WO2011073628A1

WO2011073628A1 - A heating or cooling system and method

Info

Publication number: WO2011073628A1
Application number: PCT/GB2010/002293
Authority: WO
Inventors: Allan Robert Thomson
Original assignee: Aquamarine Power Limited
Priority date: 2009-12-17
Filing date: 2010-12-17
Publication date: 2011-06-23
Also published as: GB2476274B; GB2476274A; GB0922065D0

Abstract

A heating or cooling system comprises a heating or cooling apparatus; means for transferring fluid from a body of water to the heating or cooling apparatus to provide a heating or cooling effect; a wave power system comprising a wave energy conversion device connectable to a turbine fluid supply conduit for supplying fluid to a turbine, in operation the wave energy conversion device operating in response to wave motion to transfer fluid through the turbine fluid supply conduit to drive rotation of the turbine; and a motor for at least partially driving operation of heating or cooling apparatus and/or at least partially driving operation of the means for transferring fluid from the body of water, wherein the turbine and the motor are operably connectable to a common transmission such that in operation rotation of the turbine provides mechanical energy via the transmission to also at least partially drive operation of the heating or cooling apparatus and/or to also at least partially drive operation of the means for transferring fluid from the body of water.

Description

A heating or cooling system and method

Field of the invention The present invention relates to a heating or cooling system and method, for example a heating or cooling system or method in which heating or cooling is provided by the sea or other body of water.

Background to the invention

It is known to use sea water in heating or cooling systems. For example, sea water air conditioning (SWAC) uses available deep, cold seawater to cool water that is circulated around one or more buildings. The main components of a known seawater air conditioning system are a seawater supply system, a heat exchanger system and a fresh water distribution system. Fresh water is circulated through one side of the heat exchanger system comprising titanium (or other corrosion-resistant alloy) plates, giving up its heat to the cold seawater on the other side of the plates, and is then passed around the fresh water distribution system, where it is used to cool air in one or more buildings. The fresh water distribution system usually comprises a closed loop, in which the water is circulated around a circuit of pipes passing between the one or more buildings and the heat exchanger. In contrast, the cold seawater passes through the heat exchanger only once before being returned to the sea, for example via an effluent pipe.

The seawater is usually in the temperature range of 5-10^°C, and is taken from a suitable depth beneath the surface of the sea to have a desired temperature. Seawater air conditioning systems are particularly well suited to locations with a steep seabed slope so that the onshore cooling station is a small distance from the seawater supply.

Sea water heating systems operate on the same general principles as sea water cooling systems, for example SWAC systems. Warm (relative to the surface temperature) water is sourced from the sea and provides thermal energy to increase the temperature of the freshwater, which is then used to provide heat via the distribution system. In some existing sea water heating systems the sea water is at a temperature of around 2-6^°C and is sourced at depths of less than 50m. Vartan Ropsten, currently the largest seawater heat pump facility worldwide, sources seawater from a depth of 15m. Sea water heating/cooling systems are one of the fastest growing utility sectors and the industry is expected to receive significant attention and investment in the coming years. In Oahu building cooling is the largest component of commercial and industrial electricity usage accounting for 33.4% of such usage. In China energy consumption in buildings is expected to account for 35% of the total energy consumption by 2020, 50% of which is solely used for air conditioning. The need for air conditioning is expected to continue to grow due to:- increased reliance on computers in the workplace, which generate heat; potential increased temperatures due to climate change; longer working hours and thus increased duration of heating or cooling loads; and higher expectations from employees for better working conditions. The predicted increase in demand and the rising cost of electricity suggest that sea water air conditioning will become a popular scheme in the future. It provides a reliable, low cost heating/cooling solution, which can for example reduce isolated communities' reliance on imported energy. A small sea water air conditioning system has been developed at The Intercontinental Resort and Thalasso Spa, Bora Bora. Sea water (or lake water) heat pump facilities are already in operation in Stockholm, Cornell University, Toronto, and at the Statoil Research Centre in Trondheim, Norway. Although sea (or lake) water heating and cooling systems are seen as being environmentally friendly, they require large amounts of energy to pump water, often over large distances and from significant depths, from the sea (or lake) to the heat exchanger. The aim of the present invention is to provide an improved, or at least alternative, heating or cooling system.

Summary of the invention An independent aspect of the invention provides a heating or cooling system comprising:- a heating or cooling apparatus; means for transferring fluid from a body of water to the heating or cooling apparatus to provide a heating or cooling effect; and a wave power system that is operable to obtain power from waves of the body of water, wherein the wave power system is arranged to provide the power obtained from the waves of the body of water to drive operation of the means for transferring fluid from the body of water and/or to drive operation of the heating or cooling apparatus.

Thus, operation of a heating or cooling system in which heating or cooling is provided by a body of water can be powered in a particularly efficient manner. As the heating or cooling system is usually be close to the body of water to operate efficiently, the use of a wave power system is particularly convenient.

The wave power system may comprise a wave energy conversion device connectabie to a turbine fluid supply conduit for supplying fluid to a turbine, in operation the wave energy conversion device operating in response to wave motion to transfer fluid through the turbine fluid supply conduit to drive rotation of the turbine; and a motor for at least partially driving operation of the heating or cooling apparatus and/or at least partially driving operation of the means for transferring fluid from the body of water, wherein the turbine and the motor may be operably connectabie to a common transmission such that in operation rotation of the turbine provides mechanical energy via the transmission to also at least partially drive operation of the heating or cooling apparatus and/or to also at least partially drive operation of the means for transferring fluid from the body of water.

By providing such a system, a particularly effective way of operating a heating or cooling system can be provided in which any shortfall in power provided by the wave power system can be compensated by an externally powered motor, and vice versa. Thus, the natural variations (both intra-wave and inter-wave) of power from the wave power device can be compensated for by operation of the motor to ensure steady operation of the heating/cooling system. Furthermore, by the use of a common transmission that provides mechanical energy from the turbine and is also connected to the motor, efficiency can be increased by avoiding the need to convert the mechanical energy from the wave power device to electricity in order to drive operation of the heating/cooling system. The transmission may be or include a drive shaft. The drive shaft may be connectabie to the turbine and/or means for performing work on the heating or cooling fluid and/or means for transferring fluid from the body of water. The motor may be configured to operate as an electrical generator when the wave power system provides excess power and, when there is a shortfall in power from the wave power system, to operate as a motor to at least partially drive operation of the heating or cooling apparatus and/or to at least partially drive operation of the means for transferring fluid from the body of water. Thus, further efficiencies can be provided and the system may operate as a combined heat and power source.

