GB2573107A

GB2573107A - Refrigerant-based power generation

Info

Publication number: GB2573107A
Application number: GB1806577.1A
Authority: GB
Inventors: Gora Pawel
Original assignee: Gora Invent Ltd
Current assignee: Gora Invent Ltd
Priority date: 2018-04-23
Filing date: 2018-04-23
Publication date: 2019-10-30
Anticipated expiration: 2038-04-23
Also published as: GB201806577D0; GB2573107B

Abstract

An apparatus for a refrigerant-based power generation system comprises an evaporator unit 6, a condenser unit 12, a turbine 20, and a generator 22 which is possibly hydro-electric. The turbine, evaporator and condenser unit are in fluid communication and contain refrigerant such that they allow refrigerant to travel cyclically around the system. The turbine is mechanically coupled to the generator. The evaporator unit, turbine and condenser unit are arranged so that, in use, the refrigerant is dropped onto the turbine using the force of gravity to drive the generator for the production of electricity. The system may comprises a control valve 19 and a level transmitter 17, which may measure the refrigerant level in a receiver unit 16. The valve may be controlled based on the volume of refrigerant detected by the transmitter. A plurality of evaporators and turbines may be connected to a single condenser. The heat absorbed by the evaporator may be industrial waste heat, geothermal energy from mines (fig. 4), or heat from atmospheric air (fig. 3). A compressor (15, fig. 4) is not needed with this system but may be used.

Description

REFRIGERANT-BASED POWER GENERATION

This invention relates to refrigerant-based power generation.

Background of the Invention

The majority of heat generated by todays modern manufacturing industries is inadvertently lost and wasted during the manufacturing process. For the generation of power by modern day steam cycle plants, such as coal and nuclear power plants, there remains a massive typical loss of about two thirds of the available energy of the fuel source due to the intrinsic limitations of converting heat into mechanical energy.

Many types of manufacturing industries using vast amounts of heat during their manufacturing processes are showing similar levels of heat wastage with the glass and ironworks industries wasting around one third of the heat generated during their respective production processes. This wasted heat is generally discharged directly into the atmosphere and calculated as loss associated with production. Heat wastage can also be seen during the cooling down process of manufactured products further adding to the calculated loss.

For the mining industry, ventilating and cooling the underground infrastructure of a mine may consume up to a third of the energy used up by the mine; this ventilation process only encompasses the removal of heat from the virgin rock found deep within the mine and subsequently discharging it into the atmosphere. The waste heat generated from these industrial processes is not only a massive loss of potential useful energy but also contributes to the negative effects seen by today’s varying climate, which is a result of both C02 and heat pollution.

The present invention aims to overcome or at least ameliorate one or more of the problems set out above.

Summary of the Invention

In particular, the present invention relates to apparatus for a refrigerant based power generation system which can absorb low temperature heat to generate electricity by combining the principles of refrigerant based heat absorption with that of hydro-electric power generation; the present invention provides a system suitable for absorbing the wasted heat produced by various industrial processes and converting it into electricity, and mainly comprises an evaporator, condenser, turbine and generator units.

The present invention not only aids in allowing industrial processes that discharge heat to become more efficient, but also contributes to reducing the amount of heat pollution introduced into the atmosphere, by both society and the environment, therefore helping to reduce the negative effects of climate change which contribute to global warming.

In a first aspect of the invention, there is provided apparatus for the conversion of waste industrial heat into electricity, whereby the apparatus comprises a combination of refrigerant based heat absorption with hydro-electric power generation. The first aspect of the invention utilises artificial structures to elevate the condenser unit to achieve the required head height.

In a second aspect of the invention, there is provided apparatus for the conversion of waste industrial heat into electricity, whereby the apparatus comprises a combination of refrigerant based heat absorption with hydro-electric power generation. The second aspect of the invention utilises artificial structures to both elevate the condenser unit and lower the evaporator unit to achieve the required head height.

In a third aspect of the invention, there is provided apparatus for the conversion of atmospheric heat into electricity, whereby the apparatus comprises a combination of refrigerant based heat absorption with hydro-electric power generation. The third aspect of the invention utilises natural structures to both elevate the condenser unit and lower the evaporator unit to achieve the required head height.

