Growing cannabis indoors certainly has some advantages. Not only is it easier to control temperature, humidity, and irrigation, but it’s easier to conceal an indoor grow op when compared to an outdoor field of crops. Some strains in particular, like Amnesia Haze, Blue Dream, and Zkittlez, are even known for their ability to thrive indoors.
But there is a downside, too – especially when it comes to large-scale grow ops. This article explores these drawbacks, including greenhouse gas (GHG) emissions, energy requirements, water usage, and waste management, while providing insight into how today’s growers can decrease the carbon footprint of small and large gardens alike.
Where Are All These Greenhouse Gas Emissions Coming From?
You’ve probably already learned about the dangers of greenhouse gas (GHG) emissions and their impact on the ozone layer. Gases like methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) are all major contributors to climate change, especially in large concentrations. Many GHG emissions come from fossil fuels, transportation, landfills, agriculture, and livestock farming, but did you know that GHG emissions are also a byproduct of indoor cannabis cultivation?
Whether it’s contained within an outdoor greenhouse, an indoor growing facility, or even tucked away in a basement, an indoor cannabis garden can – and will – produce GHG emissions over the course of time. Although this is a bigger concern with commercial grow ops, smaller operations produce GHG emissions, too.
According to a recent study by researchers at Nature.com, who created an indoor cannabis cultivation model to track and analyze GHG emissions across the United States, indoor cannabis grow ops produce a median of 3,658 kilograms (kg) of GHG emissions per kg of dried cannabis flower. But these numbers are subject to a variety of factors.
For example, the production of GHG emissions varies greatly by region. The lowest numbers, seen in Long Beach, CA, were around 2,283 kg of GHG emissions, while the highest, seen in Kaneohe Bay, HI, reached up to 5,184 kg of GHG emissions. Mountainous regions also tend to experience above-average GHG emissions.
Energy Usage
One of the biggest drawbacks of growing cannabis indoors is the hefty energy requirements. While outdoor grow ops depend on the sun for lighting, indoor gardens don’t have this option. Depending on the region, some gardens also require HVAC systems for heating, cooling, or humidity management. In many cases, these HVAC units require more energy than the grow lights themselves.
Again, gardens in Kaneohe Bay, HI, rank the highest when it comes to using HVAC for humidity management, with those in Jacksonville, FL, following close behind. Grow ops in other areas, like Anchorage, AK, and Denver, CO, primarily use their HVAC systems for heating during the winter and air conditioning during the summer.
In the locations mentioned above, which were all included in Nature.com’s study, HVAC accounts for more GHG emissions than grow lights. But there are some assumptions made here, too. For example, the study assumes an air supply rate that represents 30 volumetric air changes per hour (ACH). In reality, actual values range from 12 ACH on the low end all the way up to 60 ACH for some indoor gardens in the U.S. To put it into perspective, homes within the U.S. are recommended to maintain an ACH of 0.35 or greater.
Water Consumption
Every plant needs water to survive, and cannabis is no exception. According to some commonly accepted studies, most cannabis grow ops require six gallons of water per plant per day. But the actual amount depends on several different factors – including temperature, humidity, and even the growing medium itself. Some indoor gardens, particularly those utilizing hydroponic systems, use significantly less than the average of six gallons per day.
Regardless, cannabis plants still require more water than many other crops. The biggest environmental hazards regarding water consumption come in the form of local rivers and streams that are being diverted in order to water outdoor grow ops – many of which aren’t properly vetted or licensed to begin with. Unlawful usage such as this often introduces pollutants into local water sources, which also contributes to GHG emissions.
But indoor growers can control their garden’s water consumption in a variety of ways. Installing hydroponics will help minimize water requirements from the start while collecting rainwater is a great way to lower the monthly water bill. Some large-scale facilities have even begun implementing drip irrigation systems and real-time moisture monitoring to get the most out of their H2O consumption.
Waste Management
Both indoor and outdoor cannabis gardens can produce a lot of waste. While waste plant material can be a hassle to dispose of, growers also have to dispose of consumer packaging on items like grow lights and nutrients.
Thankfully, many states are beginning to address the issue of cannabis waste management with various composting and recycling programs that are designed specifically with cannabis in mind. Some dispensaries even offer discounts and rewards to customers who return their used packaging for recycling purposes.
Making Strides Toward Sustainability
While the legal cannabis cultivation industry is still in its infancy, there’s no better time than the present to address issues of environmental sustainability. Some great strides have already been made in the effort to minimize GHG emissions, lower energy usage, reduce water consumption, and properly manage waste on behalf of indoor cannabis gardens, but there’s still quite a bit of work to be done if we want to avoid a complete environmental disaster in the near future.
Stay tuned: Volume 2 coming in April!
