Estimates show that the agriculture industry produces over 6.4 billion tons of greenhouse gases annually. This amounts to approximately 8.5% of the world’s yearly emissions. With the continuously growing human population, the food industry’s demands will have to be met despite the inevitable effects of climate change. These include limited access to water, inconsistent weather patterns and poor soil quality. Hence, agricultural innovations will be required to grow substantial quantities of produce to meet our needs. One of the agricultural processes that could do this is vertical farming. This is a subcategory of Controlled Environment Agriculture (CEA), where conditions are fulfilled to support the growth of specific plants.

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The development of Controlled Environment Agriculture systems

CEA systems and vertical farming are not new practices. Vertical gardens stem from the time of the Babylonians almost 2,500 years ago. Their hanging gardens are believed to be the earliest form of vertical farms.

Related: Vertical farm building in China feeds 40,000 people

About 1,500 years later, the Aztecs invented a form of hydroponics. This is the process of growing plants without soil. Instead, plants are suspended in a nutrient-rich solution. The Aztecs grew crops on marshy beds that would float in shallow water bodies.

In the 1600s, vertical farming was used in Europe to maintain thermal comfort using fruit walls. The plants would grow along masonry walls that would absorb the heat and create a microclimate. This thermal stability would allow Mediterranean crops to grow in places like England and the Netherlands.

Present-day vertical farming stacks crops in enclosed environments and uses LED lights to replace sunlight and closed-loop water systems. Since the produce is grown in indoor spaces, there is no need for pesticides, and crops can be consumed without washing them before eating. Indoor farms do not use soil and can grow using hydroponic, aeroponic or aquaponic systems.

While hydroponics features plants in a water- and nutrient-based solution, aeroponics suspends the plants in the air and mists them with the nutrient solution. Aquaponics uses the same methodology to store plants as hydroponics, but it combines agriculture (harvesting of plants) and aquaculture (harvesting of fish). Fish waste accumulates in the water, making it a nutrient-rich solution. The plants absorb these nutrients and thus clean the water, allowing it to be reused for the fish.

Narrow passage between shelves that hold hydroponic lettuce

The pros

Vertical farms are extremely efficient, especially with regard to spatial requirements. Vertical systems can fit 280 hectares (700 acres) worth of agricultural space into the space of a supermarket (about 2,000 square meters, or 21,000 square feet). That is 0.02% of the space for the same amount of produce!

Traditional agricultural methods often result in water overconsumption and waste. Of the limited freshwater that is easily accessible, 70% of it is used for agriculture. Unlike conventional techniques, indoor farming methods use up to 90% less water. Most of this can be recirculated in irrigation systems to limit waste. Alongside water wastage, horizontal agriculture has also led to increased land degradation. As a result of clear-cutting for agricultural land, contamination of the air, soil and water, as well as urban encroachment, soil health has seen a rapid decline in recent years. This impacts the quality and quantity of the food we produce and consume.

Another advantage of these CEA systems is that by optimizing plant growth, various types of produce can be grown throughout the year, consistently. This means that there are no seasonal crops because measures have been taken to ensure their growth and maximize the production quantities. Optimization of the crops also allows for shrunken growth cycles. In fact, cycles are so rapid that their entire growth can be shrunk down to the span of 10 days. This is much more cost-effective and can result in a 700% yield increase compared to traditional agriculture, depending on the crop.

Since vertical farms are located in urban areas and use advanced technologies, they can cut down on certain costs. Because of their accessible locations, there is less transport required to shuttle fresh produce to retail sites. This also results in less transport-related emissions, which benefits the planet. Furthermore, because of optimized growing conditions and technological advances, labor costs are lower than in traditional farming.

Spectators watching a keynote presentation at the VertiFarm conference

The cons

Unfortunately, there are still many challenges facing vertical farming. One of them is that with current technological advancements, vertical food production can have high costs, excessive energy use and huge carbon emissions.

The energy required to power photosynthetic light from LED lamps is one of the primary concerns. For example, for every head of lettuce grown, carbon dioxide emissions could fill three 55-gallon drums. By growing 4,000 heads of lettuce, the energy required would be the same as the annual emissions of a passenger car. Though renewable energy can be used to alleviate some of these energy and emission-related concerns, certain forms of renewable energy may not be enough for the farm’s self-sufficiency. Furthermore, not all indoor systems are compatible with certain forms of renewable energy.

Some crops may be more sustainable to grow using vertical farms than others. While small plants like leafy greens and strawberries are easy to grow, cereal crops like corn and wheat are hard to stack efficiently and require lots of photosynthetic light. In fact, a loaf of bread produced with vertically-farmed wheat would cost around $23, just to power the LED lights.

Man touching the leaf of a vertically-farmed lettuce

Where are we headed?

This year, the Association for Vertical Farming (AVF) launched an international trade show called VertiFarm to showcase innovations within the agriculture industry. AVF is a non-profit organization that supports sustainable growth and indoor/vertical farming. The conference was held in Dortmund, Germany, in late September and featured over 70 stalls from 17 different countries. VertiFarm is the world’s first business and information exhibition for cultivation-related methods and products. The trade show highlighted current issues faced in the industry, including crop failures, produce supply and urban sustainability.

In conclusion, since the world’s population is growing rapidly and is expected to reach approximately 10 billion by 2050, we will require a 70% increase in food production. The current outputs of traditional agriculture cannot keep up with these demands, especially because of climate change-induced factors that impact produce and quality. By 2026, vertical farming is expected to rise by almost 25%. With this, research within the field is likely to also increase.

By maximizing the sustainability of our agricultural methods, we can make them more efficient and limit traditional farming, which is proving to be quite harmful to the planet. Though we may not be able to make the switch to more efficient CEA urban farming systems such as vertical agriculture right away, we can slowly work to incorporate and adapt methods that have a lower carbon footprint to keep up with human food demands.

via Science Focus, Bowery Farming, Conserve Energy Future, and VertiFarm

Images via VertiFarm and Unsplash