AU2013100968A4 - Hybridized-solar thermal power plant - Google Patents

Abstract

A hybridized-solar thermal power plant including at least one solar thermal collector or an array containing a thermal medium, the thermal medium being at least partially heated by solar 5 radiation, a fuel powered boiler for maintaining thermal medium at a temperature conducive for converting liquid refrigerant in to refrigerant vapour, a heat scavenger, a heat exchanger, a shell heat scavenger, a commercially available condenser and expansion chamber and an organic rankine cycle turbine operating a generator for generating electricity from the refrigerant vapour. - 27 - 4) r tr

Description

INNOVATION PATENT APPLICATION HYBRIDIZED-SOLAR THERMAL POWER PLANT FIELD OF THE INVENTION This invention relates to electric power generation in particular but not exclusively to a hybrid 5 solar thermal power plant for generating electricity. BACKGROUND OF THE INVENTION An example of a traditional arrangement for scalable solar thermal power generation, is 10 described in Innovation Patent 2010101462, wherein there is an insulated heat trap containing solar thermal tubes and an array of piping to permit the flow of a thermal medium within the tubes and between multiple heat traps and a boiler. The boiler, or steam generator, acts as a heat exchanger and draws energy from the thermal medium in encased internal tubes and deposits it in the water stored in the tank. When the water reaches a point where steam of 15 sufficient temperature and pressure is formed, the steam is released into a traditional steam turbine generator, and electricity is produced. This prior art arrangement includes the following limitations: the heat trap can only heat the thermal medium when sufficient solar thermal energy is available. The system is unable to operate at night or during adverse weather conditions; 20 a) loss of energy (heat) occurs at the heat trap to boiler connection point and the condenser to boiler connection point; b) superheated steam at high volumes and pressures are required to turn the turbine, which requires a great deal of solar thermal energy. This can only be achieved by increasing the number of heat traps and therefore increasing the size and complexity of the installed unit; and 25 c) the comparably low temperatures that the prior art produces restricts the turbine generators to micro-turbines, which has a generating capacity of only a few kilowatts. - 1 - OBJECT OF THE INVENTION It is the object of the invention to ameliorate some or all of the above disadvantages of the prior art by providing a novel and innovative hybridized-solar thermal power plant and to at least provide the public with a useful alternative and choice. 5 STATEMENT OF INVENTION In one aspect the invention resides in a hybridized-solar thermal electricity plant including: a) at least one solar thermal collector containing a thermal medium, the thermal medium adapted to be partially heated by solar radiation; 10 b) a fuel powered boiler for heating the thermal medium to a temperature to convert liquid refrigerant to refrigerant vapour in a heat exchanger; c) one or more heat scavengers for pre-heating the thermal medium prior to entering the solar thermal collector and the fuel powered boiler respectively; d) an organic rankine cycle turbine driven by the refrigerant vapour, and 15 e) a generator connected to the turbine to generate electricity. Preferably, the plant includes transport pipes and pumps for circulating thermal medium through the at least one solar thermal collector, heat scavenger and fuel powered boiler. 20 Preferably, the temperature of the thermal medium converts liquid refrigerant into refrigerant vapour in the heat exchanger which is transferred by a refrigerant vapour pipe to the turbine. Preferably, the plant includes a condenser and an expansion chamber for condensing refrigerant vapour from the organic rankine cycle turbine and a heat scavenger to pre heat liquid 25 refrigerant before transferring it to the heat exchanger for conversion to refrigerant vapour. Preferably, the fuel powered boiler includes a thermal medium heating vessel having: a) a first inlet for receiving thermal medium from the solar thermal collector; b) a second inlet for receiving thermal medium from the heat exchanger; -2c) a first outlet for returning thermal medium to the solar thermal collector, and d) a second outlet for transferring thermal medium to the heat exchanger. Preferably, the fuel powered boiler includes a burner attached to a fuel storage container. 5 Preferably, the fuel powered boiler burner maintains thermal medium at a temperature conducive to the production of refrigerant vapour in a heat exchanger. Preferably, the fuel powered boiler includes a thermostat to control the temperature to which 10 the thermal medium is heated. The plant according to any one of the above claims, wherein the plant includes a controller for controlling pumps adapted to selectively circulate thermal medium through the solar thermal collector and the fuel powered boiler. 15 Preferably, the controller is coupled to one or more sensors for sensing at least one of the following items: a) thermal medium temperature in the solar thermal collector; b) presence and amount of available solar radiation; 20 c) thermal medium temperature at a solar thermal collector inlet; d) thermal medium temperature at a solar thermal collector outlet; e) thermal medium temperature at the point of entry of the solar thermal collector to a heat scavenger or heat exchanger; f) thermal medium temperature at a point of entry to any part or component; 25 g) thermal medium temperature at a point of exit to any part or component; h) thermal medium temperature at point of entry to the fuel powered boiler or to a refrigerant heat exchanger or a heat scavenger; i) thermal medium temperature at a heat exchanger pump; j) that the burner is consuming fuel; 30 k) quantity of fuel contained in the fuel container; I) temperature of refrigerant vapour entering the organic rankine cycle turbine, and -3m) temperature of liquid refrigerant prior to vaporization within the refrigerant heat exchanger. Preferably, the controller compares signals from a plurality of sensors pursuant to 5 predetermined operating ranges and selectively controls one or more thermal medium pumps and/or fuel to power the boiler burner in accordance with results of the comparison. Preferably, the controller selectively stores the signals from one or more sensors. 