CO2 considerations for Vertical Farming

Leafy greens and lettuce producers in controlled environments have long-utilized multi-tier cultivation rooms. Now, this trend is starting to gain some traction in cannabis cultivation as well. However, there are also some drawbacks. Excerpts from MMJ Daily May 19, 2020 article Considerations for multi-level cultivation:

Multi-level irrigation design: an uphill battle Irrigation design is another variable to take into consideration when planning a multi-tier facility. Pump performance decreases as vertical flow requirements (lift) increases, so this must be taken into account within the irrigation design. Access to sprayers and drip heads for maintenance is also important. Assume that you’ll need access to each plant in the room on any given day of its growth cycle to ensure that you can properly maintain not just the plants, but every irrigation and trellising component as well.

Homogeneous environments in multi-tiered facilities Perhaps most important, as it’s extremely difficult to correct in an active cultivation environment, is the HVAC design. Without proper airflow patterns, every cultivation facility is prone to temperature and humidity fluctuations from zone to zone. Multi-tiered designs are especially vulnerable to stagnation within each layer due to the vertical and horizontal interference with airflow created by having multiple layers.

Because supply air from HVAC systems comes out far colder and dryer than the room’s set-points, it’s not as simple as just pointing some HVAC supply air into a row of plants. The supply air from the HVAC system must be correctly mixed with room air to obtain a homogeneous temperature and humidity. Then that air is supplied to the canopy. In addition, be sure to design the velocity and direction of the airflow with care. Too little velocity will fail to deliver the air to every plant in each row. Too much will force rapid transpiration and other crop damage.

What about homogeneous CO2?

One important input not covered in the article is carbon di-oxide (CO2) enrichment. Atmospheric enrichment of CO2 by gassing is a popular method for providing plants with supplemental CO2 in order to maximize photosynthesis and growth. However, providing homogeneous amounts of CO2 to all plants from the top to the bottom of the vertical levels is difficult. CO2 is 50% heavier than air, therefore the CO2 molecules tend to drop to the lower parts of the rooms, leaving the upper plants with less CO2. In order to provide all the plants with the same amounts of CO2, expensive HVAC systems are required with continual air flow which have to take into account both CO2, humidity and temperature, making it far trickier than if only humidity and temperature were to be controlled.

CO2 Delivery Solutions™ provides consistent CO2 to all plants.

Delivering CO2 to plants via misting aqueous CO2 directly on to plants enable vertical growers to provide consistent, homogeneous amounts of CO2 to all the plants, regardless of the upper, middle or lower levels. Installation is simply a matter of smaller irrigation piping between each row above the plants with appropriate fogging nozzles to target the plants directly. 

Not only does direct aqueous CO2 misting provide a more homogeneous amount of CO2 to all the plants, CO2 gas usage and costs are over 90% less than atmospheric enrichment by CO2 gassing, does not require more expensive HVAC to manage CO2-air flow, and also provides Perimeter Protection™ against the spread of microbial pathogens such as powdery mildew and E. coli. All these benefits while ensuring maximum photosynthesis for increased plant growth and yield.

For more information about CO2 Delivery Solutions™ visit our website co2delivery.ca

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