The system may further comprise control means for controlling the amount of power supplied by the motor and/or the amount of power supplied by the turbine.

The control means may be configured to control the amount of power supplied by the motor and/or the amount of power supplied by the turbine to provide at least one of:- a desired torque; a desired rate of rotation; a desired pressure of the fluid or the or a heating or cooling fluid; or a desired rate of flow of the fluid or the or a heating or cooling fluid.

Each of the desired torque, the desired rate of rotation, the desired pressure and/or the desired rate of flow may be substantially constant and/or may be within a respective predetermined range.

The system may further comprise an electrical generator that is operably connectable to the wave power system to generate electricity. The electrical generator may be operably connectable to the turbine. The motor may be configured to operate as the electrical generator.

The control means may be operable to connect the wave power system to the electrical generator to generate electricity from excess energy provided by the wave power system, foe example excess rotational energy of the or a turbine.

The system may further comprise an electrical heater, wherein the electrical generator is arranged to provide electricity to power the electrical heater.

The fluid provided from the body of water may be fluid of the body of water (for example, sea water) or fluid that has been in thermal contact with the body of water. The heating or cooling apparatus may comprise a heat pump and the wave power system may be arranged to provide power to drive operation of the heat pump.

The heat pump may comprise or be operable as a reverse cycle heat pump, for example for cooling applications.

The use of a heat pump can provide for a particularly efficient way of obtaining heating or cooling from the sea or other body of water. For every unit of mechanical/electrical energy consumed by a heat pump, a multiple of this value can be returned as heat energy, and thus the efficiency of the system can be greater than 100%. In contrast, the maximum efficiency of other forms of heating or cooling (for example electrical resistance heating) can not exceed 100%, and is often considerably lower than 100%. The means for performing work on the heating or cooling fluid may comprise a compressor or a circulating pump.

The wave power system may comprise a wave energy conversion device. The wave energy conversion device may be operable to convert the energy of the motion of the waves to thermal or mechanical energy. For example, the conversion of energy performed by the wave energy conversion device may comprise using the motion of the waves to pressurise a fluid. The wave energy conversion device may be arranged to operate so that mechanical energy from the waves is used (for example without intermediate conversion to electrical energy) to pressurise the fluid, thus to force it along the fluid supply conduit. That may provide for particularly efficient and reliable operation. The wave energy conversion device may comprises a moveable member arranged to move in response to wave motion, wherein in operation the moveable member moves in response to wave motion to force fluid from the body of water along a fluid supply conduit. The moveable member may comprise a flap, for example a flap pivotably mounted on a support structure.

The turbine may comprise an impulse turbine, for example a Pelton wheel. The turbine may be arranged to supply energy to drive operation of heating or cooling apparatus and/or to drive operation of the means for transferring fluid from the body of water. The heating or cooling apparatus may comprise a heating or cooling fluid circuit for circulating heating or cooling fluid, at least one heat exchanger and a device for performing work on the heating or cooling fluid.

The performing of work on the fluid may comprise, for example, pressurising or increasing or decreasing the flow rate of the fluid.

The heating or cooling fluid circuit may be a closed circuit or an open circuit.

The means for transferring fluid from a body of water to the heat exchanger may be arranged so that in operation heat is exchanged at the at least one heat exchanger between the fluid from the body of water and the heating or cooling fluid.

The wave power system may be arranged to provide power to drive operation of the means for performing work on the heating or cooling fluid.

The means for performing work on the heating or cooling fluid may comprise a compressor or pump.

The heating or cooling fluid circuit may form part of the heat pump and the at least one heat exchanger may be or form part of a condenser or evaporator of the heat pump.

The system may comprise a motor for at least partially driving operation of heating or cooling apparatus and/or at least partially driving operation of the means for transferring fluid from the body of water. The transmission may be a common transmission for both the motor and the turbine, and both the motor and the turbine may be operably connectable to the transmission.

The system may further comprise monitoring means for monitoring the amount of power supplied to the further pump or heating or cooling fluid pump by the turbine and/or for monitoring the amount of power supplied to the further pump or heating or cooling fluid pump by the motor. The control means may be configured to control the amount of power supplied by one of the motor and the turbine to make up a shortfall in power supplied by the other of the motor and the turbine.

The control means may be configured to control the level of power supplied by the motor and/or the turbine to ensure that the rate of change of power supplied by the motor and/or the turbine is within a predetermined threshold. The wave power system may comprise a wave energy conversion device that is arranged to operate in response to wave motion to transfer the fluid from the body of water along a fluid supply conduit to the heating or cooling device.

Thus, the wave power system can provide the fluid, for example sea water, to the heating or cooling apparatus, as well as providing power for operation of the heating or cooling apparatus.

In a further independent aspect of the invention there is provided a heating or cooling system comprising a heating or cooling apparatus for providing a heating or cooling effect from fluid obtained from a body of water, and a wave energy conversion device arranged to operate in response to wave motion to transfer the fluid from the body of water along a fluid supply conduit to the heating or cooling device.

The fluid supply conduit may comprise a turbine fluid supply conduit for supplying fluid to a turbine, and the turbine may be arranged so that the fluid from the body of water is transferred to the heating or cooling apparatus from the turbine.

The heating or cooling apparatus may comprise a heat exchanger having a heat exchanger input for providing fluid to the heat exchanger. The system may be arranged so that in operation fluid output from the or a turbine fluid supply conduit is passed to the heat exchanger input and heat is exchanged in the heat exchanger between the fluid provided via the heat exchanger input and the heating or cooling fluid. Thus, the wave energy conversion device can provide the dual role of providing power for driving operation of the system and supplying cool (or warm) fluid, for example sea water, to the heat exchanger. It has been found that even after passing through the turbine, the fluid supplied to the heat exchanger may have a suitable pressure, flow rate and temperature to provide a desired heating (or cooling) effect at the heat exchanger. The turbine may comprise a turbine fluid output arranged to output fluid to the heat exchanger input after the fluid has driven rotation of the turbine.

The fluid supply conduit may be connected to the heat exchanger input. The heat exchanger input may form part of the fluid supply conduit.

