WO2020204858A1

WO2020204858A1 - A lighting system for multi-layer greenhouses

Info

Publication number: WO2020204858A1
Application number: PCT/TR2020/050182
Authority: WO
Inventors: Refet Ali YALCIN; Hakan Erturk
Original assignee: Bogazici Universitesi
Priority date: 2019-03-29
Filing date: 2020-03-06
Publication date: 2020-10-08
Also published as: TR201904787A2

Abstract

The present invention relates to a lighting system (1) for multi-layer greenhouses (S) comprises at least one light collector (2) to be positioned on a multi-layer greenhouse (S) roof (R) for collecting daylight/sunlight (G); a fiber optic array (3) on which the light collector (2) focuses the daylight/sunlight (G); at least one fiber optic splitter (5) for distributing the daylight/sunlight (G) in the fiber optic array (3) to the fiber optic cables (4) located in at least one layer (O) of the multi-layer greenhouse (S); and a reflector unit (6) having at least one light reflecting surface (6.1) provided at the back to be positioned in an area above at least one fiber optic cable (4) end for reflecting the daylight/sunlight (G) coming out from the end of a fiber optic cable (4) to a photosynthesizing biomass (B) in the layer (O), a middle layer (6.3) containing fluorescent particles (6.2) which absorb the light in the spectrum that the biomass (B) cannot utilize and/or utilizes with low efficiency for photosynthesis and which emit in the spectrum that it uses in high efficiency, and an anti-reflection coating (6.4) at the front.

Description

A LIGHTING SYSTEM FOR MULTI-LAYER GREENHOUSES

Field of the invention

The present invention relates to a lighting system for multi-layer greenhouses.

Background of the invention

Agricultural production is carried out in indoor or outdoor areas. While the cost of outdoor agricultural production is relatively low, production efficiency is limited since it depends on climate conditions. Greenhouses are enclosed environments for cultivating plants with roofs built from radiation transmitting materials, which shield the plants from climate related constraints and diseases. Agricultural areas are decreasing despite an increase in demand for food due to an increase in population. Therefore, nowadays the importance of greenhouses is increasing day by day. Accordingly, scientific studies are carried out to increase the efficiency of greenhouses. These studies include indoor temperature control, checking the condensation on the outer coatings in order to reduce the light blockage occurring due to condensation, ensuring the transmission and scattering of light through the outer surface coatings, and enabling light to be more efficient for photosynthesis with fluorescent materials. (S. Pearson, A.E. Wheldon, P. Hadley, "Radiation transmission and fluorescence of nine greenhouse cladding materials", Agric. Eng. 62 (1995) 61-70. doi: http://dx.doi.org/10.1006/jaer.1995.1063).

Vertical farming practices have been launched in greenhouses in recent years in order to prevent cost and transportation difficulties due to the distances of the greenhouses to cities. Systems defined as multi-layer or vertical greenhouses are becoming more and more common and there have been significant developments regarding multi-layer greenhouses. The cost of land for greenhouses has been reduced by means of applying multilayers within the same area, thus making it possible for the greenhouses to be installed near cities. However, high lighting costs arise in multilayer greenhouses due to the installment of light fixtures and the amount of electricity consumption. In order to reduce these costs, systems which are installed onto the roof of greenhouses and distribute the light that is collected therein into the structure are being utilized.

In addition, the world’s leading space research institutions have declared plans for space colonization as a result of developing space research. It is a known fact that the radiation spectrum distribution will be different in an environment where there is no atmosphere or the atmosphere is different. The Earth’s atmosphere filters the spectra of the radiation from the sun that are harmful for plants such as ultraviolet (UV) and it is unsuitable for plants that have evolved in our world to be exposed to a different light wavelength such as UV. Therefore, it is predicted that plant cultivation beyond earth and its atmosphere will be carried out within enclosed greenhouses where plants will not be exposed to direct light. It is foreseen that systems that collect and distribute sunlight or artificial light sources will be utilized in the greenhouses mentioned above.

Plants cannot absorb every spectrum of radiation from the sun with the same efficiency, for example green plants reflect green light more. This brings a natural limit to product yield.

Coatings that use fluorescent or scattering particles on standard single-layer greenhouses reflect more than half of the radiation from the sun to the exterior of the greenhouse. Due to the rays reflected off the exterior of the greenhouse, the radiation in the unit area decreases significantly. Plants are exposed to less radiation compared to a situation where there is no coating and greenhouse efficiency decreases as the amount of utilizable light decreases. Installation costs for lighting systems in multi-layer vertical farming are high. The high cost of electricity and the cost of replacing the end-of-life lamps are faced in greenhouses where lamps are utilized for lighting.

As an alternative to lighting with lamps, there are greenhouses that collect sunlight and distribute the light throughout the building through fiber optic cables. In these types of greenhouses, the light is distributed with the help of lenses that have been designed to be compatible with the human eye. The light is unable to be distributed evenly to the shelves where the plants are located due to the lenses that are used. Various attempts of finding a solution such as increasing shelf height and/or the number of fiber cables have not yielded the desired efficiency and increased greenhouse installation costs.

