Energy up in Smoke: The Carbon Footprint of Indoor Cannabis Production

The full report can be downloaded HERE. Energy benchmarking survey.

SUMMARY
What kind of facility has lighting as intense as that found in an operating room (500-times more than needed for reading), 6-times the air-change rate of a biotech laboratory and 60-times that of a home, and the electric power intensity of a datacenter?

The emergent industry of indoor Cannabis production results in prodigious energy use, costs, and greenhouse-gas pollution. Large-scale industrialized and highly energy-intensive indoor cultivation of Cannabis is driven by criminalization, pursuit of security, and the desire for greater process control and yields. The practice occurs across the United States and in many other countries.

The analysis performed in this study finds that indoor Cannabis production results in energy expenditures of $5 billion each year, with electricity use equivalent to that of 2 million average U.S. homes. This corresponds to 1% of national electricity consumption or 2% of that in households. The yearly greenhouse-gas pollution (carbon dioxide, CO2 ) from the electricity plus associated transportation fuels equals that of 3 million cars. Energy costs constitute a quarter of wholesale value.

In California, the top-producing state—and one of 17 states to allow cultivation for medical purposes—the practice is responsible for about 3% of all electricity use or 8% of household use. Due to higher electricity prices and cleaner fuels used to make electricity, California incurs 70% of national energy costs but only 20% of national CO2 emissions.

From the perspective of individual consumers, a single Cannabis cigarette represents 2 pounds of CO2 emissions, an amount equal to running a 100-watt light bulb for 17 hours with average U.S. electricity (or 30 hours on California’s cleaner grid). Each four-by-four-foot production module doubles the electricity use of an average U.S. home and triples that of an average California home. The added electricity use is equivalent to running about 30 refrigerators. Processed Cannabis results in 3000-times its weight in CO2 emissions. For off-grid production, it requires 70 gallons of diesel fuel to produce one indoor Cannabis plant, or 140 gallons with smaller, less-efficient gasoline generators.

Minimal information and producer consideration of energy use, coupled with adaptations for security and privacy, lead to particularly inefficient configurations and correspondingly large energy consumption and greenhouse-gas emissions. If improved practices applicable to commercial agricultural greenhouses are any indication, the energy use for indoor Cannabis production can be reduced dramatically. Cost-effective efficiency improvements of 75% are conceivable, which would yield energy savings of about $25,000/year for a generic 10-module growing room. Shifting cultivation outdoors eliminates most energy uses (aside from transport), although the practice can impose other environmental impacts.

FREQUENTLY ASKED QUESTIONS

What is the purpose of this study?

This study simply aims to quantify a previously undocumented component of energy demand in the United States, to understand the underlying technical drivers, and to establish baseline impacts in terms of energy use, costs, and greenhouse-gas emissions. This study does not pass judgement on the merits of Cannabis cultivation or make recommendations for how to reduce this energy use, but observes that many reversible inefficiencies are embedded in current practices.

Has the media covered the story accurately and responsibly?

The problem is a lot more complicated and nuanced than most pundits in the blogosphere make it out to be, and most in the mainstream media have actually missed the real story (a roster of articles is provided at the bottom of this page). Among the (few) relatively thorough, non-selective, and un-spun stories are those in the New York Times, FastCompany, Southern California Public Radio, San Francisco Bay Guardian, and the Huffington Post. First place for the most inane coverage is an editorial from the Calgary Herald. The Week did a particularly inept job at providing an objective cross-section of the coverage.

What’s missed or bungled:

•A number of media reports inaccurately associate the work with Lawrence Berkeley National Lab. The work was conducted independently of LBNL on the author’s own time.
•Most media reports have sensationalized the numbers without putting them in perspective or looking at solutions. If the media applied the same concern to greenhouse-gas emissions for all human activities as they have to the release of this report we would be well on our way towards addressing the climate change problem.
•This isn’t simply a California issue, let alone a “counter-culture” or “hippie” issue. Its mainstream and it’s pervasive. The UN says 10% of North American citizens use Cannabis on a regular basis, and most of the production is actually not even in California any more…. Only 1/5th of national Cannabis-related emissions come from California (and an unknown fraction of that is for products consumed outside the state).
•Some observers have spun the story into a blame-game rather than a “what do we do about this problem?” challenge, with responsibility being dumped exclusively on the growers’ doorstep rather than the consumers and others who can powerfully influence the energy choices being made.
•Few of the reports recognize that there are solutions here. There’s a lot of room for a more virtuous cycle…. Using good-old market forces (see final entry on this FAQ page). This is an energy-using sector that has almost uniquely been passed over by decades of efforts from many quarters to improve efficiency …. The time for that has come and there is a lot of low-hanging fruit, which is good news to everyone concerned.
•Legalization is a simplistic answer. The reality is that people will seek to grow indoors irrespective of their legal status. More has to be done if carbon emissions are to be curbed. More on this below....

