Energy up in smoke: The carbon footprint of indoor cannabis production

The following is an excerpt from a paper published by Evan Mills Ph.D.

What kind of facility has lighting as intense as that found in an operating room (500-times more than needed for reading), 6-times the air-change rate of a biotech laboratory and 60-times that of a home, and the electric power intensity of a datacenter?

The emergent industry of indoor Cannabis production results in prodigious energy use, costs, and greenhouse-gas pollution. Large-scale industrialized and highly energy-intensive indoor cultivation of Cannabis is driven by criminalization, pursuit of security, and the desire for greater process control and yields. The practice occurs across the United States and in many other countries.

The analysis performed in this study finds that indoor Cannabis production results in energy expenditures of $6 billion each year--6-times that of the entire U.S. pharmaceutical industry--with electricity use equivalent to that of 2 million average U.S. homes. This corresponds to 1% of national electricity consumption or 2% of that in households. The yearly greenhouse-gas pollution (carbon dioxide, CO2 ) from the electricity plus associated transportation fuels equals that of 3 million cars. Energy costs constitute a quarter of wholesale value.

In California, the top-producing state—and one of 17 states to allow cultivation for medical purposes—the practice is responsible for about 3% of all electricity use or 9% of household use. Due to higher electricity prices and cleaner fuels used to make electricity, California incurs 70% of national energy costs but only 20% of national CO2 emissions.

From the perspective of individual consumers, a single Cannabis cigarette represents about 10 pounds of CO2 emissions,* an amount equal to running a 100-watt light bulb for 75 hours with average U.S. electricity (or 135 hours on California’s cleaner grid). Each four-by-four-foot production module doubles the electricity use of an average U.S. home and triples that of an average California home. The added electricity use is equivalent to running about 90 refrigerators. Processed Cannabis results in 4,600-times its weight in CO2 emissions. For off-grid production, it requires 70 gallons of diesel fuel to produce one indoor Cannabis plant, or 140 gallons with smaller, less-efficient gasoline generators.

Minimal information and producer consideration of energy use, coupled with adaptations for security and privacy, lead to particularly inefficient configurations and correspondingly large energy consumption and greenhouse-gas emissions. If improved practices applicable to commercial agricultural greenhouses are any indication, the energy use for indoor Cannabis production can be reduced dramatically. Cost-effective efficiency improvements of more than 75% are conceivable, which would yield energy savings of about $25,000/year for a generic 10-module growing room. Shifting cultivation outdoors eliminates most energy uses (aside from transport), although the practice can impose other environmental impacts, such as poisoning of animals by rodenticides and other chemicals used by growers.

Who is the author of this report and who sponsored it?

The research described in this report was conducted and published independently by Evan Mills, Ph.D., with no external sponsorship or institutional affiliation. Dr. Mills is a scientist specializing in energy analysis and the role of energy in climate change, with a focus on the efficiency of energy use as the number-one strategy for reducing climate change. He has been working in this field for 30 years and is currently a scientist at one of the national laboratories as well a Research Affiliate with the Energy and Resources Group at U.C. Berkeley. However, this study was done on the author’s own time. More information on the author is available here.