ES2603985T3 - Methods for cooling a transport fluid of a solar power plant and a solar power plant - Google Patents

Abstract

Method for cooling a conveyor fluid (5) of a solar power plant, wherein - the conveyor fluid (5) is used to drive a turbine (29) of the solar power plant (2 '); - the transport fluid comprises water; and - at least a part of a cooling process is carried out by driving the fluid (5) underground transporting a soil to a depth (41) in which the soil is substantially colder than ambient air; characterized in that - the depth is selected so that there is at least a temperature difference of 10 ° C between the ambient air and an underground region in which the cooling takes place, using the thermal inertia of the underground soil.

Description

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DESCRIPTION

Methods for cooling a transport fluid of a solar power plant and a solar power plant

The present invention relates to a method for cooling a transport fluid, whose transport fluid is used to drive a turbine in a solar power plant. The invention also relates to solar power plants with a conveyor circuit with a conveyor fluid whose operating conveyor fluid drives a turbine of the power plant.

In power plants, a typical way to generate energy out of heat is to bring a conveying fluid to a certain level of heat and so on! provide a certain level of kinetic energy. The transport fluid, like water, evaporates and turns into steam. The water, which is subjected to a considerable pressure of approximately 270 bar, is converted into steam, which means to further increase the volume of the transport fluid. Therefore, the steam has enough energy to drive a large turbine whose movement will then move the generator. After driving the turbine this steam has to be cooled, which is usually done in a condenser. Said condenser is often a heat exchanger with a cooling circuit along which a conveyor circuit is conducted with the conveying fluid. In this way, the conveyor circuit is a pipe system that is connected to the turbine, the cooling circuit is filled with cooling liquid that is put in indirect contact with the conveying fluid and that is considerably cooler than the conveying fluid before condensation Part of the heat of the carrier fluid, that is, the steam, is transferred as! to the cooling liquid in the refrigeration circuit so that the steam is converted back into water.

In today's power plants that use this technology, to cool the temperature inside the refrigeration circuit, wet cooling towers or dry cooling towers are used. Such technology is described in WO 2008/154427 A1 or in US 4 315 404 A. Therefore, a separate cooling circuit is used. Such a technique is also described in WO 2009/031747 A1 for an energy plant that has a pure oxygen combustor. US 7 340 899 B1 describes a solar power plant. In addition, WO 2009/064378 A2 describes a possibility to store thermal energy from a solar power plant, while US 2009/0121488 A1 describes a solar power plant comprising a heating subsystem with a cooling loop.

In wet cooling towers, part of the cooling liquid, again usually water, will evaporate and be released into the air. The other part of the cooling fluid can be reused within the cooling circuit or released in a stream from which cooler water is extracted again to return the cooling circuit with fresh cooling water at the temperature of the water.

Said power plant according to the state of the art is represented in Figure 1. An electric power plant 2 whose components are schematically shown in this figure has a conveyor circuit 1 and a cooling circuit 11. In the circuit 1 conveyor of the conveying fluid 5, in this case the water 5, respectively the water vapor is pumped through a pipe system. By means of a pump 3 of conveyor circuit. In order to cool the water vapor 5 to a considerably lower temperature in order to transform it back into liquid water 5, a heat exchanger 9 is used. The condensed water is pumped by a conveyor pump 3. The heat exchanger 9 is also connected to the refrigeration circuit 11 with cooling fluid 13, namely cooling water 13. The cooling water 13 is extracted from a line 27 and is pumped by a pump 23 from the cooling circuit to the heat exchanger 9. Before reaching the heat exchanger 9, the cooling water 13 has the temperature of approximately 27. After leaving the heat exchanger 9, the cooling water 13 has removed a large amount of heat from the water vapor 5 in the 1 conveyor circuit. Therefore, it is much hotter than before and also needs to be cooled to be driven back to the 27. To do so, a wet cooling tower 19 is used. Here the hot cooling water 13 of the cooling circuit 11 is sprayed into the tower while the air 17 is vented in the cooling tower 19. Vapor clouds 21 result from this process while the rest 25 of the cooling water 13 is brought back to the river 27 at a considerably lower temperature level than before entering the wet cooling tower 19.