The system may be arranged so that, the input to the fluid supply conduit is at a location in the body of water where the temperature of the water is between 2°C and 12°C, optionally between 5° and 10°C or between 2°C and 6°C. The system may be arranged so that, the input to the fluid supply conduit is at a location in the body of water where the temperature of the water is at least 5°C different, optionally at least 10°C different, optionally at least 15°C different, from the temperature at the surface, for example the outside air temperature at the location of the heat exchanger.

The system may be arranged so that, in operation, the water experiences a temperature change of between 2° and 10°C, optionally between 5° and 7°C, during its passage through the at least one heat exchanger. That may be obtained by selection, for example, of operating characteristics of the wave power device, for example its average power output, selection of the size of the fluid conduit, and/or selection of operating characteristics of the pump and/or flow rate of the heating or cooling fluid.

The system may further comprise a desalination sub-system comprising a reverse osmosis device, and the system may be arranged to provide the fluid from the body of water to the reverse osmosis device.

The system may further comprise a thermal storage device. The thermal storage device may be arranged to be heated or cooled by the heating or cooling apparatus.

In a further independent aspect of the invention there is provided a method of heating or cooling comprising:- transferring fluid from a body of water to a heating or cooling apparatus to provide a heating or cooling effect; using a wave power system comprising a wave energy conversion device to transfer fluid through the turbine fluid supply conduit to drive rotation of the turbine; and using a motor and the wave power system to provide power via a common transmission to drive transfer of the fluid from the body of water and/or to drive operation of the heating or cooling apparatus.

The method may comprise configuring the motor to operate as an electrical generator when the wave power system provides excess power and, when there is a shortfall in power from the wave power system, to operate as a motor to at least partially drive operation of the heating or cooling apparatus and/or to at least partially drive operation of the means for transferring fluid from the body of water.

The method may further comprise controlling the amount of power supplied by the motor and the amount of power supplied by the turbine. The method may comprise controlling the amount of power supplied by one of the motor and the turbine to make up a shortfall in power supplied by the other of the motor and the turbine.

The method may comprise controlling the amount of power supplied by the motor and the amount of power supplied by the turbine to provide at least one of:- a desired torque; a desired rate of rotation; a desired pressure of the fluid; a desired pressure of a heating or cooling fluid used in the heating or cooling apparatus; a desired rate of flow of the fluid; or a desired rate of flow of a heating or cooling fluid used in the heating or cooling apparatus. The method may comprise connecting an electrical generator to the wave power system to generate electricity. The method may comprise generating electricity from excess energy provided by the wave power system.

The method may comprise providing power from the motor and/or the turbine to drive operation of a heat pump.

In another independent aspect of the invention there is provided a method of heating or cooling comprising transferring fluid from a body of water to the heating or cooling apparatus to provide a heating or cooling effect; and obtaining power from the waves of the body of water to drive transfer of the fluid from the body of water and/or to drive operation of the heating or cooling apparatus. In a further independent aspect of the invention there is provided a method of heating or cooling comprising using a wave energy conversion device to transfer fluid from a body of water along a fluid supply conduit to a heating or cooling device to provide a heating or cooling effect at the heating or cooling apparatus.

In another independent aspect of the invention there is provided a wave power system that is operable to obtain power from waves of the body of water, wherein the wave power system is arranged to provide power obtained from the waves of the body of water to drive operation of a heating or cooling apparatus and/or to drive operation of a means for transferring fluid from a body of water to the heating or cooling apparatus to provide a heating or cooling effect.

A closed loop hydraulic system may be provided which provides fresh water or other fluid at a desired temperature to the heat exchanger by operation of the wave energy conversion device. The freshwater or other fluid may be passed at sea through a capillary network of pipes to return it to a desired temperature.

In a further independent aspects there is provided a system substantially as described herein with reference to the accompanying drawings, and a method substantially as described herein with reference to the accompanying drawings.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, apparatus features may be applied to method features and vice versa.

Features from any combination of independent or dependent claims may be combined in any appropriate combination regardless of the dependency or category of those claims. Brief description of the drawings

At least one embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a heating or cooling system according to one embodiment; 1

Figure 2 is a graph of COP versus heat source temperature for a heat pump, with heat sinks at either 0°C or 7°C

Figure 3 is a schematic illustration of a wave power system forming part of the heating or cooling system of Figure 1 ;

Figure 4 is an schematic illustration of a heating or cooling system according to an alternative embodiment;

Figure 5 is an schematic illustration of a heating or cooling system according to a further alternative embodiment;

Figure 6 is a graph of efficiency versus flow rate for various types of turbine; and Figure 7 is a graph of efficiency versus load for an electric motor.

Detailed description of embodiments

Embodiments of the present invention are now described, by way of example only.

A sea water heating system according to one embodiment is illustrated in overview in Figure 1 (not to scale). The system comprises an on-shore heating/cooling plant 19 that includes a heat pump 2. The heat pump 2 comprises a compressor 6, a condenser 8, an expansion valve 10 and an evaporator 12, connected in a closed loop by fluid pipes. Each of the condenser 8 and the evaporator 12 comprises a heat exchanger. A heating or cooling fluid, also referred to as a refrigerant is provided within the closed loop of the heat pump 2. Any suitable refrigerant can be used, for example 1 ,1 ,1 ,2-Tetrafluoroethane (this is a hydrofluorocarbon known as R-134-a), Ammonia (R-717), Isopropane (R-290a), or Isobutane (R-600a).

The compressor 6 of the heat pump is mechanically connected to a turbine device in the form of a Pelton wheel 20, either directly via a drive shaft 18 as shown in Figure 1 , or indirectly via a gearbox. An electric motor 17 and a flywheel 13 are also provided on the shaft 18.

The Pelton wheel 20 forms part of a wave power system 22 that also comprises a wave energy conversion device 24, usually installed on the sea-bed or suspended beneath the sea surface, that is connected to a turbine fluid supply conduit 26 for supplying fluid to the Pelton wheel 20. A controller 28 (not shown in Figure 1) is connected to the electric motor 17 and to the wave power system 22. The controller 28 is connected to sensors (not shown) associated with the electric motor 17 and the wave power system 22. 1

An electrical power generator (not shown) can also be connected to the drive shaft 18 via a clutch coupling, and may also be driven by the rotation of the Pelton wheel 20.

The evaporator 12 of the heat pump 2 is connected on the input side to a high pressure pump 4 for supplying warm (relative to the environment on land) sea water to the evaporator 12 from a sea water input pipe 11. The sea water is output from the evaporator 12 via a sea water outlet pipe 15 that returns the sea water to the sea.

