Vertical farming
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Vertical farming is the practice of growing crops in vertically stacked layers. It often incorporates controlled-environment agriculture, which aims to optimize plant growth, and soilless farming techniques such as hydroponics, aquaponics, and aeroponics. These high-tech farms drastically reduce the space needed to grow foods, as they can be housed in warehouses, industrial buildings or even skyscrapers rather than using farmland or traditional greenhouses.
The modern concept of vertical farming was proposed in 1999 by Dickson Despommier, professor of Public and Environmental Health at Columbia University.
Controlled-environment agriculture in vertical farming
Vertical farms are fully controlled indoor environments based on controlled-environment agriculture (CEA) technology. Controlled-environment agriculture is the modification of the natural environment to increase crop yield or extend the growing season as well as ensures that the crops grow in a perfect microclimate. CEA systems are typically hosted in enclosed structures such as greenhouses or buildings, where control can be imposed on environmental factors including air, temperature, light, water, humidity, carbon dioxide, and plant nutrition.
The harvest cycles are much faster than in traditional agriculture, and the yield is predictable: CEA excludes uncertainties like flood or drought, which are impossible to predict in outdoor agriculture. In vertical farming systems, CEA is often used in conjunction with soilless farming techniques such as hydroponics, aquaponics, and aeroponics.
There are three types of vertical farming system
01. Hydroponics
Hydroponics refers to the technique of growing plants without dirt. In hydroponic systems, the roots of plants are submerged in liquid solutions containing macronutrients, such as nitrogen, phosphorus, sulphur, potassium, calcium, and magnesium, as well as trace elements, including iron, chlorine, manganese, boron, zinc, copper, and molybdenum. Additionally, inert (chemically inactive) mediums such as gravel, sand, and sawdust are used as soil substitutes to provide support for the roots.
The advantages of hydroponics include,
1. Ability to increase yield per area
2. Reduce water usage
A study has shown that, compared to conventional farming, hydroponic farming could increase the yield per area of lettuce by around 11 times while requiring 13 times less water. Due to these advantages, hydroponics is the predominant growing system used in vertical farming.
02. Aquaponics
The term aquaponics is coined by combining two words: aquaculture, which refers to fish farming, and hydroponics—the technique of growing plants without soil. Aquaponics takes hydroponics one step further by integrating the production of terrestrial plants with the production of aquatic organisms in a closed-loop system that mimics nature itself. Nutrient-rich wastewater from the fish tanks is filtered by a solid removal unit and then led to a bio-filter, where toxic ammonia is converted to nutritious nitrate. While absorbing nutrients, the plants then purify the wastewater, which is recycled back to the fish tanks. Moreover, the plants consume carbon dioxide produced by the fish, and water in the fish tanks obtains heat and helps the greenhouse maintain temperature at night to save energy. As most commercial vertical farming systems focus on producing a few fast-growing vegetable crops, aquaponics, which also includes an aquacultural component, is currently not as widely used as conventional hydroponics.
03. Aeroponics
Aeroponically-grown chives and the invention of aeroponics was motivated by the initiative of NASA (the National Aeronautical and Space Administration) to find an efficient way to grow plants in space in the 1990s. Unlike conventional hydroponics and aquaponics, aeroponics does not require any liquid or solid medium to grow plants. Instead, a liquid solution with nutrients is misted in air chambers where the plants are suspended. By far, aeroponics is the most sustainable soil-less growing technique, as it uses up to 90% less water than the most efficient conventional hydroponic systems and requires no replacement of growing medium. Moreover, the absence of growing medium allows aeroponic systems to adopt a vertical design, which further saves energy as gravity automatically drains away excess liquid, whereas conventional horizontal hydroponic systems often require water pumps for controlling excess solution. Currently, aeroponic systems have not been widely applied to vertical farming, but are starting to attract significant attention.
Optimal conditions for the plants under CEA technology
CEA technology regulates all the essential variables of a vertical farm’s ecosystem to provide the optimal conditions for the plants:
Lighting
Temperature
Climate control
Watering
Nutrition
1. Artificial lighting
Properly balanced artificial light is crucial for plants since there is no natural sunlight in an indoor environment. On a vertical farm, LED lights are normally used to provide artificial light for sustainable plant growth. The LED lamps are located above the plants on each of the racks of a vertical farm facility.
Light is the most important and usually the most energy-intensive element of indoor plant cultivation. The costs of the power usage from artificial lighting depend on various factors, including the type of crop. For example, strawberries need almost twice as much light as Romaine lettuce.
2. Temperature and climate control
Climate control is absolutely necessary for plant growth in an indoor environment. That is why vertical farms are equipped with heaters, coolers, CO2 enrichment and air-conditioning units, humidifiers and dehumidifiers to create and maintain the optimal conditions for crops.
