Full Title: When going green is dirty: Colorado's indoor cannabis farms produce 30% more greenhouse emissions than the state's coal mining industry due to electricity use and natural gas consumption, study reveals Growing cannabis indoors requires a lot of energy for lights and climate controls Many states forbid outdoor farming or require operations to be near retail outlets In Colorado, indoor pot farming's carbon footprint is over 30 percent bigger than coal mining Depending on where you are, growing an ounce of weed indoors has the same carbon footprint as burning 7 to 16 gallons of gasoline