GB2589925A

GB2589925A - Crop growth system

Info

Publication number: GB2589925A
Application number: GB1918412.6A
Authority: GB
Inventors: Frost Mark; Denham Nicholas
Original assignee: I Growing Ltd
Current assignee: I Growing Ltd
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2021-06-16
Also published as: GB201918412D0

Abstract

A crop growth system comprises an array 5 of light emitting devices mounted within an enclosure 1 and arranged over a crop growing surface 4, the array of light emitting devices providing the light used by the crop while in the container. A photovoltaic array 11 is mounted externally of the enclosure 1, the photovoltaic array providing at least 50% of the energy required to power the array of light emitting devices while the crop is in the container. The photovoltaic array may be connected to storage means (40, figure 3) configured to power the light emitting devices, the light emitting devices maybe light emitting diodes (LEDs) which may comprise red, blue and UVA LEDs. The colour mix and intensity may be varied. In another embodiment, a crop growth system comprises an array of light emitting devices 36 mounted within a wheeled enclosure (figures 3 and 4) and locatable over a crop growing surface, and a power supply mounted on the wheeled enclosure providing electrical power for the light emitting devices.

Description

CROP GROWTH SYSTEM

Field of the Invention

This invention relates to a crop growth system providing artificial growth light using arrays of light-emitting devices.

Background to the Invention

There has been a lot of development in the use of artificial lighting to promote crop growth in glasshouses in the last 2 decades years. Even more recently, many of these developments have been adapted and applied to growing crop in cabins and warehouses, often in the complete absence of any natural light source. The development of LEDs has accelerated this trend providing the possibility to better match the spectrum of the light to the crop being growing. Such systems have often featured red and blue LEDs in arrays or individual LEDs designed to output spectra rich in red and blue Light. Some systems have included other spectrally different LEDs in order to provide a broader spectral 'recipe' to the crop.

Much of the focus recently has been on lighting recipes for specific crops with some LED chips providing specific remote phosphor materials to create a specific spectral output that cannot be achieved with a single LED chip. Such LEDs often give a pink or purple output rich in red and blue light. Light in these parts of the spectrum are known to promote photosynthesis and so are often preferred for growing crops. However, most plants require a variety or wavelengths to develop and grow healthily and the optimum spectral composition and intensity changes throughout the plants life, through germination, propagation, vegetative growth to fruiting and harvesting. In nature, these wavelengths are provided by the sunlight but in indoor farming some or all of this light is must be provided from the artificial light sources (in most cases LEDs). All such lights require electricity to power them and consequently, total power required to arrive at the final desired plant is a critical factor.

However, up to know, the systems in use have been very wasteful in terms of energy with many inherent inefficiencies built in to the system architec-tures. The inefficiencies manifest in three main ways: 1. The generation of excess heat; 2. The misdirection of light (so the generated light does not fall on the plants); 3. The waste of light by generation of wavelength that the plant cannot absorb either the wrong wavelengths or a level of intensity of the right wavelengths greater than the plant can absorb.

It is worth noting that, in a fully enclosed growing space, any of the above inefficiencies can create heat in the environment which may need to be removed via air conditioning. The air conditioning energy load gives rise to a secondary parasitic energy load. In a system where the energy is supplied via the to grid, these inefficiencies add to running costs and capital costs of the installa-tion. If, however, the installation is intended to run on energy generated only from self-generated sources (e.g. solar panels, wind turbines, small scale CHP units etc.) the inefficiencies give rise to a significant over-specification of such devices (in terms of output and cost).

Summary of the Invention

According to the invention, there is provided a crop growth system comprising an array of light emitting devices mounted within an enclosure and arranged over a crop growing surface, a photovoltaic array mounted externally of the enclosure, the photovoltaic array being electrically connected to electricity storage means and the light emitting devices being powered by the electricity storage means.

Preferably, the light emitting devices are light emitting diodes and are suitably configured to emit light in the blue and red wavelengths.