In a fourth aspect of the invention, there is provided apparatus for the conversion of virgin rock heat into electricity, whereby the apparatus comprises a combination of refrigerant based heat absorption with hydro-electric power generation. The fourth aspect of the invention utilises multiple evaporator, turbine and generator units, whereby the evaporator units are embedded into the virgin rock infrastructure of an underground mine to absorb the heat discharged by the virgin rock.

Brief Description of the Drawings

Embodiments of the invention will now be described by way of example, with reference to the drawings in which:-

Figure 1 is a schematic view of the refrigerant based power generation system using artificial structures for elevation;

Figure 2 is a schematic view of the refrigerant based power generation system using artificial structures for both elevation and lowering;

Figure 3 is a schematic view of the refrigerant based power generation system using natural structures for both elevation and lowering;

Figure 4 is a schematic view of the refrigerant based power generation system using multiple evaporator, turbine and generator units;

Figure 5 is a pressure enthalpy diagram for a refrigerant based power generation system without a compressor; and

Figure 6 is a pressure enthalpy diagram for a refrigerant based power generation system with a compressor.

Detailed Description

With reference to Figure 1, apparatus for a refrigerant-based power generation system comprises an evaporator unit 6, condenser unit 12, turbine 20 and generator 22 which are used to absorb atmospheric heat, from a heat source 2, and generate electricity.

The refrigerant-based power generation system is a hybridisation of a refrigerant loop and a hydro-electric generator. A conventional refrigerant loop utilises liquid refrigerant, within an evaporator unit, to absorb surrounding heat. Absorption of the surrounding heat causes the refrigerant to evaporate, expand and travel towards a condenser unit. The refrigerant is cooled down, within the condenser unit, and condenses back into liquid form where it travels back into the evaporator unit and the cycle repeats again.

For a conventional hydro-electric generator, potential kinetic energy is stored in water by elevating the water above a turbine which is coupled to a generator. The elevated water is then dropped onto the turbine which, due to the mass flow rate of the water and its differential pressure with respect to the turbine, causes the turbine to turn and therefore, the generator to generate electricity.

The evaporator unit 6 sits at a low altitude close to the heat source 2. The support tower 13 is used to considerably elevate the condenser unit 12 above the evaporator unit 6 allowing a large differential, or ‘head’, pressure to exist in the refrigerant residing within the condenser unit 12. The output 7 of the evaporator unit 6 is connected to the input 10 of the condenser unit 12 via the insulated pipe 8 whereby, the output of the condenser unit 12 is connected to the receiver unit 16 via the liquid pipe 14.

Heat from the heat source 2 is presented to the evaporator unit 6 as a heat input 4. Cool liquidised refrigerant, contained within the evaporator unit 6, absorbs the heat presented to the evaporator unit 6 by the heat input 4. The cool liquid refrigerant begins to heat up, as more of the heat input 4 is absorbed, and subsequently beings to boil whereby, the refrigerant changes state from a liquid into a vapour. The now vaporised refrigerant exits the evaporator unit 6, via the evaporator unit output 7, into the insulated pipe 8 and is auto-compressed by the vapours of the refrigerant in the insulated pipe 8. As the vaporised refrigerant expands, it travels up the insulated pipe 8 and into the condenser unit 12 via the condenser unit input 10. During this transition, from the evaporator unit 6 to the condenser unit 12, the vaporised refrigerant’s temperature and pressure is slightly reduced but the vapor remains saturated; the insulated pipe 8 helps to reduce these effects by insulating the refrigerant from external temperatures and pressures.

On entering the condenser unit 12, the vaporised refrigerant begins to cool down; the refrigerant continues to cool down, within the condenser unit 12, until it finally condenses, becoming liquidised refrigerant again. The now cool, liquidised refrigerant exits the condenser unit 12 and travels into the receiver unit 16 via the liquid pipe 14. The receiver unit 16 is a sufficiently large vessel which is able to hold all of the refrigerant in the refrigerant-based power generation system during periods of system maintenance. Here, when the system needs to be switched off, to replace parts of the system and or fix existing parts, the system can be drained of refrigerant by using the receiver unit 16 as a storage vessel; this unit 16 may hold excess refrigerant to both account for potential leaks in the system and to prevent refrigerant shortages assuring a stable flow of refrigerant through the system.

