In recent years, there has been a growing plethora of vertical farming companies: Gotham Greens, Bowery Farming, and Aerofarms to name a few. They have attracted millions in investment as they sell the promise of a sustainable agriculture revolution. The question is, do they live up to their hype, environmentally-speaking?
Vertical farms are “plant factories” that grow crops at scale indoors, stacked in vertical layers. Rather than growing plants in soil, vertical farms use hydroponics (i.e., growing plants in nutrient-rich water), aeroponics (i.e., delivering nutrients to plants via spraying water mist), or aquaponics (i.e., growing crops in an aquatic environment with fish and / or crustaceans). Indoor growing means that vertical farms make use of artificial lighting and climate control.
One of the key environmental benefits of vertical farming is greater space water efficiency. According to an IEEE article, one vertical farming expert estimates that if every city produced 10% of its food indoors, we could free up 881,000 km2 of farmland, which could then be used reforested. Bowery Farms claims that by making use of vertical space, they are 100x more productive field-grown operations in the same land footprint.
Vertical farms also use much less water than traditional farms, as indoor operations are able to more precisely control water usage and less water is lost to evaporation. Vertical farms are also able to recycle water, further reducing loss. In general, vertical farms use 95% less water than traditional outdoor farms — a major environmental benefit, especially since the agriculture industry currently accounts for ~70% of global water usage.
The third key environmental benefit of vertical farms comes from the decreased use of pesticides and fertilizers. Since crops are grown indoors, the need for pesticides is much lower. This is in contrast to traditional farms, which as in industry use ~2 million tons of pesticides globally. Pesticides accumulate in the soil and leak into waterways, poisoning animals and decreasing biodiversity. Traditional farms also make use of fertilizers which deplete soil quality, pollute waters and escape into the atmosphere as greenhouse gases. Vertical farms do not make use of fertilizers in the same manner, as nutrients are mixed into the water supply and delivered with much less risk of leakage into the environment.
With all of these positives, it might seem that vertical farms as a climate change solution is a given. However, there is a major challenge that vertical farms face in truly being “clean”— their energy usage. According to Agritecture, many vertical farming production methods emit more greenhouse gases compared to traditional methods, even after accounting for transportation. Given the indoors environment, vertical farms require energy to power lighting, water systems, and climate control systems (e.g., air conditioning, heating, and humidifiers). The carbon footprint of vertical farms is therefore highly dependent on their electricity source. As shown through analysis by the Water & Development Research Group, when powered by coal, vertical farms are quite harmful to the environment in terms of greenhouse gas emissions. However, when powered by clean, renewable sources, the heavy energy usage of vertical farms is much less detrimental.
Vertical farms still have a long way to go before they can truly make an positive impact on the environment at scale. However, if and when they do account for a more significant portion of our agricultural production, in order to truly have a net benefit to the environment, like many other of our emerging climate change solutions, they will require a decarbonized grid.
Source:
https://www.ecowatch.com/vertical-farming-2650271709-2650271709.html