Who is the author of this report and who sponsored it?

The research described in this report was conducted and published independently by Evan Mills, Ph.D., with no external sponsorship or institutional affiliation. Dr. Mills is a scientist specializing in energy analysis and the role of energy in climate change, with a focus on the efficiency of energy use as the number-one strategy for reducing climate change. He has been working in this field for 30 years and is currently a scientist at one of the national laboratories as well a Research Affiliate with the Energy and Resources Group at U.C. Berkeley. However, this study was done on the author’s own time. More information on the author is available here.

What information sources were used for this work?

Data and assumptions for building the energy-demand model were drawn from the open literature, trade press, equipment specifications, and interviews with horticultural equipment retailers. A detailed list of sources and technical assumptions are provided at the end of the report and in the notes to the data tables.

Does this report pertain only to medical Cannabis?

No. A number of media reports have misreported this. The analysis pertains to all Cannabis production.

Isn’t the solution to just grow outdoors?

Complicated. Many of the issues, and emerging opportunities (including achieving comparable quality in vs out) are discussed here.

How does the energy use of this sector compare to others?

The approximately 22 billion kilowatt-hours/year estimated for indoor Cannabis production is about one/third that of US data centers or one-sixth that of US household refrigerators. The shares would be much higher in states where Cannabis cultivation is concentrated. Automobiles are responsible for about about 33% of U.S. greenhouse-gas emissions, which is 100-times as much as indoor Cannabis production (0.3%).

You say that the resulting electricity intensities are 200 watts per square foot. This is absurd.

The 200W/sf value is a side note, and not integral to the energy and emissions calculations, which has somehow been misinterpreted as being the constant rate of energy use for lighting. It's actually the installed power density of lighting plus all other equipment, and none of those "watts" are assumed to be running 24x7. For example, for lighting this assumes 600W-MH (37.5 W/sf) for the vegetative stage and 1000W-HPS (62.5W/sf) for flowering (summing to ~100W per the definition of power density -- but for energy calculation purposes the 600W and 1000W devices are never drawing power simultaneously). The rest of the demand is for all the other loads (AC, dehumidification, fans, ballasts, etc.).

Why are you singling out Cannabis when so many other things use more energy?

The study hardly singles out Cannabis. On the contrary, there has been a de facto double standard for decades in which virtually every other energy use has been met with efforts to improve efficiency and reduce emissions. Cannabis should no more be singled out for attention than it should be overlooked.

Doesn’t the mainstream pharmaceutical industry use more energy?

From a "carbon-accounting" it would be challenging--if at all possible--to meaningfully go about the comparison to other Pharma, since to do that you'd have to have an apples and apples comparison not only of the energy/carbon (relatively easy) but also the impact benefit at the macro level. In any case, "two wrongs don't make a right" and the extreme inefficiency of this process should be reduced. The good news is that this is quite possible if there is the will and the right information. Arguably, the mainstream Pharma industry already does much more than the Cannabis industry to reduce its carbon footprint... It has been reported that the Viagra market is about the same size as the medical Cannabis market; i will leave it to others to debate the relative carbon footprints.

Is Cannabis production intrinsically polluting?

No. Like virtually any other energy-using activity (driving, preparing food, making aluminum, heating a home) energy is commonly wasted and used inefficiently. And, as observed in virtually every energy use domain, there are enormous prospects for improving efficiency and using low- or no-carbon energy sources. Outdoor production involves particularly low energy inputs, although when mismanaged, the practice imposes other environmental impacts.

Does this study enable or endorse illegal activity?

No. On the contrary, the analysis sheds light on certain adverse consequences of indoor cultivation in its current form. Moreover, an increasing fraction of Cannabis cultivation is legally sanctioned at the state level (17 states at present, and many more deliberating), which places the related use of energy in the same domain the many other energy-intensive activities routinely addressed by energy policies such as codes, standards, incentives, and labeling.

Does this study support the case for criminalization?

No. In fact, many argue that criminalization is an important driver towards energy-intensive indoor production. Criminalization also contributes to many of the energy inefficiencies in the process, including long driving distances, noise and odor suppression measures that undercut ventilation efficiencies, and off-grid power production that is far less efficient produces more greenhouse-gas emissions than many electric grids. Moreover, decades of criminalization has resulted in this energy-using sector being passed over by massive efforts to incentivize and mandate efficiency improvements. The analysis does suggest a role for improved management of energy use, in much the same way that we address the energy use and fuel economy of our cars, buildings, and appliances.