The condenser 8 of the heat pump 2 is connected to a fresh water (or other fluid) distribution circuit 19 that comprises a pump 16 for pumping warmed fresh water from the condenser 8 around a heating circuit that can be used, for example, to heat one or more buildings.

In operation, the refrigerant is circulated around the closed loop of the heat pump 2 and acts to transfer heat from the relatively warm sea water to the fresh water (or other fluid) that is circulated around the distribution circuit Considering the process in more detail, the evaporator 12 is immersed in a fluid (in this case sea water) at a relatively high temperature. The refrigerant is in liquid form at a lower temperature than the surrounding fluid, and hence absorbs heat from its surrounding environment causing it to vaporise. The temperature of the refrigerant does not necessarily experience a significant increase as the latent energy of vaporisation can account for a substantial proportion of the energy absorbed by the refrigerant from its surrounding environment. The gaseous form of the refrigerant, which is still relatively cool, then passes to the next stage of the refrigeration cycle, at the compressor 6. In stage 2 the compressor 6 raises the pressure of the now gaseous refrigerant, thus increasing its temperature above the temperature of the surrounding environment, and forces the now hot gaseous refrigerant into the next stage of the refrigeration cycle. In stage 3 the refrigerant passes to the condenser 8 where it is in thermal contact with the relatively cool fresh water of the distribution circuit 19. Heat passes from the refrigerant to the cool fresh water, warming that water and cooling the refrigerant. The refrigerant usually changes state from a gas to a liquid at this stage, causing a relatively large transfer of heat energy to the fresh water or other fluid. The refrigerant then passes onto the next stage of the refrigeration cycle. In stage 4 the cool refrigerant passes through the expansion valve 10, causing a reduction in pressure and hence temperature of the refrigerant. The refrigerant is then returned to the evaporator 12 at a lower temperature than the supply of relatively warm sea water, for the cycle to begin again. An advantage of a heat pump over traditional heating methods such as electrical resistance heating is that for every unit of mechanical/electrical energy consumed by a heat pump, a multiple of this value can be returned as heat energy. This multiplier effect can be quantified as the "Coefficient of Performance", or "COP", of a heat pump. This is defined as the ratio of the heat energy output to the mechanical/electrical energy input. In mild Winter conditions, the COP of known domestic heat pump system can be as high as 300%. Higher COPs can be achieved in industrial and community applications.

Higher COPs are achieved when the temperature differential between the heat source and the heat sink is minimized as illustrated in Figure 2, which is a graph of COP versus heat source temperature for heat sinks at either 0°C or 7°C. It can be seen that in general it is beneficial for the heat source to have a relatively high temperature if possible and for the heat sink to have a relatively low temperature. In many locations, the sea provides a heat source which is consistently and reliably warmer than air and soil temperatures on land during Winter. As such, high COPs can be achieved by using a heat pump system as illustrated in Figure 1 to heat industrial and domestic properties throughout Winter, with the sea being used as the heat source.

It is a feature of the embodiment of Figure 1 that wave power is used to power operation of the heat pump, by driving operation of the compressor 6. As the heating or cooling system must be close to the body of water (for example the sea) being used as the heat source in order to operate efficiently, it is particularly convenient to provide power using such a wave power system. Furthermore, a higher level of wave power is in general obtainable during those periods (for example, in Winter) when heating is most necessary, which makes the use of wave power particularly suitable.

In operation, action of the waves on the wave energy conversion device 24 pressurises fluid in the turbine fluid supply conduit 26. The high pressure fluid output by the turbine fluid supply conduit 26 drives the Pelton Wheel 20, which in turn drives operation of the compressor 6 used to operate the heat pump, by providing mechanical energy via the shaft 18 or other transmission arrangement. In the event that the wave power system 22 provides less than the necessary power required to maintain operation of the heating/cooling plant 19, then the electric motor 17 is excited so as to maintain the necessary input torque, drawing electrical energy from an alternative source (for example from the national grid or from an onsite generator). The electric motor is rated such that it can power the heating/cooling plant 19 even if there is zero power output from the wave power system 22. In operation the motor can be controlled so that it continually compensates for any shortfall of power from the wave power system, either during each wave period or between wave periods. In the event that the wave power system 22 produces more power than is required, electricity can be generated using the excess power for export to the national grid or another electrical energy load nearby. For example, the generated electricity can be used to power an electrical heating device to heat water or other fluid in the or a heating circuit.

In the embodiment of Figure 1 electricity can be generated using a separate electric generator that is couplable or decouplable to the driveshaft 18 depending on the power output of the wave power system 22. Alternatively any suitable electric machine can be used, for example the motor on the driveshaft can be used as a generator should the power output of the wave power system 22 rise above a suitable threshold value. The flywheel 13 on the driveshaft helps to maintain a smooth power output.

As well as driving the turbine and, thus the compressor 6, in some alternative embodiments sea water pumped ashore by operation of the wave energy conversion device 24 can also be used as the sea water input to the evaporator 12. In such alternative embodiments, a separate sea water input pipe 11 and high pressure 1 pump 4 is not needed. In other alternative embodiments, the sea water pumped ashore by operation of the wave energy conversion device 24 supplements the sea water provided via the sea water input pipe 11 to the evaporator 12, thus reducing the required capacity of the sea water input pipe 11 and high pressure pump 4.

In further alternative embodiments, the Pelton wheel is connected via a drive shaft or other transmission arrangement to the high pressure pump 4 and is thus used to power the pumping of sea water to the evaporator 12, as well as or instead of powering operation of the compressor 6.

The system of Figure 1 can be used in cooling applications, for example air conditioning applications, as well as in heating building on land as described above. The main difference in such cooling applications is that the sea is used as a heat sink rather than a heat source, and the properties on land become the ultimate heat source rather than the heat sink. Heat pump systems can be readily controlled and adjusted to provide heat transfer in either direction, and the refrigeration cycle occurs as described above, except that the cool sea water now causes the condensing of the refrigerant and the heat provided by buildings on land cause the evaporation of the refrigerant. In the embodiment of Figure 1 , the evaporator 12 acts as a condenser and the condenser 8 acts as an evaporator, when the system is used for cooling, and the direction of operation of the compressor and thus the direction of flow of refrigerant is reversed. The heat pump then operates as a reverse cycle heat pump.

