JP2011000012A - Plant factory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plant factory solving the following problem in a conventional plant factory utilizing solar light and artificial light for illumination: the solar light containing the wave length area of near-infrared ray damaging for plants is radiated to plants; and the illumination of the artificial light requires much electric power and thereby results in having a problem from the aspects of economical efficiency, energy saving and environmental burden.SOLUTION: The plant factory works as follows: splitting the solar light into visible light useful for the growth of the plants, and near-infrared light making solar battery have highest power generation efficiency while damaging for the growth of the plants; irradiating the plants with only the visible light; and irradiating the solar battery with the near-infrared light to generate and store electric power so as to utilize also to the power supply for the artificial light.

Description

  The present invention is economical in that a plant factory that uses sunlight and artificial light as illumination to grow a plant can irradiate a part of solar rays to a solar cell to generate power and use it for supplying artificial light. It relates to a plant factory with low energy consumption and low environmental impact.

  When agricultural products such as vegetables are cultivated in outdoor fields, the degree of growth is easily affected by the weather, and the yield may be reduced due to damage such as typhoons and heavy rains or damage by pests. Moreover, since a large land area is required for cultivation of these agricultural products, it is difficult to secure a sufficient cultivation area in a narrow land.

  Therefore, recently, a technique for artificially cultivating these agricultural products in the factory has been developed and is known as a plant factory. Since plants grow by photosynthesis, it is most important in plant factories to irradiate plants with sunlight or artificial light instead of sunlight. In recent years, as described in Non-Patent Document 1, etc., the performance of fluorescent lamps and LEDs has been improved, and attempts have been actively made to grow vegetables in basements, buildings, or factories by artificial light illumination. Is in a situation.

  When cultivating vegetables using LEDs, as shown in FIG. 1, there is a method of arranging and arranging a large number of LEDs directly above a stock such as vegetables. Here, 1 is a shelf, 2 is a trench, and 3 is an LED. Many vegetables are installed in the trench 2 and are hydroponically cultivated. One shelf is generally stacked vertically and horizontally in multiple stages.

  There is also a method in which LEDs are installed at a location different from the vegetable cultivation location, and the light from the LEDs is guided to the top of the vegetable stock by optical fiber. There is also a method in which sunlight is condensed by a Fresnel lens, incident on an optical fiber, and guided directly to the vegetable stock.

  Further, as shown in FIG. 2, a method of using both LED and sunlight is possible by using an optical fiber and an optical switch. Here, 41, 42, 43, and 44 are optical fibers, 5 is a sunlight condensing lens, and 6 is an optical switch.

  In this case, LED light and sunlight can be electrically switched by an optical switch, and can be automatically switched to either LED or sunlight depending on the intensity of sunlight, and always irradiates the LED. Compared to the case, there is an advantage that the energy cost is lowered.

  On the other hand, the combined use of LED and sunlight has attracted much attention recently as it can stably irradiate vegetables with light compared to the case where only sunlight is always used.

  A vegetable factory using these optical fibers has been filed as Japanese Patent Application No. 2009-025523.

"LED Light Source, Plant Factory Handbook" Tokai University Press, 1997

  From the viewpoint of energy saving, the combined use of sunlight and LED light is considered the most suitable as a light source for plant factories, but in this case, there were the following problems.

  In general, light of a red wavelength is suitable for plant growth, and it is considered that a part of blue is also necessary. When only LEDs are used, the wavelength is determined by the type of LED. Therefore, if LEDs that emit red and blue light are arranged and irradiated at desired ratios, irradiation can be performed only at the optimum wavelength for the plant.

  On the other hand, it is said that irradiation in the wavelength region near 950 nm is not preferable for plant growth. However, for example, if sunlight is guided to a plant strain using an optical fiber made of silica glass and irradiated, light in a wide range of wavelengths including the near infrared wavelength region near 950 nm is irradiated on the plant. Become.

  Therefore, in a plant factory in which sunlight is guided by an optical fiber, there has been a problem that irradiation in a wavelength range that is undesirable for plants is unavoidable.

  In addition, if a wavelength filter or the like is used, it is possible to remove the wavelength range unnecessary for plant growth from sunlight and enter the optical fiber to irradiate the plant. In this case, the sunlight blocked by the wavelength filter is used. In the end, the light was wasted, and there was a problem that it was not preferable from the viewpoint of realizing an economical plant factory that uses more of the light energy of the sun and saves energy and has a low environmental impact.

  The present invention is obtained by further improving Japanese Patent Application No. 2009-025523 in order to solve the problems described above.

  In order to solve the problems in the prior art, in the present invention, light in the wavelength range near 950 nm that is unnecessary and harmful to plants is conversely matched with the wavelength range in which the luminous efficiency of the silicon solar cell is highest. The characteristics were used.

  FIG. 3 schematically shows the wavelength dependence of the photoelectric conversion efficiency of a single crystal silicon solar cell. The horizontal axis indicates the wavelength of light, the left vertical axis indicates the sunlight intensity, the right vertical axis indicates the photoelectric conversion efficiency of the solar cell, the dotted line indicates the sunlight intensity, and the solid line indicates the conversion efficiency of the solar cell. In both cases, the vertical axis is expressed as a relative value.

