SEATTLE — Marijuana growing is not a green industry.
Done mostly indoors in, pot production often uses hospital-intensity lamps, air conditioning, dehumidifiers, fans and carbon-dioxide generators to stimulate plants and boost their potency.
The power-hungry crops rival data centers or server farms in intense use of electricity, according to a peer-reviewed study last year in the journal Energy Policy. One kilo, or 2.2 pounds, of pot grown indoors, the study says, leaves a carbon footprint equivalent to driving across the country seven times. Producing one joint is equivalent to leaving a light bulb on for 25 hours.
There’s little question sun-grown pot is a cleaner alternative, even in Washington state, which uses mostly hydropower, considered greener than most energy sources.
“It’s great we have relatively low-carbon electricity, but that’s not a license to waste it,” said KC Golden, policy director for Climate Solutions, a Northwest nonprofit working against global warming.
It doesn’t make sense to move agriculture indoors, Golden said, given the sun’s track record of “encouraging photosynthesis for some 4 billion years now, without an outage.”
But in this blue-green state, very few folks are lobbying for pot grown under the sun in eastern Washington where the climate is suitable, in part because of security concerns about outdoor grows. And absent a stronger push, it appears state-regulated retail stores will open next year without sun-grown weed on their shelves.
Golden said he hasn’t studied the issue, particularly the implications of outdoor pot for law enforcement. Leaders at other environmental groups such as the Sierra Club and Conservation Northwest say they have other priorities. Even in Seattle, where the City Council is writing new zoning rules allowing large indoor grows, no one seems very concerned with the carbon footprint of indoor pot.