Does this study support the case for decriminalization or legalization?

Not really. People grow indoors for many reasons aside from criminalization, e.g., quality control, pest control, and year-round yield. Many legally sanctioned producers choose to grow indoors. It is not known whether decriminalization will reduce or increase the rate of indoor cultivation. That said, in a scenario where production is legalized it is, in principal, easier to address the energy issues.

How significant are the energy costs for producers?

The answer varies widely depending on the production method, prevailing energy prices, and wholesale prices of the final product. Averaged nationally, about one-quarter of the wholesale price is attributed to energy costs. In regions with high electricity tariffs or the use of inefficient off-grid power generators, this value can approach half the total cost.

Wouldn’t just “going solar” solve this problem?

Nope. Using solar to power inefficient systems is a waste. A costly, mega-sized solar system to run a bunch of inefficient lights, fans, and chillers in a single house would just give solar a bad name. For the same investment, many dozens of conventional houses could be made highly energy efficient and then be solar-powered all the way to zero carbon emissions. This would provide much more carbon-bang for the buck.

How does this energy intensity compare to that for other indoor horticultural practices?

Good question. According to one study, the energy use for indoor horticulture (all crops) is 7% of total energy use in the Netherlands. According to research from the Netherlands, the production of ornamental flowers is 2.2 GJ per 250 flowers. This translates to about 1,200 kilowatt-hours (including indirect embodied energy for fertilizer, pesticides not counted in the Cannabis analysis). For comparison, the annual kilowatt hour use of a 4x4x8-foot Cannabis cultivation module is estimated at about 13,000 kWh. It is hard to identify the right “apples-to-apples” comparison metrics. Another study for Belgium places national energy use for greenhouses at about 1000 MJ/m2, which is 1% that of indoor Cannabis production.

Are we barking up the wrong tree? Doesn’t law enforcement spent even more energy on suppression and eradication?

Not likely. Certainly a study in and of itself, but per a quick look: Total federal government energy expenditure for vehicles for all purposes is less than half that of Cannabis production and jet fuel for aviation, including military (see page 96 of this report) is “only” $7 billion per year (including overseas operations) -- that was FY 2007, so maybe more now. Total federal government for aviation gasoline (small planes0 is $10 million/year... In any case, two wrongs don’t make a right - seriously. We need to reduce emissions wherever they occur. If we do nothing but point to others who emit more we will never get out of the greenhouse.

What can be done with the results?

The study is policy-relevant, but is not policy prescriptive. Carbon footprint could be reduced by 75% without even shifting production outdoors (which reduces emissions almost completely). Top-level pathways to reducing the carbon footprint of indoor production include:

•Growers selecting better, commercially available equipment.
•Equipment vendors developing even more efficient equipment, and educating their customers.
•Reducing the use of off-grid power generators fired with fossil fuels. The worst case is a gasoline-fueled generator, which results in 140 gallons of fuel burned to produce each plant.
•Applying science to understanding how to achieve necessary environmental conditions in a less energy-intensive manner.

The opportunity to influence a constructive, climate-friendly response rests with all involved parties.

•Producers lack information, motivation, and market or regulatory pressure to improve.
•Designers and manufacturers of the energy-using equipment could more precisely analyze and consider the issues from an engineering and market standpoint.
•Medical dispensaries could support more responsible consumer decision-making, by providing disclosure of product carbon content and other dimensions of environmental footprint.
•Planning and building officials at the city, state, and federal level may choose to seek better understanding of the energy and safety consequences of this activity in their localities. Some (Berkeley, Boulder, Fort Bragg) have already made steps in this direction.
•Electric and gas utilities have already begun to recognize legal producers, granting them lower (agricultural) tariffs in exchange for safety inspections.
•Energy providers, policymakers, and forecasters could better account for this particular driver of energy demand, and thus more accurately evaluate the effects of unrelated programs and policies on the consumption of energy at the macro scale.
•Consumers and the general public can become informed about the carbon footprint associated with this practice and better consider the environmental consequences of their actions.