  As can be seen from FIG. 3, the photoelectric conversion efficiency of the single crystal silicon solar cell is maximum near 950 nm, and is less than about 70% of 950 nm below 800 nm.

  In other words, sunlight is divided into long-wavelength light (mainly near-infrared light) of, for example, 800 nm or more by a wavelength filter and short-wavelength light (mainly visible light) of 800 nm or less, and near-infrared light of 800 nm or more If the light is used for solar power generation and used to supply LED power, and sunlight in the visible wavelength range including red below that is incident on an optical fiber and used for plant cultivation, the problems of the prior art can be solved. become.

  Specifically, in the space before sunlight enters the optical fiber, a wavelength filter that reflects a long wavelength region of 800 nm or more and transmits the other short wavelength region is inserted, and a solar cell is provided on the reflected light side of 800 nm or more. And a means for arranging an optical fiber on the wavelength transmission side below that.

  The electric power generated by the solar battery is charged into the battery and can be used as power to the LED as needed.

  Here, the wavelength divided by the wavelength filter is typically 800 nm, but this is intended to remove light near 950 nm, so there is an essential difference between dividing at 750 nm and dividing at 850 nm. Is not included in the scope of the present invention.

  In the present invention, when sunlight is guided by an optical fiber for use in plant cultivation, irradiation suitable for plant cultivation is possible because it can be irradiated with sunlight excluding light in the wavelength range near 950 nm that is harmful to plant growth. An environmental plant factory can be realized.

  In addition, light in the long wavelength range of 800 nm or more that is not used for irradiation of plants is used as light-electrical conversion energy for silicon solar cells, and is used as power for irradiation with artificial light such as LEDs. The energy saving effect is extremely large. Furthermore, according to the present invention, the entire wavelength range of sunlight can be used effectively, so the load on the environment as a whole plant factory is extremely small.

Schematic diagram of a plant factory with LED lighting. A schematic diagram of a plant factory that uses both sunlight and LEDs. Schematic diagram of wavelength dependence of light-electric conversion efficiency of a single crystal silicon solar cell. The schematic diagram of the plant factory by the present invention (Example 1).

FIG. 4 shows a schematic diagram of a plant factory according to the present invention. Here, 7 is a wavelength filter, 8 is a solar cell, 91 and 92 are power cables, and 10 is a capacitor.
An actual plant factory has a structure in which a plurality of units shown in FIG. 4 are combined, and only a part of them is shown here.

  Sunlight is collected by a condenser lens 5 and is incident on 41 optical fibers. A wavelength filter 7 is inserted between the condenser lens 5 and the optical fiber 41 to reflect a long wavelength region of 800 nm or more and transmit a short wavelength region of 800 nm or less.

  The optical fiber used may be a normal germanium-doped silica fiber or a fluorine-clad silica fiber. However, air-clad silica optical fiber was used here because of its economic viewpoint and NA, which is very large and suitable for illumination.

  Long wavelength sunlight of 800 nm or more reflected by the wavelength filter 7 was made incident on the solar cell 8 and used for power generation.

  On the other hand, mainly visible light transmitted through the wavelength filter 7 was irradiated to the plant through 41, 43 and 44 optical fibers.

  During the period of direct sunlight, the 6 optical switch operated to guide sunlight with a wavelength shorter than 800 nm to 43 optical fibers, and the 3 LEDs stopped emitting light.

  In a time zone where it was not exposed to direct sunlight or in rainy weather, 3 LEDs were turned on and entered into 42 optical fibers. In this case, the optical switch 6 was operated so as to optically couple 42 optical fibers and 43 optical fibers. The electricity that was generated by 9 solar cells when it was clear and charged to 10 capacitors with 91 cables was provided for light emission of 3 LEDs via 92 cables.

  In this way, sunlight and LEDs are used together, and plants are cultivated with light that blocks light components harmful to plants from sunlight, and the blocked solar energy is used for power generation of solar cells. Therefore, the energy saving effect has been doubled compared to the plant factory where the irradiation light source is only LED. Moreover, since the harmful wavelength was not included in illumination light, the growth condition of the plant was also very favorable.

  Furthermore, compared with the case where sunlight and LED are used in combination, in this embodiment, the supply from the commercial power source to the LED can be reduced, and the energy saving effect is remarkable.

1 Shelf 2 Trench 3 LED
41, 42, 43, 44 Optical fiber 5 Condensing lens 6 Optical switch 7 Wavelength filter 8 Solar cell
91,92 power cable
10 Battery

Claims (4)

  In a plant factory that cultivates plants by sunlight and artificial light, a wavelength filter that separates sunlight into visible light and near infrared light, and an optical fiber that guides the visible light or artificial light and irradiates the plant A solar cell for generating power using the near-infrared light, a capacitor for storing the power generated by the previous solar cell, and at least artificial light that emits light using the power from the capacitor. A feature plant factory.   2. The plant factory according to claim 1, wherein the near infrared light has a wavelength range of 800 nm or more.   A plant factory comprising an optical switch for switching so that light incident on the optical fiber according to claim 1 is either the sunlight or the artificial light. The optical fiber according to claim 1, wherein the core is a quartz glass, and is an air-clad optical fiber surrounded by a protective quartz glass tube that is not in contact with most of the side surface of the core. factory.