Would you guess that growing marijuana indoors consumes 1% of US electricity? Yikes!
America's fledgling marijuana industry uses $6 billion worth of energy per year, creating greenhouse gas pollution equivalent to 3 million cars.
Why? Because it still has to be grown covertly - and that means using lots of energy-intensive grow lights indoors.
Although the sale of medical marijuana has been approved by voters in 20 states and the District of Columbia - and Colorado and Washington State will begin selling pot legally to recreational users next year - cannabis is still subject to federal seizure and penalties under America's archaic drug enforcement policies.
In fact, indoor marijuana production facilities use lighting as intense as surgery operating rooms; warehouse-style farms require six-times the air-exchange rate of a biotech lab and 60 times that of a home, according to an independent study conducted in 2011 at Lawrence Berkeley National Lab.
Dozens of these warehouses are in the Denver area.
Think of it this way: smoking one joint represents two pounds of CO2 emissions, the same as a 100-watt light bulb produces in 24 hours.
In real numbers, the monthly energy bill for the Denver-based River Rock dispensary - a medical marijuana retailer with a local warehouse - exceeds $21,000. And that's low compared to other retailers, who have electric bills of $100,000, reports CBS Denver.
What to Do?
Colorado's medical retailers project the marijuana market will grow by at least 400% percent when recreational users start buying in January.
In preparation for capacity crowds at dispensaries, the City of Boulder is ready with the same environmental regulations as any polluter. The city mandates marijuana growers either install or buy wind or solar energy, or purchase carbon offsets.
We can't have a burgeoning industry that is driving our carbon emissions up," Boulder City Councilman Macon Cowles, told CBS Denver. "Marijuana is going to be greener in Boulder and we are very proud of that."
As for River Rock in Denver, its new 18,000-square-foot greenhouse will primarily run on solar, using 6% of the energy needed to grow indoors. "Our primary goal is to lower our costs as much as possible and pass it on to our patients," owner John Kocer told CBS Denver.
Growers are also experimenting with lighting systems that use about five times less power.
Growing pot outdoors is much less energy-intensive, but there we have the problem of pesticide use. Surprisingly, the House of Representatives passed an amendment to the Farm Bill this year that would making industrial hemp farming legal. We'll see if it ends up in the final bill.
Read our article, A Sea Change for Hemp, Marijuana in the US?