SELF SUSTAINING ENERGY SYSTEM FOR A BUILDING

Abstract

A self sustaining energy system for a building is provided part of which is typically driven by geothermal energy. The energy system typically uses a ground source heat pump for heating and cooling the building airspace and an organic Rankine cycle drive for producing electricity. A solar powered heating system may also serve as a heat source for providing domestic hot water and supplemental airspace heating.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This applications claims priority from U.S. Provisional Patent Application Ser. No. 61/416,603, filed Nov. 23, 2010; the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention relates generally to a total self sufficient energy system typically including a heating and cooling system. More particularly, the present invention relates to a self sustaining system for heating and cooling a building, providing hot water for the building and generating electricity for the building electrical system. Specifically, the invention relates to such a system which utilizes solar energy, an organic Rankine cycle which is driven by geothermal energy, and a ground source heat pump.

[0004] 2. Background Information

[0005] The heating and cooling of buildings in a manner which provides a desirable work environment increases productivity and job satisfaction while reducing absenteeism. However, the heating and cooling of buildings represents a substantial consumption of energy, with some estimates indicating about 40% of global energy consumption. Thus, there is always a need for improving the energy efficiency of such heating and cooling systems. Furthermore, there are various energy regulations and standards in various countries mandating specific goals. For example, the European Union Building Performance Directive requires net-zero energy by 2019 for all new buildings, and carbon neutrality by 2019 for all new commercial buildings. By way of further example, new and renovated buildings in the United States must achieve 55% fossil fuel reduction targets in 2010 and be carbon neutral by 2030. Future federal legislation may apply additional requirements in the United States. Meanwhile, various state and local governments have already passed pertinent regulations, such as in New York and California. Thus, there is a need in the art to improve the efficiency of heating and cooling systems for buildings both in order to minimize electric energy costs and to meet various regulations. The present invention addresses this need.

BRIEF SUMMARY OF THE INVENTION

[0006] The present invention provides an energy system comprising a heat pump comprising a first earth-coupled heat exchanger; an electric motor operatively connected to the heat pump; an organic Rankine cycle drive; a second earth-coupled heat exchanger which provides a geothermal heat source for the organic Rankine cycle drive; and an electric generator driven by the organic Rankine cycle drive and in electrical communication with the motor.

[0007] The present invention also provides a method comprising the steps of operating an electric motor to circulate a working fluid in a heat pump which comprises a first earth-coupled heat exchanger; providing a geothermal heat source for an organic Rankine cycle drive with a second earth-coupled heat exchanger; driving an electric generator with the organic Rankine cycle drive to produce electricity; and using the electricity to power operation of the electric motor.

[0008] The present invention further provides an energy system comprising a first earth-coupled heat exchanger configured to absorb heat energy from soil; and a second earth-coupled heat exchanger configured to release heat energy to the soil to prevent the soil from freezing as a result of the heat energy absorbed by the first heat exchanger.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims.

[0010] FIG. 1 is a diagrammatic view of the energy system of the present invention.

[0011] FIG. 2 is a diagrammatic view similar to FIG. 1 in which the energy system of the present invention uses an alternate heat pump configuration.

[0012] Similar numbers refer to similar parts throughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The self sustaining energy system of the present invention is shown generally at 10 in FIG. 1 with an alternate embodiment shown generally at 10A in FIG. 2. System 10 is configured to provide energy to a building 12 which defines an enclosed building airspace 14. Airspace 14 may be divided into multiple compartments such as rooms or units which are part of a recirculation loop of air provided by ducts in between these respective rooms. System 10 includes an airspace heating and cooling system in the form of a ground source heat pump (GHP) 16A configured for heating and cooling airspace 14. System 10 further includes a solar-powered heating system 18 which is in part configured to provide domestic hot water (DHW) to building 12. System 10 further includes an electricity generation system 20 configured to provide electrical energy needed to building 12. Each of systems 16, 18 and 20 utilizes an earth-coupled heat exchanger as described further below. Building 12 is built on top of the ground, earth or soil 22 and may be positioned above an aquifer 24 typically far below an upper surface 26 of the ground or soil 22. Various components of systems 10, 10A may be above ground or underground and may include above-ground portions and underground portions, respectively above and below surface 26. Although these portions may not be specified herein elsewhere, such terminology is applicable to these various components or portions, as will be evident from the Figures. To take advantage of ground source heat or geothermal heat, one or more boreholes such as boreholes 28A and 28B are typically bored into the earth extending downwardly from upper surface 26 either directly beneath building 12 or adjacent building 12. It will also be appreciated that the portion of upper surface 26 which is directly below building 12 may be substantially lower than that portion which extends outwardly from building 12, such as when building 12 includes a basement and/or underground parking deck.