More preferably, the system comprises a plurality of LED chips of fixed spectral output connected electrically such that the power to the chips can be varied simultaneously to alter the intensity of the light output from the plurality of connected chips. The electrical connections between the chips may be made by wiring them together or mounting them on a PCB or some combination of the two. The power supply to the chips will be direct current (DC) with a voltage typ-ically less than 100V and more preferably less than 66V.

The DC power is preferably be provided to the LED chips via cabling from one or a plurality of DC buses or by PoE (power over Ethernet) or some -3 -combination thereof with any AC power entering the container being inverted into low voltage DC prior to connection to the DC buses or PoE injectors.

The system may further comprise a plurality of arrays of similarly connected LED chips of different spectral outputs enabling the system to light di- rected to the growing area to be varied in both spectral composition and intensi-ty simultaneously. The effect of this approach ensures the crop can receive only a sufficiency of light to promote the required rate of growth without wasting energy on generation of light that cannot be used by the crop at its stage of growth.

Another feature of the system is the minimal use of lenses and coverings for the LED chips. Any membrane that covers the chip will absorb some of its output. However, as the growing environments are typically high in moisture, some level of covering may be necessary for electrical safety and integrity. A thin and highly optically transparent membrane is therefore selected to ensure that at least 90% and more preferably 95% of the light generated from the LED is transmitted into the growing area. One preferred embodiment is the use of a conformal coating to cover the LED, though other approaches are also contemplated such as glass coatings or vapour deposited transparent layers, polymer coatings or thin and highly transparent glass or polymer or composite covers or films.

The LED chips in each array are preferably arranged in such a way as to provide uniform light intensity across the target growing area and use of lenses and reflectors may be required to direct the light to retain as much of the light within the growing area as possible.

The spectrally different arrays of LEDs may be independently varied to create spectral recipes that can be changed with time as the crop develops and even varied during the course of a day, for example to simulate the spectral and intensity changes of sunlight over a day. Each system may comprise at least 3 but more preferably 3 or more spectrally specific arrays. The system will often comprise a red and a blue array and may add other arrays with different visible and non-visible emission spectra including UV and Near Infrared. In one such embodiment, an array consisted of 5 LED arrays including red, blue, UVA, far -4 -red (NIR) and a broad spectrum white LED. Some of the arrays may only be illuminated intermittently. For example, the white array may be lit for crop inspection only or to provide light for illuminating sticky pest control cards to attract aphids and other pests away from the crop. These cards are often yellow and do not function in some light sources. The UV may be lit to control mildew or other deleterious effects or similarly to provide a light source illuminate a fluorescent sticky pest control card.

The use of a UV or blue array may also fulfil a further function to provide a source of light for the creation of alternative spectra that the LED arrays in the basic arrangement do not provide. These additional spectra may be provided by down-converting the blue or UV light using a film or coated transparent material containing a remote phosphor such as the Luminsphere materials supplied by Chromition Ltd. This approach provides a flexible means to modify the lighting spectra without the need for many more LED arrays as most of these spectra will only be required at specific points in the plant's growth cycle and may be added to promote development of specific flavour or colour chemicals within the plant. The film or transparent substrate containing or supporting the remote phosphor material may be on a roll that can be rolled out between the lighting unit and the crop when the spectrum generated by the remote phosphor is re-quired and removed when it is not. The power supplies to the individual LED arrays may be computer controlled to provide pre-programmed lighting regimes and such regimes may be visualised and altered remotely via cloud based databases or network server systems.

The lights may be combined in the container to create a growing system with hydroponics or other plant support and nutrient transport systems, fans and air circulation systems and air conditioners. In a preferred embodiment, all power to fans, air conditioning and pumps for watering and irrigation systems shall be low voltage DC, with voltages less than 100V and more preferably less than 66V. Such devices may be powered directly from batteries using stored energy from the grid or from solar, wind or some other form of local generation.

Alternatively, the devices may be powered directly from the solar array via a charge controller feeding power into a DC power distribution and control unit -5 -such as a 'Solar Primed' power bar supplied by Extreme Low Energy Limited. Preferred embodiments may have no supply of AC electricity or only take a single supply of AC electricity and convert this supply via an inverter into a single DC supply prior to distributing said DC supply thorough the container.

