Farming Goes 3-Dimensional
Vertical farming offers opportunities to grow more crops on a smaller footprint, especially in urban areas. It also presents unique educational opportunities.
By Tom Gibson, P.E.
In 1999, Dickson Despommier, a professor of environmental health sciences at Columbia University’s Mailman School of Public Health, worked with some graduate students to explore the negative impacts of agriculture. As a result, they came up with the concept of the vertical farm.
It only made sense. For eons, we’ve thought of farming as taking place on a two-dimensional plane in the form of rolling, flat, soil-laden fields. With land becoming scarcer and our world population constantly growing, we had to find additional ways to produce enough food to feed everyone. Vertical farming would accomplish this by growing in a three-dimensional framework in a controlled indoor environment.
So where do we stand with vertical farms nearly 20 years later? According to Neil Mattson, associate professor in the Horticulture Section of the School of Integrative Plant Science in the College of Agriculture and Life Sciences at Cornell University, “It’s an idea that’s talked about a lot. It’s still an emerging field where there are not that many commercial operations, especially on a larger scale.”
Vertical farming has the earmarks of a ground floor opportunity for engineers. Murat Kacira, a professor in the Department of Agricultural and Biosystems Engineering and acting director of the Controlled Environment Agriculture Center (UA-CEAC) at the University of Arizona, states, “We need engineers who are excited about this.” He adds, “For certain high-value crops and localities and climates, this technology might be economical now. But there is room for improving these vertical farming systems, especially the engineering, because the costs are still high to operate these systems.”
Current-design vertical farms typically occupy two to three stories of a building with up to 12 layers of short-statured plants stacked in trays in each floor. The plants are grown using hydroponics, aquaponics, and aeroponics. Hydroponics involves submerging the roots of the plant in water, while aeroponics is suspending them in air and bathing them with mist. Aquaponics gets into aquaculture, where you raise fish such as tilapia in the water, and nutrients, oxygen, and carbon dioxide are exchanged in a symbiotic relationship. Most vertical farms use some form of scissors lifts, ladders, or stairs, rolled around manually, to access the plants to maintain and harvest them.
Crops grown include mostly leafy greens such as lettuce, spinach, kale, and basil. Penny McBride, Interim vice chair of the Association of Vertical Farming (AVF) based in Munch, Germany, says, “A lot of criticism has been that people are mostly growing lettuce. That’s largely because the amount of time it takes to grow lettuce is shorter. So they can grow it quickly and get it out the door.”
But McBride says you could grow things like carrots and vining crops like peppers, beans, and cucumbers. Tomatoes, strawberries, and medical herbs might come into play. In theory, corn and wheat could be grown as well as biofuel crops and plants used to make drugs. Transplant seedlings are also grown, and the industry is interested in cannibas, mushrooms, and edible flowers.
McBride co-founded and is part owner of Vertical Harvest of Jackson in Jackson, Wyoming, one of the world’s first vertical greenhouses. Located on a sliver of vacant land next to a parking garage, the 13,500 square-foot, three-story facility uses a tenth of an acre to grow produce equivalent to five acres of traditional agriculture and supplies fresh produce to local grocery stores and restaurants. The top floor grows tomatoes, which require high amounts of light, while the lower two layers have rotating shelves of leafy greens that get sunlight through windows and artificial light when they’re rotated further into the building. Working with the University of Wyoming, Vertical Harvest produces 100,000 pounds of produce each year. Racks of plants extend through the floors, so employees can tend to them from each floor.
According to Mattson, vertical farming falls under controlled environment agriculture (CEA), “ a term encompassing both greenhouse production as well as plant factory, warehouse-style production. It’s a combination of controlling and manipulating the environment to optimize it for plant production and then combining that with horticulture practices.”
At the University of Arizona, the UA-CEAC provides education, research, outreach, and extension activities and is heavily involved with the school’s Agriculture & Biosystems Engineering, Plant Sciences/SWES, and Agricultural Technology Management Departments. The center sports 20-plus computer-controlled greenhouses.
