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The Carbon Footprint Of Indoor Cannabis Cultivation

There are three main methods to growing cannabis these days – outdoor, in greenhouses, and in indoor grow rooms. While all are viable, they have different limitations and different levels of control over the grow. One big difference is the carbon footprint of the cannabis cultivation.

The carbon footprint of growing cannabis has a major impact on the viability, and ultimately profitability of the industry. It’s important to understand what impacts cannabis cultivation has on the environment, in order to reduce and prevent them.

Cannabis Cultivation Methods

The first, and the most basic method to grow cannabis, is outdoors. This way, the cannabis grows outside, utilizing the sunlight, but leaving the crops unprotected from weather or pests.

The second, is greenhouse cultivation. Greenhouses let growers harness sunlight and improve their protection and control over the grow. But greenhouse control isn’t absolute, as the weather outside still has a great effect on the conditions inside.

The third, most precise method, is indoor cultivation – growing cannabis in a completely closed structure, fully isolated from the environment. This way the sunlight doesn’t reach the plants, but the the environment are controlled. Indoor growing requires a great use of energy for lighting and climate control.

As the legalization of marijuana spreads throughout the world, more and more growers invest in indoor cannabis cultivation. In this commercial cultivation method, growers invest a large amount of energy to produce larger yields. The idea is to isolate the plant from the natural environment and create an optimal climate for cannabis, in a closed structure, in order to increase the quality and size of the yield.

While this method is widely used, in part to uphold strict regulations, it’s energy intensive, and is associated with larger carbon footprint.

Indoor Cannabis Cultivation Is Energy Intensive

A couple examples of high-intensity energy uses are heating and cooling – maintaining the ideal temperature in the growing space, and lighting.

As a result of high energy usage, indoor cannabis production has a much larger carbon footprint than outdoor or greenhouse cultivation. In average U.S. climate conditions, the carbon footprint of one kg of indoor cannabis is 4,600 kg of CO2.

One single cannabis cigarette represents roughly 1.5 kg of CO2 emissions, equivalent to 25 hours of 100 watt light bulb average emissions.

The majority of CO2 emissions come from 3 main categories: air conditioning, humidity control, and lighting. Focusing on the first two categories, inefficient traditional humidity control methods and air conditioning constitute 25% and 27% of total emissions, respectively.

Air conditioning, including space heaters, and CO2 injections, to increase foliage, require 1,681 kWh per kg of yield, emitting 1,120 kg of CO2 per kg of yield, based on average U.S. carbon burdens of 0.666 kg per kWh.

Dehumidification using traditional methods (including air ventilation) requires 1,848 kWh per kg yield, emitting 1,230 kg of CO2 per kg of yield.

Greenhouse Cannabis Has a Smaller Carbon Footprint than Indoor

Indoor cultivation is a common method to grow cannabis, but it isn’t as sustainable. On the one hand, it lets growers grow larger amounts of cannabis per sq. ft.. But on the other hand, it doesn’t utilize the advantages of free sunlight and comfortable weather patterns. The greenhouse method combines the advantages of the indoor and outdoor.

Both methods create systems isolated from the external weather. As a consequence, they require efficient dehumidifiers to remove excess water vapor from the air.

Traditionally, humidity forces growers to open the greenhouse in order to release humidity. But ventilating doesn’t only remove water vapor, it also extracts heat and CO2, which are benefitial to the growing facility.

The high density of the cannabis flowers prevents water vapor escape to air and thus causing diseases like gray mold, known as bud rot in cannabis circles. This makes humidity a huge issue in cannabis cultivation.

The only way to sustainably control humidity, is with a dehumidifier.

Scaling Cannabis Cultivation

Many of the dehumidifiers cannabis growers use these days are a relic of small-scale operations. When scaling to commercial levels, the technology and growing methods have to adapt.

Most dehumidifiers small-scale growers use can’t manage the massive amounts of transpiration in commercial growing facilities. DryGair’s expertise is in large-scale, horticulture humidity control.

DryGair offers several solutions for air dehumidification in greenhouses and commercial indoor production. Our solution provides humidity control, while improving energy efficiency and creating uniformity and uniform conditions in greenhouses and grow rooms.

DryGair’s units are designed to answer the plants’ needs. One unit can cover 300-1,400 m2 (3,000-14,000 ft2) of cannabis cultivation, and removes 45 L/h (12 G/h) at the design conditions (18°C and 80% relative humidity).

DryGair saves as much as 50% of the energy consumption compared to other solutions, and thus prevents at least 920 kg of CO2 emissions per kg yield in indoor production. The energy savings in greenhouses is achieved through low electricity consumption, saving energy on heating and CO2 production, by keeping the greenhouse completely closed.

Cannabis growers face many challenges. The increasing competition requires more advanced techniques and technologies to reduce setup and operation costs, while reducing the carbon footprint.

This article is based on Evan Mills’ “The Carbon Footprint of Indoor Cannabis Production“, April 2012.

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