In a reminder that heat from conventional high-pressure sodium (HPS) horticultural lighting can damage crops in tightly stacked indoor vertical farms, Canada's GoodLeaf Community Farms has gone all LED at its new 43,000-ft2 facility in Guelph, where baby kale, baby arugula, micro broccoli, and pea shoots grow as close as 6 in. to the lights.
While LED modules emit heat that has to be vented out, the amount is below that of less energy-efficient HPS, thus making LEDs more manageable from a temperature perspective in the year-round growing operation.
GoodLeaf has deployed Signify's Philips GreenPower production modules, tuned to a preset spectra that GoodLeaf and Signify together determined would be the optimal level across the facility, with input from Signify's GrowWise research center in Eindhoven, Holland. The vertical farm opted not to deploy tunable spectra, a more costly option. The light duration is adjustable.
The LED-only approach marks a contrast to other recently announced horticultural projects that have utilized both HPS and LED. Belgian flower grow Lugt Lisianthus, for instance, moderated HPS heat by tempering it with about a 25% mix of LED illumination from Signify. The LEDs also provided more precise spectral mixes than the HPS. European tomato growers Bryte and Den Berk Délice used HPS for heat and LEDs for spectral tuning, as did Dutch rose grower Marjoland.
The hybrid lighting examples all took place in greenhouses, where the lights are further away from the crops than they are at vertical farms, where growing chambers sit atop each other.
At GoodLeaf, the greens sit 6–12 in. from the light modules, “depending upon the crop and its growth stage,” Signify business development manger for horticulture LED solutions Blake Lange told LEDs Magazine. The Guelph site — about 60 miles west of Toronto — is not a greenhouse, but is enclosed with solid walls and roof that block the sun.
The existing vertical layers are stacked fully high, but the structure has room to expand horizontally with more vertical chambers.
Across the industry, with heat ramifications in mind, the choice of HPS versus LED is one that is shaping up on an idiosyncratic, case-by-case basis. For instance, unlike the tomato growers that deployed a mix of HPS and LED, Belgium's Tomato Masters went all LED in its greenhouse, but took measures to ensure it would have enough heat — measures that were necessary given the absence of heat-producing HPS lights.
One reason that growers might want to use HPS, or an HPS mix with LEDs, is that the upfront cost of LED lighting is higher than HPS.
Signify and GoodLeaf did not reveal how many lights they installed, how much GoodLeaf paid, or what spectra they are using.
GoodLeaf supplies retail chains around Canada. It is backed financially by Florenceville, New Brunswick-based frozen potato product company McCain Foods, known for packaged fries, wedges, hash browns and the like. Privately held McCain is believed to be the world's largest producer of frozen fries, a market that the COVID-19 pandemic has reportedly buoyed in the home sector but deflated in fast food circles.
MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]m).
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