Cannabis growers in the US are under increased scrutiny for straining the electric grid. They have been blamed for water shortages in California and Oregon. They face complaints about the plant’s strong skunk-like odor and potential to lower air quality. The industry also generates a growing amount of waste, including paper and plastic consumer packaging and electronic waste from vaping devices.
Cannabis uses far less water than other top agricultural commodities in California.
Credit: Will Ludwig/C&EN
Source: New Frontier Data.
But data on energy and water use, air emissions, and waste from the cannabis industry are limited. A small fraction of the US industry is embracing the opportunity to fill those data gaps and address problem areas. A few state regulators are also stepping in to address concerns about air quality and energy use. And academics are relying on bootstrapped funding to conduct energy-efficiency research.
Cannabis is federally illegal in the US, but 19 states and Washington, DC, have legalized it for adult use. Dozens of states have also legalized the medical use of cannabis.
The federal prohibition means that the Department of Energy and other federal agencies can’t fund research to determine how to improve energy efficiency and minimize carbon dioxide emissions at cannabis cultivation facilities. The Environmental Protection Agency is barred from researching cannabis production to determine air-emission factors, which companies use to estimate how much air pollution they produce.
Also, cannabis growers can’t get federal tax breaks for installing new technologies to reduce their energy use, as other industries can. They also don’t have decades of agricultural research on how to optimize cannabis growing conditions in greenhouses and indoor facilities.
The US Department of Agriculture (USDA) has funded research for other agricultural commodities since the 1970s, says Shawn Cooney, cofounder of the Sustainable Cannabis Coalition, a group of North American cannabis cultivation and manufacturing experts. Founded in early 2021, the organization promotes best practices related to the environmental sustainability of cannabis cultivation and manufacturing.
Cooney grows lettuce and greens in shipping containers in the Boston area. When he began looking to add cannabis to his business, the lack of research on growing cannabis was “like night and day” compared with other crops, he says.
The USDA can fund research on hemp, defined as cannabis with no more than 0.3% ∆9-tetrahydrocannabinol (THC) on a dry-weight basis, thanks to legislation that Congress passed in 2018 to legalize hemp in the US. But the USDA still lacks the authority to fund research on cannabis that does not meet the hemp definition.
When Cooney first started talking with industry peers and vendors about sustainability, most had little interest, he recalls. “People were always afraid of it” because of the industry’s intense energy use, he says.
The coalition hopes to change that mindset by supporting academic research, working with international standard-setting bodies, and promoting software solutions that make it easy for the cannabis industry to monitor energy use, waste, and other environmental effects.
The group persuaded the standard-setting organization ASTM International to establish a subcommittee on cannabis sustainability. Cooney chairs that panel, which formed in March. Its goal is to determine “what to measure, how to measure it, and what to report in a consistent way across global cannabis industries—focusing mainly on energy, water, waste, and social responsibility,” Cooney says. “We’re not in the business of establishing standards of what the end goal should be,” he adds. The subcommittee hopes to vote on the standards by early next year, he says.
ZAPPING ENERGY GLUTTONY
Energy use is one of the biggest environmental impacts of the cannabis industry, particularly when plants are grown indoors. In cities, cannabis is often grown in retrofitted industrial warehouses that were not designed for agriculture. In many other places, cannabis is grown in large-scale greenhouses. Regulations in some municipalities, such as Denver, make growing cannabis indoors the only practical option.
Most states where cannabis is legal, including Colorado, do not require cultivation facilities to meet specific energy standards, though Illinois and Massachusetts do.
Installing light-emitting diode (LED) bulbs can help cannabis growers lower their energy use and meet state regulatory standards. But it’s not always feasible, and it doesn’t always make a big difference in electric bills.
Credit: Dartmouth Student Sustainable Cannabis Team
Dartmouth College engineering student Jason Carpio conducts energy-efficiency research at a cannabis cultivation facility in Maryland.
“LED lights have come a long way,” says Melinda Kadinger, chief operating officer and chief financial officer at Smokey’s Cannabis, a cannabis cultivation and retail company in Colorado known for its sustainability efforts. “We tried LED lights when they first came out, and it was a bomb. But now we have converted an entire room to LED lights, and it is our best-performing room” in terms of cannabis quality and amount, she says.