In accordance with this principle, a considerable portion of cooling water 13 that was used to condense the water vapor 5 in the heat exchanger 9 will evaporate into the air in the wet cooling tower 19. This provides a very high cooling efficiency, since considerably lower temperatures of the remaining remainder 25 of the cooling water 13 occur. As the efficiency of the power plant 2 directly depends on the capacity of this cooling system to cool the conveyor fluid 5, this type of condenser system provides high efficiency in the power plant in general. However, wet cooling towers consume large amounts of water. Depending on the environmental conditions, the consumption reaches values higher than 500 kg / s of water for a 500 MW power plant.

Therefore, an alternative to wet cooling towers is the so-called dry cooling towers, the principle of which will be described with reference to Figure 2. A dry cooling tower 33 directly cools a conveyor fluid 5 within a conveyor circuit 1. The conveyor fluid 5 comes from a turbine 29 in

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a power station 2. The turbine 29 drives a generator 31 that generates electric energy from the rotation of the turbine 29. Within the dry cooling tower 33, water 5 is conducted through a pipe system 37 that functions as a heat exchanger fin tube. In order to cool the pipe system 37, a fan 35 provides fresh air that is vented around the pipe system 37 so that a constant stream of air 17 is conducted around the pipe system 37. The conveyor fluid 5 cools like this! slowly in the piping system 37 and can be pumped back to a heating unit (not shown) by means of a conveyor circuit pump 3. Said heating unit may comprise a heating chamber in which the substances (oil, carbon, waste and other combustible materials) are burned or may comprise a nuclear reactor or a solar-thermal field.

Dry cooling towers 35 do not necessarily require water supply, however, they are limited in their effectiveness by ambient temperature. A high ambient temperature will result in a less efficient thermodynamic process, since the temperature of the condenser in the dry cooling tower 35 and therefore the respective pressure at the outlet of the turbine 29 will increase.

It is also possible to combine a wet cooling tower 19 and a dry cooling tower 35 within a power plant. However, there is still a certain dilemma for the operation of all power plants based on one or both of the cooling technologies. In some regions water is scarce and / or the air is very hot at peak times. Usually, these two effects can be found at the same time. These arid places, such as deserts, however, have the advantage that usually a large amount of solar energy is available. Therefore, it is an important problem to provide an effective cooling system, while sufficient heating energy will be theoretically available at very low costs.

The object of the invention is to further optimize the cooling processes for the central condensation of energy. In particular, it is the object of the invention preferably to reduce the consumption of water or any other cooling fluid during said process for a solar power plant.

This object is satisfied by a method according to claim 1 and by a solar power plant according to claim 13.

In accordance with the invention, a method is provided for cooling a transport fluid of a solar power plant. The transport fluid is used to drive a turbine of the solar power plant. The transport fluid comprises water. At least a part of a cooling process is performed by driving the underground conveying fluid to a depth at which the ground is substantially colder than ambient air. The method is characterized in that the depth is selected in such a way that there is at least a temperature difference of 10 ° C between the ambient air and an underground region in which the cooling takes place.

As for the definition of "underground," essentially any region below the soil surface can be considered as underground. For the purpose of the invention it is necessary to cool the conveying fluid and optionally also a cooling fluid so that the underground region must be substantially cooler than the ambient air, that is, the air above the ground. This means that there is at least a temperature difference of 10 ° C, more preferably 20 ° C between the ambient air and the underground region in which the cooling takes place. It is further preferred to conduct the conveying fluid and optionally also the cooling fluid of an underground region that is at least 0.5 m, more preferably at least 1 m below the surface level of the soil. In this region tubes are conducted to transport the fluid along a certain length, so that the temperature of the underground region effectively absorbs part of the higher temperature of the fluid. Said length of pipes is preferably at least 10 m, more preferably at least 20 m, but the pipes must not necessarily be driven only in the direction, but can comprise turns and windings, for example, in the form of a heat exchanger typical. As for the transport fluid, as! as with the cooling fluid, they may comprise a liquid and / or a gas such as air. They can comprise the same material, but they can also comprise different materials, for example, water as the carrier fluid and oil as the cooling fluid. The refrigeration circuit in which the refrigerant fluid is transported can also comprise several separate cooling subcircuits so that, for example, a first refrigerant fluid is cooled by a second cooling fluid in a heat exchanger or the like.

