Cannabis use for medicinal purposes is now legal in 33 states in the country. Hawaii was the first state to legalize medical cannabis via the Legislature. With the increase of indoor cannabis production in the U.S. has come an unwelcome reality to those of us concerned with climate change: indoor cultivation practices without sustainability measures deployed have an unusually high carbon footprint.

Indoor cannabis production is in the early stages of industrial growth, and yet it is responsible for the equivalent of 1 percent of U.S. electrical usage. In fact, typical U.S. indoor cannabis production energy usage is on a scale with mainstream carbon-intensive industries.

For example, indoor cannabis production, nationally, uses as much energy as is produced by seven large electric power plants. That amount of energy use equates to emissions of 15 million metric tons of CO2 emissions every year or the equivalent emissions from three million cars. As discussed presently, this impact is increasing rapidly.

Medical marijuana plants are growing legally in Hawaii thanks to a law allowing medical cannabis dispensaries. But it adds to climate change when fossil fuels are used to power growing operations. Anthony Quintano / Civil Beat

The medical cannabis market is expected to grow from $7 billion in 2016 to $45 billion by 2025. Using current practices, this six-fold increase would add to the climate impact of medical cannabis. Recreational cannabis adds another 70 percent to both sales ($150 billion) and climate impact. With few exceptions, little action has been taken by state and local governments to address the climate impact of legal cannabis production.

As an energy systems engineer during the 1980s, I find this extremely surprising and disappointing given the energy efficiency progress made in the last 40 years. This is even more indefensible, given the clear impacts of climate change on the frequency and magnitude of catastrophic fires and floods.

Power Drain

In Hawaii, indoor cannabis production is required by law but is extremely energy intensive. Regulators maintain that it is essential because outdoor grown plants may be exposed to heavy metals and synthetic chemicals such as pesticides and herbicides — not things patients want in their medicines. Furthermore, growing medicinal cannabis indoors is required by many states for security.

An indoor facility through thoughtful design and technology can reduce energy consumption.

In an indoor facility, plants are grown in a clean environment where pests and pathogens can be more easily controlled organically and by mechanical means. Indoor cannabis production is energy intensive because lighting, heating, ventilation, air-conditioning, dehumidifiers, and pumps often operate 24 hours per day, 365 days per year.

The power density of all components of cannabis production is about 200 watts per square foot. This is about the same power density of a large computer data center.

Astonishingly, aluminum production, a notorious energy hog, consumes a mere 7 kilowatt-hours of energy for every pound of aluminum produced compared to 2,000 kilowatt-hours per pound of indoor grown cannabis. The huge energy footprint of indoor cannabis production means that each kilogram of cultivated plant produces 4,600 kilograms of CO2 per kilogram. Put another way, each kilogram of cannabis produced uses the energy equivalent of burning 1,533 kilograms of oil (or 398 gallons).

So, what is the solution?

The most obvious energy management opportunity in an indoor facility is lighting, which accounts for 38 percent of the total energy requirements. The lighting component is actually low hanging fruit for attaining big reductions in energy use. Energy consumption can be reduced by 60 percent to 75 percent by using a combination of daylighting with transparent or translucent roofing and LED lighting in place of fluorescent and high-intensity discharge lamps.

There are many more opportunities for reducing a facility’s carbon footprint such as through energy efficiency measures for HVAC which can reduce HVAC energy consumption by 40 percent.

All in all, it is estimated that an indoor grow facility through thoughtful design and available technology can reduce its energy consumption by 35 percent. That equates to taking more than a million cars off the road in the U.S.

High quality cannabis medicines are in demand for good reason: They are a natural and effective way to treat many medical problems such as cancer, epilepsy, pain, rheumatoid arthritis, PTSD and other conditions. We can take a triple bottom line approach to produce those products in a:

  1. sustainable, environmentally conscious way; that,
  2. meets a social need (reasonably priced, quality medicines); and
  3. minimizes production costs to ensure that the industry is financially sustainable and provides benefits to local economies.

Hawaii was the first state to set a deadline for generating 100 percent of its electricity from renewable sources, which is required to be achieved by 2045. If Hawaii is to meet that goal, commercial and industrial companies must use best available technology to operate as sustainably as possible. Fortunately, investment in those technologies can produce triple bottom line benefits.

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