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There is a growing issue in the cannabis industry that has just begun to come to light – energy use. An independent study by Dr Evan Mills, a researcher at the Lawrence Berkeley National Laboratory, found that 1% of all electricity in the United States is used by indoor marijuana grow operations – costing the country around $6 billion annually. If you grow at home, you may have noticed a sharp spike in the amount of energy your household consumes, or your energy use might have doubled since you began the twelve-hour light and dark cycling for your plants. According to UC Berkeley researchers, in-door plant grow lamps are 500 times more intense than a standard reading light; they are comparable to high-intensity lamps used in surgery operating theaters in hospitals. So how much energy does the typical home grow use? How can you tell if you’re using more than the standard amount, and what can you do to reduce your grow’s energy consumption? How much energy does a large commercial grow use, and how much does it cost? How much of commercial cannabis’ energy use is renewable, and what are the alternatives for home growers and commercial growers? Is it possible to break even on energy use so that power is put back into the grid? These are all questions we may ask ourselves when we see that expensive energy bill this month.

How much energy does the typical home grow use and how much does it cost?

First, let’s take a look at the small, home-grow – say you’re growing about eight plants currently. You may be using the spare room, the closet, or a grow tent inside your basement – for the sake of argument, let’s assume that your space is five feet by five feet. According to Ed Rosenthal, author of Marijuana Grower’s Handbook (an official course book of Oaksterdam University), sativa plants need about 66 watts per square foot; sativa-indica hybrids 60 watts; and indicas 40-45 watts. This means your indoor grow needs two 1000-watt lamps for sativas; two 600 watt lamps for hybrids; or three 400 watt lamps for indicas to produce a good crop. There are all kinds of lighting methods designed to increase your yield, but let’s just assume that these eight plants can produce the amount of cannabis you need, for now. Generally speaking, and within limits, more light for your plants produces better and more potent cannabis. In addition to lights, cannabis grows may need heaters; CO2 or ozone generators; humidifiers if you live in a dry climate, or dehumidifiers if you don’t; carbon filters; and fans or air conditioning units. (Of course, in the past, growing marijuana indoors or otherwise was illegal; and there is still a strong tradition of stealing electricity from the grid so the grows won’t be detected through astronomical electricity bills.)

How much energy does the typical large commercial grow use and how much does it cost?

From 2012 to 2013, electricity use in Denver, Colorado, increased by 1.2 percent; commercial marijuana grows were responsible for almost half of the increase in energy consumption. In 2013, Denver grows used 1.85 percent of the city’s overall electricity use. At the Colorado Harvest Company, twenty-two 1000-watt grow lamps are used just in Room No. 1, and an air-conditioning system keeps the lights from overheating and burning the plants. Colorado Harvest Company’s monthly electric bill is an average of $12,000, and according to NPR, another grow in city limits has bills that are about $24,000 a month. The intense lighting is needed to produce the flowers on the cannabis plants; Colorado Harvest Company noted that they tried using LED lights, but the plants did not produce enough flowers. In other words, LED lights don’t work as well – High Pressure Sodium (HPS) lights still work best.

Pueblo is the center of commercial grows in Colorado, with 30 businesses and 16 warehouses, some of which run on sunshine much of the year. In general, 10 grow facilities in Pueblo County and city used 2.1 million kilowatt hours (kWh) in 2014. That’s 210,000 kWh and 0.1% of the overall energy used in Pueblo. In California, according to Mother Jones’ Brenton Mock, energy consumption due to marijuana grows is as high as 3 percent of the state’s total usage.

How Can Cannabis Growers Reduce Energy Consumption?

Luckily, there are many resources for reducing energy consumption in both home grows and commercial grows. Solar panels, investment in subscription renewable energy credits through local energy companies, establishment of state and local guidelines and laws, and the development of brighter, more energy-efficient lighting options in the LED area are some options. Howard Geller of the Southwest Energy Efficiency Project (SWEEP) in Boulder, Colorado, noted that rebates, financing programs, and education efforts are the fastest ways to decrease energy consumption in any industry. ESource, an energy industry research company, recommends the following changes in indoor grow operations in order to reduce energy consumption:

  1. Reduce utility demand charges by changing the operation’s lights-on and lights-off times to take advantage of the cheapest rates; the highest rates are usually charged between 2:00 and 6:00 p.m. It’s also possible to stagger the lights-on and lights-off times for different rooms to reduce the overall energy draw at any one time – energy companies often base their rates on the top-draw times.
  2. Grow operations should replace single-ended HPS lights with double-ended HPS (DE-HPS) lights, providing up to 70 percent more usable light per watt than those with electronic ballasts.
  3. Grows should move the plants close enough together that their leaves are touching, like the canopy of a rain forest; this ensures that more light reaches the plants as opposed to the walls and the floor of the room; be aware of the effect of the light on your plants, and move the lamp up or down accordingly. Trellising is another great option: the plant is tied to stakes or a lattice in order to ensure all parts of the plant are exposed to the maximum amount of light.
  4. The use of variable-frequency drive retrofit devices for cooling equipment decreases the energy consumption of fans or compressors used. For a 120-plant facility, David Podorson of ESource noted, this would save the grow operation up to $15,000 annually.
  5. The use of cold, free, outside air in cooler months can replace the costs of year-round air-conditioning entirely, although growers should be sure that outside moisture is not affecting the plants.

As Renee Lewis of Al Jazeera noted, cannabis production is not cheap – it’s one of the most energy-intensive industries in the United States and elsewhere in the world. SWEEP’s Howard Geller noted that grow facilities can “cut energy use by 50 percent or more with state-of-the-art technology,” but did not relate the costs of this technology. In Boulder, Colorado, licensed cannabis growers must use 100 percent renewable energy to power their grows, and an energy-impact offset fund has been provided in case options like solar panels and building infrastructure investments are not possible. Ron Flax is Boulder County’s Sustainability Examiner for Land Use, and believes that the industry will eventually change toward greenhouse and outdoor cultivation designs and move away from indoor, artificial lighting and all the energy consumption that comes with it.  No matter which type of grow you have, consideration of ways to save energy and reduce your energy footprint is worth it – bringing down those energy bills will affect your life, as well as those of generations to come.

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