When LED re­places the sun



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.

Newspapers in English

Newspapers from Thailand

© PressReader. All rights reserved.