In the United States, the cannabis industry is expanding like never before, as various states legalise its use for varied purposes. The psychoactive drug has been marketed as the upcoming ‘business boom’ that has both medicinal and recreational uses. However, even with the industry becoming extremely popular, there is a lack of awareness regarding its environmental impact.
To fill this gap, researchers from Colorado State University conducted a new study that provides a detailed analysis of the cannabis industry’s carbon footprint in the form of greenhouse gas emissions from commercial, mostly indoor production. The results show that indoor cultivations of cannabis results in massive amounts of carbon emissions ranging from 2,283 and 5,184 kilograms of carbon dioxide per kilogram of dried flowers.
“We knew the emissions were going to be large, but because they hadn’t been fully quantified previously, we identified this as a big research opportunity space,” said Hailey Summers, the graduate student leading the study, in a statement.
Currently, 36 states in the US have legalized the medical use of cannabis, and 15 have legalized recreational use. The cannabis industry has captured a wide range of consumers from college students who need a break to adults who are looking for a sunny Sunday after a long week.
As a part of the study, the team from Colorado State University performed a life-cycle assessment of indoor cannabis operations across the United States. This methodology assesses the environmental impact of the various stages a commercial product undergoes during production. They analyzed the use of energy and materials in growing the plant and tallied the corresponding greenhouse gas emissions.
Compared to the massive carbon emissions from indoor cannabis cultivation, emissions from outdoor and greenhouse cannabis growth are 22.7 and 326.6 kilograms of carbon dioxide, respectively, according to the 2018 Cannabis Energy Report. While this indicates a substantial difference between the numbers, it is important to note that the Energy Report mainly considers electricity usage for studying greenhouse gas emissions, whereas the current research was a comprehensive life cycle assessment.
The higher results of indoor cannabis production were largely due to electricity and natural gas consumption that was used for environmental control. Moreover, this study also captures the potential cross-country spread of large commercial warehouses for cannabis production and models emissions for various high-growth locations across the country.
These results of the study also include a map that highlights the relative emissions, defined as emissions per kilogram of cannabis flower, in the United States.
The problems related to the high energy consumption of cannabis are not just limited to its production, but are also to how the end product is regulated, said Jason Quinn, an associate professor in the Department of Mechanical Engineering.
In Colorado, the first state to legalize cannabis in 2012, many cannabis operations are required to be in proximity to retail stores. In urban areas like Denver, this policy has led to an increase in indoor warehouses that consume high amounts of energy. This has led the total electricity consumption to rise from 1% to 4% between 2013 and 2018, according to a report from the Denver Department of Public Health and Environment.
Currently, the team is seeking funds to expand their research and compare indoor and potential outdoor production operations. “We would like to try and improve environmental impacts before they have become built into the way of doing business,” said Evan Sproul, a research scientist in mechanical engineering of the Colorado State University.
The study was published in Nature Sustainability on Monday, March 8, and can be accessed here.
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