In a preferred embodiment, the cooling process is further carried out by conducting a cooling fluid to cool the underground ground transport fluid to the depth. In other words, use is made of an underground region where the transport fluid cools and optionally also the cooling fluid. It is used as! the thermal inertia of the underground soil. Even in the deserts, the underground soil is relatively cold compared to the daytime ambient temperature on the ground that is mainly due to a strong cooling effect at night times.

Two principles can be used in the context of this embodiment: Direct cooling of the conveyor fluid can be performed by routing the conveyor circuit of this conveyor fluid through the

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underground region. Indirect cooling means that a cooling fluid, such as water or other fluid with a high heat capacity, is routed through underground pipes. This refrigerant fluid then cools the transport fluid in a heat exchanger.

The method according to the invention can be performed instead of using evaporation or ventilation techniques as described above or in addition to using any such techniques. Therefore, an underground region below the surface level of the soil in the area of the power plant is used as a cooling region in which the transport fluid and optionally also the cooling fluid is cooled at least partially.

According to a further embodiment of the invention, said cooling effect can also be achieved by means of a method of the type mentioned above, whereby at least part of a cooling process is performed by supplying at least part of the transport fluid and / or at least some of a refrigerant fluid used to cool the conveyor fluid, from a cold storage that stores the fluid at a temperature significantly below the temperature of the conveyor fluid in the turbine. Such cold storage, which is additionally provided to the configuration of the invention as defined in independent claims 1 and 13, may be located underground as described above, but may also be above ground level and preferably comprise a thermally insulated container. This vessel is preferably fed with a liquid or gas that has been cooled below ground. However, it is also possible to have a cold storage that receives fluid at a low temperature level during the night and then stored at cold temperature during the day. For example, such cold storage can be performed as a large pond that opens overnight so that its contents (i.e., the fluid) cool down and that it is closed and thermally insulated during the day in order to maintain the level Low temperature for as long as possible. Cold storage can also be fed with a fluid that has been cooled by an above-ground cooling process (for example, by exchanging air to liquid, which means using dry cooling techniques) and / or underground ( that is, according to the first embodiment of the invention). The following principle is provided: it is stored at a low temperature or is provided in a specific place. In the first embodiment, it is stored at low temperature in the underground region due to the low underground temperatures that are available anyway. In the second embodiment, the invention additionally makes use of a specially designated container in which the low temperature is artificially preserved. In both embodiments of the invention evaporation techniques are not necessary and the loss of water due to cooling and condensation is greatly reduced. A ventilation technique is also not essential, although such technology can be used in addition to the cooling technology according to the invention.

According to the foregoing, depending on the use of any of the embodiments described above, an energy plant of the type mentioned above can be carried out in two different ways.

According to the first embodiment of the method according to the invention comprising all the characteristics of the independent revindication 1, a solar power plant of the type mentioned above can be improved by the fact that at least part of the conveyor circuit and optionally also part of at least one cooling circuit with a cooling fluid used to cool the conveyor fluid is conducted underground to a depth that is substantially colder than ambient air.

For this, the power plant preferably comprises underground pipes and / or tanks. The underground region serves as a "heat sink" or as a kind of low temperature tank. Such tubes or tanks are preferably made of a material with a high heat transfer coefficient so that the transfer of heat from the fluid to the underground region outside the tube or tank is as effective as possible. Therefore, the heat transfer coefficient of said pipe or tank is preferably greater than 15 W / mK, most preferably greater than 100 W / mK, that is at least in the range of the transfer coefficient of metals such as steel stainless or superior. Therefore, it is preferred to use tubes or tanks not thermally insulated. Heat transfer can even be improved by means of heat transfer improvement such as fin tubes.

Second, that is, additionally, a solar power plant of the type mentioned above can be improved by the fact that at least part of the transport fluid and / or at least part of a cooling fluid used to cool the transport fluid is stored in a cold storage at a temperature significantly below the temperature of the transport fluid in the turbine.