When the vaporised refrigerant condenses back into a liquid, within the condenser unit 12, its associated pressure head significantly increases whereby, pressure head describes the pressure of a liquid as a result of the liquid being above a geodetic datum. Therefore, the pressure head of the refrigerant corresponds to the height of the fluid column in which it is travelling which, in this case, is the height of the receiver unit 16 relative to the turbine 20. This increased pressure head of the now liquid refrigerant is because liquid refrigerant is a few hundred times heavier than when in it is in a vaporised state; the liquid refrigerant remains saturated when exiting the condenser unit 12 but becomes sub-cooled as it moves towards the turbine 20 due to the increase in pressure and constant temperature.

The level transmitter 17 is used to measure the level of refrigerant stored in the receiver unit 16 to allow the availability of the refrigerant for the turbine 20 to be measured, a similar level transmitter is used for the evaporator unit 6 but is not shown whereby, this level transmitter is coupled to a controller. The controller is then coupled to the control valve 19 such that a signal may be transmitted to the controller by the level transmitter when the refrigerant in the evaporator unit 6 becomes sufficiently low, due to the refrigerant being continually boiled. On receiving a signal from the level transmitter, the controller then transmits a signal to the control valve 19 to open to allow the refrigerant stored in the receiver unit 16 to freely flow through it. In this way, the level transmitter and control valve 19 are able to control the flow of refrigerant to the turbine 20, and therefore, to the evaporator unit 6.

With the control valve 19 open, the liquidised refrigerant stored in the receiver unit 16 is now released, by the control valve 19, onto the turbine 20 via the turbine liquid feed pipe 12. The head pressure and mass flow of the liquid refrigerant causes the turbine 20 to turn, driving the generator 22. On entry into the turbine 20, if the pressure of the liquid refrigerant is lower than its intrinsic critical pressure, the refrigerant running through the turbine 20 behaves as a liquid; if the pressure of the liquid refrigerant is higher than its intrinsic critical pressure, the refrigerant now achieves a super critical state whereby, distinct liquid and gas phases do not exist. The refrigerant now effuses through the turbine 20 expanding in volume; here, the refrigerant behaves similarly to that of supercritical steam used in conventional power generation. This phenomenon may improve power generation efficiency and may be important for the selection of an appropriate turbine, refrigerant and condenser elevation.

The refrigerant reduces in pressure as it makes contact with and passes over the turbine 20; excess energy, in the form of heat, is transferred from the refrigerant to the turbine 20 causing the refrigerant to further become increasingly sub-cooled. As the turbine 20 is turned, the generator 22 begins to generate electricity converting the kinetic energy of the refrigerant to electrical energy. The sub-cooled refrigerant exits the turbine 20 and re-enters the evaporator unit 6 via the evaporator input pipe 24 where it is ready to absorb heat from the heat input 4, which replaces the energy previously lost from the refrigerant to the turbine, ready to begin the cycle again.

The mass flow of the refrigerant is driven by the expansion of the vaporised refrigerant in the evaporator unit 6, the decompression of the vaporised refrigerant as it travels up to the condenser unit 12 via the insulated pipe 8, and its subsequent contraction, at the condenser unit 12, which is caused by the temperature difference between the evaporator unit 6 and condenser unit 12. As the system only needs to overcome heat transfer resistance this temperature difference, required for the operation of the refrigerant-based power generation system, therefore is not required to be substantial. Heat transfer resistance is generated by the material of the evaporator unit 6 separating the heat source and the refrigerant, and the material of the condenser unit 12 separating the refrigerant and the external environment; this heat transfer resistance, together with the mass flow rate of the refrigerant, affect the heat transfer ability of the system.

For the refrigerant-based power generation system to generate electricity, the heat source 2 must be able to fulfil the energy demand of the system. Therefore, the system requires a large volume of heat input, rather than a high differential temperature, to be absorbed by a large heat exchange surface to induce the required mass flow of refrigerant. This may be achieved by a large evaporator surface area to allow higher volumes of heat transfer to occur from a heat source 2 to the evaporator unit 6 and therefore, to the refrigerant. Additionally, the refrigerant-based power generation system requires a high liquid column, such as the turbine liquid feed pipe 8, to ensure high pressure liquid refrigerant enters the turbine 20 whereby, the high liquid column may be achieved by an artificial and or natural means.