One embodiment of the lighting system described above is a unit de-signed for assisting the growing of plants outdoors. In this embodiment the LED lighting panels are mounted on a framework that is sufficiently strong to support small scale energy generation equipment, optionally also energy storage in the form of batteries or heat stores and electric and heating control housings and associated circuitry. The framework is designed in such a way as to support the LED lights at an optimal height above the crop and may be adjustable in height to be deployed on different crops or different stages of growth of a specific crop. The framework may also preferably have wheels mounted in such a way as to allow the lighting framework to be easily moved. The wheels may optionally be powered by motors taking power from the generation equipment or battery stor-age and may in some embodiments be capable of steering such that the unit may receive directional commands from a steering control unit, which may be remotely programmed and tracked using GPS locational feedback to take up a certain position and orientation at a specific time or be manually controlled via a tethered or wireless handset. In such a manner, the unit may be able to position itself according to a pre-programmed set of requirements such that, were the unit to be used for enhancing the growth of grass on a green on a golf course, the unit could provide light to the grass during certain hours and then move to a resting location during the hours in which the green is in use by golfers playing the course. Optionally, the framework may feature a towing point so that the wheeled unit can be connected to some type of towing vehicle to allow the unit to be moved to the appropriate position or the unit may be moved manually. The wheels of the unit will be suitable for the terrain over which they may be expected to travel and in one embodiment, the wheels may be designed to be suitable for travelling on tracks so that the unit might run up and down a line of growing beds lighting sections of the crop as it goes or stopping in specific locations to accelerate the growth of the crops over which it stands. -6 -

In addition to supporting the LEDs, the framework may optionally also support heating panels or strips designed to generate radiant heat where the heat generated will be directed down towards the crop. Additionally, if the unit includes a gas or liquid fuelled (running on a hydrogen or hydrocarbon fuel) generator unit outputting exhaust gases, these gases may be directed to exit the unit (provided they are adequately cleaned to be free of pollutants that could harm the crop under the unit) in the area being lit by the LEDs. Alternatively, the exhaust pipes may run below the LED lights in a configuration designed to radiate heat from the cooling exhaust gases into the area lit by the LEDs before the o exhaust gases are finally expelled to atmosphere outside the growing unit.

One preferred feature of these wheeled growing units is that the aforementioned framework allows for the fixing of solar panels in such a configuration as to form a roof. The layout of the panels may optionally be inclined to improve solar generation and promote water runoff. Some embodiments may support gutters to collect water run-off and optionally direct this to the area be- neath the LEDs to water the crops. This water may be stored in a tank located on the framework or run directly to irrigation pipes below the LEDs. A small low voltage DC transfer pump may help transfer the water to the tank and the tank may also optionally be fillable from an external water source via a hose connec-tion. Timing and amount of watering may optionally be controlled via low voltage DC powered valves and pumps linked to a central processor controller unit housed on the framework. The arrangement of the solar panels may be such as to form a single pitch or a roof with a plurality of pitches and some or all pitches may be optionally adjustable, either manually or automatically via a pneumatic, hydraulic or powered lead screw mechanism or such other similarly effective system for the purposes of maximising solar generation or moderating the profile of the device for transport or to protect the device in stormy conditions and high winds.

An additional optional feature of the device is the use of a flexible or fixed set of panelling or a tent-like covering to cover the framework and optionally ex-tend towards the ground level to provide protection from the environment for the -7 -batteries, generators and control devices and create a microclimate beneath the growing unit.

The control unit and central processor unit may support the connection of sensors such as air temperature, humidity, soil temperature, leaf temperature, dew point, pH and spectral light intensity sensors and use this data to control the LED arrays and heating panels. This data may optionally be reported to a cloud based or remote data capture portal for collation and manipulation and control commands may be fed back to the unit to be interpreted by the central processor to control lighting, heating and positioning of the unit.