10 Preferably, the controller includes an electronic processing device. Preferably, the electronic processing device includes a microprocessor, a memory, a input/output device, and an external interface. 15 Preferably, the solar thermal collector includes an array of or a plurality of connected solar thermal collectors. Preferably, the generator for generating electricity from a rotating shaft of the organic rankine cycle turbine is a dynamo or an alternator. 20 Preferably, there is a condenser and an expansion chamber for condensing refrigerant vapour from the organic rankine cycle turbine. Preferably, there are refrigerant pipes for transporting refrigerant vapour from the heat 25 exchanger to the organic rankine cycle turbine, then to a condenser and an expansion chamber, and then to another heat exchanger via a shell heat scavenger. Preferably, there is a fuel container and fuel transfer means to supply the burner of the fuel powered boiler with fuel 30 Preferably, there is a frame for supporting parts and components of the plant. -4- In another aspect the invention resides in electricity generated by the plant as described above. In yet another aspect the invention resides in an electrical tool, implement, device or apparatus using electricity generated by the plant as described above. 5 - 5- BRIEF DESCRIPTION OF THE DRAWINGS In order for the invention to be better understood reference will now be made to the accompanying drawings, wherein: 5 Figure 1 is a schematic diagram of an example of a hybridized-solar thermal power plant; Figures 2A to 2C are schematic perspective, cut-away, top and bottom views of an example of a cylindrical type of heat scavenger; 10 Figures 3A to 3C are schematic perspective, cut-away and end views of an example of a plate condenser type of heat scavenger; Figure 4 is a schematic diagram of an example of a control system for a hybridized-solar thermal 15 power plant, and Figure 5 is a schematic diagram of a specific example hybridized-solar thermal power plant. 20 - 6- DETAILED DESCRIPTION OF THE DRAWINGS An example hybridized-solar thermal power plant will now be described initially with reference to Figure 1. The hybridized-solar thermal power generating plant includes at least one solar thermal 5 collector array 100. The solar thermal collector array is composed of a number of commercially available solar thermal panels; an example of a commercially available solar thermal panel is the SRB solar thermal collector UHV available from SRB in Switzerland. The number of solar thermal panels in the solar thermal collector will depend on the geographical and climatic condition of the installation, and the amount of electricity required to be produced. Commercially available 10 solar thermal panels contain either a single or an array of tubes containing thermal medium being at least partially heated by solar radiation transmitted through the optically transparent portion of the solar thermal panel. A cylindrical heat scavenger 103 is provided for capturing energy (heat) from fuel powered boiler bound thermal medium and transferring it to solar thermal collector bound thermal medium, reducing the amount of energy (heat) required to be 15 absorbed by the thermal medium circulating within the solar thermal collector. A fuel powered boiler 105; any commercially available vertical in-shot boiler, is provided for the generation and maintenance of thermal medium at a temperature suitable for the production of refrigerant vapour. A fuel container for the storage of combustible material for consumption of the fuel powered boiler's burner. A plate condenser type of heat scavenger 114 is provided for capturing 20 energy (heat) from heat exchanger bound thermal medium and transferring it to fuel powered boiler bound thermal medium, reducing the amount of energy (heat) required to be absorbed by the thermal medium maintained within the fuel powered boiler. A heat exchanger 116, which produces refrigerant vapour by transferring energy (heat) from the thermal medium to the liquid refrigerant. An organic rankine cycle turbine 119 coupled to a generator for generating 25 electricity from the refrigerant vapour. A shell heat scavenger 121 is provided for capturing energy (heat) from the commercially available condenser and expansion chamber bound expelled refrigerant vapour from the organic rankine circuit turbine, and transferring it to heat exchanger bound liquid refrigerant, reducing the amount of energy (heat) required to be absorbed by the liquid refrigerant, reducing the energy (heat) needed to convert it to a 30 refrigerant vapour and a commercially available condenser and expansion chamber 122 for -7producing refrigerant condensate from the expended refrigerant vapour from the organic rankine cycle turbine. This provides a straightforward system for generating electrical power, allowing electricity to be generated at a low cost under a wide range of different ambient conditions. In particular, by 5 using both a solar thermal collector array and a fuel powered boiler, the thermal medium can be maintained at a temperature conducive to producing refrigerant vapour, at a much lower level of fuel consumption, and by providing a mechanism whereby the temperature can be maintained during periods of low or no sunlight. in this regard, the preferred commercially available solar thermal panel should consist of a 10 absorber surface coating of Black-Chromium ensuring high absorptive in the visible spectrum and low emissivity in the infrared spectrum, vacuum sealed into a single flat panel component, mounted above a compound cylindrical mirror. An example of a commercially available solar thermal panel is the ultra high vacuum solarflat collector produced by SRB energy in Switzerland. 