Said cold storage can be performed as a container or tank above the ground or below ground level. It can be incorporated into buildings of the power plant to reduce the need for thermal insulation, but it can also be located outside these buildings to be further away from the heating process. Preferably, said container is thermally insulated such that little heat is transferred into the container, which in turn means that the low temperature within the cold storage is maintained as long as possible. Especially it is preferred that cold storage keep the temperature of its content at a certain level that does not exceed 20 ° C above its lowest level during

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course of a day. This is the preferred value for cold storage in a state where it is filled with the designated fluid during a day in which no fluids are inserted or removed from the cold storage.

As indicated above, both embodiments of the power plant according to the invention also follow the common principle that has been described with reference to the two embodiments of the methods according to the invention. In a combination of these embodiments, cold storage is supplied underground beneath the ground surface and, therefore, does not necessarily need to be equipped with insulating means because the insulation is actually performed by the surrounding soil instead of insulating material. additional.

Finally, a cooling system for an energy plant is described in which at least part of a conveyor circuit with a conveyor fluid and optionally also part of at least one refrigeration circuit with a refrigerant fluid used to cool the conveyor fluid that is conducted underground A depth that is substantially cooler than ambient air as described in the independent claims and in which at least part of the transport fluid and / or at least part of the cooling fluid is optionally further stored in a system of refrigeration in a cold storage at a temperature significantly below the temperature of the transport fluid in the turbine.

With said cooling system, the power plants can be retrofitted to become a power plant in accordance with the invention of any of the embodiments described above.

The particularly advantageous embodiments and features of the invention are given by the dependent claims, as disclosed in the following description. Thus, the features disclosed in the context of one of the methods can also be realized in the context of the other respective method and / or in the context of any of the embodiments of the electric power plant according to the invention unless otherwise it is explicitly fixed.

It is particularly preferred that cooling be carried out in a power plant in a hot environment. This hot environment occurs particularly in desert environments or in analogously arid environments. They can be characterized by the fact that a maximum temperature of 40 ° C is reached for at least 100 days of the year. In such circumstances, water is particularly scarce. This implies that the water consumption of power plants directly competes with the water needs for food production and urban life, so that local life and food production are likely to have the highest priority over the generation of energize Therefore, power plants in such regions can only function successfully if they have a very low footprint of very low water consumption, that is, as few running water losses as possible. The use of the methods according to the invention is particularly useful for not wasting valuable water for the generation of energy. Said water can now be saved for other purposes, such as agriculture and domestic use.

At the same time, the solar impact in these regions is particularly high. Therefore, such arid environments offer the possibility of operating solar power plants, however, so far the dilemma regarding efficient cooling speaks as described in the introductory paragraphs. Therefore, it is preferred that cooling be carried out for a conveyor fluid in a solar power plant, in particular in a concentrated solar power plant. First, such solar power plants are often located in arid areas as described above. Second, such power plants, particularly concentrated solar power plants, produce conveying fluids with very high temperatures. Concentrated solar power plants are characterized by the fact that the rays of sunlight are concentrated in small spots to produce very high temperatures at these points. The result is that the temperatures generated by concentrated solar power plants are particularly high and sufficient for the central electric cycle. However, the efficiency of the cycle is determined by the lower temperature of the cold end (condensation). This temperature defines the lowest achievable pressure at the turbine outlet. The lower the higher efficiency and therefore the output of extra power from the power plant. This can be improved by the procedures according to the invention.

In order to further cool any of the fluids, additional cooling may be necessary apart from the cooling performed by the method according to the invention. A first possibility is that the cooling according to the invention is carried out for a conveying fluid in a central electrical apparatus comprising an air-cooled condenser or a dry cooling tower that performs part of the cooling. As shown above, dry cooling towers with fans have the advantage that, again, essentially no cooling fluid is lost in the air. The combination of the cooling method according to the invention with a cooling method using an air cooled condenser makes a closed cooling circuit or a closed conveyor circuit possible in which no fluid is lost to the environmental environment.