A further optional feature of the unit may be to electrically connect the output from the solar panels and/or from the on board' battery storage devices to external electrical networks and/or storage systems. Such connection systems may optionally support the aggregation of electrical output from a plurality of growing units and the growing unit may include an inverter/converter to op-tionally provide such 'exported' electrical energy in either AC or DC form at whatever voltage may be desired by the external networks and/or storage devices. In such cases the central controller/processor of each growing unit may be designed to allow for the 'export' of none, some or all of the electrical energy generated and/or stored depending on what is deemed surplus to that required for the 'on board' lighting, heating and other operational electrical load of the unit at any moment in time.

Brief Description of the Drawings

In the drawings, which illustrate exemplary embodiments of the invention: Figure 1 is side elevation of a fixed growth system according to one em-bodiment of the invention, with the side panel of the enclosure removed; Figure 2 is a top plan view, on a slightly reduced scale, of the system shown in Figure 1, with the roof removed for clarity; Figure 3 is a perspective view of a movable growth system according to another embodiment of the invention; Figure 4 is a view corresponding to Figure 3, but with the photovoltaic panels removed to show the internal form of the system; and -8 -Figure 5 is an underneath plan view of the system shown in Figures 3 and 4.

Detailed Description of the Illustrated Embodiment

Referring first to Figures 1 and 2, the enclosure is in the form of a steel container 1 in which are mounted racks 2, each having a plurality of shelves 3 for supporting trays 4 containing growth medium and growing plants. The undersides of the shelves 3 carry arrays 5 of LEDs. The container 1 also houses a water tank 6 and a water treatment unit 7, as well as an irrigation controller 8 for supplying water to the plants from the water tank 6 via the treatment unit 7.

The treatment unit 7 can add nutrients to the water. Electrical controls 9 and a battery 10 are also mounted within the container. Rainwater run-off from the enclosure may be collected and delivered to the tank 6.

Photovoltaic panels 11 are mounted on the roof 12 of the container to supply electricity to the battery 10 and thence to the LED arrays 5 when need- ed. The output of the photovoltaic panels 11 can be supplemented as neces-sary by mains power or by wind turbines, for example, but it is expected that the photovoltaic panels will be able to provide a significant proportion of the growth light required, as they will be able to convert a wider spectrum of light into electricity than is normally used by the plants in growing.

The LED arrays 5 are mounted so as to produce optimum lighting for the plants growing in the trays 4 and will include LEDs whose spectral output closely matches the optimum growth light required for the plants. The electrical controls 9 will be programmable to provide the required spectral mix and intensity for each growth phase of the particular plants being grown and the LEDs will typically emit a controlled mixture of red and blue light with UVA as required.

Some white or other spectrally more specific lights may be included, and the unit may optional provide for the inclusion of down converting films or other systems, as hereinbefore described.

Referring now to Figures 3 to 5, the external appearance of the movable or mobile growth unit is shown in Figure 3, comprising 4 x 275W solar panels 31 located over a flexible tent-like cover 32 which incorporates flaps that may be raised to allow access to the equipment within the framework. The tent-like coy- -9 -er in this embodiment extends almost to the floor around the whole framework. In Figure 3, the end flap 32 is shown cut away to expose an electrical control box 33 mounted on a metal central frame 34. Also shown as the wheels 35 with associated optional drive motor 41. Figure 4 shows the same view prior to the mounting of the solar panels and tent-like cover. The LED lighting panels 36 mounted on the framework 34 are shown with the LED chips facing downwards. Other optional items are also mounted on the framework above the LED lighting panels. These include the battery storage unit 40 and the gas generator unit 39 and accompanying fuel bottle 38. It may be readily understood that the location of these units may be altered to suit design, maintenance and operational con-siderations. The generator and battery are connected electrically to the control box which contains a solar charge controller and battery charger and a DC power supply providing the electrical supply to the lights, motorised wheels and to the optional heating panels. The control box provides control and switching for the lights, heating panels, generator and battery charging. Figure 5 shows a view from beneath the unit indicating the LED panels 36 which have a plurality of LED chips of at least 2 different spectral outputs and the radiant heating panels 42 as well as the exhaust pipe for the gas generator 43.