“Our energy impacts are large, and we’re well aware that growing indoors is not the most sustainable way to do it,” says Jason MacDonald, director of cultivation operations at Native Roots, one of the largest cannabis producers in Colorado. “But it is the way to get final, quality product that people are looking for. So we have tried to make changes wherever we possibly can save power,” he says.
Native Roots has two facilities in Denver where it grows cannabis. One facility produces about 45 kg of dried cannabis flowers every 10 days. The other produces that amount in a day, MacDonald says.
The company started out using about 2,000 high-pressure sodium bulbs, 1,000 metal halide bulbs, and 4,000 T5 fluorescent bulbs, MacDonald says. Replacing the T5 bulbs with LED lights that last five times as long halved the company’s power use, he says. Native Roots is now replacing all the metal halide bulbs with LEDs, he adds.
Unlike most grow facilities, which must counter the heat generated by non-LED grow lights, Native Roots needs that warmth at its largest facility.
“We count on high-pressure sodium lights for part of our heating,” MacDonald says. “If we were to switch from those bulbs to an LED solution, we would lose that heat. We don’t know if our system can handle that much heat loss,” he says.
To replace all its grow lights with LEDs, Native Roots would have to invest about $10 million to improve the heating and ventilation system at its largest facility, MacDonald says. It’s hard to justify that investment, he says. In addition, because cannabis is federally illegal, the company would not be able to claim any tax credits or deductions for the upgrade, unlike other businesses.
To better understand how cannabis cultivation facilities can reduce their energy use beyond switching to LED lights, the Sustainable Cannabis Coalition sponsored a project led by researchers at Dartmouth College. Over the past year, the team metered energy use from grow lights, dehumidifiers, and cooling systems at two indoor cannabis cultivation facilities—one in Massachusetts and one in Maryland. Preliminary results of that study, which have yet to be published, suggest that these facilities use two to three times the energy needed for optimum production, says Stephen Doig, senior research and strategy adviser at Dartmouth’s Arthur L. Irving Institute for Energy and Society and one of the lead researchers of the study.
The project is one of the first independent analyses of the potential for the cannabis industry to reduce costs while improving metrics, such as kilowatt-hours per gram of product and grams of CO2 emissions per gram of product, Doig says.
Doig and colleagues found their own funding for the study without help from federal or state government agencies. “We used our own time and money to get the initial results,” Doig says. Industry provided time, labor, and expert advice and allowed the researchers to access data and facilities, he adds.
The work has important implications for decreasing cannabis’s burden on the US electric grid, Doig says. The cannabis industry is responsible for about 1% of US energy demand, and that percentage is growing, he notes.
Our energy impacts are large, and we’re well aware that growing indoors is not the most sustainable way to do it.
Jason MacDonald, director of cultivation operations, Native Roots
Federal legalization of cannabis is critical so that the federal government can fund this type of research, he says.
Some science on the energy efficiency of buildings conducted for other industries could be used as a starting point for the cannabis industry. So if federal funding becomes available, researchers would not have to start from scratch, Doig says. Federal money for research could lead to “a common way of measuring and monitoring and metering these facilities that would allow comparisons to be made,” he says. Such standardization would be a great boon to state regulators, the cannabis industry, and companies that provide equipment to the industry, he adds.
“Energy is the one area where cannabis is and continues to be phenomenally resource intensive,” says John Kagia, chief knowledge officer at New Frontier Data, a market research firm focused on the global cannabis industry. Outside California, most cannabis in the US is grown indoors. But “we’re also seeing a lot of interest in transitioning out of fully enclosed indoor environments to greenhouses,” Kagia says. In those mixed-light environments, growers can use the sun and supplement with artificial light as needed, he says.
“Our goal in the future, as long as rules and regulations allow, would be to go toward a greenhouse type of hybrid situation,” Smokey’s Kadinger says. “The greenhouse is, in my opinion, a better way to grow as opposed to doing it indoors,” for both the environment and product quality, she says.