15 The ultra high vacuum solar flat collector concentrates the heat of the sun onto aninternal arrangement of pipes. The Black-Chromium coating reduces back radiation and directs the heat inwards. As the temperature increases the inner most layer of the metal coating becomes increasingly hot and radiates this heat to the internal arrangement of pipes. However, in addition to this, further heating is achieved by heating of thermal medium in the 20 fuel-powered boiler. The plant typically includes thermal medium transport pipes 101, 104, 111, 110, 112, 113, and 115, two heat scavenger 103 and 114, and two thermal medium pumps 102 and 117 for circulating thermal medium through the at least one array of solar thermal collectors 100 and the fuel powered boiler 105, thereby heating the thermal medium and transferring the heated 25 thermal medium to the heat exchanger 116. At least one refrigerant vapour pipe 118 is used for transferring refrigerant vapour from the heat exchanger 116 to the organic rankine cycle turbine 119, with a commercially available condenser and expansion chamber 122 being provided for condensing refrigerant vapour from -8the organic rankine cycle turbine 119 and at least one liquid refrigerant pipe 123 and a vane pump 124 for returning refrigerant to the heat exchanger 116 via the shell heat scavenger 121. In one particular example, the hybridized-solar thermal power plant includes of the solar thermal collector array 100, fuel powered boiler 105, two thermal medium pumps 102 and 117, 5 two heat scavengers 103 and 114, heat exchanger 116, organic rankine cycle turbine and electricity generator 119, as described above. In addition a commercially available condenser and expansion chamber 122, thermal medium, refrigerant, thermal medium transport pipes 101, 104, 111, 110, 112, 113, and 115, liquid and vapour refrigerant pipes 118, 120, 123,125, and 126, and a vane pump 124 are also provided. 10 In use, the solar thermal collector array 100 is connected via the thermal medium transport pipes 101,111, 104 and 110, to a thermal medium pump 102, a heat scavenger 103 allowing a thermal medium, such as a thermal oil, to be circulated through the solar thermal collector array 100 and the fuel powered boiler 105 under control of the thermal medium pump 102. The fuel powered boiler 105 is connected via thermal medium pipes 112, 113, and 115 to a thermal 15 medium pump 117, a heat scavenger 114 allowing a thermal medium, such as thermal oil, to be circulated through the fuel powered boiler 105 and the heat exchanger 116. The heat exchanger 116, is connected via the liquid and vapour refrigerant pipes 118, 129, 123, 125, and 126 to the organic rankine cycle turbine 119, the commercially available condenser and expansion chamber 122, the vane pump 124, and via the shell heat scavenger 121 allowing the refrigerant to be 20 circulated through the heat exchanger 116, organic rankine cycle turbine 117, commercially available condenser and expansion chamber 122, vane pump 124 and shell expansion chamber 121. The organic rankine cycle turbine 117 is coupled to a generator, via an optional gearbox (not shown), or magnetic coupling (not shown) depending on generator type selected, allowing electricity to be generated. 25 In one example, each component can be modular in order to allow ease of replacement and to add additional components as and when required. Examples of the components will now be described in more detail. The solar thermal collector array 100 typically includes of four to six ultra high vacuum solar flat collectors with attendant compound cylindrical mirrors and their associated plumbing. The solar -9thermal collection arrays' purpose is to collect heat and transfer it to the thermal medium contained in the ultra high vacuum solar flat collectors. The number of ultra high vacuum solar flat collectors with attendant compound cylindrical mirrors used will vary dependent on the installation and may depend on parameters such as the environment, and in particular the 5 available solar radiation, the amount of electricity to be generated, or the like. In one example, the thermal medium is a class C1 (Combustible Liquid) low viscosity mineral oil, such as transformer oil (BSI Caltex product code 1692), or Shell heat transfer oil s2 (product code: 001d8388). It will be appreciated that other thermal mediums, such as water or the like, could be used. However, the use of mineral oils is particularly beneficial as these typically have 10 a high specific heat capacity, allowing a large amount of heat to be transferred. Additionally, such oils typically have a high boiling point, around 900 degrees C. allowing the thermal medium to remain unpressurised within the solar thermal collector array 100 and the fuel powered boiler 105, without the risk of the thermal medium evaporating. The thermal medium is contained within the plumbing of the solar thermal collector array 100, 15 the containment vessel of the fuel powered boiler 105 and the thermal medium transport pipes 101, 104, 111, 110, 112, 113, and 115. Thermal medium is circulated using a suitable thermal pump 102, 114, such as an oil pump. The speed of the thermal medium pump 102, 114 can be controlled by an electronic controller, as will be described in more detail below, thereby allowing the flow rate of the thermal medium to be adjusted. The thermal mediums' purpose is 20 to transfer heat from the solar thermal collector array to the fuel powered boiler 105, allowing the production and maintenance of thermal medium at a temperature conducive to the production of refrigerants vapour in the heat exchanger 116, allowing refrigerant vapour to be generated for driving the organic rankine cycle turbine 117: In use, alteration of the flow rate of the thermal medium can be used to control the amount of heat energy transferred to the heat 25 exchanger 116, and hence the amount of refrigerant vapour and hence electricity generated. The thermal medium transport pipes 101, 104, 111, 110, 112, 113, and 115 can include 25.4mm to 50.8 mm diameter copper pipes. The thermal medium transport pipes' purpose is to act as a conduit for the thermal medium. - 10- The organic rankine cycle turbine 117 can be any organic rankine cycle turbine generator and typically includes the organic rankine cycle turbine, an optional gear box or magnetic coupling, generator, and electrical control panels. The organic rankine cycle turbines' purpose is the production of mechanical power to drive the generator for the generation of electricity. 