How Much Water does Vertical Farming Save

In many places around the world, for example in the Middle East, water resources are limited and their price is high. Reducing water consumption on a vertical farm in such regions can have a very positive economic and environmental impact. iFarm engineers have recently developed and patented a dehumidification system allowing to reuse the water that farm plants evaporate during growth.

How does it work? Let's take a look at a vertical farm with a cultivation area of ​​1,000 m2. It produces 3.6 tons of fresh salads and herbs every month. To get such a yield, you need 2,020 liters of water daily, most of which — 1,400 liters — is used for plant nutrition. However, the daily actual water consumption is almost three times less. 2,020 liters are poured into the system once, and then the "engineering magic" begins.

At iFarm vertical farms we use flow hydroponics, i. e the roots of plants are constantly placed in the nutrient solution and consume it whenever they need, getting all the macro- and microelements in the right ratio and concentration.

From 1400 liters of the water, plants use only 120 liters for weight gain (consumption of nutrients from a larger volume is a prerequisite). The remaining 1,280 liters the plants simply evaporate. In the process of transpiration, a lettuce leaf can evaporate an amount of water that exceeds its own weight many times. We collect this water with air conditioners and dehumidifiers, purify it and reuse it in production, maintaining the optimal humidity inside at 60-70%.

The second "source" of water on the farm is the water supply system — another 700 liters are collected from it and then run through a special filtration unit, resulting in 560 liters of purified and 140 liters of untreated water. The latter is collected in a special tank for technical needs (washing hands, pallets, floors, etc.).

Thus in order to save water, we started collecting it from air conditioners and dehumidifiers that were originally designed to maintain optimal moisture on the farm. This approach allows the production to use only 700 liters of tap water per day, which is three times less than growing plants in conventional hydroponic greenhouses.

We are currently improving the automation of the nutrient solution replacement. The system will determine what macro- and microelements are missing in the trays at a given time and adjust them. According to the calculations of engineers, this will reduce the number of times the sewerage has to be drained completely and almost halve its consumption — from 360 liters to 150 liters. The amount of tap water required by a vertical farm to produce delicious and reach yields then will be just 490 liters, which is five times less than what a hydroponic greenhouse needs.