The following is a guest post by Skippy Massey:

Excuse me, but are you stepping on me or is that just your carbon footprint? Big weed is also a big energy suck. As if we didn’t know?

Dr. Evan Mills, staff scientist at the Lawrence Berkeley National Laboratory, delivered a surprising lecture at Humboldt State University on October 6 of his study on the carbon footprint of  indoor cannabis production. Dr. Mills previously garnered international attention with his research paper, “Energy Up in Smoke,” before hitting Humboldt’s Ground Zero for the first time Thursday.

“INDOOR marijuana cultivation as a whole, including both medical and illegal grows, is a multi-billion-dollar business,” Mills said. “It’s also one that consumes a huge amount of electricity.” Mill’s work estimated that 1 percent of the nation’s electricity is consumed by indoor marijuana cultivation and indoor pot grows carry a heavy carbon price tag. “The amount of energy needed to grow a  single joint’s worth of marijuana indoors could keep a 100-watt light bulb running for 17 hours. In California alone, the amount would power about 3 million homes— representing the enormous carbon footprint used by growers,” he said.

THE average indoor marijuana grow is obviously very energy intensive. Mills’ study found that growing the average kilogram of marijuana indoors produced 4,600 kilograms of CO2; or, about “the same level of emissions created by driving a Toyota Prius across the country eight times.” The worst of these indoor grows produced nearly 7,500 kilograms of CO2 per marijuana kilogram, he noted.

PUTTING this into another perspective, the average four-by-four-by-eight-foot indoor grow space consumes the electricity of 30 refrigerators— or an average home. Diesel generator powered grows— common in Humboldt County—have an even larger carbon footprint, producing three times more emissions creating electricity than does Pacific Gas and Electric Co. Mills pointed out the array of energy sucking equipment used ranges from 1,000 watt lights, fans, pumps, air conditioners, dehumidifiers, dryers, and more. There are even gas powered bud trimmers with built-in iPod docks.

CRAFTING a model of the average grow space for research, Mills also utilized interviews with people in the indoor garden supply business, trade literature, and published reports. “In the best case model,” Mills said, “CO2 production dropped to around 1,000 kilograms” and noting that “being carbon neutral is possible.”

“THE indoor marijuana industry spends $6 billion a year on energy,” Mills said, and “better efficiencies can be found resulting in energy cost savings of up to $1,000 a pound for producers.”

THE basic problem, Mills says, is that there are “no best-practice” manuals for energy efficient indoor marijuana cultivation. Many grow houses are assembled using “friends’ advice, cultural habits— and a lot of misinformation, he believes. “The range of practices are wide, varying— and rarely optimal. The solution to creating a more energy-efficient industry is largely one through education. Mills would like to see more studies on the topic, examining efficiency potentials, yield-to-strain ratios, energy impacts associated with transporting marijuana to market, and the carbon footprint of outdoor grows. He advocates having third parties evaluate and rate indoor garden equipment for energy efficiency.

ADDITIONALLY, Mills suggests medical marijuana dispensaries post a carbon footprint grade on their products as some do with THC content and strand names. There’s also the budding question to ask of whether legalization could result in better efficiencies and what types of regulations could lead to a more carbon-neutral product.

MILLS also put overall marijuana usage into perspective for the 30 members of the audience attending:

“16 states have some form of a medical marijuana industry and at least 730,000 Americans holding some form of doctor’s recommendation for medical marijuana. There are almost 17 million regular marijuana users in America.” Dr. Mills said. “In California, there are 2,165 McDonald’s restaurants, 2,010 Starbucks coffee shops— and 2,600 medical marijuana dispensaries. Annual medical marijuana sales receipts outpace Viagra almost two-to-one,” he added.

That’s some potent pot and profits— producing a costly carbon footprint to boot.

(More information about Dr. Evan Mills is found at his Energy Associates website.

Information for this report was sourced from Thadeus Greenson’s Times-Standard article, “Indoor Pot Grows Carry Heavy Carbon Price”

Readers may also be interested in Mr. Greenson’s recent Times-Standard article, Keeping the Lights On: Indoor Pot Growers Skirt High Electric Bills Through Discount Program for Low Income Households”)