5 The commercially available condenser and expansion chamber 122, typically includes an evaporative or convection condenser and expansion chamber with a connection from the exhaust refrigerant vapour pipe organic rankine cycle turbine, and a liquid refrigerant pipe 123, vane pump 124 and shell heat scavenger 121 connected to the heat exchanger 116. The purpose of the commercially available condenser and expansion chamber is to capture exhaust 10 refrigerant vapour, liquefy it and feed it back into the heat exchanger. The fittings for the thermal medium transport pipes and refrigerant pipes can be any suitable 25.4 mm and 50.8 mm flare compression fittings or similar. Depending on the expected power output the environmental and geographical characteristics of the site the hybridized-solar thermal power system can have 4 or more groupings of solar 15 thermal collector arrays i.e. 4 x solar thermal collector arrays, 6 x solar thermal collector arrays, 8 x solar thermal collector array ... etc. It will be appreciated however that any suitable configuration used, depending on the preferred implementation, and a more detailed example will be described in more detail below. In use, operation of the system is typically controlled using a controller that controls at least the 20 two thermal medium pumps 102 and 117, and the vane pump 124 to thereby selectively circulate thermal medium through the solar thermal array 100, the fuel powered boiler 105 and heat exchanger 116, and to circulate refrigerant through the heat exchanger 116, organic rankine cycle turbine 119, the commercially available condenser and expansion chamber 122, and the shell heat scavenger 121. An example controller will now be described with reference 25 to Figure 4. In this example the controller 400 is in the form of an electronic processing device typically including a microprocessor 401, a memory 402 and optional input/output device 403, such as a keypad and display, and an external interface 404 interconnected by a bus 405. In use the external interface 404 is used to connect the controller 400 to a number of sensors. - 11 - The sensors include at least one solar thermal collector array internal temperature sensor 406, for sensing internal thermal medium temperature, a solar thermal collector array inlet temperature sensor 408 for sensing thermal medium temperature at a solar thermal collector array inlet point, a solar thermal collector array outlet temperature sensor 409 for sensing 5 thermal medium temperature at a solar thermal collector array outlet point, and a photometer sensor 407 for sensing the amount of ambient sunlight available. A thermal medium pump temperature sensor 410 and 419 may be provided for sensing a heat transfer medium temperature at the heat transfer medium pumps 102 and 117. Sensors include a heat scavenger thermal medium inlet point sensor 410 on the solar thermal 10 collector array 100 side for sensing the thermal medium temperature as it passes into the heat scavenger 102 from the solar thermal array 100, a heat scavenger thermal medium outlet point sensor 412 on the solar thermal collector array 100 side for sensing the thermal medium temperature as it passes out of the heat scavenger 102 to the solar thermal array 100, a heat scavenger thermal medium inlet point sensor 417 on the heat exchanger 116 side for sensing 15 the thermal medium temperature as it passes into the heat scavenger 114 from the fuel powered boiler 105, a heat scavenger thermal medium outlet point sensor 418 on the heat exchanger 116 side for sensing the thermal medium temperature as it passes out of the heat scavenger 114 to the fuel powered boiler 105. Sensors include a thermal medium inlet point temperature sensor 413 on the solar thermal 20 collector array side of fuel powered boiler 105 for sensing the thermal medium temperature as it enters the fuel powered boiler, a thermal medium outlet point temperature sensor 414 on the solar thermal collector array side of the fuel powered boiler 105 for sensing the thermal medium temperature as it transits towards the heat scavenger 102, a thermal medium inlet point temperature sensor 415 on the heat exchanger 116 side of fuel powered boiler 105 for sensing 25 the thermal medium temperature as it enters the fuel powered boiler, a thermal medium outlet point temperature sensor 416 on the heat exchanger 116 side of the fuel powered boiler 105 for sensing the thermal medium temperature as it transits towards the heat scavenger 102, and a fuel consumption sensor 420 on the fuel powered boiler burner 107 for sensing the operation of the fuel powered boiler burner 107. - 12- A fuel quantity sensor 421 can be included on the fuel storage container 109 to sense the volume of fuel available for burning, a turbine inlet temperature sensor 422 can be included on the organic rankine cycle turbine 119 inlet point for sensing the temperature of the refrigerant vapour entering the organic rankine cycle turbine, and a heat exchanger inlet point temperature 5 sensor 423 can be included on the heat exchanger 116 for sensing the temperature of liquid refrigerant as it enters the heat exchanger. The controller 400 is also adapted to provide control signals to the thermal medium pumps 102 and 117, as well as the fuel powered boiler burner 107, allowing the flow of thermal medium and the consumption of fuel to be controlled. 