[0014] The airspace heating and cooling system or GHP 16A includes an earth-coupled heat exchanger 30A which extends downwardly within borehole 28A below surface 26 and is in the exemplary embodiment directly below building 12. Heat exchanger 30 is part of a tubular closed recirculation loop through which is circulated a working fluid for moving heat energy to and from soil 22 and a water cooled condenser 32 of GHP 16A. The working fluid may be a water-antifreeze solution (such as a water-glycol solution), brine or other water based solution or any other suitable working fluid. GHP 16A further includes a separate closed recirculation loop which includes condenser 32, an air cooled condenser 34, and in which a turbo compressor 36 may be disposed such that turbo compressor 36 is operatively connected to and driven by an electric motor 38. Condenser 34 includes an air intake and air exhaust each in fluid communication with airspace 14 to allow for air to flow through condenser 14 and for air recirculation within airspace 14 as indicated at arrows A.

[0015] Solar-powered heating system 18 includes thermal solar collectors 40 which are exposed to sunlight during the day and are typically located on the roof of the building. System 18 further includes or is interconnected with a domestic hot water (DHW) system 42 which includes a pump 44, a hot water tank 46 and appropriate piping or water pipes 48 which provide recirculation loops in combination with pump 44 and tank 46 and also lead to the various water taps (which may include or feed showers, hot tubs, whirlpool baths or Jacuzzis, swimming pools, etc.) within or otherwise adjacent building 12. Water pipes 48 also include an underground pipe or earth-coupled heat exchanger 50 which extends below surface 26 within soil 22 and borehole 28B. A thermal storage tank 51 is also provided and typically has thermally insulated walls defining an interior chamber 53 with a phase change material (PCM) 55 therein. Tank 51 is shown as an underground tank although tank 51 may also be above ground. Water pipes 48 extend into tank 51 and thus include a loop or heat exchanger 57 which is within interior chamber 53 and is in direct contact with and surrounded by PCM 55. PCM 55 changes phase by melting or solidifying typically at a melting or freezing phase change temperature in the range of about 80° F. to 300° F. While material 55 may be a good heat absorbing material able to absorb or release a substantial amount of heat energy even without changing phase, it is preferably a phase change material so that the latent heat of fusion provides substantial thermal storage during the phase change. In one embodiment, PCM 55 may be a paraffin, paraffin wax or black wax paraffin although other suitable materials may be used.

