While so-called urban agriculture has deep historical roots, as I described in a blog on this topic in October 2017, efforts to raise crops without full access to sunlight in a controlled environment, known as vertical farming or agriculture, is a much more recent development.
The first commercial vertical farm was established in Singapore in 2012. Sky Greens Farms, initially consisted of six aluminum towers, each 120 feet high, which combined could produce 1 metric ton of fresh vegetables every day, sold in local supermarkets to consumers. The operation has since expanded to growing vegetables in 300 towers, and hopes to expand further in coming years. The company is financially supported by the government of Singapore, but is seeking to export its technology to other countries as well. Unlike many subsequent vertical farming or controlled environment agriculture (CEA) ventures, this approach relies on natural sunlight and soil to grow its plants, primarily leafy vegetables.
Even though the technology used has evolved considerably since Sky Greens Farm was established, these ventures still focus on growing high value crops such as fruits and vegetables, especially leafy green vegetables, which are highly perishable and often degrade in quality when shipped long distances from farms to markets. The facilities’ design structures are also geared in this direction, focusing on low-height, light-weight crops with short growing seasons that can accommodate multiple harvests annually.
In the last ten years, the CEA industry worldwide has grown from its humble beginnings in Singapore to producing an estimated $79 billion worth of fresh product in 2021, projected to nearly double in the next five years by Pitchbook, a firm that tracks data on private and public capital markets. While these estimates represent a tremendous rate of growth, it is important to put it in context. That 2021 figure amounts to less than 1 percent of the estimated value of global fruit and vegetable production in 2020 (about $918 billion), according to data reported by the UN’s Food and Agriculture Organization.
As of 2020, there were vertical farming operations in place in at least a dozen countries, primarily in the United States, in developed countries in Asia such as Taiwan, South Korea, Japan, China, and Singapore, in western European countries such as the United Kingdom, France, Germany, and the Netherlands, and wealthy Middle Eastern countries such as the United Arab Emirates (UAE) and Kuwait.
Most vertical agriculture facilities rely on artificial LED lights as substitutes for natural sunlight, and hydroponic solutions with all the necessary nutrients included to replace soil. These structures utilize a much smaller land footprint than do either conventional farms or greenhouse operations. Such farms are also highly typically water efficient, as the closed systems allow for precision application on the growing trays as well as the ability to better clean and recycle water.
Many vertical farms are established in existing buildings, which helps to reduce construction costs, although remodeling costs can be significant. However, the major disadvantage of these types of operations is the very heavy use of energy associated with them, especially as compared to conventional outdoor or greenhouse farming operations. Activities such as operating the artificial lights, circulating the water and hydroponic solutions throughout the system, conditioning the environment, and all the automation features of some CEA operations all require utilization of energy. It is estimated that the average greenhouse facility uses 2.5 kilowatt-hours (kWh) for every pound of produce it grows, while the average vertical facility uses about 17.6 kWh per pound, or about seven times greater. This substantial gap is the main reason that vertical facilities focus on producing high value crops, to offset their high energy input costs.
In recent years, some operations and academics have been exploring ways to reduce those energy expenditures. CubicFarm Systems, a Canadian company, has developed technology that allows the growing plants to rotate on an ‘undulating path’ through a single layer of LED lights to better mimic natural plant growth rather than lighting the whole environment equally. The company claims that this approach is 62 percent more energy efficient than a typical vertical ‘rack and stack’ farming arrangement.
A company called Eden Green, headquartered in Texas, is promoting its approach, which uses vertical towers like the original Sky Greens Farms, allowing use of sunlight to reduce the need for artificial lighting. The company also tries to focus its climate control around the plants themselves, and not spending as much energy conditioning empty spaces within the facility where plants are not being grown. They claim that their system is ten times more energy efficient than the typical vertical farm.
Dr. Qingwu (William) Meng, an assistant professor of controlled environment horticulture at the University of Delaware, has been studying whether plants in vertical farming need full-spectrum (white) light to grow in an efficient manner, or can they thrive in single spectrum light environments, which are less costly to radiate. He is also exploring how a range of other environmental factors, such as carbon dioxide concentration, air temperature, and the content of the nutrient solution, can affect plant growth rates. His work is partially funded by NASA, which is interested in better ways of growing food on long-term manned space voyages that may be launched in the future, such as to Mars.