10 In use the controller 400 is adapted to receive signals from the sensors, interpret the signals to determine the current operating parameters of the hybridized-solar thermal plant and then control operation of the thermal medium pumps 102 and 117 and, fuel powered boiler burner 107, accordingly. In particular, the controller 400 can compare signals from at least one sensor to desired operating range and selectively controls the thermal medium pumps and fuel 15 powered boiler burner in accordance with results of the comparison. For example, the controller can selectively control the thermal medium pumps in accordance with signals from a solar thermal collector array internal temperature sensor, and selectively control the fuel powered boiler burners' fuel consumption for adjusting the thermal mediums temperature within the fuel powered boiler. 20 To achieve this, the microprocessor 401 typically executes instructions stored in the memory 402, for example as applications software. It will be appreciated from this that the controller 400 can be any form of electronic processing device such as a microprocessor, microchip processor, logic gate configuration, firmware optionally associated with implementing logic such as an FPGA field programmable gate array, or any other electronic device, system or 25 arrangement, and that the example of Figure 4 is for the purpose of illustration only. Operation of the controller 400 to control the hybridized-solar thermal system will now be described. -13- Typically, the start-up process for the hybridized-solar thermal system is completely automated and will only commence when the parameters required for operation of the solar thermal collector array 100, the fuel powered boiler 105 and organic rankine cycle turbine 119 are met. In particular, the controller 400 uses signals from the temperature sensors 406, 408 and 409 5 associated with solar thermal collector array to determine an air temperature averaged across all solar thermal collectors. When the temperature reaches a predetermined temperature threshold stored in memory 402, which is sufficient to heat the fuel powered boiler105, the controller 400 activates the thermal medium pumps102 and 117, and the fuel powered boiler burner 107. This causes thermal medium to be circulated through the solar thermal collector 10 arrays 100 and fuel powered boiler 105, the burning of fuel in the fuel powered boiler burner 107, thereby heating the thermal medium in the fuel powered boiler 105. Following activation of the thermal medium pumps 102 and 117, the fuel powered boiler burner 107, thermal medium will be heated and thereby cause the temperature in the fuel powered boiler to increase to a preset level controlled by a thermostat 106, thereby producing thermal 15 medium at a temperature conducive for the production of refrigerant vapour, which is supplied to the heat exchanger 116. The controller 400, also uses signals from the photometer 407 to determine the level of solar radiation available for use by the solar thermal collector arrays. Should the solar radiation not fulfil the preset minimum value maintained in the controller memory 402, then the controller 20 can stop the thermal medium pump which transfers thermal medium from the solar thermal collector array to the fuel powered boiler, thus isolating the solar thermal arrays, and increase the rate of fuel consumption in the fuel powered boiler burner 107. This can therefore be used to maintain required operating parameters even if the temperature within the solar thermal collector array alters, for example depending on the amount of ambient sunlight 25 The controller 400 will typically control the thermal medium pumps 102 and 117, and the fuel powered boilers burner 107 depending on whether the parameters fall within normal operating ranges. For example, if the thermal medium temperature and/or pressure rise above safe limits, the thermal medium pumps 102 and 117 can be deactivated or reduced in speed, and fuel powered boiler burner can have its fuel supply reduced to stopped to reduce the transfer of - 14 heat to the fuel powered boiler, thereby allowing the temperature and/or pressure to fall back within normal limits. The controller 400 can also control a shut-down process, which is implemented when the parameters required for non-operation or un-safe operation of the solar thermal collector arrays 5 100, fuel powered boiler 105 or organic rankine cycle turbine 119 are met. This can be determined by comparing signals from any of the sensors to desired operating ranges, for example stored in the memory 402, and selectively controls the thermal medium pumps and the fuel powered boiler burner in accordance with results of the comparison. For example, if signals from the sensors indicate any temperatures or pressures are outside the defined operating 10 ranges, the controller 400 can stop operation of the plant by stopping the thermal medium pumps and fuel powered boiler burner. Thus, if the temperature averaged across all solar thermal collector array sensors 406, 408 and 409 drops below a predetermined average temperature, the controller deactivates the thermal medium pump 102. This stops circulation of the thermal medium to the fuel powered boiler 15 and allows the fuel powered boiler to cool. Similarly, if the thermal medium temperature and pressure within the fuel powered boiler or fall below or above predetermined limits, then the controller similarly deactivates the fuel powered boiler burner 107 or increases the fuel consumption rate dependent on the conditions detected. In either case, when the thermal medium pumps are deactivated, and the fuel powered boiler 20 burner is extinguished the heat exchanger will stop converting liquid refrigerant into refrigerant vapour and feeding it to the organic rankine cycle turbine, causing the organic rankine cycle turbine coupled generator to stop generating electricity. In use, information from each of the sensors 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, and 423 can be stored, for example in memory 402, or in an 25 external store, allowing operation of the system to be reviewed. This information can be stored with a unique code designating the equipment item type and its unique identifier, the date information was gathered and the number