[0016] Electricity generation system 20 includes an organic Rankine cycle (ORC) drive 52 configured to drive the generation of electricity. ORC drive 52 includes a ground-coupled heat exchanger 54 which is part of a tubular closed recirculation loop which circulates an appropriate working fluid and which serves as a heat sink. A portion of the recirculation loop which serves as heat exchanger 54 is, like the other earth-coupled heat exchangers, underground and is shown here in borehole 28A, although it may be in a separate borehole. Heat exchanger loop 54 may extend into aquifer 24 whereby aquifer 24 and/or soil 22 serves as the heat source for ORC drive 52. Pump 56 is also provided to pump the working fluid through the recirculation loop including the heat exchanger 54. This recirculation loop also passes through a heat exchanger 58, which is part of ORC drive 52. ORC drive 52 may be a relatively simple organic Rankine cycle drive or may be a more complex one. FIG. 1 illustrates ORC drive 52 as a relatively simple organic Rankine cycle which includes the closed recirculation loop for recycling the refrigerant or refrigerant mixture to pass through heat exchanger 58, to drive rotation of a turbine 60, which is within the closed loop and drivingly coupled to generator 62, and through a condenser 64 and a pump 66. In the exemplary embodiment, this recirculation loop includes a ground loop 30C which extends downwardly within another borehole 28C and which is another earth-coupled heat exchanger which serves as heat exchanger 64. Various refrigerants or refrigerant mixtures known in the art may be used within this recirculation loop. In the exemplary embodiment, the preferred refrigerant mixtures are those described in U.S. patent application Ser. No. 12/406,187 of the present inventor entitled Power Generator Using an Organic Rankine Cycle Drive With Refrigerant Mixtures and Low Waste Heat Exhaust As a Heat Source, which has also published as U.S. Patent Application Publication No. 2010/0126172, which is incorporated herein by reference for all purposes. Simple and more complex organic Rankine cycle drives are described in greater detail in the above noted Patent Application Publication (2010/0126172), and may be used in the present invention. Generator 62 is in electrical communication with the building electrical system 68, which is represented diagrammatically and which typically includes electrical outlets throughout the building which are available to electrically power various electrical appliances and other electrical machinery within or adjacent building 12.

[0017] FIG. 1 further illustrates that heat exchangers 30A and 30C extend downwardly below upper surface 26 by a depth D1 which is typically in the range of about 5 to 10 feet. At a depth of about 6 feet, the ground temperature is usually on the order of about 45° F. to 48° F. although this may vary somewhat. FIG. 1 also illustrates that heat exchanger 50 extends downwardly into soil 22 a depth D2 which is typically roughly the same as depth D1 although this may vary somewhat. Heat exchanger 54 extends much deeper into the ground as indicated by depth D3, which is typically on the order of 1500 to 2000 feet and is usually at least 500 or 1000 feet.

[0018] Referring now to FIG. 2, system 10A is fairly similar to system 10 except that system 10A uses a modified ground source heat pump 16B instead of heat pump 16A. Heat pump 16B utilizes a direct exchange (DX) ground loop or earth-coupled heat exchanger 30B which is part of the heat pump's refrigerant loop buried underground. Thus, the working fluid within the loop (which is the same as described above for heat pump 16A) flows through a single recirculation loop including heat exchanger 30B and air cooled condenser 34. As with heat pump 16A, electric motor 38 is drivingly connected or coupled to compressor 36 to power or drive rotation of compressor 36, which pumps the working fluid through the recirculation loop in which compressor 36 is disposed.

[0019] The operation of systems 10 and 10A is now described starting with reference to FIG. 1. Generally, working fluid is circulated by a suitable pump through the recirculation loop which includes heat exchanger 30A and condenser or heat exchanger 32. Meanwhile, working fluid is also circulated through the recirculation loop which includes condenser or heat exchanger 32 and condenser or heat exchanger 34. At the same time, air is blown with appropriate fans or blowers through heat exchanger 34 via its intake and exhaust to circulate through the recirculation loop or loops within airspace 14 as shown at arrows A. In the heating mode of heat pump 16A, working fluid passing through heat exchanger 30A absorbs heat from soil 22 and any water within soil 22 and carries it to heat exchanger 32 whereby the heat energy is released via heat exchanger 32 to the working fluid within the other recirculation loop, which circulates to condenser or heat exchanger 34 to likewise release heat energy to the air circulating at arrows A in order to heat the air within airspace 14. As previously noted, rotation of turbo compressor 36, which pumps the working fluid for circulation within the latter recirculation loop, is driven by the rotational drive of motor 38, which is powered by electricity which may be supplied or fed from electrical system 68. Motor 38 is typically in electrical communication with generator 62 via electrical system 62. Thus, heat pump 16 may be powered by electricity produced by the ORC drive via turbine 60 and generator 62, which is operatively connected to and driven by the ORC drive. In the air cooling mode, heat pump 16A is operated so that the working fluid within exchanger 30A rejects heat into the ground which is delivered there via the working fluid from exchanger 32. Thus, the working fluid within this recirculation loop absorbs heat within heat exchanger 32 from the working fluid circulating in the other recirculation loop which includes the exchanger 34. Recirculation of air (arrows A) through heat exchanger 34 thus involves a transfer or rejection of heat from the air to the working fluid within condenser 34 so that the air is cooled. Heat from air within the building is ultimately transferred and rejected to the soil 22 via the heat exchanger 30A. This process thus cools the air being exhausted from heat exchanger 34 in order to cool the air within building 12 while also rejecting heat to soil 22 and water therein to prevent freezing of this soil and water, such as may result from transfer of heat energy from soil 22 to the working fluid in heat exchangers 30C and 54 and thus to ORC drive 52.

