The cannabis industry in the US is booming and is showing no sign of slowing down. At the same time, amounts of greenhouse gas (GHG) emitted by cannabis indoor cultivation are booming, posing questions on how the industry can address the challenge of growth and climate change combined. Yet, addressing these challenges can be quite difficult, considering the lack of in-depth study of the GHG emissions of indoor cannabis growing.
In a recent paper published on Nature Sustainability, Hailey M. Summers et al. have carried out an analysis assessing the life cycle GHG emissions range according to the location. Far from representing the actual reality of the situation throughout the US, the analysis shows the GHG emissions if indoor cultivation was the chosen cultivation method.
The main elements that contribute to GHG emissions are air condition modifications and supply by HVAC. Especially humidity management can be quite energy-intensive when the external climate is hot and humid. Consequentially, the best places to grow indoor would be where the external climate did not require much adjusting to make it optimal for cannabis growing.
Of course, another element that is responsible for the great GHG emissions are the high-intensity grow lights. One way to address this problem is to switch to LED lights, and we can already see that states like California will make LEDs mandatory for any new cannabis operation, precisely to address these environmental issues.
Indoor facilities also use to inject CO2 into the grow room to boost plants growth thus shortening the cycle. However, as the paper points out, the GHG emissions are not caused by the introduction of CO2, but rather “from the production processes associated with the compression of the gas into liquid form and subsequent storage within a cylinder.”
The study concludes that such a report can be used to drive policymakers to regulate the cultivation of cannabis in such a way that is more environmentally friendly without necessarily impacting the quality of the end product. Indeed, there are some regions where indoor cannabis cultivation would have low GHG emissions, making them preferable to create some sorts of cannabis hubs. At the same time, since cannabis is still federally illegal, interstate commerce is not possible making a geographic optimization of cannabis growing not something achievable in the near future.
On the other hand, there is the possibility to switch production to outdoor or greenhouse growing. Yet, there is a lack of analysis about their environmental impact as well: for instance, water consumption for outdoor cultivation is quite a heavy burden on the environment, as well as land preparation or fertilizers. All of these factor into indoor cultivation only for a small part, where the study of the environmental impact is more focused on emissions associated with energy consumption. That aside, Summers et al. conclude that regardless of the geographical location, indoor cannabis cultivation leads to considerable GHG emissions, and thus it is important to address this, both from a grower and a policymaker perspective.