start/stop time of the operating cycle in which it was operating, allowing operation of the system to be subsequently analysed and any problems diagnosed. - 15 - Typically the hybridized-solar thermal system needs to be taken off line and the systems shut down, so that the thermal medium level, refrigerant level and condition can be examined, and topped up or replaced. During this process, the organic rankine cycle turbine condition can be ascertained and any remedial action taken if required, and the condition of the fuel powered 5 boiler and its ancillary equipment determined. A specific example of a particular hybridized-solar thermal plant will now be described with reference to Figure 5. In this example, like reference numerals are used to refer to the components described above. In this example, the plant 500 includes an array of four solar thermal collectors 100, connected 10 via thermal medium pipes 501, 502, 503, and 504, to the fuel powered boiler 105 with a thermal medium pump 102 being used to circulate thermal medium through the heat scavenger 200 to the fuel powered boiler 105. The fuel powered boiler 105 is coupled to a heat exchanger by thermal medium pipes 506, 507, 508 and 509 with a thermal medium pump 117 being used to circulate the thermal medium through the heat scavenger 300 to the heat exchanger 116. 15 The heat exchanger 116 is connected to the organic rankine cycle turbine 119 by the refrigerant vapour pipe 511. The organic rankine cycle turbine is connected to the commercially available condenser and expansion chamber 122 via the shell heat scavenger 121 by the refrigerant vapour pipe 514. The commercially available condenser and expansion chamber connects to the heat exchanger, via the shell heat scavenger 121, by refrigerant pipes 513 and 512, the vane 20 pump 124 is used to circulate the refrigerant. In use, the hybridized-solar thermal power plant 500 can be used in a modular fashion, with each module 500 including the components shown in Figure 5. The modules 500 can be mounted on respective frames, to provide a fully self-contained compact unit capable of operating away from fixed infrastructure sites. The size and weight of 25 each module 500 means that it can be mounted on an off-road trailer or the back of a four wheel drive. The modules 500 are also air portable, and can be flown as a slung load under a helicopter or in the cargo bay of a fixed wing transport aircraft. - 16- In use, each module 500 can generate between 10kW and 30kW of electricity, depending on ambient conditions, and the number of solar thermal collector arrays used, the size and power of the fuel powered boiler and the generating capacity of the organic rankine cycle turbine. By combining a number of modules 500 larger power generation capabilities can be achieved. For 5 example, an array of four hundred and twenty 30 kW modules can generate 12.6 MW for 24 hour use. When forming an array, the modules 500 may be provided in a triangular arrangement so as to reduce shadows from adjacent modules. The solar thermal collector arrays 100 can also be provided orientated towards the sun, and may optionally be provided on a tracking platform, 10 allowing the solar thermal collector arrays to face towards the sun and maximise the solar radiation incident on the solar thermal collectors. However, it will be appreciated that this is not essential and static arrangements can be used. In one example, each module 500 is interconnected by a medium voltage power collection system and a communications network. The medium voltage power collection system then 15 terminates at an electricity substation, where medium-voltage electrical current can be increased in voltage via a step-up transformer for connection to the high voltage transmission system. Even when provided as an interconnected array, each module 500 can operate independently of its neighbours, allowing it to be brought on line and off line without affecting the performance 20 of the array as a whole. The array described above, including the transmission cables and electricity substation covers an acre of land. This compares favourably with traditional solar thermal power plants, which require 40 acres for a similar sized facility, (Sierra Sun Tower, in California). It will be appreciated however that the arrangement can be scaled to any size, and for any 25 power generating requirements. For example, a 40 MW combined array would extend over a 3.2-acre block of land, whilst a traditional solar thermal power station generating the equivalent amount of electricity would require 247 acres (Alvarado 1 facility in Spain). Despite this, economies of scale mean the power plant could be manufactured for up to 60% less than a -17traditional solar thermal power plant (based on internationally averaged manufacture costs per watt). Additionally, unlike traditional solar thermal power plants combined arrays and are not limited to flat ground, allowing individual modules to be arranged on any terrain type that allows the 5 module 500 to face the sun. This includes mountainous, industrial, semi-urban and urban environments. Additionally modules 500 do not need to be adjacent to other modules 500 in order to form an array, for example if used in built up areas or regions having severe land use restrictions. Accordingly, this allows the above described arrangement to allow a solar thermal power plant 10 with sufficient generating capacity to be established in areas where traditional solar thermal power plants cannot. Despite this, the modules 500 can also be used separately, for example for domestic purposes, allowing heat boxes to be roof mounted or provided in other suitable locations. Again, the solar thermal collector arrays 100 can also be provided orientated towards the sun, and may 15 optionally be provided on a tracking platform. It will be appreciated that the above described arrangement can be used to provide a scalable solar thermal power plant capable of generating electricity. The system utilises solar thermal collector arrays, thermal medium pipes used to transport a thermal medium, such