[0020] Turning to FIG. 2, heat pump 16B provides the similar overall result of heating or cooling air within airspace 14 and either rejecting heat to or releasing heat from soil 22 via heat exchanger 30B. The direct exchange arrangement of heat pump 16B utilizes a single closed loop instead of the two separate closed loops of heat exchanger 16A. Thus, in the air heating mode, the working fluid within heat exchanger 30B absorbs heat from soil 22 and releases heat to the circulating air at exchanger 34 to heat the air within building 12. In the cooling mode, the working fluid within this recirculation loop rejects heat to the ground or soil 22 via exchanger 30B and absorbs heat from the circulating air in airspace 14 at exchanger 34 in order to cool the air circulating through exchanger 34 and into airspace 14. Rejection of heat to the ground via exchanger 30B may also prevent freezing of soil 22 as noted above.

[0021] It is further noted that outside air may be mixed with the inside air within airspace 14. More particularly, heat pumps 16A, 16B may include a desuperheater which may be used to heat outside air which is mixed with the inside air typically for the purpose of dehumidification. The desuperheater may also be used to heat water and thus produce hot water, which would typically be the case if hot water otherwise runs out.

[0022] The operation of solar-powered heating system 18 is now described with reference to either FIG. 1 or FIG. 2. The solar collectors 40 absorb heat energy from sunlight (represented by the arrows adjacent collectors 40) and reject the heat therefrom to potable water flowing through pipes 48 in order to heat the water so that hot water subsequently flows through pipes 48 into hot water tank 46. The heated water within system 42 remains at a temperature below the boiling point of water and thus remains in a liquid state. In the embodiment shown, pump 44 pumps water from tank 46 and/or various portions of pipes 48 into the heat exchanger of solar collectors 40. It is noted that a thermosyphon arrangement may also be provided in which the water storage tank 46 is higher than thermal collector 40 whereby the need for pump 44 is eliminated. In addition to providing potable water to the various taps of building 12, hot water is also circulated through the heat exchanger 50 whereby heat is rejected from the water within exchanger 50 to soil 22 adjacent exchanger 50. It is noted that boreholes 28A and 28B may be backfilled with soil or other material so that the pipes or tubes are in direct contact with the soil and water within the soil. The purpose for providing heat exchanger 50 is to prevent the ground or soil from freezing as a result of heat which is rejected from the soil primarily via heat exchanger 30A or 30B during operation of the respective heat pump 16 in the air heating mode and also via heat exchanger 54.

[0023] Hot water also flows through pipes 48 into thermal storage tank 51 where heat is rejected from the solar heated water to PCM 55 via the heat exchanger 57 loop of pipes 48. Generally, thermal storage tank 51 is used for heat storage during the day and heat discharge during the night to ensure full 24/7 supply of domestic hot water to building 12. More particularly, heat energy rejected from the hot water to PCM 55 is stored in PCM 55, which is insulated against heat loss by the thermal insulation in the walls of tank 51. Subsequently, when there is a need to heat water within system 42 which has dropped below a predetermined threshold temperature and when solar heating of the water directly via the heat exchanger of thermal solar collectors 40 is no longer possible or is not sufficient (such as at night time or during certain weather conditions), the heat energy stored in PCM 55 is rejected to water in heat exchanger 57 to heat the undesirably cooled water to a chosen desired temperature sufficiently above the threshold temperature to be suitable for use as domestic hot water.