Various different types of wave energy conversion devices 24 and various different wave power systems may be used to drive operation of the turbine using wave energy. The power system used in the embodiment of Figure 1 , including one example of a suitable wave energy conversion device 24, is illustrated in Figure 3.

As shown in Figure 3, the wave energy conversion device 24 is coupled by a suitable linkage and a driving rod 34 to a hydraulic ram (piston) 36 which reciprocates in a cylinder 38 and is double acting.

The cylinder 38 forms part of a hydraulic circuit 40 to which it is connected by an inlet/outlet port 42 at one end of the cylinder, an inlet/outlet port 44 at the opposite end of the cylinder 38, and an arrangement of non-return valves 46, 48, 50, 52. The wave energy conversion device 24 comprises a base portion 33 anchored to the bed of the sea or other body of water and an upstanding flap portion 35, of generally rectangular form, mounted for rotation about a pivot axis to the base 33. An example of a suitable wave energy conversion device 24 is described, for example, in WO 2006/100436. In operation the flap portion 35 is placed to face the direction of wave motion, and the wave motion causes the flap portion to oscillate about the pivot axis, which in turn drives the ram 36 back and forth in the cylinder 38.

In operation, the ram 36 is driven backwards and forwards in the cylinder 38 by oscillation of the flap portion 35 caused by the wave motion. On each forward stroke of the ram, low pressure sea water from inlet pipe 47 is drawn into the cylinder 38 through port 44 via non-return valve 46, and high pressure sea water is pumped out of the cylinder 38 through port 42 and non-return valve 52 into the fluid conduit 26.

On each backward stroke of the ram, low pressure sea water from inlet pipe 47 is drawn into the cylinder 38 through port 42 via non-return valve 48, and high pressure sea water is pumped out of the cylinder 38 through port 44 and non-return valve 50 into the fluid conduit 26.

The fluid conduit 26 forms part of the hydraulic circuit 40 and connects the outlets 42, 44 of the cylinder 38 to a pair of spear valves 56 (only a single spear valve is shown for clarity). The spear valves 56 are aligned with the Pelton wheel 20. The Pelton wheel 20 comprises a number of cups (also referred to as buckets) attached to the periphery of a wheel. The high-pressure water from one or more nozzles of the valves 56 hits the buckets on the wheel converting the hydraulic pressure of the water into rotational mechanical energy at the wheel's shaft 18, and driving rotation of the Pelton wheel 20. The opening of the spear valves may be controlled during each wave cycle in order to reduce the variation in the rate of rotation of the Pelton wheel 20 during each wave cycle and in order to ensure that the Pelton wheel 20 is operating efficiently.

The hydraulic circuit of the system of Figure 1 is a closed circuit, in that the sea water is returned to the wave power device via a conduit after it has exited the Pelton wheel. The sea water is repeatedly pressurised, passed to the Pelton wheel 20 to drive rotation, and returned to the wave power device to be pressurised again.

An accumulator 30, comprising a pressure cylinder containing air, is connected to the fluid conduit 26 between the non-return valves 50, 52 and the spear valves 56. As fluid is pumped out of the cylinder 38 into the fluid conduit 56 the air is compressed to store some of the pressure produced by the pumping action of the ram 36. This has the effect of smoothing variations in the pressure of the fluid in the fluid conduit 56 that is delivered to the Pelton wheel 20. The Pelton wheel 20 is connected to a flywheel 13, which can also operate to smooth out to some extent variations in the rate of rotation of the Pelton wheel 26 during each wave cycle. Flow and pressure meters 70, 72 are provided in the fluid conduit 26. The controller 28 is connected to and obtains outputs from the meters 70, 72 and controls the opening of the spear valves 56 in dependence on the outputs from the meters 70, 72.

The pressure can be controlled by controlling the rate of operation of the high pressure pump, which in turn can be controlled by controlling the torque applied to the drive shaft 18. Torque can be applied to the drive shaft by both or either the electric motor 17 and the Pelton wheel 20. The Pelton wheel 20 is mechanically connected to the pump 4 and drive shaft 18 and transmits mechanical energy that alleviates the load on the electric motor 17, either wholly or completely. Thus, wave power can be used to power the cooling system.

As discussed above in relation to Figure 3, the motion of the waves drives motion of the wave power conversion device, which forces hydraulic fluid through the turbine fluid supply conduit 26 and onto the Pelton wheel 20.

Due to the oscillating nature of the waves, the pressure and rate of flow of the hydraulic fluid through the turbine fluid supply conduit 26, and thus the rotational mechanical energy provided by the Pelton wheel 20 varies periodically over each wave cycle. Furthermore, the average rotational mechanical energy provided by the Pelton wheel 20 varies in the longer term as the wave environment varies.

The controller 28 is configured to monitor the variation in power provided by the Pelton wheel 20 with time and varies the power applied by the electric motor 17 in dependence on that variation. The controller 28 monitors the variation in power produced by the Pelton wheel using the sensors (not shown) which either measure the power directly or measure one or more parameters that are representative of or associated with the power produced by the Pelton wheel (for example, the pressure of the fluid in the turbine fluid supply conduit and/or the rate of rotation of the Pelton wheel). 8

In one mode of operation, the controller 28 varies the power applied by the electric motor 17 in order to make up any shortfall in the power provided by the Pelton wheel 20 so as to maintain the rate of operation of the pump 4 at a desired level, or within a desired range. In turn, that can ensure that flow rate and pressure of cool sea water supplied to the heat exchanger 2 can be maintained at a desired level. The controller 28 can vary the power applied by the electric motor either within each wave period or from one wave period to another.

The controller 28 is also operable to selectively connect the Pelton wheel 20 and a generator via a clutch arrangement 29 to drive operation of the generator. The controller 28 is configured to control operation so that any excess power provided during each wave cycle by the Pelton wheel 20, greater than the power required to drive operation of the pump, is used to drive the electrical power generator. In variants of the embodiment, the Pelton wheel 20 can be temporarily disconnected from the drive shaft 18 under control of the controller 28 during periods when it is providing more power than required by the pump.

The controller 28 may also be configured to take into account operating limits of the motor 17 or the Pelton wheel 20 in varying the power applied by the motor 17 or the Pelton wheel 20. So, for example, if the motor 17 has a maximum ramp rate, the controller 28 may be configured to control the power applied by the motor to ensure that the ramp rate is not exceeded.