MEDIA COVERAGE - US

Atlantic - How much electricity does indoor-grown pot use?
Atlantic - Marijuana growing consumes 1 percent of nation's energy
Bay Citizen - Study: one joint equals two pounds of greenhouse gases
Bay Guardian - Cool, efficient plasma lighting technology comes online
Bay Guardian - Green Buds: Environmental cost of growing indoors is luring the marijuana industry back into the sunshine
Berkeley Daily Planet - City Council fails to pass sustainable medical marijuana ordinance
Boston Business Journal - Up in smoke
California Watch - Pot growers burn through energy
Cannabisfantastic.com - The carbon footprint of cannabis
CBS Television - Smoke on this: marijuana growers use one percent of U.S. electricity supply
Chicago Tribune - National Marijuana Day: not as green as you might think
Columbus Dispatch - Indoor marijuana's carbon footprint is extra large
Consumer Reports - Growing marijuana gets you high ... energy costs, study finds
Culture - In a brand new light
Daily Californian - Growing marijuana indoors could damage environment
Daily Kos - The carbon footprint of Cannabis
Denver Post - Growing pot, guzzling energy
Discovery News – Pot growers not so green
Environmentalguru.com - Pot: the hidden power hog
Fast Company - Buzzkill of the day: U.S. marijuana industry responsible for $5 billion in energy Consumption
Forbes – New study reveals massive energy consumption of pot industry
Freakonomics - The $5 billion carbon footprint of indoor marijuana
Good - Not so kind: weed growers suck down 1 percent of all U.S. electricity
Grand Rapids Press - Report: indoor marijuana growing consumes 1 percent of U.S. electricity
Green Economy Post - Grass is not so green: marijuana has a huge carbon footprint
Green Tech Media – Marijuana, top US crop, has a $5B power bill
Grist.org - Climate change kills our buzz, and vice versa
Honolulu Weekly - How green is your pot?
Huffington Post - Marijuana carbon footprint: indoor pot production uses 1 percent of U.S. electricity, study says
KALW Radio - Connecting the dots
KCBS Radio - Pot growers account for 8 percent of household electricity use in CA
LA Weekly - Marijuana grown indoors is bad for the environment: could legalizing it change that?
National Geographic - The energy drain of recreational drugs
New York Times - Marijuana growing gobbles electricity, study finds
New York Times - Study: pot growers inhale 1% of U.S. electricity, exhale GHGs of 3M cars
Next 100 - Pot: the hidden power hog
NPR - Marijuana not so green: study finds growing pot indoors Is energy intensive
Philly Inquirer - Pot farms burn $5B of US electricity/year: report
Press Democrat - North Coast: Pot-growing power grab
Redheaded Blackbelt - Buy only sustainably grown marijuana and reduce america’s dependence on foreign oil
Redheaded Blackbelt - Their weed habit causes a Fukoshima worth of power every year.
Richmond Confidential - City council fails to pass sustainable medical marijuana ordinance
San Francisco Business Times - Marijuana causes global warming, uses 1% of U.S. electricity
San Francisco Chronicle - Pot grow houses eat 8 percent of California's residential electricty use
Seattle Post Intelligencer - Dude, your marijuana grow is sucking up megawatts (NY Times)
Southern California Public Radio - Greener pot: is there such a thing as energy efficient Cannabis?
The 420 Times - Indoor marijuana growing accounts for 1% of U.S. energy use
The Week - Marijuana isn't 'green?'
Treehugger.com - Marijuana industry responsible for 1% of US electricity consumption, has $5 billion energy bill
Tuscon Citizen - Marijuana causes global warming
WSBT - A study finds that indoor marijuana grows consume a staggering 1 percent of nation’s electricity

MEDIA COVERAGE - International

Austria - Ein Prozent des US-Stroms für Marihuana Belgium - Le joint est mauvais pour l'environnement Brazil - Plantio de maconha nos EUA alimenta efeito estufa, diz cientista Canada - Calgary Herald - Grass is not green
- Boston Globe and Mail - The cost of growing marijuana
France - La culture du cannabis : une mauvaise chose pour l'environnement ? - La culture de cannabis aux Etats-Unis représente 1 % de la consommation
- Fumer un joint est mauvais pour l'environnement Germany - Energiefresser Marihuana
Greece - Η μαριχουάνα προκαλεί παγκόσμια υπερθέρμανση! Iceland - Good - Not So Kind: Weed growers suck down 1 percent of all U.S. electricity
Italy - La marijuana fa male: ai consumi energetici Mexico - Consume cultivo de mariguana en interiores 1% de la producción de electricidad en EU Poland - Zaskakujące badanie nt. marihuany
Portugal - EUA: Produção caseira de cannabis representa 1% de todo o consumo de electricidade
Romania - Marijuana provoacă încălzirea globală - Producatorii de marijuana din SUA consuma energie de 5 miliarde de dolari Sweden - Cannabisodlare hot mot miljön Turkey - Esrar küresel ısınmaya sebep oluyor