as thermal oil, to a fuel powered boiler via a heat scavenger, thence to a heat exchanger by another heat 20 scavenger. The heat exchanger then generates refrigerant vapour from the liquid refrigerant using the energy (heat) provided by the thermal medium in the heat exchanger. The generated refrigerant vapour can then be used to generate electricity, for example using an organic rankine cycle turbine. Furthermore, by increasing the number of solar thermal collectors in an array and/or the type of solar thermal collectors, and the size and efficiency of the fuel powered 25 boiler burner the amount of heat energy available to heat the thermal medium can be increased, thereby increasing the refrigerant vapour generating capacity of the heat exchanger, and hence the amount of electricity produced. It will therefore be appreciated that this allows the capacity of the system to be adjusted to suit a wide range of applications. - 18- The traditional arrangement for solar thermal power generation is to have a large field of reflectors focusing sunlight upon either tubes containing water or a boiler, which then uses the heat to produce steam and drive a turbine generator. The traditional arrangement is good for large-scale applications such as a town, but is not easily scalable and cannot be transported. In 5 contrast to this, the above described system provides a scalable and transportable solar thermal power system, which can be used in a traditional field array arrangement capable of powering a small town, domestically as a single unit providing electricity to a family, or as a transportable unit to provide electricity to remote sites for mining, construction and other activities. This allows a scalable and portable solar thermal electricity generating system to be deployed 10 using commercial off the shelf components, and can provide enough electricity and capacity to power various domestic, industrial and urban installations. Accordingly, a scalable hybridized-solar thermal power system can be constructed which uses solar thermal collector arrays and a fuel burner as the heat source. The scalable hybridized-solar thermal power system can be a single unit construction with all components making up an 15 integral package, which can be moved as a single unit. The scalable hybridized-solar thermal power system can be scaled up by simply connecting additional scalable hybridized-solar thermal power systems up to a single distribution system to meet any power demands for any facility or urban area, or operated individually for small-scale electricity requirements. The scalable hybridized-solar thermal power system can be mounted on a trailer or flat bed vehicles 20 and operated in remote locations or areas where electricity supply has been disrupted. The scalable hybridized-solar thermal power system does not need to be permanently fixed in a single geographical location in order to function. The scalable hybridized-solar thermal power system can be assembled using a mixture of commercially available solar thermal collectors and a organic rankine cycle turbine generator, 25 two bespoke heat scavengers two commercially available heat shell type heat exchangers, one being used as a shell heat scavenger, and a vertical fuel powered boiler. Typically the solar thermal collector array and fuel powered boiler burner can generate sufficient heat and can transfer that heat to a thermal medium, which can deliver sufficient heat to a heat exchanger to produce refrigerant vapour to drive a organic rankine cycle turbine generator. -19- The design of the scalable hybridized-solar thermal power system can be modular to allow the installation of additional solar thermal collector arrays or there removal, larger or smaller fuel powered boilers and larger or smaller organic rankine cycle turbine generators depending on need of the installation. There is no set design for the assembly frame, and the arrangement 5 can depend on the geographic, environmental and power requirements of each installation. Accordingly, this allows the hybridized-solar thermal plant to be configured for small or large scale applications and to be either installed in a permanent location or configured for mobile use. It is to be appreciated that reference to "one example" or "an example" of the invention is not 10 made in an exclusive sense. Accordingly, one example may exemplify certain aspects of the invention, whilst other aspects are exemplified in a different example. These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention in any way unless the context clearly indicates otherwise. Features that are common to the art are not explained in any detail as they are deemed to be 15 easily understood by the skilled person. Similarly, throughout this specification, the term "comprising" and its grammatical equivalents shall be taken to have an inclusive meaning, unless the context of use clearly indicates otherwise. Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the 20 art should be considered to fall within the spirit and scope of the invention broadly appearing and described in more detail herein. The examples presented within this document are intended to give an impression of the components and overall structure of the invention. Some installations, as a result of climate or geographic conditions may result in a modification of the number of components or a 25 modification of the arrangement of components. The purpose of the examples is to illustrate the key components in an ideal arrangement for climatic conditions likely to be found in South East Queensland. - 20 - The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this 5 specification relates. - 21 - VARIATIONS It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be 5 apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth. In the specification the terms "comprising" and "containing" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a 10 stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the terms "comprising" and "containing" such as "comprise", "comprises", "contain" and "contains". 15 - 22 -