The efficiency of operation of the electric motor 17 is around 90%, the efficiency of the Pelton wheel 20 is around 88% and the efficiency of the high pressure pump 4 is around 75%. That provides an overall efficiency of around 60%.

In the embodiment of Figure 1 , heating or cooling effects are provided by operation of a heat pump, which transfers heat to (or from) relatively cool (or warm) sea water depending on whether the system is operating as a heating or cooling system.

In alternative embodiments, a heat pump is not provided and instead heat is exchanged directly between the relatively cool (or warm) sea water and a heating or cooling fluid (for example fresh water) circulating in a district or other cooling (or heating) system. An example of one such alternative embodiment is illustrated in Figure 4, in which like reference numerals indicate like parts. The system of Figure 4 comprises a heat exchanger 80, forming part of a cooling station 82. The heat exchanger 80 is connected on the input side to a high pressure pump 4 for supplying cool sea water to the heat exchanger 80 from a sea water input pipe 1 1. The sea water is output from the heat exchanger 80 via a sea water outlet pipe 15 that returns the sea water to the sea.

The heat exchanger 80 is also connected to a fresh water distribution circuit 19 that comprises a pump 16 for pumping cooled fresh water from the heat exchanger 80 to one or more buildings 84 and back to the heat exchanger 80. Each building 80 is connected to the main fresh water distribution circuit via a distribution branch, and a two-way control valve 86 is provided at each distribution branch for regulating the chilled water supply to each building. The same pump 16 is used to distribute fresh water around the fresh water distribution circuit. The cooling station 82 comprising the heat exchanger 80 is usually situated at a depth below the intake pipes so that seawater flows into the system due to static pressure difference, and is then pumped by pump 4 through the heat exchanger 80.

The pump 4 is a centrifugal pump, although any suitable pump can be used. The seawater pipelines 11 , 15 are constructed from large diameter high density polyethylene which avoids issues relating to corrosion, although any suitable material can be used.

Any suitable heat exchanger can be used, but in the embodiment of Figure 4 the heat exchanger 80 is a large plate heat exchanger that is 6m long by 4m high by 1 m wide. The heat exchanger 80 is of a plate and frame type, with at least one spare heat exchanger frame installed for redundancy. The frames are of carbon steel with plates of a corrosion-resistant alloy, for example titanium. The heat exchanger 80 comprises numerous closely spaced thin metal plates that have a hole near each corner and have been stamped with a corrugated pattern. The plates are suspended from a steel carrying bar and clamped between heavy steel flanges using long threaded rods. The gap between each plate is sealed with a narrow rubber gasket that is compressed as the rods are tightened. Each plate has inlet and outlet ports that lead to four flanged pipe connections on the frame. Such a heat exchanger can have efficiencies in excess of 99%. Although only a single heat exchanger is shown in Figure 4 for clarity, usually more than one heat exchanger is provided depending on the desired cooling capacity. An array of 16-24 large plate heat exchangers could provide approximately 100MW cooling capacity.

In operation, cool sea water from a suitable depth beneath the surface to have a desired temperature is continually pumped by pump 4 through the heat exchanger 80, whilst fresh water is pumped simultaneously by pump 16 around the fresh water distribution circuit. Heat is transferred from the fresh water to the sea water in the heat exchanger. Pipe material for the fresh water distribution system is selected in dependence on pipe strength, durability, corrosion resistance and cost. Steel pipe is most commonly used because the welded joints are good for leakage prevention. Since the cooling system is usually intended for continuing operation and the design temperature differential is small, the thermal stresses in the pipes are insignificant and can be easily tackled through pipe bends or offsets. A corrosion inhibitor is normally introduced to the chilled water for interior surface protection. The outside surface can be wrapped with polyethylene tape to protect against soil moisture. A cathodic- protection system is required for aggressive-soil conditions. Thermal insulation on the pipe not only helps reduce cooling energy loss but also avoid moisture condensation. For pipes running inside plant rooms and utility tunnels, where the pipes can be readily accessed and maintained, fibreglass is widely used. For pipes directly buried underground, polyurethane (PUR) may be chosen.

The flow rates and pressures of the sea water and fresh water are selected in dependence on the desired cooling effect. For a 100MW system with a temperature rise in the sea water of 5-7°C during passage through the heat exchanger (a typical allowable temperature rise to ensure minimal/negligible biological impact of the outflow water) a sea water flow rate of roughly 2.75 cubic metres per second is used. Heat exchangers are typically rated up to pressures of 15-30bar however lower pressures are often used as dictated by the flow rate requirements. The pressure of the fresh water in the fresh water distribution circuit are of the order of 10bar for a 10- 15km distribution network but could be higher depending on the length. Flow rates in the fresh water distribution circuit are usually less than those through the sea-water side of the heat exchanger as the temperature change in the chilled fluid is larger. It is a feature of the embodiment of Figure 4 that power for powering operation of the sea water supply pump 4 (or the fresh water pump 16) is at least partially provided by a wave power system 22 such as that already described above. In the embodiment of Figure 4, the high pressure sea water supply pump 4 is connected to the electric motor 17 via a transmission that comprises the drive shaft 18. As already described, the Pelton wheel 20 is connected to the drive shaft 18 and is driven by pressurised fluid provided by operation of the wave power system 22. In operation, sea water is circulated between the Pelton wheel 20 and the wave power device in a closed loop, and mechanical energy from the Pelton wheel is used to drive the sea water pump 4 to pump further sea water via the separate pipe 11 to the heat exchanger 80.

As the wave power device is already transferring sea water from the sea to the surface (to drive the Pelton wheel) it has been found, for further embodiments, that it can be more efficient to pass the sea water provided by the wave power device directly to the heat exchanger 80 rather than pumping further sea water via a separate pipe 11. Thus, the wave energy conversion device can play the dual role of providing mechanical power for driving operation of a pump and supplying sea water to the heat exchanger. An example of such a further embodiment is illustrated in Figure 5.

In the embodiment of Figure 5, the Pelton wheel 20 is connected to the fresh water pump 16 via drive shaft 18 and mechanical energy from the Pelton wheel 20 is used to drive the fresh water pump. Again the electric motor and controller (not shown) are provided to make up any shortfall in the energy supplied to the pump by the Pelton wheel 20.

