By: Sonja Brankovic
Food deserts and the case for farming up
By 2050, the world’s population is expected to surpass 9 billion people. Two thirds of those people will live in urban areas, far from the farms that supply their produce (currently, fresh produce can travel thousands of miles by truck/plane to reach grocery stores). To address these produce “food deserts” and the resulting food insecurity in large cities that have minimal/no arable land, urban farmers have recently made the case for vertical agriculture. Vertical farms are (relatively) small-land area crop systems in urban settings that grow plants in tiered trays, control plant nutrients through solution baths or misting, use no/minimal soil, and shine LEDs on the plants to mimic natural sunlight. Most vertical farms use 70-80% less water than convention farms, which is significant considering that humans use 70% of available fresh water for agriculture.
In addition, the environmental control over vertical farms allow farmers to avoid pesticide use. Soil treatments and fertilizers are the unintentional contaminants that threaten conventional field crops; with precision agriculture in vertical systems, the lack of soil improves plant health and crop yield.
NASA and “Ponics” farming: how to go soil-less
Back in the late 1970s, NASA launched the Controlled Ecological Life Support System (CELSS) program, a series of research projects to develop a bioregenerative system to service long-duration manned mission. The Breadboard Project (located at the Kennedy Space Center) was a major component of the CELSS program, aiming to control plant growth using a specialized Biomass Production Chamber (BPC) equipped with high-pressure sodium lamps, a reservoir of nutrient solution, a dedicated HVAC system, and a monitoring system.
Today’s vertical farmers are still reaping the benefits of NASA’s research into environmentally-controlled food production. Gary Stutte, a horticulture professor at the University of Maryland and the principal investigator for several NASA research projects looking to grow plants in microgravity, helped pioneer much of this research (one of the first examples of a “vertical farm”) by using hydroponics. This soil-less growing method is commonly used in vertical farming and involves a tiered setup of trayed plants placed in close contact with LEDs with their roots submerged in a circulating nutrient solution.
Two common variations of a hydroponic vertical farm are aeroponic (nutrients misted over the plants) and aquaponic (combination of fish and plants in the same system – fish living in indoor ponds produce the nutrient-rich waste that feeds the plants) farms. Regardless of the system used, the “ponics” farming methods allow farmers to grow their crops in cramped urban settings – for example, in shipping containers, warehouses, or several floors of skyscrapers.
Challenges for mainstream vertical farming
Despite the need to lower transportation costs and provide fresh food to populous areas, vertical farming faces many challenges. Despite the ability to go vertical, urban farmers still need to purchase expensive real estate for their systems. Aside from rent, they must also be close to their end buyers (either a restaurant or grocery store) and ensure their facility is capable of housing the vertical farm (for example, what are the HVAC and lighting requirements?). To offset these costs and make a profit, vertical farms must produce high crop yields, which means smartly planning their crop density within the system space. Too few crops per square foot can ruin a vertical farming operation.
The tiered layers of plants are ideal for space management but make it difficult for farmhands to perform basic tasks like planting and harvesting. Scissor lifts are one solution, but they’re bulky and can block access to other areas of the farm. These ergonomic issues reduce worker efficiency.
Another challenge for vertical farmers is to diversify their crops. Since leafy greens need less light to grow than nutrient-dense grains or beans, most vertical farms grow and market perishable crops. The energy costs to grow corn or wheat or other primarily dry-matter crops may be prohibitively high for small-scale vertical farmers.
As may be expected, leveraging a vertical farm’s crop monitoring system is essential to improve yields. However, local farmers are finding it difficult to invest in expensive data collection systems (for example, sensors and cameras to monitor plant growth). Once the data is collected, another task is to extract useful information that can tangibly improve yields.
How can engineers make VF viable?
High energy costs are one of the main challenges to the future of vertical farming. Engineers are currently attempting to connect renewable energy sources (solar, wind) to help power the LEDs needed for plant light or, in the case of solar, to use a plant rotation system in a windowed-space to take advantage of natural sunlight instead of LEDs.
Being able to effectively interpret and implement crop data from cameras and sensors is another task engineers must face. Instead of finding new ways to monitor plant growth or health, data from existing tools should be leveraged for better yields