Colorado, the first state to roll out legalized recreational marijuana, no longer is at the forefront of the marijuana debate. Visitors to Alaska, Colorado, Oregon and Washington, the four states that allow recreational use, may be greeted by the familiar green cross that flags a dispensary. In addition, 21 states, the District of Columbia, Guam and Puerto Rico have laws legalizing marijuana for medical purposes. That means that in nearly half the states, cultivators are working to provide users with variations of the plant. States that address marijuana use also are encountering a less-discussed issue: the immense amount of electricity required for indoor production, the style of growing highest in electricity requirements.
On a structural level, indoor cultivators must consider special lighting, ventilation and air conditioning systems when designing greenhouses. Each of these systems uses a substantial amount of energy. Many growers, in order to ensure the maximum harvest of their crop, use intensely bright lighting systems paired with powerful air conditioners to shorten a plant’s growing cycle.
The electricity consumption of growhouses is staggering when compared to business and residential use. In 2015, the average electricity consumption of a 5,000-square-foot indoor facility in Boulder County was 41,808 kilowatt-hours per month, while an average household in the county used about 630 kilowatthours. A 2012 report on the carbon footprint of indoor production found that cannabis production makes up 1 percent of national electricity use, and in California, the top-producing state, that number rises to 3 percent.
An indoor facility can have lighting intensities similar to hospital operating rooms, which are 500 times greater than recommended reading light levels. These facilities can also have 30 hourly temperature or fan speed air changes, which is 60 times the rate in a normal home. Put another way, a four-plant lighting module uses as much electricity as 29 refrigerators.
On a monetary level, the finished products come in at an energy cost of $2,500 per kilogram. The energy used to produce one marijuana cigarette would also produce 18 pints of beer.
The link between cultivation and energy consumption, although not commonly on a legislature’s agenda, is an issue becoming increasingly more relevant, especially with more states opening the door to both medical and recreational usage.