The movable growth unit can be provided with channels (not shown) along the lower edges of the solar panels 31 to collect rain water, which can then be delivered to an on-board tank for use in watering the crop. If power is to be exported from, or supplied to, the unit, a trailing connecting lead will be required.

Either of the illustrated embodiments could be configured to supply all the electrical power required from the solar panels, with battery storage to en-sure continuity.

Claims

-10 -CLAIMS1. A crop growth system comprising an array of light emitting devices mounted within an enclosure and arranged over a crop growing surface, the array of light emitting devices providing the light used by the crop while in the con- tamer, a photovoltaic array mounted externally of the enclosure, the photovolta-ic array providing at least 50% of the energy required to power the array of light emitting devices while the crop is in the container.
2. A crop growth system according to Claim 1, wherein the photovol-taic array is configured to provide at least 75% of the energy required to power the array of light emitting devices while the crop is in the container.
3. A crop growth system according to Claim 2, wherein the photovol-taic array is configured to provide at least 90% of the energy required to power the array of light emitting devices while the crop is in the container.
4. A crop growth system according to Claim, 2 or 3, wherein the pho-tovoltaic array is electrically connected to storage means configured to power the light emitting devices.
5. A crop growth system according to any preceding claim, wherein the light emitting devices are light-emitting diodes (LEDs).
6. A crop growth system according to Claim 5, wherein the LEDs are powered by a direct current electrical supply.
7. A crop growth system according to Claim 5 or 6, wherein the array of LEDs comprises at least red, blue and UVA LEDs.
8. A crop growth system according to any preceding claim, wherein the array of light emitting devices is configured to enable the colour mix and in-tensity of the light emitted by the array to be varied.
9. A crop growth system comprising an array of light emitting devices mounted within a wheeled enclosure and locatable over a crop growing surface, and a power supply mounted on the wheeled enclosure providing electrical power for the light emitting devices.
10. A crop growth system according to Claim 9, wherein the power supply includes a photovoltaic array mounted externally of the enclosure.
11. A crop growth system according to Claim 10, wherein the power supply includes storage batteries connected to receive and store electricity from the photovoltaic array and to supply electricity to power the array of light emitting devices.
12. A crop growth system according to Claim 11, wherein the photo-voltaic array provides at least 50% of the energy required to power the array of light emitting devices while the crop is in the container.
13. A crop growth system according to Claim 12, wherein the photo-voltaic array is configured to provide at least 75% of the energy required to to power the array of light emitting devices while the crop is in the container.
14. A crop growth system according to Claim 13, wherein the photo-voltaic array is configured to provide at least 90% of the energy required to power the array of light emitting devices while the crop is in the container.
15. A crop growth system according to any of Claims 9 to 13, wherein the light emitting devices are light-emitting diodes (LEDs).
16. A crop growth system according to Claim 15, wherein the LEDs are powered by a direct current electrical supply.
17. A crop growth system according to Claim 15 or 16, wherein the ar-ray of LEDs comprises at least red, blue and UVA LEDs.
18. A crop growth system according to any of Claims 9 to 17, wherein the array of light emitting devices is configured to enable the colour mix and intensity of the light emitted by the array to be varied.
19. A crop growth system according to any of Claims 9 to 18, wherein the wheeled enclosure has heated members within the enclosure.
20. A crop growth system according to Claim 19, including a gas-or liquid-fuelled generator unit to provide heating and additional power for the light emitting array.
21. A crop growth system according to any of Claims 9 to 20, wherein at least some of the wheels of the wheeled enclosure are provided with a motor to assist in moving the enclosure.
22. A crop growth system according to Claim 21, wherein at least some of the wheels are steerable and the enclosure includes a steering control -12 -unit for controlling the steerable wheels, the steering control unit being programmable or receiving directional commands wirelessly or via a tether from a remote controller.