The trend toward indoor vertical farming holds promise for growing more vegetables per square foot safely, potentially without using insecticides or worrying about animals fouling the plants, as it’s easier to control temperature, humidity, and other conditions.
Vertical farms also offer year-round food produced locally and with higher yields because growing cycles can be shortened by controlling lighting and other conditions. Some experts even suggest they may one day help play at least a small role in relieving food shortages.
To Ed Harwood, PhD, chief scientific officer at vertical farming company AeroFarms, Newark, N.J., the air quality and pest control inherent in the method he developed and that is used by the company help to improve food safety.
“Food safety is much more easily accessible,” he says. “The processes are predictable and repeatable.” The company can control temperature, relative humidity, and lighting. He adds that since the growing cycle of the plants can be controlled to be 16-18 days compared to the typical 30-45 days in outdoor soil farming, the plants are harvested before the reproduction cycle of most pests is completed. The company also tests its plants and uses current Good Manufacturing Practices.
Marc W. van Iersel, PhD, professor of plant nutrition and physiology at the University of Georgia in Athens, says a well-trained workforce is key for food safety. “The biggest food safety issue is humans,” he adds.
Costs Still High
But others question how widely such gardening can spread given the current high costs of the energy for indoor LED lighting and air conditioning. Dr. Harwood says his company has developed a more efficient lighting process that cuts electricity costs to 40-50 percent of overall production costs. Other savings come from being able to grow about 37 times as many plants per square foot as traditional soil farming. AeroFarm grows its six different small, leafy plants in cloth in 12 layers of vertical trays topping 30 feet in height. Nutrients are sprayed on, and the plants are not touched by humans from planting through harvesting and packing.
But at other vertical farming companies’ energy costs can go up to 60 percent of overall production, according to Dr. van Iersel. “You can grow more in fewer acres when you spread the plants in layers, but the biggest hurdle is it’s a really expensive way to grow produce,” Dr. van Iersel says. “Until we find a solution to the high energy costs, I question how sustainable vertical farming is.
“Vertical farming needs to grow high value-added products to sell at a high price per pound to succeed like microgreens, which are small leafs of lettuce, mustard and kale,” he adds.
At least a couple farms have already gone under because of the high cost of doing business, Dr. van Iersel says. Among them is the once-largest indoor vertical farm, the 90,000-square-foot FarmedHere of Bedford Park, near Chicago, which closed in January.
By contrast, AeroFarms plans to expand into 70,000 square feet of growing space—more than double what it has now—by the first quarter of 2018. At that point, it aims to be growing up to 2 million pounds per year. It had its first seedlings in September 2016, and now sells its vegetables at its farmstand and at ShopRite and Whole Foods.
It also is looking to expand to other locations in New Jersey and New York, and recently raised more than $40 million in equity to do that.
A Growing Trend
Market.biz lists more than 40 vertical farming companies worldwide. Allied Market Research, Portland, Ore., valued the global vertical farming market at $1.5 billion in 2016, projected to reach $6.4 billion by 2023. The hydroponics sector of the market comprised 46 percent of the market share in 2016.
As for the farms being a panacea to solve world hunger, Rick Sachleben, PhD, a chemist and member of the ACS panel of experts, says he expects they’ll make an incremental contribution. “They make sense to set up in areas where the land has more value, like cities, because they have a small footprint and there will be savings on water and the fossil fuel costs of transporting the plants,” he says.
Types of Vertical Farms
There are three main types of vertical farms, all soil-free. First, hydroponic farms are the predominant growing system in vertical farms, according to ATTRA, a sustainable agriculture program run by the National Center for Appropriate Technology in Butte, Mont. Hydroponics involves growing plants in nutrient solutions in water. Second, aeroponic farms, originally developed by NASA, nourish plants by spraying solutions onto their suspended roots. ATTRA says they use 90 percent less water than hydroponic systems. AeroFarms is the largest aeroponic farmer in the U.S. Finally, aquaponics combines plants and fish in the same ecosystem in which the fish provide the nutrients for the plants, which filter and purify the wastewater from the fish and return it to the fish ponds.