Robert Morrow of Orbital Technologies Corp. of Madison, Wis., co-developed the LED light towers that Mitchell is using and is a collaborator in the current USDA-funded research. He notes that costs of most new products are high at first but eventually come down when they are refined and produced in large quantities as demand increases. The same would be true, he says, for LEDs in greenhouses. Because there is little demand at this point, building the necessary hardware in small quantities is very expensive.
“They definitely will be appropriate for use in agriculture” he says, “but there are a lot of details yet to be work out.”
John Burr, continuous term lecturer in Purdue’s Krannert School of Management, is researching LEDs’ economic feasibility and life cycle as a collaborator with Cary Mitchell. His study is showing that whether LEDs should be used in a greenhouse can depend on its location in the U.S., the cost of electricity there and what the greenhouse grows. Growers with greenhouses in parts of the country with abundant sunlight don’t need them, but LEDs could become economical at some point for those in areas where overcast skies are frequent. He has shown that LEDs in a lab can reduce energy costs by more than half.
Burr also thinks that LEDs possibly could reduce greenhouse gas emissions by more than half. He says every 10 acres converted to LEDs from high-pressure sodium lamps in an environment needing high levels of supplemental lighting, such as for growing tomatoes or cucumbers, would be equal to removing 12,000 vehicles from the road.
“There is little doubt in my mind that we’re moving in this direction,” Burr says. “It’s just a question of when.”
Marco DeBruin of Bushel Boy Farms in Owatonna, Minn., operates 20 acres of greenhouse tomatoes with supplemental high-pressure sodium lights. He says his costs would double at this time if he were to invest in a hybrid lighting system in which LEDs would supplement the existing system, which is needed for tomato production. While there would be savings in electricity costs, heating expense would increase to compensate for heat lost from the removal of some HPS lights. He also says that based on his operation’s use of lights—about 2,500 hours a year—LEDs lights would last about 10 years and HPS lights about 14.
He doesn’t think LEDs will be economically viable for another 3-5 years.
“But I think the technology is a huge development and a great prospect,” he says.