated with a selectively absorbent material which converts radiant energy to thermal energy.

9. The vacuum tube, as claimed in claim 8, wherein the fins are manufactured from aluminum.

10. The vacuum tube, as claimed in claim 8, wherein the thermal energy heats a heat transferring fluid in the heat pipe which heated heat transferring fluid is then conveyed into the second heat pipe which contacts the thermoelectric unit wherein said thermal energy is converted into electrical energy in said thermoelectric unit.

1 1. A thermoelectric unit, for use in a vacuum tube energy array, comprising: a housing comprising thermoelectric material; at least one heat transmitting device located within the housing which is connectable to, and when connected, in thermal communication with, a radiant energy converting device of a vacuum tube; and a cooling device which, in use, externally cools the housing to create a temperature difference between the heat transmitting device and the cooling device, so that the thermoelectric material of the housing can convert the thermal energy in the heat transmitting device to electrical energy.

12. A thermoelectric unit, as claimed in claim 1 1 , wherein the heat transmitting device is a copper backbone which is connectable to a second heat pipe of the radiant energy converting device of the vacuum tube.

13. A thermoelectric unit, as claimed in claim 1 1 , wherein multiple vacuum tubes are connectable to the heat transmitting device.

14. A thermoelectric unit, as claimed in claim 1 1 , wherein the heat transmitting device operatively receives thermal energy from the vacuum tube.

15. A thermoelectric unit, as claimed in claim 11 , wherein the housing comprises at least one stack structure.

16. A thermoelectric unit, as claimed in claim 15, wherein the at least one stack structure is cooled externally by the cooling device which forms part of a water cooling system.

17. A thermoelectric unit, as claimed in claim 16, wherein the water cooling system comprises an inlet through which cold water is received, the cold water externally cooling the at least one stack structure and an outlet which connects to a water tank inlet.

18. A thermoelectric unit, as claimed in claim 16, wherein the water cooling system comprises of at least one water pipe that abuts the at least one stack structure.

19. A vacuum tube energy array comprising: at least one vacuum tube comprising: a housing tube; an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water; and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy,; and at least one thermoelectric unit which is attachable to and in thermal communication with a the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity.

20. A vacuum tube energy array, as claimed in claim 19, wherein a plurality of vacuum tubes is used, said vacuum tubes being positioned parallel to each other.

21. A vacuum tube energy array comprising: at least one water vacuum tube comprising: a housing tube; and an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water within the inner tube; at least one heat pipe energy tube comprising: a housing tube; an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water; and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy; and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity.

22. The vacuum tube energy array, as claimed in claim 21 , wherein a plurality of water vacuum tubes and heat pipe energy tubes is used.

23. The vacuum tube energy array, as claimed in claim 22, wherein the vacuum tube energy array comprises water vacuum tubes that alternate with heat energy tubes.

24. A solar water and thermal power generating apparatus comprising: a vacuum tube energy array comprising: at least one vacuum tube comprising: a housing tube; an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, said thermal energy being used to heat water; and a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of converting said radiant energy to thermal energy; and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity; and a water tank, which receives and stores water which has been heated by contact with the vacuum tube energy array.

25. A solar water and thermal power generating apparatus comprising: vacuum tube energy array comprising: at least one water vacuum tube comprising: a housing tube; and an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water; at least one heat energy tube comprising: a housing tube; an inner tube having a radiant energy receiving surface which is capable of absorbing radiant energy from the sun and converting said radiant energy to thermal energy, the thermal energy being used to heat water; a radiant energy converting device, located within the housing tube, the radiant energy converting device being capable of receiving radiant energy and converting said radiant energy to thermal energy; and at least one thermoelectric unit which is attachable to and in thermal communication with the radiant energy converting device of the at least one vacuum tube, said thermoelectric unit, in use, receiving thermal energy, from the radiant energy converting device and converting said thermal energy to electricity; and a water tank, which receives and stores water which has been heated by contact with the vacuum tube energy array.

26. A vacuum tube, substantially as described herein with reference to and as illustrated in Figure 1.

27. A thermoelectric unit, substantially as described herein with reference to and as illustrated in Figures 2 and 3.

28. A vacuum tube energy array, substantially as described herein with reference to and as illustrated in Figures 4 and 4 b.

29. A solar water and thermal power generating apparatus, substantially as described herein with reference to and as illustrated in Figure 5.