Vertical farm system providers use a closed-loop ventilation system. through that, can control the optimal climate balance on a farm, and use a special precision agriculture tool for remote control of climate, lighting and other parameters.
3. Smart water harvesting and plant nutrition
Over 70% of water resources worldwide are used by the agriculture sector. To reduce the ecological footprint, controlled-environment agriculture opts for a smart water harvesting system. CEA uses water-saving technologies that significantly reduce water consumption in this farming.
Depending on the method, crop cultivation on a vertical farm requires up to 95% less water than in conventional, highly water-dependent agriculture. Limited water resources, climate change and population growth make vertical indoor farming a sustainable food production method for the future.
Types of vertical farms
✸ Building-based farms
Abandoned buildings are often reused for vertical farming, such as a farm at Chicago called "The Plant", which was transformed from an old meatpacking plant. However, new builds are sometimes also constructed to house vertical farming systems
✸ Shipping container vertical farms
Recycled shipping containers are an increasingly popular option for housing vertical farming systems. The shipping containers serve as standardized, modular chambers for growing a variety of plants, and are often equipped with LED lighting, vertically stacked hydroponics, smart climate controls, and monitoring sensors. Moreover, by stacking the shipping containers, farms can save space even further and achieve higher yield per unit area
✸ Deep farms
A "deep farm" is a vertical farm built from refurbished underground tunnels or abandoned mine shafts. As temperature and humidity underground are generally temperate and constant, deep farms require less energy for heating. Deep farms can also use nearby groundwater to reduce the cost of water supply. Despite low costs, a deep farm can produce seven to nine times more food than a conventional farm above ground on the same area of land, Coupled with automated harvesting systems, these underground farms can be fully self-sufficient.
✸ Floating farms
Floating platforms and barges have been proposed as sites for vertical farming in urban areas where land is scarce. The ongoing Science Barge project first demonstrated urban hydroponic agriculture in New York City in 2007, including several vertical farming systems. A much larger vision of sloped, floating skyscrapers has been proposed for Singapore. In this case, the unusual, angular design is intended to exploit the open space over the water to capture more sunlight.
Advantages
1. Efficiency
Vertical farming allows for, in some cases, over ten times the crop yield per acre than traditional methods. Unlike traditional farming in non-tropical areas, indoor farming can produce crops year-round. All-season farming multiplies the productivity of the farmed surface by a factor of four to six, depending on the crop. With crops such as strawberries.
2. Resistance to weather
Crops grown in traditional outdoor farming depend on supportive weather and suffer from undesirable temperatures, rain, monsoon, hailstorm, tornado, flooding, wildfires, and drought.
The issue of adverse weather conditions is especially relevant for arctic and sub-arctic areas so, traditional farming is largely impossible. Food insecurity has been a long-standing problem in remote [long distance]communities where fresh produce has to be shipped large distances resulting in high costs and poor nutrition. Container-based farms can provide fresh produce year-round at a lower cost than shipping in supplies
3. Environmental conservation
Up to 20 units of outdoor farmland per unit of vertical farming could return to its natural state, due to vertical farming's increased productivity. Vertical farming would reduce the amount of farmland, thus saving many natural resources.
Deforestation and desertification caused by agricultural encroachment on natural biomes could be avoided. Producing food indoors reduces or eliminates conventional plowing, planting, and harvesting by farm machinery, protecting soil, and reducing emissions as well as Traditional farming is often invasive to the native flora and fauna because it requires such a large area of arable land. One study showed that wood mouse populations dropped from 25 per hectare to 5 per hectare after harvest, estimating 10 animals killed per hectare each year with conventional farming. In comparison, vertical farming would cause nominal harm to wildlife because of its limited space usage.
Disadvantages
1. Economics Problems
Vertical farms must overcome the financial challenge of large startup costs. Urban occupancy costs can be high, resulting in much higher startup costs – and a longer break even time – than for a traditional farm in rural areas.
Opponents question the potential profitability of vertical farming. In order for vertical farms to be successful financially, high-value crops must be grown since traditional farms provide low-value crops like wheat at cheaper costs than vertical farms and Current methods require enormous energy consumption for lighting, temperature, humidity control, carbon dioxide input and fertilizer and consequently but unlikely to be economically competitive with current market prices. So, according to a report, in The Financial Times as of 2020, most vertical farming companies have been unprofitable
2. Problems of energy use
During the growing season, the sun shines on a vertical surface at an extreme angle such that much less light is available to crops than when they are planted on flat land. Therefore, supplemental light would be required.so, cost of providing enough supplementary light to grow the grain for this farming system.
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