The refrigerant-based power generation system uses the force of gravity to drop the refrigerant onto the turbine 20 to drive the generator 22 to produce electricity. Refrigerant circulation throughout the system is ensured by utilising the heat input 4 to vaporise the refrigerant, within the evaporator unit 6, whereby the refrigerant is then able to overcome the force of gravity as it subsequently travels up the insulated pipe 8 and into the condenser unit 12.

Advantageously, the refrigerant-based power generation system does not require the use of a compressor to ensure mass flow of the refrigerant unless there is a desire to shift the temperature of the refrigerant to a higher temperature. Here, a compressor may be used to provide additional cooling, heating, of the refrigerant, or both; using a compressor with the refrigerant-based power generation system would reduce the amount of electricity generated as the compressor requires electrical energy to function.

By introducing the refrigerant-based power generation system with industries, such as manufacturing industries, that inadvertently generate unwanted waste heat during the various industrial processes pertaining to that industry, manufacturing processes in particular, this unwanted, wasted heat, which is often disposed of to the atmosphere, can be used to generate power. Therefore, not only can the efficiency of existing power plants be increased, by implementing the refrigerant-based power generation system in the manner described above, but the power demand of such power plants and industrial systems can also be reduced.

The refrigerant-based power generation system can be coupled with existing industry infrastructure, to allow power generation, by placing the system in-between the wasted, excess heat source and cooling tower; the system may replace the cooling tower entirely. The excessive wasted heat from that particular industrial infrastructure process may be channelled, as a heat input 2, to the proximate, low level evaporator unit 6; whereby the heat input 2 would vaporise the refrigerant contained within the evaporator unit 6; whereby the vaporised refrigerant would condense in the elevated condenser unit 12; and whereby the condensed liquid refrigerant would be gravitationally fed to the turbine 20 to drive the generator 22 to subsequently generate electricity. The elevation required for the condenser unit 12 may be achieved by way of an artificial structure 13 purposely built for the condenser unit to be elevated to the required elevation or this elevation may be achieved by way of a natural elevation used as a platform for the condenser unit 12 to reside.

With reference to Figure 2, in another embodiment, the refrigerant-based power generation system now utilises a ground recess 3 to house the evaporator unit 6, turbine 20 and generator 22. Advantageously, a large differential head pressure between the evaporator unit 6 and condenser unit 12 may be achieved without the need to either find a suitably high natural elevation or construct a suitably high artificial elevation as a platform for the condenser unit 12 to be suitably elevated above the evaporator unit 6. This embodiment offers greater flexibility where no such suitable natural elevations can be found, or the construction of an artificial structure proves to be excessively expensive and or challenging. The ground recess 3 may also be of an artificial or natural construct.

With reference to Figure 3, in another embodiment, the refrigerant-based power generation system can be used to generate power directly from atmospheric heat with this atmospheric heat now acting as the heat input 4. The refrigerant-based power generation system can achieve heat transfer and generate electricity with a differential temperature, with respect to the evaporator unit 6 and condenser unit 12, as little as a few °C. With air temperature dropping between 6°C to 9°C for every thousand meters climbed in altitude, this temperature difference may be achieved with an elevation of a few hundred meters using either a natural structure, artificial structure or both.

To allow the system to function in low ambient temperatures, a different refrigerant may be selected for use with the system that would be able to operate within the desired low ambient temperature range. With such a refrigerant being used with the system, for temperatures below 0°C, if the air temperature at the evaporator unit 6 is below 0°C, the moisture in the air would freeze before reaching the evaporator unit 6 allowing the refrigerant in the system to operate without water being introduced into the system, and subsequently freezing. In this way, different refrigerants may be used with the refrigerant-based power generation system for different applications and climate zones; as the system relies on a temperature differential to operate, a change in weather would affect the ambient temperature at both the lower and higher altitudes of the system causing the required temperature differential to remain substantially the same. This would allow the system to function independent of weather changes to the ambient environment.