A second possibility that also includes additional cooling is that the cooling according to the invention is carried out in a power plant comprising a wet cooling system that performs part of the cooling. The first and the second possibility can be combined so that, in fact, three

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Cooling systems together provide the overall cooling effect of the transport fluid, and optionally also the cooling fluid. However, the cooling method according to the invention can also be combined with a wet cooling system only. This means that a wet cooling tower takes part of the cooling while the rest of the cooling is performed by the cooling system according to the invention. As indicated above, wet cooling provides the most effective cooling in general, so that a particularly effective system is achieved, whereby the methods according to the invention help reduce fluid consumption. Whether the wet cooling tower is located above or below, the cooling system according to the invention can be chosen according to technical preferences and according to space availability, as well! as in dependence on other presuppositions. In some special cases, however, it is preferred to place in a wet cooling tower below the cooling system according to the invention. This is particularly the case when water losses from the wet cooling tower are to be reduced by the cooling system, which can be improved by the arrangement of the two cooling systems.

To summarize, the combination of such different refrigeration systems with the method according to the invention provides a more efficient system. It also makes possible the temporary use of any of the cooling methods at different times. For example, a main cooling circuit may comprise a dry cooling tower system, while only during peak hours is a cooling system operated in accordance with the invention.

While according to the invention it is intended to simply conduct the transport fluid and optionally also the cooling fluid through an underground pipe system, it is also possible, in combination with the features of independent claims 1 and 13, it is also possible that the conveying fluid and / or the cooling fluid is cooled in a heat exchanger connected to a refrigeration circuit. Said cooling circuit contains a cooling fluid. The conveying fluid can be cooled directly in the heat exchanger or the cooling fluid is cooled in the heat exchanger by a second cooling fluid circulating in the cooling circuit. The latter means that two refrigeration circuits are used together, both of which contain refrigerant fluid, so that the refrigeration fluids in the different refrigeration circuits may be different in kind, but not necessarily.

As for the method according to the second embodiment of the invention (ie, additionally using a cold storage), the cold storage is preferably located underground at a depth that is substantially cooler than ambient air. In fact, this means that both embodiments of the methods according to the invention are combined so that cooling takes place underground in a cold underground storage.

It is particularly preferred that said cold storage be filled with fluid overnight, which is then applied during the day. This means that the transport fluid and / or the cooling fluid are cooled at night and collected in cold storage so that they can be supplied during the day, especially during those hours of the day when the weather is particularly hot.

Additionally, part of the transport fluid and / or part of the cooling fluid can be stored in a plurality of cold stores. For example, there may be a main cold storage for what may be called "normal operation" and a second additional cold storage for operating times under severe conditions such as very hot weather or times of maximum energy consumption. However, different cold stores can also be used at different times, for example, in different days, so that the time to recover the low temperature in each of the cold stores is longer. In addition, all cold stores can be used in parallel at any given time to provide a combined cooling effect.

The cooling method according to the invention is particularly useful for those times when it is particularly necessary to cool the transport fluid. Therefore, it is preferably applied under extreme heat conditions and / or during times of maximum energy consumption.

For such extreme conditions, it is further preferred that the use of the cooling method be initiated by a drive unit according to variable input data related to temperature information and / or energy consumption information. Said drive unit receives information on the ambient temperature and / or information on the current energy consumption within the power supply network and from it derives orders to activate or deactivate those parts of the power plant that will operate the cooling system. according to the invention. For example, the valves inside and / or outside the refrigeration system according to the invention can be opened and closed depending on such orders of the drive unit. This means that the cooling system can be opened and closed according to the current need.

Other objects and features of the present invention will be apparent from the following detailed descriptions considered in conjunction with the accompanying drawings. It should be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention.

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The invention is defined only by the appended claims.

In the drawings, similar reference numbers refer to similar objects everywhere. The objects in the diagrams are not necessarily drawn to scale.

Figure 1 shows a schematic view of a power plant with a first cooling system according to the state of the art,

Figure 2 shows a schematic view of a power plant with a second cooling system according to the state of the art,

Figure 3 shows a schematic view of a power plant with a refrigeration system according to a first embodiment comprising features that optionally complement the features of the invention,

Figure 4 shows a schematic view of an energy plant with a cooling system according to a second embodiment comprising features that optionally complement the features of the invention,

Figure 5 shows a schematic view of a power plant with a cooling system according to a third embodiment comprising features that optionally complement the features of the invention,

Figure 6 shows a detailed view of a part of the cooling system of Figure 5.