Claims (23)

1. A hybridized-solar thermal electricity plant including: a) at least one solar thermal collector containing a thermal medium, the thermal medium 5 adapted to be partially heated by solar radiation; b) a fuel powered boiler for heating the thermal medium to a temperature to convert liquid refrigerant to refrigerant vapour in a heat exchanger; c) one or more heat scavengers for pre-heating the thermal medium prior to entering the solar thermal collector and the fuel powered boiler respectively; 10 d) an organic rankine cycle turbine driven by the refrigerant vapour, and e) a generator connected to the turbine to generate electricity.

2. The plant according to claim 1, wherein the plant includes transport pipes and pumps for circulating thermal medium through the at least one solar thermal collector, heat scavenger 15 and fuel powered boiler.

3. The plant according to claim 1 or claim 2, wherein the temperature of the thermal medium converts liquid refrigerant into refrigerant vapour in the heat exchanger which is transferred by a refrigerant vapour pipe to the turbine. 20

4. The plant according to any one of the above claims, wherein the plant includes a condenser and an expansion chamber for condensing refrigerant vapour from the organic rankine cycle turbine and a heat scavenger to pre heat liquid refrigerant before transferring it to the heat exchanger for conversion to refrigerant vapour. 25

5. The plant according to any one of the above claims, wherein the fuel powered boiler includes a thermal medium heating vessel having: a) a first inlet for receiving thermal medium from the solar thermal collector; b) a second inlet for receiving thermal medium from the heat exchanger; 30 c) a first outlet for returning thermal medium to the solar thermal collector, and d) a second outlet for transferring thermal medium to the heat exchanger. - 23 -

6. The plant according to any of the above claims, wherein the fuel powered boiler includes a burner attached to a fuel storage container.

7. The plant according to any one of the above claims, wherein the fuel powered boiler 5 burner maintains thermal medium at a temperature conducive to the production of refrigerant vapour in a heat exchanger.

8. The plant according to any of the above claims, wherein the fuel powered boiler includes a thermostat to control the temperature to which the thermal medium is heated. 10

9. The plant according to any one of the above claims, wherein the plant includes a controller for controlling pumps adapted to selectively circulate thermal medium through the solar thermal collector and the fuel powered boiler. 15

10. The plant according to claim 9, wherein the controller is coupled to one or more sensors for sensing at least one of the following items: a) thermal medium temperature in the solar thermal collector; b) presence and amount of available solar radiation; c) thermal medium temperature at a solar thermal collector inlet; 20 d) thermal medium temperature at a solar thermal collector outlet; e) thermal medium temperature at the point of entry of the solar thermal collector to a heat scavenger or heat exchanger; f) thermal medium temperature at a point of entry to any part or component; g) thermal medium temperature at a point of exit to any part or component; 25 h) thermal medium temperature at point of entry to the fuel powered boiler or to a refrigerant heat exchanger or a heat scavenger; i) thermal medium temperature at a heat exchanger pump; j) that the burner is consuming fuel; k) quantity of fuel contained in the fuel container; 30 I) temperature of refrigerant vapour entering the organic rankine cycle turbine, and m) temperature of liquid refrigerant prior to vaporization within the refrigerant heat exchanger. -24-

11. The plant according to claim 10, wherein the controller compares signals from a plurality of sensors pursuant to predetermined operating ranges and selectively controls one or more thermal medium pumps and/or fuel to power the boiler burner in accordance with results of the comparison. 5

12. The plant according to claim 11, wherein the controller selectively stores the signals from one or more sensors.

13. The plant according to claim 12, wherein the controller includes an electronic processing 10 device.

14. The plant according to claim 13, wherein the electronic processing device includes a microprocessor, a memory, a input/output device, and an external interface.

15 15. The plant of any of the above claims wherein the solar thermal collector includes an array of or a plurality of connected solar thermal collectors.

16. The plant of any of the above claims wherein the generator for generating electricity from a rotating shaft of the organic rankine cycle turbine is a dynamo or an alternator. 20

17. The plant of any of the above claims wherein there is a condenser and an expansion chamber for condensing refrigerant vapour from the organic rankine cycle turbine.

18. The plant of any of the above claims wherein there are refrigerant pipes for transporting 25 refrigerant vapour from the heat exchanger to the organic rankine cycle turbine, then to a condenser and an expansion chamber, and then to another heat exchanger via a shell heat scavenger.

19. The plant of any of the above claims wherein there is a fuel container and fuel transfer 30 means to supply the burner of the fuel powered boiler with fuel - 25 -

20. The plant of any of the above claims wherein there is a frame for supporting parts and components of the plant. 5

21. The plant of any of the above claims wherein the entire plant can be mounted on an off-road trailer or the back of a four-wheel drive vehicle.

22. Electricity generated by the plant as claimed in any one of the above claims. 10

23. An electrical tool, implement, device or apparatus using electricity generated by the plant as claimed in any one of the above claims. 15 - 26 -