Advantageously, in this embodiment, the refrigerant-based power generation system can be applied anywhere over the world, independent of weather, time of the day or seasonal restrictions to provide cheap, renewable energy at minimal running costs, provided there is a suitable elevation, natural or artificial, to achieve a sufficient differential temperature between the evaporator unit 6 and condenser unit 12. The system may be combined with various types of power generation or heat sources to generate additional power. Excess heat from solar panels may be used to provide additional heat input 4 to the evaporator unit 6. The wasted heat generated by skyscraper boilers and cooling systems may be other potential uses as additional heat input 4 to the evaporator unit 6. The refrigerant-based power generation system may use the heat from warm water streams found in the ocean to generator power in polar and subpolar regions of the world. Additionally, absorbing heat directly from the atmosphere and transforming it into electricity on a wide scale across the world may contribute to reducing the negative effects of the greenhouse effect.

With reference to Figure 4, in another embodiment, the refrigerant-based power generation system can be utilised for geothermal applications in the mining industry to both provide cooling for the underground infrastructure and to generate power. Virgin rocks in mines have a high intrinsic temperature, especially for substantially deep mines 1, and consequently emanate heat.

The excess heat given off by the virgin rock, in a deep mine 1, is suitable for use as a heat input 4 for the evaporator units 6 of the refrigerant-based power generation system. Here, evaporator units (6b,6c,6d) can be embedded within the mine tunnels 9 to increase the surface area of heat exchange between the evaporator units (6b,6c,6d) and the heat inputs (4b,4c,4d). In this way, the evaporator units (6b,6c,6d) remain protected from mechanical damage, from the mining traffic travelling through the mining tunnels 9, and corrosion whilst providing additional structural integrity to the mine tunnels (9a,9b). Advantageously, the evaporator units (6b,6c,6d) also provide thermal insulation for the mining tunnels (9a,9b).

Evaporator units (6b,6c,6d) embedded within mining tunnels (9a,9b) absorb heat from the outside of the mining tunnel (9a,9b) whilst keeping the inside of the mining tunnel (9a,9b) at refrigerant evaporation temperature; the units (6b,6c,6d) allow complete access of the mining tunnels (9a,9b) by onsite mining traffic, ensuring no restrictions are made to the mobility of the onsite mining traffic. An evaporator unit 6a may occupy an entire blocked off mining tunnel 9c which is filled with saturated refrigerant. In this arrangement, a substantial amount of refrigerant may be used to fill a mining tunnel 9c to provide larger subsequent outputs of generated electricity. Here, a refrigerant ‘mist’ may be sprayed onto the walls of the mining tunnel 9c to allow heat exchange between the virgin rock and saturated refrigerant to occur. These mining tunnel 9c walls may be sealed and flushed to prevent contamination and leakages.

The evaporator units 6 are all coupled to the same insulated pipe 8 which allows vaporised refrigerant, from within the evaporator units 6, to converge and travel up towards the condenser unit 12. As previously described, the condensed refrigerant is fed into the receiver 16 via the liquid pipe 14. In this embodiment, each evaporator unit 6 has its own level transmitter 17 which is coupled to a controller; not every level transmitter, or the controller, is shown by Figure 4. Each turbine 20 has its own control valve 19 which is also coupled to the controller in a similar fashion as described above. In this way, each evaporator unit 6 may demand more refrigerant flow from the receiver unit 16 independently. Consequently, the refrigerant flow to each turbine 20 is controlled via the level transmitters 17 as required.

The potential to achieve massively large pressure heads, with respect to the evaporator units 6 and condenser unit 12, is made possible due to the large distance between evaporator units 6 placed within the depths of a mine 1 and corresponding condenser unit 12 residing on the surface of the mine 1; this distance could be over one thousand meters, depending on the mine 1. In this way, relatively small volumes of refrigerant flow can generate sufficiently high kinetic energies due to the massive height of the fluid column, which in this embodiment is the turbine liquid feed pipe 18. This high kinetic energy will result in similarly high pressures being placed upon the turbines 20, driving the generators 22 to generator electricity. The kinetic resistance of the turbines 20 will function in a similar fashion to expansion devices used in conventional refrigeration systems. Here, the refrigerant pressure reduces as it passes through the turbines 20 placing a differential pressure and temperature upon the turbines 20 to restrict the flow of the refrigerant entering the evaporator units 6 from the kinetic energy stored in the pressurised liquid refrigerant to turn the turbine blades, generating mechanical power, and subsequently electricity by the generators 22.

