Patent Application
20190271300
The present invention is encompassed within the technical field of thermosolar energy, specifically to the generation of energy in thermosolar plants, and more specifically to the harvesting, storing and reusing of solar radiation to heat a heat transfer fluid (HTF) to a temperature suitable for the operation of a power island during periods of low or non existent solar radiation.
The invention relates, in particular, to a cogeneration system for thermal and electric energy production from thermosolar energy, with a solar field connected to a power island by means of a piping system through which a heat transfer fluid (HTF) flows. The piping system comprises at least a photovoltaic panel placed over the piping system, connected to at least a power storage battery, which is further connected to heating means placed at the piping system, which receive electric power from the battery and heat the heat transfer fluid to a temperature suitable for the operation of a power island during periods of low or non existent solar radiation.
The thermosolar technology has experienced a great growth in terms of the generation of electric energy from solar energy, due to its potential and cleanliness with respect to conventional thermal technology.
A thermosolar plant is composed of a solar field in charge of harvesting energy, and of a power island where the harvested energy is processed for the generation of thermal and/or electric energy. This power island can also include a thermal storage system to store the harvested energy for its subsequent contribution when there is no solar radiation. The solar field and the power island are connected by means of a piping system through which a heat transfer fluid (HTF) flows.
In thermosolar technology, the solar energy harvested in the solar fields heats a heat transfer fluid which flows through the piping system. This heat transfer fluid may consist of thermal oil, molten salts, water-steam directly, or others. The heat transferred to this heat transfer fluid is used in the power island for the generation of steam supplying a turbine for the generation of electric energy.
Viability and profitability of thermosolar energy systems mainly relies on improving and developing energy storage systems during daytime with great solar radiation, in order to maintain the thermosolar plant working after sunset. The main competitive advantage of thermosolar plants is the ability to provide energy during the night in geographic areas where it is needed, due to energy storage. Thermosolar energy is currently the only renewable energy having this massive energy storage, which allows to provide energy on demand.
One of the problems of the present energy storage systems used in thermosolar plants is that they are based on molten salt technology. This technology requires a high investment and technically it is a very complex system, what means a blocking factor for the growth and development of this energy systems.
Currently, the most widespread technologies of thermosolar concentration systems are cylindrical parabolic collectors and Fresnel linear concentrators, which concentrate solar radiation into a tube through which the heat transfer fluid flows, this heat transfer fluid being heated to a temperature between 300-600° C. during daytime, by means of the solar radiation reflected by collectors that impact on the surface of the piping system through which the heat transfer flows, and which reaches the power island. The piping system has a plurality of pipe collectors and a thermal insulating system with a metal cladding which protects the insulation, and it may comprise additionally different vessels and/or tanks for storing the heat transfer fluid.
These pipe collectors cover the entire solar fields and form lines of dozens of thousands linear meters of pipes and dozens of thousands square meters of vessels and tanks. So, the outer metal cladding which covers the pipe collectors, vessels and tanks form a metal surface with an area of about dozens of thousands square meters constantly exposed to solar radiation during daytime, since thermosolar plants are located in high solar radiation areas, typically at least 2200 productive solar hours per year. The solar radiation concentrated on this great area of the surface of the metal cladding is an excess of energy not actually used, and it is therefore a wasted energy.
An additional problem associated with the above one is that this excess of energy due to the solar radiation damages little by little the surface of the outer metal cladding, and so this metal cladding will have to be replaced after a few years generating an extra cost to the thermosolar plant.
It is therefore desirable a cogeneration system and method for thermal and electric energy production from thermosolar energy, which takes advantage of the excess of the solar radiation not actually used and additionally protects the metal cladding from this solar radiation.
The present invention provides an advantage with respect to the current generation systems using thermosolar energy, providing a cogeneration system for thermal and electric energy production from thermosolar energy, which takes advantage of the excess of the solar radiation not actually used and additionally protects the metal cladding from this solar radiation.
This is achieved by means of a cogeneration system for thermal and electric energy production from thermosolar energy as disclosed in claim 1 of the present application.
This is a cogeneration system, since it provides both thermal and electric energy from thermosolar energy, and it comprises a solar field which is connected to a power island by means of a piping system through which a heat transfer fluid (HTF) flows.
The piping system comprises a plurality of pipe collectors through which the heat transfer fluid flows, a thermal insulating system covering the pipe collectors, and it may comprise additionally different vessels and/or tanks for storing the heat transfer fluid.
Further, the cogeneration system comprises at least a photovoltaic panel placed over at least a section of the piping system, and fixed to the thermal insulating system. The photovoltaic panel is connected to at least a power storage battery, which is further connected to heating means placed at the pipe collectors, which are configured to receive electric power from the power storage battery and to heat the heat transfer fluid to a temperature suitable for the operation of the power island, that is between 300-600° C. during periods of low or non-existent solar radiation.