Figures 1 and 2 have been described above in the context of the description of the state of the art.

In the following description of embodiments comprising features that optionally complement the features of the invention, it should be understood that the invention comprises at least all stages of the method or features of the attached independent claims 1 and 13.

Figure 3 shows a power plant 2 'according to a first embodiment comprising features that optionally complement the features of the invention. In this and in the following figures, the other components of the power plant 2 ', such as the heating chamber, the turbine, the generator and the power system, are not shown for reasons of clarity.

In a cooling circuit 11, the cooling fluid 13, here the cooling water 13, is pumped through a tube system by a pump 3 of the cooling circuit. First, a dry cooling tower 33 of the type described in the context of Figure 2 passes. Next, the cooling water 13 is conducted further down the ground into the earth to an underground depth 41 . Part of the cooling circuit 11 is therefore an underground tube 40, in which the cooling water 13 can be cooled by the low temperatures in the underground depth 41. The underground tube 40 constitutes as! a refrigeration system 4. The cooling water 13 is additionally conducted to a wet cooling tower 19 of the type described in Figure 1. Water vapor leaves the wet cooling tower 19 in the form of steam clouds 21. The rest of the cooling water 13 is collected and pumped to a heat exchanger (not shown) to cool a conveying fluid of the power plant 2 '.

The underground tube 40 and therefore the refrigeration system 4 can be fed with cooling water 13 through a first valve 59, while a direct connection 60 avoiding the underground tube 40 can be opened and closed by a second valve 61 If the cooling water 13 is to be cooled in the underground tube 41, the first valve 59 opens while the second valve 61 is preferably closed. On the other hand, if the cooling by the dry cooling tower 33 and the wet cooling tower 19 is sufficient in itself to cool the cooling water 13 to the desired low temperature, the second valve 61 can be opened while the first valve 59 can be closed to cut the connection in the underground tube 40. For this, a control unit 63 gives orders SB to both the first valve 59 and the second valve 61, by means of which the two valves are actuated. The control unit 63 comprises an input interface 64 for information information information ID, for example, information on the ambient temperature of the power plant 2 'and / or on the current consumption of the power network being fed by the central 2 'of energla. A drive unit 57 derives from this ID information data the orders SB that will close and open the first valve 59 and the second valve 61. Therefore, the opening and closing of the valves 59, 61 depends on the fact that the data of ID information supplied through the interface is 64. In other words, the underground tube 40 may be cut or accessed depending on the ID information data. For example, during the day, under hot weather conditions, the ID information data will contain information about high temperatures. The information data may also comprise date and time information from which a certain expected temperature level can be extracted in arid zones. For example, the information that is medium will be sufficient in the deserts as an indication of very hot ambient temperatures without an additional measure of

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temperatures From the information information ID, the drive unit 57 obtains orders SB to open the first valve 59 and to close the second valve 61 so that additional cooling is made available in the underground tube 40. The same may be the case in times of extremely high energy consumption in the energy supply network.

Said control unit 63 can be used in any of the following embodiments as described with reference to Figures 4 and 5. Therefore, it is not shown in the following figures.

Figure 4 shows a power plant 2 ', according to a second embodiment comprising features that optionally complement the features of the invention. Again, the cooling water 13 is pumped through a cooling circuit 11 by a pump 3. It passes through a dry cooling tower 33 as described before entering an underground depth 41 in which an exchanger is located 45 heat In the heat exchanger 45 the cooling water 13 is cooled and additionally conducted to a wet cooling tower 19 as described with reference to Figure 3. The heat exchanger 45 is supplied with a second cooling liquid 46 which is conducted through a second cooling circuit 47 by a second pump 49 of the cooling circuit. This second cooling circuit 47 is in the underground depth 41 so that it is cooled by the underground ground. The second cooling circuit 47 together with the heat exchanger 45 and the second cooling circuit pump 49 therefore constitutes a cooling system 4 according to a second embodiment of the invention.