Refrigerant vaporised in the evaporator units 6 expands rapidly and is able to travel to the condenser unit 12 without the need for compressor suction. An optional compressor 15 may be used to adjust the evaporation and or condensation temperatures and pressures of the refrigerant being used by the refrigerant-based power generation system. Use of the optional compressor 15 will reduce the amount of electrical energy being produced by the system as the compressor 15 requires power to operate. As virgin rock temperatures one thousand meters below the ground surface level often exceed 45°C, which is higher than most ambient temperatures around the world, the vaporised refrigerant will condense on the surface level without the need for the optional compressor 15.

Advantageously, the number of evaporator units 6 being used can be increased as the mine 1 beings to grow. Mining tunnels 9 that have been abandoned may be turned into additional heat exchangers, by installing evaporator units 6, to increase the generated power output of the mine 1; underground infrastructure may be used for power generation long after there is nothing left to ore and the mine 1 is abandoned.

The present invention may be used in conjunction with or to replace conventional power generation plants as the process of generating electricity by heating water to produce steam is highly inefficient. Here, instead of heating water to produce steam, the heat source may be used directly as a heat input to the refrigerant-based power generation system. Additionally, it may be possible to use geothermal energies of low temperature hot water sources as the heat input to the refrigerant-based power generation system; as only a small differential temperature, described previously, is required to generate mass refrigerant flow, underground hot water may be suitable as the heat input for this application to convert the geothermal energies of the low temperature, underground hot water into electricity.

With reference to Figure 5, on the right, the pressure enthalpy diagram for the refrigerant-based power generation system without a compressor can be seen. This diagram shows the energy changes of the refrigerant that occur throughout various stages of the system. The imaginary saturation curve, shown by Figure 5, indicates the change of state, evaporation and condensation, experienced by a given refrigerant at different temperatures and pressures for that given refrigerant. Inside the saturation curve, the refrigerant is a mixture of both saturated vapour and saturated liquid and changes state by absorbing energy to evaporate and releasing energy to condense; this saturation curve is different for each type of refrigerant. The lines to the left and outside of the saturation curve depict a liquidised refrigerant and the lines outside and to the right of the saturation curve depict a vaporised refrigerant. The area above the highest point of the saturation curve depicts when the refrigerant will be in its super critical state.

It can be seen, from Figure 5, that refrigerant flows to the evaporator unit 6 as a liquid and then heats up by absorbing energy from a heat input 2 to evaporates. As the refrigerant absorbs energy its enthalpy increases but its pressure remains the same; this is represented by the line going from right to left marked ‘Evaporator’. The refrigerant is then vaporised, losing pressure and enthalpy, and travels to the condenser unit 4 where it condenses. The refrigerant releases energy decreasing its enthalpy, shown by the line travelling from right to the left marked ‘Condenser’. As the refrigerant condenses into a liquid, it increases in pressure, shown by the line marked ‘Liquid pressure head’. As the refrigerant is dropped onto the turbine 20, shown by the marked vertical line ‘Turbine’, it rapidly decreases in pressure and enthalpy where it enters the evaporator to begin the cycle again.

The diagram on the left of Figure 5 shows a simplified system diagram showing the heat input, Qin, at the evaporator unit 6, this heat then being released in the condenser unit 4, Qout, and subsequently power being generated at the generator, W1out; it also shows the condenser elevation, h.

With reference to Figure 6, on the right, the pressure enthalpy diagram for the refrigerant-based power generation system with a compressor can be seen. This diagram shows the same energy changes of the refrigerant but now with an optional compressor 15 included.

The diagram on the left of Figure 6 shows a similar simplified system diagram but now with the optional compressor 15 included and shows the power lost using the compressor 15, W2in.