Although the system can work with only a photovoltaic panel, a preferred embodiment of the invention comprises a plurality of photovoltaic panels, which cover the entire surface of the piping system.
According to different particular embodiments of the invention, the photovoltaic panels may be rigid or flexible.
In case that the piping system further has one or more vessels and/or tanks for storing the heat transfer fluid, the thermal insulating system will cover said vessels and/or tanks, and according to the present invention, one or more photovoltaic panels will be placed covering the vessels and/or tanks. These photovoltaic panels will also be connected to heating means placed at the pipe collectors, vessels and/or tanks, which are configured to receive electric power from the power storage battery and to heat the heat transfer fluid to a temperature suitable for the operation of the power island during periods of low or non-existent solar radiation.
According to different embodiments of the invention, the heating means may be selected between an electric tracing system wound around at least a section of the pipe collectors, and immersion heaters immersed inside at least a section of the pipe collectors.
In accordance with a preferred embodiment, the thermal insulating system comprises an insulating material, a cladding system that covers the insulating material, and a support structure supporting the insulating material and the cladding system. The support structure comprises in turn a plurality of spacer rings placed under the cladding system. According to this preferred embodiment, the photovoltaic panels are fixed to the thermal insulating system by means of fixing structures which are placed over the cladding system and fixed to the spacer rings. This fixation to the thermal insulating system provides the advantage of avoiding the expensive concrete foundations and steel structures to support the photovoltaic panels properly.
So, the object of the present of the present invention is a system which harvest, store and reuse solar radiation for thermal energy by means of implementing photovoltaic panels directly located on the cladding system of pipe collectors, vessels and/or tanks, using specific fixing structures. The final aim is to maintain the temperature of the heat transfer fluid between a range suitable for the operation of the power island, that is 300-600° C., during periods of low or non-existent solar radiation, for instance at night-time or in cloudy days.
The present invention refers to the development of a new complete system to harvest solar energy by means of photovoltaic panels during sun hours, store it in electrical batteries and later transfer the energy to the heat transfer fluid by means of electrical tracing system and/or immersion heaters. Preferably, the photovoltaic panels are supported on the spacers rings of the insulation and the cladding system using a specific fixing structure designed for a proper panel fixation and, at the same time, with a high absorption of the expansions due to temperature variations.
In this way, the solar radiation, which previously fell on the metal cladding of the piping system and was not actually used, now is harvested by the photovoltaic panels and is stored to be used during periods of low or non-existent solar radiation.
Therefore, the total hours of electric and/or thermal energy production are increased, with a small investment compared to the current storage energy systems of the current thermosolar plants. So, profitability grows, and the present system make thermosolar plants more competitive within the renewable energy field.
Additionally these photovoltaic panels protect the metal against strong solar radiation, lengthening the working life of the whole system and increasing the thermosolar plant profitability according a long-term view.
The invention also relates to a cogeneration method for thermal and electric energy production from thermosolar energy, as disclosed in claim 9 of the present application.
This cogeneration method provides both thermal and electric energy from thermosolar energy, and it comprises the steps of harvesting solar energy by means of a solar field and transferring said energy to a power island by means of a piping system through which a heat transfer fluid flows.
Additionally, the method comprises the steps of harvesting solar energy by means of at least a photovoltaic panel placed over at least a section of the piping system, storing the energy in at least a power storage battery connected to the photovoltaic panel, and heating the heat transfer fluid of the piping system by means of heating means placed at the piping system. These heating means are connected to the photovoltaic panel, and they are configured to receive electric power from the power storage battery and to heat the heat transfer fluid to a temperature suitable for the operation of the power island during periods of low or non existent solar radiation.
The features, functions and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings.
Next, in order to facilitate the comprehension of the invention, in an illustrative rather than limitative manner an embodiment of the invention with reference to a series of figures shall be made below.
These figures refer to the following set of elements:
1. pipe collectors
2. thermal insulating system
3. photovoltaic panels
4. power storage battery
5. heating means
6. heat transfer fluid
7. insulating material
8. cladding system
9. spacer rings
10. fixing structures
11. electric wiring system
An object of the present invention is a cogeneration system for thermal and electric energy production from thermosolar energy.
This cogeneration system has a solar field connected to a power island by means of a piping system through which a heat transfer fluid (HTF) 6 flows.
As shown in the figures, the piping system comprises a plurality of pipe collectors 1 through which the heat transfer fluid 6 flows, a thermal insulating system 2 which covers the pipe collectors 1, and it may comprise additionally different vessels and/or tanks for storing the heat transfer fluid 6 when necessary.
