In the most detailed study of its kind, researchers at Colorado State University have found that the booming cannabis industry in the United States has a massive carbon footprint. The $13 billion cannabis industry may be a huge success, but the research suggests that this success comes along with consequences for the environment.
The researchers performed a life-cycle assessment of indoor cannabis operations across the country. They calculated the energy and materials used to grow the cannabis, as well as the corresponding greenhouse gas emissions.
The study revealed that greenhouse gas emissions from cannabis production are largely attributed to high energy demands, including electricity production and natural gas consumption. The energy is used for indoor environmental controls, high-intensity grow lights, and carbon dioxide supplies that are used to accelerate plant growth.
“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 study lead author Hailey Summers said. “We just wanted to run with it.”
The research builds on previous work by experts at the Lawrence Berkeley National Laboratory, who analyzed small-scale cannabis operations in California. That particular study was conducted prior to the new laws that legalized medical use of cannabis in 36 states and recreational use in 15 states.
The CSU team expected to find substantial differences in emissions depending on where cannabis was being grown. The researchers modeled emissions for several high-growth locations around the country.
The team also created a map that shows relative emissions anywhere in the United States – defined as emissions per kilogram of cannabis flower.
The experts found that U.S. indoor cannabis cultivation generates greenhouse gas emissions of between 2,283 and 5,184 kilograms of carbon dioxide per kilogram of dried flower.
The researchers were surprised to find that heating, ventilation, and air conditioning systems had the largest energy demand, with numbers fluctuating depending on the local climate.
According to study co-author Jason Quinn, the high energy consumption of cannabis is due in part to how the product is regulated. In Colorado, for example, many grow operations are required to be in close proximity to retail storefronts. As a result, a large number of indoor warehouses have popped up in places like Denver.
Ultimately, the CSU team would like to help the industry tackle environmental concerns while legal cannabis is still relatively new in the United States. “We would like to try and improve environmental impacts before they have become built into the way of doing business,” said study co-author Evan Sproul.
The research is published in the journal Nature Sustainability.
By Chrissy Sexton, Earth.com Staff Writer