Figures 5 and 6 may be important for the designer of the refrigerant-based power generation system in designing variants of the system for specific applications to be used with different refrigerants at different temperature differentials and different pressures.

Claims

1. Apparatus for a refrigerant-based power generation system comprising an evaporator unit, condenser unit, turbine and generator, wherein the turbine, evaporator unit and condenser unit are in fluid communication to each other, and contain refrigerant such that they allow the refrigerant to travel cyclically around the system; wherein the turbine is also mechanically coupled to the generator; and wherein the evaporator unit, turbine and condenser unit are arranged so that in use, the refrigerant is dropped onto the turbine using the force of gravity to drive the generator for the production of electricity.

2. Apparatus according to claim 1, wherein the condenser unit is elevated above the evaporator unit using artificial and naturally occurring structures.

3. Apparatus according to claim 2, wherein the system further comprises a level transmitter, controller and control valve, wherein the level transmitter is arranged to be wirelessly coupled to controller; wherein the controller is further arranged to be coupled to the control valve; wherein the level transmitter is arranged to detect the volume of proximate refrigerant and transmit and signal to the controller; and wherein when in use, upon receiving the transmitted signal, the controller causes the control valve to open or close.

4. Apparatus according to claim 3, wherein a storage vessel is coupled between the condenser unit and turbine to allow the entirety of the refrigerant used by the system to be stored within the storage vessel.

5. Apparatus according to claim 4, wherein the control valve is mechanically coupled to the storage vessel and turbine to allow refrigerant flow to the turbine to be controlled by the level transmitter.

6. Apparatus according to any of the preceding claims, wherein the refrigerant within the evaporator unit is arranged to absorb heat from an ambient external heat source using the surface area of the evaporator unit as a heat exchanger.

7. Apparatus according to any of the preceding claims, wherein a compressor is coupled between the evaporator unit and condenser unit to allow the operational temperatures and pressures of the refrigerant within the evaporator unit and condenser unit to be adjusted by introducing a controllable refrigerant flow restriction.

8. Apparatus according to claim 1 for use in geothermal mining applications comprising a plurality of evaporator units which are coupled to a plurality of turbines, wherein the evaporator units are also coupled to the same condenser unit; and wherein each turbine is also mechanically coupled to a generator and coupled to the condenser unit.

9. Apparatus according to claim 8, wherein the condenser unit is elevated above the evaporator units using artificial and or naturally occurring structures.

10. Apparatus according to 9, wherein a storage vessel is coupled between the condenser unit and turbines to allow substantially, the entirety of the refrigerant used by the system to be stored within the storage vessel.

11. Apparatus according to claim 10, wherein each evaporator unit comprises a level transmitter as claimed by claim 3, wherein a plurality of level transmitters can be wirelessly coupled to a controller; wherein the controller can be further coupled to a plurality of control valves.

12. Apparatus according to claim 11, wherein each turbine comprises a control valve which is coupled between both the storage vessel and turbine and to the controller to allow the refrigerant flow to each turbine to be controlled by the level transmitters of each evaporator unit that is mechanically coupled to each corresponding turbine.

13. Apparatus according to any of claims 8 to 12, wherein the refrigerant within each evaporator unit is arranged to absorb heat from an ambient external heat source using the surface area of the evaporator units as heat exchangers.

14. Apparatus according to claim 12 or 13, wherein an evaporator unit is partially or wholly embedded within underground virgin rock.

15. Apparatus according to claim 12 or 13, wherein an underground tunnel is filled with refrigerant to allow heat absorption by an evaporator unit, directly from the surface of underground virgin rock.

16. Apparatus according to any of claims 8 to 15, wherein a compressor is mechanically coupled between the evaporator units and condenser unit to allow the operational temperatures and pressures of the refrigerant within the evaporator units and condenser unit to be adjusted by introducing a controllable refrigerant flow restriction.

17. Apparatus according to any of the preceding claims, wherein the refrigerant within the condenser unit is arranged to dissipate heat to the ambient air using the surface area of the condenser unit as a heat exchanger.

18. Apparatus according to any of the preceding claims, wherein the fluid communication of the system is achieved using insulated material to allow the refrigerant to travel cyclically around the system.