[0024] Typically, the heat rejected from hot water to PCM 55 via heat exchanger 57 will cause all or part of PCM 55 to change phase by melting, thereby storing a relatively large amount of heat energy as latent heat of fusion, although as previously noted, material 55 may nonetheless store a substantial amount of heat energy even without melting. Later, when the water below the threshold temperature absorbs heat from PCM 55 when circulated through heat exchanger 57, all or part of PCM 55 typically changes phase from liquid to solid, thus again providing a substantial amount of heat energy via latent heat of fusion although heat energy may likewise be transferred from PCM 55 at temperatures both above and below its melting or freezing temperature.

[0025] Although the Figures show that water in pipes 48 is circulated through heat exchanger 57, other fluids or liquids may be used to circulate in a similar or separate recirculation loop passing through the heat exchanger of thermal solar collectors 40 to absorb heat therefrom and through a heat exchanger analogous to heat exchanger 57 within thermal storage tank 51 to likewise release heat to PCM 55 for storage thereof. Then, relatively cooler water may be circulated through heat exchanger 57 to absorb heat from PCM 55 to heat the water to a temperature suitable for use as domestic hot water in building 12. The use of certain fluids or coolants other than water in such a separate recirculation loop may be useful at various temperatures, and certainly would be appropriate at relatively higher temperatures which would cause water to boil. Such other liquids or coolants may thus also be used to transfer heat from the solar powered heating system to the ground via heat exchanger 50.

[0026] Although solar powered heating system 18 is described here primarily as being used to supply heat for the domestic hot water system, it may also be used as a supplemental heat source for heating airspace 14. Thus, system 18 may include a solar-heated heat exchanger with suitable ducting and a fan to blow air across the heat exchanger whereby system 18 rejects heat via the heat exchanger to the air so that the heated air may be circulated within airspace 14.

[0027] The operation of electricity generation system 20 is now described. Pump 56 is operated to circulate the working fluid within the closed loop which includes earth-coupled heat exchanger 54 in order to absorb heat from soil 22 and/or aquifer 24 typically at the depths noted with respect to depth D3 as well as all along the borehole to provide a geothermal heat source for the ORC drive 52. The working fluid flows within heat exchanger 58 and rejects heat to the refrigerant within the other closed recirculation loop, which is circulated therethrough via pump 66. As described in greater detail in the above noted patent application publication, the working fluid within this closed loop drives the rotation of turbine 60, which in turn drives the rotation of generator 62 to produce electrical energy or electricity, whereby an electric current runs from generator 62 to the building electrical system 68 such that the electrical current is available to power electrically powered devices within or adjacent building 12. Heat energy in the working fluid in the loop of ORC drive 52 which includes turbine 60 is rejected to the ground via heat exchanger 30C, thereby cooling the working fluid and also preventing or helping prevent freezing of a portion of the ground which may otherwise occur as a result of heat energy being rejected from this portion of the ground via heat exchangers 54 and/or 30A or 30B.

[0028] It is further noted that energy systems 10 and 10A may include a branching recirculation loop configured to transfer heat energy from aquifer 24 and/or the soil along borehole 28A via heat exchanger 54 to PCM 55 within thermal storage tank 51. More particularly, such a branching recirculation would be connected to and branch off from the loop which includes heat exchanger 54 and extend into interior chamber 53 to serve as a heat exchanger similar to heat exchanger 57 except that the working fluid used in this branching recirculation loop would be the same as that circulating through heat exchangers 54 and 58. This option may, for instance, be useful when there is no demand or a decreased demand on ORC drive 52 to produce electricity.

[0029] Thus, systems 10 and 10A provide a self sustaining configuration for providing various energy to building 12. More particularly, each of these systems provide the air heating and cooling system or heat pump, a solar-powered domestic hot water system, and an ORC-driven electrical generation system, each of which is coupled to the earth or soil to either reject heat energy to the earth or soil or absorb heat energy therefrom. Energy systems 10 and 10A are highly efficient and thus substantially reduce operating costs.

[0030] In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.

[0031] Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.

