The Dirty Truth Behind Colorado's Legal Weed Growhouses

The green, it turns out, is not always so green. Despite a bumper crop of cutting edge, energy efficient grow technologies, producing lots of pot indoors puts a massive strain on the grid while exhaling equally massive amounts of greenhouses gases.

Just ask John Kocer, who co-owns north Denver's River Rock retail medical marijuana dispensary. In Colorado, where dozens of large-scale cannabis growhouses like his are vying to cash in on recent legalization measures that'll legalize recreational pot use beginning January 2014, the environmental costs of doing business are getting higher and higher.

“Energy consumption in this business is pretty astronomical,” Kocer tells CBS Denver. His most recent electricity bill was $21,500. The latest bill of one of his (unnamed) hometown competitors? $100,000.

That's not to pick on Kocer, or Colorado for that matter. The dirty reality faced by many of today's big domestic pot grows, poised as they are to scale up to commercial levels, finds them continuing to employ hulking high-pressure sodium (HPS) lights and climate control system that run round-the-clock. And right now, at least, it's still difficult to get a handle on the true scope of doing so.

But we can look to a 2011 study by Lawrence Berkeley National Laboratory researcher Evan Mills for an idea. Mills looked at energy consumption within the cannabis industry, and found that indoor pot production uses about $6 billion worth of energy annually, or enough electricity to power two million average-sized homes. That accounts for one percent of total national energy usage, and spews as much greenhouse gases as three million cars.

Which is where today's new green grow tech, stuff like the smart LED lighting rigs that we saw first hand while filming our documentary High Country in and around Denver, come in.

Cary Mitchell, a horticulture professor at Purdue University whose heading up a $5 million project to audit and improve LED lighting capabilities in America's "specialty crop" (see: greenhouse grown fruits, vegetables, nursery plants, etc.) industry, thinks mainstream commercial agriculture has a lot to learn from the pot industry's gradual embrace of LED tech. He tells the Guardian that specialty crops net about $50 billion a year, and that their growers are seeking out ways to slash energy costs while increasing yields, much like cannabis farmers.

"They've undoubtably been doing this for years and years," Mitchell explains, referring to pot grower's LED usage. "Since they don't publish their research, we don't really know how far they've taken the optimization. They probably are ahead of the specialty crop commercial production industry."

Time will tell, of course, whether the environmental toll of growing heroic amounts of cannabis will keep shooting up, or if a big enough shift toward low-footprint grow tech will clear the air. For now, Kocer tells CBS that he anticipates sales of his operation's product to grow 400 percent next year.

@thebanderson