When LED replaces the sun
A LOOK AT THE CUTTING-EDGE TECHNOLOGY THAT WILL CHANGE FARMING
MIKE ZELKIND stands at one end of what was once a shipping container and opens the door to the future.
Thousands of young collard greens are growing vigorously under a glow of pink-purple lamps in a scene that seems to have come from a sci-fi movie. But Zelkind is at the helm of an earthbound enterprise. He is chief executive of 80 Acres Farms, with a plant factory in an uptown Cincinnati neighbourhood where warehouses sit cheek by jowl with detached houses.
Since plants emerged on Earth, they have relied on the light of the sun to feed and grow through the process of photosynthesis.
But Zelkind is part of a radical shift in agriculture – decades in the making – in which plants can be grown commercially without a single sunbeam. A number of technological advances have made this possible, but none more so than innovations in LED lighting.
“What is sunlight from a plant’s perspective?” Zelkind asks. “It’s a bunch of photons.”
Diode lights, which work by passing a current between semiconductors, have come a long way since they showed up in calculator displays in the 1970s. Compared with other forms of electrical illumination, light-emitting diodes use less energy, give off little heat and can be manipulated to optimize plant growth.
In agricultural applications, LED lights are used in ways that seem to border on alchemy, changing how plants grow, when they flower, how they taste and even their levels of vitamins and antioxidants. The lights can also prolong their shelf life.
High-tech plant factories are sprouting across the United States and around the world. Entrepreneurs are drawn to the idea of disrupting the status quo, confronting climate change and playing with a suite of high-tech systems, not least the LED lights. Indoor farming, in sum, is cool.
It has its critics, however, who see it as an agricultural sideshow unlikely to fulfil promises of feeding a growing urbanised population.
Zelkind agrees that some of the expectations are unrealistic, but he offers an energetic pitch: He says his stacked shelves of crops are fresh, raised without pesticides and consumed locally within a day or two of harvest. They require a fraction of the land, water and fertilisers of greens raised in conventional agriculture. He doesn’t need varieties bred for disease resistance over flavour or plants genetically modified to handle the stresses of the field. And his harvest isn’t shipped across the country in refrigerated trucks from farms vulnerable to the effects of climate change.
In addition to shaping the plants, LEDs allow speedy, year-round crop cycles. This permits Zelkind and his team of growers and technicians to produce more than 100,000 kg of leafy greens, vine crops, herbs and microgreens annually in a 1,150square-metre warehouse, an amount that would require 80 acres of farmland (hence the company’s name).
Zelkind says he can grow spinach, for example, in a quarter of the time it takes in a field and half the time in a greenhouse. Growing year-round, no matter the weather outside, he can produce 15 or more crops a year.
Grown hydroponically, the plant roots are bathed in nutrient-rich water. The moisture and unused nutrients exhaled by the plants are recycled.
But it is the LED lighting that has changed the game. Conventional greenhouses have relied on highpressure sodium lamps to supplement sunlight, but HPS lights can be illsuited to solar-free farms because they consume far more power to produce the same light levels. They also throw off too much heat to place near young greens or another favoured factory farm crop, microgreens. Greenhouses, still the bulk of enclosed environment agriculture, are moving to a combination of HPS and LED lighting for supplemental lighting, though analysts see a time when they are lit by LEDs alone.
The visible spectrum is measured in minuscule wavelengths, shifting at one end from violet-blue light through green to red at the other. For decades, scientists have known that photosynthesis is optimised within the red band, but plants also need blue lightwaves to prevent stretching and enhance leaf color.
A barely visible range beyond red, known as far red, promotes larger leaves, branching and flowering. With advances in LED technology, light recipes – determining the number of hours illuminated, the intensity of photons directed at plants and the mix of colours – can be finely tuned to each crop and even to each stage in a crop’s life.
Lettuce, for example, likes as much as 18 hours of light per day, but basil prefers brighter light for 15 hours.
Although the permutations are still under study, the sun suddenly seems so analog. “The spectrum from sunlight isn’t necessarily the best or most desirable for plants,” says Erik Runkle, a plant scientist at Michigan State University. “I think we can produce a better plant” with LED lights, he says. “The question becomes: Can you do it in a way that is cost-effective considering the cost of plants indoors?”
Mike Zelkind, chief executive of 80 Acres Farms, grows produce with artificial-light made possible with new LED technology.
Grower Julie Flickner inspects kale.
Grower David Litvin picks tomatoes at 80 Acres Farms.