Claims

1. An energy system comprising: a heat pump comprising a first earth-coupled heat exchanger; an electric motor operatively connected to the heat pump; an organic Rankine cycle drive; a second earth-coupled heat exchanger which provides a geothermal heat source for the organic Rankine cycle drive; and an electric generator driven by the organic Rankine cycle drive and in electrical communication with the motor.

2. The energy system of claim 1 further comprising a building defining an airspace; an air intake of the heat pump in fluid communication with the airspace; and an air exhaust of the heat pump in fluid communication with the airspace.

3. The energy system of claim 1 further comprising a compressor of the heat pump; wherein the electric motor is operatively connected to the compressor.

4. The energy system of claim 1 wherein the organic Rankine cycle drive comprises a third earth-coupled heat exchanger configured to reject heat to the ground.

5. The energy system of claim 1 further comprising a third earth-coupled heat exchanger configured to release heat energy to the ground to prevent the ground from freezing as a result of the heat energy absorbed from the ground by at least one of the first and second earth-coupled heat exchangers.

6. The energy system of claim 5 further comprising a solar powered heating system coupled to the third earth-coupled heat exchanger whereby the solar powered heating system is configured to reject heat to the third earth-coupled heat exchanger.

7. The energy system of claim 6 further comprising a domestic hot water system coupled to the solar powered heating system whereby the solar powered heating system is configured to reject heat to water in the domestic hot water system.

8. The energy system of claim 7 further comprising a thermal storage tank; a phase change material within the tank; and a portion of the domestic hot water system which extends adjacent the tank whereby the water within the domestic hot water system is configured to reject heat to and melt the phase change material.

9. The energy system of claim 5 further comprising a thermal storage tank; a phase change material within the tank; a recirculation loop in fluid communication with the third earth-coupled heat exchanger; a fluid within the recirculation loop; and a portion of the recirculation loop which extends adjacent the tank whereby the fluid within the recirculation loop is configured to reject heat to and melt the phase change material.

10. The energy system of claim 5 wherein the organic Rankine cycle drive comprises a fourth earth-coupled heat exchanger configured to release heat energy to the ground.

11. The energy system of claim 1 further comprising a domestic hot water system comprising an underground pipe configured to release heat energy to the ground to prevent the ground from freezing as a result of the heat energy absorbed from the ground by at least one of the first and second earth-coupled heat exchangers.

12. The energy system of claim 11 further comprising a solar powered heating system coupled to the domestic hot water system whereby the solar powered heating system is configured to reject heat to the domestic hot water system.

13. The energy system of claim 1 wherein the second earth-coupled heat exchanger extends into an aquifer.

14. The energy system of claim 1 wherein the second earth-coupled heat exchanger extends into the ground to a depth of at least 500 feet.

15. The energy system of claim 1 further comprising a first borehole formed in earth beneath a building; wherein one of the first and second earth-coupled heat exchangers is within the first borehole.

16. The energy system of claim 1 wherein the organic Rankine cycle drive comprises a third earth-coupled heat exchanger configured to release heat energy to the ground.

17. A method comprising the steps of: operating an electric motor to circulate a working fluid in a heat pump which comprises a first earth-coupled heat exchanger; providing a geothermal heat source for an organic Rankine cycle drive with a second earth-coupled heat exchanger; driving an electric generator with the organic Rankine cycle drive to produce electricity; and using the electricity to power operation of the electric motor.

18. The method of claim 17 further comprising cooling a portion of the ground by releasing heat from the portion of the ground to at least one of the first and second earth-coupled heat exchangers; heating a third earth-coupled heat exchanger with a solar powered heating system; and rejecting heat from the third earth-coupled heat exchanger to the cooled portion of the ground.

19. The method of claim 17 further comprising rejecting heat from the organic Rankine cycle drive to the ground with a third earth-coupled heat exchanger.

20. An energy system comprising: a first earth-coupled heat exchanger configured to absorb heat energy from soil; and a second earth-coupled heat exchanger configured to release heat energy to the soil to prevent the soil from freezing as a result of the heat energy absorbed by the first heat exchanger.

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