In agricultural practices outside of Earth’s atmosphere, natural light cannot be directly utilized due to the fact that UV wavelengths are not absorbed by the atmosphere. Converting the spectra of light, which can harm plants and which is not utilized or utilized with low efficiency, to ones which can be utilized with higher efficiency accelerates plant growth and increases efficiency. For example, filtering IR rays prevents increase in greenhouse temperatures thereby both increasing efficiency and reducing ventilation expenses. In addition, plant health will be preserved by preventing the spectra of the radiation that may be harmful to plants, such as UV, from reaching the plant. Plant growth efficiency can be increased by using coatings that contain fluorescent additives, which absorb the rays in the spectrum that the plants cannot use for photosynthesis (especially UV and IR rays) and/or use in low efficiency, and which can emit in the spectrum used by the plants in high efficiency (S. Pearson, A.E. Wheldon, P. Hadley, "Radiation transmission and fluorescence of nine greenhouse cladding materials", Agric. Eng. 62 (1995) 61-70. doi: http://dx.doi.org/10.1006/jaer.1995.1063).

The patent document numbered US20090148931A1 discloses a device, method and illumination system for cultivating biomasses including plants. The patent document numbered US6603069B1 discloses a solar energy system consisting of a parabolic-dish solar concentrator and solar tracking system.

The objective of the present invention is to provide a lighting system for multi layer greenhouses, wherein daylight/solar rays are filtered and converted to spectra efficient for photosynthesis and transmitted to biomasses that perform photosynthesis and the loss of radiation reflected to the exterior of the greenhouse is prevented.

Another objective of the present invention is to provide a lighting system for multi-layer greenhouses where overall production is increased by exposing the biomasses in the multi-layer greenhouse to an equal amount of radiation.

With the present invention, a substantial increase is achieved especially in latitude-dependent biomass production. The rate of increase can be expected to be higher especially at higher latitudes, where light is relatively limited. Through the filtering of daylight/solar rays, farming outside the Earth’s atmosphere has been made possible and agricultural production has been increased.

Detailed Description of the Invention

An example embodiment of the lighting system for multi-layer greenhouses developed to fulfill the objectives of the present invention is illustrated in the accompanying figures for a better understanding of the invention. The details of the present invention should be evaluated taking into consideration the full description of the invention, and the following figures are;

Figure 1. is a schematic view of the lighting system for multi-layer greenhouses in an example embodiment of the invention. Figure 2. is a schematic view of the beam collector that is a parabolic-dish solar (G) concentrator in an example embodiment of the invention.

Figure 3. is a schematic view of the reflector unit in an example embodiment of the invention.

The components shown in the figures are each given reference numbers as follows:

1. Lighting system

2. Light collector

1.1.First parabolic reflector

1.2. Second parabolic reflector

3. Fiber optic array

4. Fiber optic cable

5. Fiber optic splitter

6. Reflector unit

6.1 Light reflecting surface

6.2 Fluorescent particles

6.3 Middle layer

6.4 Anti-reflection coating

6.5 Scattering particles

G. Sun/Sunlight/Solar

C. Roof

S. Multi-layer greenhouse

O. Layer

B. Biomass

The lighting system (1) for multi-layer greenhouses (S) comprises at least one light collector (2) to be positioned on a multi-layer greenhouse (S) roof (R) for collecting daylight/sunlight (G); a fiber optic array (3) on which the light collector (2) focuses the daylight/sunlight (G); at least one fiber optic splitter (5) for distributing the daylight/sunlight (G) in the fiber optic array (3) to the fiber optic cables (4) located in at least one layer (O) of the multi-layer greenhouse (S); and a reflector unit (6) having at least one light reflecting surface (6.1) provided at the back to be positioned in an area above at least one fiber optic cable (4) end for reflecting the daylight/sunlight (G) coming out from the end of a fiber optic cable (4) to a photosynthesizing biomass (B) in the layer (O), a middle layer (6.3) containing fluorescent particles (6.2) which absorb the light in the spectrum that the biomass (B) cannot utilize and/or utilizes with low efficiency for photosynthesis and which emit in the spectrum that it uses in high efficiency, and an anti-reflection coating (6.4) at the front.

Plants, algae, planktons, bacteria, animals (e.g. Elysia chlorotica) are examples of photosynthesizing biomasses (B).

An embodiment of the lighting system (1) of the present application comprises a middle layer (6.3) including scattering particles (6.5). Examples of scattering particles (6.5) are titanium dioxide particles, and polyethylene or polycarbonate for the material of the middle layer (6.3). The middle layer (6.3) can also be formed only by the deposition of scattering particles (6.5) and fluorescent particles (6.2) on the light reflecting surface (6.1) without utilizing polyethylene or polycarbonate. The middle layer (6.3) can also be formed only by the deposition of fluorescent particles (6.2) on the light reflecting surface (6.1) without utilizing polyethylene or polycarbonate.