Further, the cogeneration system of the present invention comprises one or more photovoltaic panels 3 placed over at least a section of the piping system, and fixed to the thermal insulating system 2. The photovoltaic panels 3 are connected to at least a power storage battery 4, which is further connected to heating means 5 placed at the pipe collectors 1. These heating means 5 are configured to receive electric power from the power storage battery 4 and to heat the heat transfer fluid 6 to a temperature suitable for the operation of the power island during periods of low or non-existent solar radiation.
Although the system can work with only a photovoltaic panel 3, a preferred embodiment of the invention comprises a plurality of photovoltaic panels 3, as disclosed in
According to different particular embodiments of the invention, the photovoltaic panels 3 may be rigid or flexible.
For certain embodiments in which the piping system further has one or more vessels and/or tanks for storing the heat transfer fluid 6, the thermal insulating system 2 will cover said vessels and/or tanks, and according to the present invention, one or more photovoltaic panels 3 will be placed covering the vessels and/or tanks. These photovoltaic panels 3 will also be connected to heating means 5 placed at the pipe collectors 1, vessels and/or tanks, which are configured to receive electric power from the power storage battery 4 and to heat the heat transfer fluid 6 to a temperature suitable for the operation of the power island during periods of low or non-existent solar radiation.
According to different embodiments of the invention, the heating means 5 may be selected between an electric tracing system wound around at least a section of the pipe collectors 1, and immersion heaters that are immersed inside at least a section of the pipe collectors 1.
The electric tracing system will wrap the outer surface of the pipe collectors 1, vessels and/or tanks that transport the heat thermal fluid 6 up to the power island, providing the suitable temperature for the operation of said power island, typically 300-600° C. In case of immersion heaters, they will be placed partially inside the pipe collectors 1, vessels and/or tanks to heat directly the heat thermal fluid 6. In both cases, the working hours of the thermosolar plant will increase, until batteries are completely discharged.
So, the photovoltaic panels 3 harvest solar energy during strong solar radiation, and it is transported through an electric wiring system 11 to the storage power storage batteries 4 located on lower part of the piping system. Therefore, during strong solar radiation periods the batteries 4 will be charged by the photovoltaic panels 3 and during periods of low or non-existent solar radiation, they will be activated to power the electric tracing system and/or immersion heaters previously installed around or inside the containment elements of the heat transfer fluid, e.g. pipe collectors 1, vessels and/or tanks.
In accordance with a preferred embodiment, the thermal insulating system 2 comprises an insulating material 7, a metal cladding system 8 that covers the insulating material 7, and a support structure supporting the insulating material and the cladding system. The support structure comprises in turn a plurality of spacer rings 9 placed under the cladding system 8. According to this preferred embodiment, the photovoltaic panels 3 are fixed to the thermal insulating system 2 by means of fixing structures 10 placed over the cladding system 8 and further fixed to the spacer rings 9. The rigid or flexible photovoltaic panels 3 are lightweight, less than 4 kg/m2, and so they can be supported on small fixing structures 10 directly located on the cladding system 8 and fixed to the spacer rings 9. Due to this low weight of the photovoltaic panels 3, the existing metal cladding system 8 and spacer rings 9 of the existing piping systems could admit this little overload with minimum resizing and alterations, without additional complex structures made of heavy steel and additional concrete bedplates that are usually needed to support conventional panels.
In this way, the solar radiation, which previously fell on the metal cladding of the piping system and was not actually used, now is harvested by the photovoltaic panels 3 and is stored to be used during periods of low or non-existent solar radiation. Additionally these photovoltaic panels 3 protect the metal cladding 8 from the solar radiation, as shown in
Another object of the invention is a cogeneration method for thermal and electric energy production from thermosolar energy, as disclosed in claim 9 of the present application.
This cogeneration method provides both thermal and electric energy from thermosolar energy, and it comprises the steps of harvesting solar energy by means of a solar field and transferring said energy to a power island by means of a piping system through which a heat transfer 6 fluid flows.
Further, the method comprises the steps of harvesting solar energy by means of one or more photovoltaic panels 3 placed over at least a section of the piping system, storing the energy in at least a power storage battery 4 which is connected to the photovoltaic panels 3, and heating thus the heat transfer fluid 6 of the piping system by means of heating means 5 placed at the piping system. These heating means 5 are connected to the photovoltaic panels 3, and they are configured to receive electric power from the power storage battery 4 and to heat the heat transfer fluid 6 to a temperature suitable for the operation of the power island during periods of low or non existent solar radiation.
Once the invention has been clearly described, it is hereby noted that the particular embodiments described above can be the subject of detail modifications as long as they do not alter the fundamental principle and the essence of the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/ES2017/070791 | 12/13/2017 | WO | 00 |