Figure 5 shows a power plant 2 'according to a third embodiment comprising features that optionally complement the features of the invention. For reasons of clarity, the common characteristics with figures 3 and 4 are not mentioned again. After leaving the dry cooling tower 33, the cooling water 13 is conducted again to an underground depth 41 in which it is located a cold storage 51. It can be seen that said cold storage 51 can also be located above the ground, in which case it is preferably thermally insulated from the outside.

The cold storage 51 is shown in more detail in Fig. 6. It is performed as a pond in which the cooling water 13 is stored in large quantities. In order to cool the cooling water 13, an additional pipe system 53 is conducted with an underground pump 55, so that the cooling water 13 is cooled below the ground and taken back to the cooling tank 51. From the cold storage 51, the cooling water 13 returns to the cooling circuit 11 as shown in Figure 5.

Although the present invention has been described in the form of preferred embodiments and variations therein, it will be understood that numerous modifications and additional variations could be made thereto without departing from the scope of the invention as defined in the appended claims. As mentioned above, cold storage can also be placed above the ground and it is not absolutely necessary to use dry cooling towers and / or wet cooling towers in addition to the cooling system used to perform the method according to the invention.

For the sake of clarity, it should be understood that the use of "a" or "one" throughout this application does not exclude a plurality, and "comprising" does not exclude other stages or elements.

Claims (14)

5 10 fifteen twenty 25 30 35 40 1. Method for cooling a conveyor fluid (5) of a solar power plant, where - the conveyor fluid (5) is used to drive a turbine (29) of the solar power plant (2 '); - the transport fluid comprises water; Y - at least a part of a cooling process is carried out by driving the fluid (5) underground transporting a soil to a depth (41) in which the soil is substantially cooler than ambient air; characterized because - the depth is selected so that there is at least a temperature difference of 10 ° C between the ambient air and an underground region in which cooling takes place, using the thermal inertia of the underground soil. 2. Method according to claim 1, wherein the cooling process is further carried out by conducting a refrigerant fluid (13, 16) to cool the underground ground conveyor fluid (5) to the depth. 3. Method according to claim 1 or 2, wherein a concentrated solar power plant is used as a solar power plant. 4. Method according to any of the preceding claims, wherein the cooling is performed for a conveyor fluid (5) in a solar electric plant (2 ') comprising an air-cooled condenser (35) that performs part of cooling 5. Method according to any of the preceding claims, wherein the cooling is carried out in a solar electric power plant (2 ') comprising a wet cooling system (19), which performs part of the cooling. 6. Method according to any of the preceding claims, wherein the transport fluid (5) and / or the refrigerant fluid (13) is cooled in a heat exchanger (45) connected to a cooling circuit (47). 7. Method according to one of the preceding claims, wherein a cooling process is provided that stores (51) the fluid at a temperature significantly below the temperature of the conveying fluid (5) in the turbine (29). 8. Method according to claim 7, wherein the cold storage (51) is located underground at a depth (41) that is substantially cooler than ambient air. 9. Method according to claim 7 or 8, wherein the cold storage (51) is filled with fluid overnight, which is then supplied during the day. 10. Method according to any of claims 7 to 9, wherein part of the transport fluid (5) and / or part of the refrigerant fluid (13) is stored in a plurality of cold storage (51). 11. Method according to any of the preceding claims, wherein the cooling method is applied during peak power consumption hours. 12. Method according to claim 11, wherein the use of the cooling method is initiated by a drive unit (57) according to variable input data (ID) belonging to temperature information and / or consumption information of power 13. Solar power plant (2 ') with a conveyor circuit (1) with a conveyor fluid (5) in which the conveyor fluid (5) drives a turbine (29) of the power plant, in which - the transport fluid comprises water and - at least a part of the conveyor circuit (1) is conducted underground to a depth (41) that is substantially cooler than ambient air; characterized because - the depth is selected so that there is at least a temperature difference of 10 ° C between the ambient air and the underground area in which the cooling of the transport fluid takes place, using the thermal inertia of the underground soil. 14. Solar power plant according to claim 13, wherein a part of at least one refrigeration circuit with a refrigerant fluid (13, 16) used to cool the conveyor fluid (5) that is driven underground to the depth (41).