It has recently launched a new two-floor vertical farm known as the UA-CEAC Urban Agriculture Vertical Farm (UAgFarm) for research and to provide experiential educational opportunities for students and educate growers and the public on indoor growing systems. It has a 750-square-foot footprint with two individually controlled chambers, one on each floor, with two racks each with two layers of floating raft-based hydroponic systems. Undergraduate and graduate engineering students designed the systems for it. Kacira says, “For a research institute, this is a large-scale facility. When we are at full production, we have 2000 heads of lettuce or basil at once. We get students through internships, volunteer basis, and those working on their masters and PhDs.”
With his background, Kacira finds himself right at home directing the UAg Farm. He comes from Erdemli, Turkey on the Mediterranean coast, a region that ranks as one of the largest contributors to the greenhouse-based food production economy of Turkey. “My interests and focus have always been in controlled environment agriculture systems. I have always been excited about engineering, design, and innovating food production systems that can produce food in a sustainable way,” he relates. “As an educator, I have also been excited about educating students and help them become leaders, innovators, and educators of sustainable food production systems in controlled environments.”
The UA-CEAC offers engineering courses on controlled environment agriculture systems covering instrumentation and hydroponics. “We bring together the engineering courses as well as science-based courses to provide hands-on learning for our students,” Kacira relates. “There’s a huge demand right now by the controlled environment industry for an educated task force who understands the biology and also the engineering of these controlled environment agriculture systems. We need to further grow these educational programs to be competitive in North America as well other parts of the world.”
Perhaps the most important factor in determining whether a vertical farm will be financially viable is the energy required to operate it. As McBride says, “One of the biggest criticisms of indoor farming is the energy use. One thing AVF is doing with some of our university partners is looking at how we can set baseline standards for lighting, energy use, and water use. It would take somebody to calculate the costs and fuel use for a tractor in fields compared to energy and compare the power for heating and cooling and lighting and the water consumption.”
Mattson happens to be doing just that. In conjunction with engineers and scientists, he’s working a on a project to look at the lifecycle of a vertical farm to determine its carbon footprint. His group is looking at the tomatoes produced in New York City as an example. They’re currently sourced from conventional farms in Florida, California, and Mexico, and that will be compared with growing them in a vertical farm in or near the city.
HVAC systems rank as one of the largest energy users in vertical farms. Kacira says, “You have to maintain air temperature and humidity; it’s a challenge to control the two. It requires special HVAC systems, and it requires an understanding of plants. There’s room to engineer these systems to make them more energy efficient. Air distribution is a major challenge. We need to design more dynamic air flow systems.” Vertical farms consist of plants stacked in layers, and this presents unique challenges because indoor spaces often stratify into layers of varying temperature and humidity.
Another area of energy use under scrutiny in vertical farms is the lighting. With the improvements made in LED lights in recent years, they have become the technology of choice. Compared to T5 fluorescents, LEDs double the efficiency. And researchers can control LED lights easier to do things like change colors and turn them on and off.
Automation Plays a Role
As a scenario that highlights this, one production method has plants in trays that flow along a narrow pond like rafts. You can place a raft on one end of the production system, and the crop keeps getting pushed along so that you harvest from the other end when they reach maturity. You can adjust the lights above the crop to deliver light intensities or spectral qualities needed at different stages along the flow path.
With technology entering the fray and the fact that some 200 variables affect the outcome of agricultural production, vertical farming is becoming a stage for data analytics. Mattson sizes it up: “Cornell is starting to talk a lot about digital agriculture, managing big data. If we’re collecting all this information because sensors are getting cheaper and more embedded systems, how can we manipulate and make sense of those data sets with millions of bytes of data.”
Kacira points to environmental monitoring, mechanization, cloud computing, and Internet of Things applications and remarks, “These kinds of opportunities are exciting for our engineering students, and I see interest now with them in the department and also other universities. I see great potential and opportunities for engineering students.”
Meanwhile, Dickson Despommier, the professor at Columbia University, has developed a concept of vertical farm skyscrapers 30 to 40 stories high with glass windows. We’re a long way from that, but it is possible. That shows the huge role engineering and technology can play in developing vertical farms as they unfold.