AeroFarms founder & CEO, Dr. Ed Harwood originally purchased an LED fixture with great claims of growing performance.  These claims did not come to fruition upon installation even with subsequent modification, driving Dr. Harwood to further investigate existing LED literature and research.  Exploration of how plants use light provided information that was highly contradictory to the claims being made by manufacturers.  Indeed, most were using lumens as the light measure for their luminaire’s output.  Light for plants is measured in moles of light per square meter per second.  Due to the many bogus claims on the internet of energy savings, less heat, and larger plant yields, Dr. Harwood searched for experts and found his collaborators. Dr. Neil Mattson of Cornell University’s Department of Horticulture researched artificial light in graduate school  and The Lighting Research Center is a well recognized center doing research into LED manufacture and providing training for LED luminaire designers.  This collaboration led to the design and development of the array seen in the photos above.

AeroFarms will build a basic understanding of light requirements for commercial growing of baby leafy greens.  The objective will be to create the recipe of light intensity, spectra, and duration required.The experimentation will be done in identical modules where only light parameters will be modulated.  Data on energy consumption, plant yield and quality, and plant shape will be collected.

It is known that a particular spectrum of light may be sufficient for growth and beneficial composition of plants.  Due to the narrow monochromatic band of light produced by Light Emitting Diodes (LEDs), LEDs seem especially useful to refine the provision of an optimal light spectrum for growing plants.  Very little of the visible spectrum in the figure to the left is used by plants.

Light emitting diodes (LEDs) are semiconductor elements that produce colored light in a specific wavelength range very efficiently.  Thus, LEDs offer the potential to fine tune the spectrum of light emitted to the spectra most useful to plants.  Using only the required spectra will increase energy efficiency and reduce operating costs.  LEDs have other advantages over traditional light sources that can result in lower operating costs, for example:

• Expected long life, 50,000 hours (more if the system is designed properly – largely to make LED operating temperatures low) reducing the lifetime operating cost of the lighting system;
• Ability to work with low voltage, direct current, reducing the costs of high voltage wiring and protection systems;
• Ability to be dimmed from 0% to 100% to adapt to plant life stages to further save electric energy;
• Lack of radiant heat emitted in the beam of light, which results in a cooler environment near the plants.  Because LEDs can be placed closer to the plants, the radiation needed for a given stimulus  at plant canopy level can be reduced even further; and the production units can be stacked closer together, doubling the growing area per unit floor space;
  

  RPI Testing Array

• LEDs can be paired with secondary optics in the form of either lenses or reflectors that direct the light only to those areas needed, resulting in a higher degree of radiation utilization and a uniform intensity unlike the puddling of HIDs (High Intensity Discharge luminaire such as High Pressure Sodium or Metal Halide).
• LEDs are more efficient converters of electricity to light as the wavelength increases Leafy greens use mostly red light (longer wavelength); and
• Supplying only the plant required spectra leaves out some spectra required by insects for reproduction, supplying a barrier to pests.

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