A turbine fluid output outputs the sea water after it has driven rotation of the Pelton wheel, and is connected to an input of the heat exchanger 80. In the embodiment of Figure 5, the circuit between the wave energy conversion device 24, the Pelton wheel 20 and the heat exchanger 80 is a closed loop and the sea water is returned to the wave energy conversion device after it has passed through the heat exchanger 80. A condenser 90 is included in the circuit, at a suitable depth beneath the sea, to cool the returning sea water before it passes to the wave energy conversion device. In variants of the embodiment of Figure 5, any suitable fluid can be circulated between the wave energy conversion device 24, the Pelton wheel 20 and the heat exchanger 2, in place of sea water.

In another variant of the embodiment of Figure 5, the circuit between the wave energy conversion device 24, the Pelton wheel 20 and the heat exchanger 80 is an open loop circuit and the sea water is returned to the sea after passing through the heat exchanger 2. In another variant of the embodiment of Figure 5, the Pelton wheel 20 is not used to provide mechanical energy to the pump but instead is used to generate electricity via a generator (not shown).

The embodiments of Figures 4 and 5 are cooling systems, but they can also be operated as heating systems if the temperature of the sea water is higher than the temperature of the fresh water in the heat exchanger. In some embodiments a reversing valve is provided to assist in using the same system for either heating and cooling.

In the embodiments of Figures 1 , 4 and 5, a single pump 16 is used to distribute fresh water around the fresh water distribution circuit. Such an arrangement is simple to install and maintain, but is not always suitable for large-scale distributed cooling systems applications since the pump head required for lengthy pipelines can be significant, the heat exchangers have to withstand a high working-pressure, and the energy cost can be high

In alternative embodiments, primary-secondary pumping is used, in which a decoupler system is provided that comprises a production loop and a distribution loop. The pump 16 forms part of the production loop and secondary variable-speed pumps are also provided to overcome pressure losses incurred by the chilled water flow and to maintain a critical pressure-differential in the distribution circuit. In other alternative embodiments, an additional distribution pump is provided at each distribution branch, and the pressure control valve mentioned above and balancing valves are not required. Such a distributed arrangement is energy efficient but installation and maintenance can be more difficult. Additional heating or cooling components can be provided in the heating or cooling station, in accordance with known heating or cooling techniques. For example, additional evaporators, condensers, and expansion valves can be provided to provide additional heating or cooling effects.

In variants of the described embodiments, thermal storage units are provided that store chilled water or ice in a tank, or that store heat. Such units can be used as a buffer to improve efficiency and to minimise variability in power output. For example, chilled water or ice, or heat, can be generated and stored during periods of maximum output from the wave energy conversion device (for example, at times of heavy sea conditions) and used when required when there may be periods of lower output from the device (for example, at times of calm sea conditions).

The thermal storage units may be used as a source of heat or cold for heating or cooling applications. In such embodiments, the heat pump does not need to provide heating or cooling effects directly to a heating or cooling fluid to be distributed to locations to be cooled, but instead such heating or cooling fluid can be heated or cooled by the thermal storage units.

For cooling applications the Calmac lcebank product, for example, can be used as the thermal storage unit. It can be cooled down to low temperatures by the heat pump and can maintain such temperatures for a long period of time. It can then be used as a source of cold for cooling applications, such as air conditioning applications.

For heating applications Rubitherm's latent heat storage materials, for example, can store large volumes of thermal energy. Such materials can be heated by the heat pump, and can subsequently be used as a source of heat for heating applications.

In the embodiment described above, a turbine in the form of a Pelton wheel 20 is used, but other turbines, in particular hydraulic turbines, may be used instead of the Pelton wheel 20 in some embodiments.

Hydraulic turbines are machines designed to convert hydraulic to mechanical energy. There are three main categories of hydraulic turbines, the Kaplan Turbine (essentially a propeller designed to operate in a duct), an axial flow turbine (a reverse running pump) and an impulse reaction turbine. A Pelton wheel is an example of an impulse reaction turbine. The three turbine types attain their peak efficiency and performance when operating at very low, medium and high pressures respectively. In embodiments such as that of Figure 1 , in which a vertical flap device is used as a wave energy conversion device, pressures are expected to be in excess of 25 bar and an impulse reaction turbine, in particular a Pelton wheel, has been found to be the most suitable device.

The Pelton wheel has a simple construction and directly produces rotational energy. Furthermore, the Pelton wheel can perform at very high efficiencies, for example around 88%, and maintain that level of efficiency for a wide range of flows, even down to 30% of the design flow of the wheel. A graph of variation of efficiency with flow rate is shown in Figure 6.

The power derived from a Pelton wheel is proportional to the product of the head and flow and hence varies with the pressure of the fluid provided by the wave energy conversion device via the turbine fluid supply conduit. The size of a Pelton wheel is sensitive to the bucket width, the jet diameter and the ratio of the wheel diameter and the jet diameter and these parameters, when taken into consideration for a wheel design will favour the operation at high pressures, usually beyond 150m. Variations in pressure cause a variation in energy output.

The wave energy conversion device is also not limited to a vertical flap device, and any suitable wave energy conversion device can be used that provides for the conversion of wave energy to rotational mechanical energy, either directly or by pressurising fluid to drive operation of a turbine. Examples of wave energy conversion devices that may be used in alternative embodiments include floating devices such as buoy devices, and articulated link devices or submerged, oscillating flap devices.

In other alternative embodiments a desalination sub-system comprising a reverse osmosis device may be included in the system, the fluid supply conduit is arranged to supply the water to an input of the reverse osmosis device, and an output of the reverse osmosis device is connected to the input of the heat exchanger.

The systems described herein may be entirely purpose built or they may be produced by retrofitting or otherwise adapting an existing heating or cooling system by adding the wave power system to provide mechanical energy to one or more pumps and/or to provide sea water to the heat exchanger(s). In adapting an existing plant, the Pelton wheel 20 may be coupled to existing equipment in the plant. For example, the Pelton wheel 20 can be inserted between an existing high pressure pump 4 and an existing electric motor 17. The Pelton wheel 20 can be manufactured with a double ended shaft to fit the existing high pressure pump 4 and existing drive shaft 18 thus saving the replacement of either the pump or shaft.