Another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof comprises a solar (G) tracking mechanism that enables the light collector (2) to be directed towards the sun (G).

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the light collector (2) is a parabolic-dish solar (G) concentrator. An exemplary parabolic-dish solar (G) concentrator includes a first parabolic reflector (2.1) that directs the daylight/sunlight (G) coming from the outer environment to a second parabolic reflector (2.2) that is located across from it. The second parabolic reflector (2.2) transmits the received daylight/sunlight (G) to the fiber optic array (3) located in the center of the first parabolic reflector (2.1).

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the light collector (2) is a parabolic groove.

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the light collector (2) is a Fresnel lens.

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the middle layer (6.3) is a translucent medium.

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the middle layer (6.3) is a borosilicate glass or lens.

In another embodiment of the lighting system (1) of the present application adaptable to all embodiments thereof, the fluorescent particles (6.2) are contained in a polyethylene-based film.

An exemplary principle of operation of the lighting system (1) of the present application is as follows;

The daylight/sunlight (G) is projected onto the fiber optic array (3) via the light collector (2) positioned on the roof (R) of the multi-layer greenhouse (S). The daylight/sunlight (G) in the fiber optic array is distributed to the fiber optic cables (4) via the fiber optic splitter(s) (5). The daylight/sunlight (G) is carried to the layer(s) (O) by means of the fiber optic cables (4) which extend to the layer(s) (O) of the multi-layer greenhouse (S). The daylight/sunlight (G) leaving the fiber optic cables (4) is directed to the reflector units (6) which are located in an area opposite to/above the ends of the fiber optic cables (4). The daylight/sunlight (G) first falls onto the anti-reflection coating (6.4) of the reflector unit (6). The vast majority of the daylight/sunlight (G) is received into the middle layer (6.3) due to the presence of anti-reflection coating (6.4). By means of the fluorescent particles (6.2) contained in the middle layer (6.3), daylight/sunlight (G) is filtered and the light in the spectrum that the biomass (B) cannot utilize for photosynthesis and/or utilizes with low efficiency is absorbed, and radiation in the spectrum that it uses with high efficiency is emitted. In practice, if the middle layer contains scattering particles (6.5), the daylight/sunlight (G) and/or the light in the said spectrum is distributed or scattered by the scattering particles (6.5). The daylight/sunlight (G) distributed or scattered by the scattering particles (6.5) is also absorbed by means of the fluorescent particles (6.2) to emit in the more efficient spectrum. Thus, the un-absorbed daylight/sunlight (G) ratio is minimized by using less fluorescent material. The light in the more efficient spectrum is reflected back through the light reflecting surface (6.1) located at the back of the middle layer (6.3) and is projected onto the biomass (B) in the multi-layer greenhouse (S) layer (O).

Claims

1. A lighting system (1) for multi-layer greenhouses (S) comprising at least one light collector (2) to be positioned on a multi-layer greenhouse (S) roof (R) for collecting daylight/sunlight (G); a fiber optic array (3) on which the light collector (2) focuses the daylight/sunlight (G); at least one fiber optic splitter (5) for distributing the daylight/sunlight (G) in the fiber optic array (3) to the fiber optic cables (4) located in at least one layer (O) of the multi-layer greenhouse (S); and a reflector unit (6) having at least one light reflecting surface (6.1) provided at the back to be positioned in an area above at least one fiber optic cable (4) end for reflecting the daylight/sunlight (G) coming out from the end of a fiber optic cable (4) to a photosynthesizing biomass (B) in the layer (O), a middle layer (6.3) containing fluorescent particles (6.2) which absorb the light in the spectrum that the biomass (B) cannot utilize and/or utilizes with low efficiency for photosynthesis and which emit in the spectrum that it uses in high efficiency, and an anti-reflection coating (6.4) at the front.

2. A lighting system (1) for multi-layer greenhouses (S) according to Claim 1, comprising a medium layer (6.3) containing scattering particles (6.5).

3. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a solar (G) tracking mechanism that enables the light collector (2) to be directed towards the sun (G).

4. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a light collector (2) which is a parabolic-dish solar (G) concentrator.

5. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a light collector (2) which is a parabolic groove.

6. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a light collector (2) which is a Fresnel lens.

7. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a middle layer (6.3) which is a translucent medium.

8. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising a middle layer (6.3) which is a borosilicate glass or lens.

9. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising fluorescent particles (6.2) contained in a polyethylene-based film.

10. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising fluorescent particles (6.2) that have been applied on the light reflecting surface (6.1).

11. A lighting system (1) for multi-layer greenhouses (S) according to any one of the preceding claims, comprising fluorescent particles (6.2) and scattering particles (6.5) applied to the light reflecting surface (6.1).