The energy provided by the Pelton wheel 20 reduces the load on the existing electric motor 17, which drives the high pressure pump 4. Presuming, in the case of retrofitting, that the motor has been selected to have a power rating optimised for an expected load in the absence of the Pelton wheel 20, it is likely that the motor will have to operate below its designed power rating. The effect of this reduced power on the motor may be a reduction in its efficiency. However, published technical data on induction motor performance on reduced loads indicates that for high capacity motors any reduction in efficiency is not likely to be significant. For example, Figure 7 shows the expected variation in efficiency with variation in load of a 600HP (500kW) motor tested under two different test regimes, including the IEEE 112b test standard. Retaining the same motor 17 can ensure that the plant will run at the designed pressure and flow since any loss of power from the Pelton wheel 20, as a result of low pressure form the wave power system 22 would be compensated by the motor 17. In extreme cases, operation of the high pressure pump 4 may be driven solely by the Pelton wheel 20 or solely by the motor 17. It can be determined whether it is more beneficial to operate a given existing heating or cooling plant with a Pelton wheel 20 designed to provide all power or designed to provide a given percentage of the power, with the remaining power provided by the electric motor, by taking into consideration the expected motor efficiency at reduced loads and the expected frequency and magnitude in variations in pressure of the fluid provided to the Pelton wheel 20.

In embodiments described in relation to Figures 1 , 4 and 5, the Pelton wheel or other turbine is used to provide mechanical energy to drive operation of components of the heating or cooling system (for example one or more compressors or pumps). In alternative embodiments, the Pelton wheel or other turbine is connected to an electricity generating system, and the rotation of the turbine is used to generate electricity. The generated electricity is then used to power electrically driven input shafts to components of the heating/cooling plant. For example the generated electricity may be used to power an electric motor to drive the various pumps and other equipment used to operate the heating/cooling plant. The motor can be connected to the electrical supply from the electricity generating system in parallel with the national grid or an auxiliary generator onsite such that the required torque to operate the heating/cooling plant can always be maintained. In the event that the wave power system produces more power than is required by the heating/cooling plant, the wave power system may be connectable to the national grid or to an electrical energy load nearby, to export excess electrical energy to the national grid or electrical energy load. In such a configuration, there may be a complete mechanical disconnection between the wave power system and the heating/cooling plant.

It can be seen that wave energy does lend itself to replacing grid power on heating or cooling plants, if implemented appropriately. In the embodiments described above, modifications to a heating or cooling plant can merely involve the addition of a Pelton wheel on the shaft of the high-pressure pump, and the resulting system can cope with any variation in the availability of wave energy from 0 -100%.

At least some of the embodiments describe herein lends themselves to large scale deployment of heat pump technologies in urban areas by the sea, and also for industrial installations in rural areas by the sea. In general, the consistently moderate temperatures throughout the year of the sea in many locations means that the required temperature differential between the heat reservoirs for both heating and cooling applications may be relatively small, hence leading to higher COPs. This makes seawater a viable heat source and sink for heating and cooling applications respectively, and wave power systems as described herein may be particularly suitable as power sources for coastal heat pump systems. The huge extent of the availability of seawater at a relatively constant temperature means that both heating and cooling applications can be relied upon to provide predictable levels of performance throughout the year.

It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.

Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Claims

1. A heating or cooling system comprising:- a heating or cooling apparatus;

means for transferring fluid from a body of water to the heating or cooling apparatus to provide a heating or cooling effect;

a wave power system comprising a wave energy conversion device connectable to a turbine fluid supply conduit for supplying fluid to a turbine, in operation the wave energy conversion device operating in response to wave motion to transfer fluid through the turbine fluid supply conduit to drive rotation of the turbine; and

a motor for at least partially driving operation of the heating or cooling apparatus and/or at least partially driving operation of the means for transferring fluid from the body of water,

wherein the turbine and the motor are operably connectable to a common transmission such that in operation rotation of the turbine provides mechanical energy via the transmission to also at least partially drive operation of the heating or cooling apparatus and/or to also at least partially drive operation of the means for transferring fluid from the body of water.

2. A system according to Claim 1 , wherein the motor is configured to operate as an electrical generator when the wave power system provides excess power and, when there is a shortfall in power from the wave power system, to operate as a motor to at least partially drive operation of the heating or cooling apparatus and/or to at least partially drive operation of the means for transferring fluid from the body of water.

3. A system according to Claim 1 or 2, further comprising control means for controlling the amount of power supplied by the motor and the amount of power supplied by the turbine.

4. A system according to Claim 3, wherein the control means is configured to control the amount of power supplied by one of the motor and the turbine to make up a shortfall in power supplied by the other of the motor and the turbine.

5. A system according to Claim 3 or 4, wherein the control means is configured to control the amount of power supplied by the motor and the amount of power supplied by the turbine to provide at least one of:- a desired torque;

a desired rate of rotation;

a desired pressure of the fluid

a desired pressure of a heating or cooling fluid used in the heating or cooling apparatus;

a desired rate of flow of the fluid;

a desired rate of flow of a heating or cooling fluid used in the heating or cooling apparatus.

6. A system according to any preceding claim, further comprising an electrical generator that is operably connectable to the wave power system to generate electricity.

7. A system according to Claim 6, wherein, in operation, the control means connects the wave power system to the electrical generator to generate electricity from excess energy provided by the wave power system.

8. A system according to Claim 6 or 7, further comprising an electrical heater, wherein in operation the electrical generator provides electricity to power the electrical heater.

9. A system according to any preceding claim, wherein the heating or cooling apparatus comprises a heat pump and the common transmission in operation provides power from the motor and/or the turbine to drive operation of the heat pump.

10. A system according to any preceding claim, wherein the heating or cooling apparatus comprises a heating or cooling fluid circuit for circulating heating or cooling fluid, at least one heat exchanger and a device for performing work on the heating or cooling fluid.

11. A system according to Claim 10, wherein, in operation, heat is exchanged at the at least one heat exchanger between the fluid from the body of water and the heating or cooling fluid.

12. A system according to Claim 10 or 11 , wherein the common transmission is connected to the device for performing work, and in operation the common transmission provides power from the motor and/or the turbine to the device for performing work on the heating or cooling fluid.

13. A system according to any of Claims 10 to 12, wherein the device for performing work on the heating or cooling fluid comprises a compressor or pump.

14. A system according to any preceding claim, further comprising a thermal storage device.

15. A method of heating or cooling comprising:- transferring fluid from a body of water to a heating or cooling apparatus to provide a heating or cooling effect;

using a wave power system comprising a wave energy conversion device to transfer fluid through the turbine fluid supply conduit to drive rotation of the turbine; and

using a motor and the wave power system to provide power via a common transmission to drive transfer of the fluid from the body of water and/or to drive operation of the heating or cooling apparatus.