As voters go to the polls this November, at least four states will consider ballot questions on marijuana legalization. Pending proposals in Nevada, Maine and California would authorize recreational marijuana use, while Floridians will vote on whether to allow medical marijuana use.


Legalization of marijuana in the United States has spread rapidly over the last few years. Half of the states have legalized marijuana in some form. Alaska, Colorado, Oregon, Washington and the District of Columbia have legalized it for recreational use. And the Democratic Party platform committee recently voted 81 to 80 to amend the federal Controlled Substances Act to remove marijuana from the list of Schedule 1 drugs. The stated purpose of this proposed amendment is to "provid[e] a reasoned pathway for future legalization."

States with some form of legalized marijuana have implemented stringent regulatory and licensing schemes with regard to the who, what, where and how of marijuana possession, cultivation, and distribution. But policymakers have failed to address an important area: the marijuana industry's energy and climate impacts. Although marijuana is a plant, it is not a "green" product when grown indoors. As more states – and, potentially, Congress – consider legalizing the marijuana industry, they should also adopt rules to make it more environmentally sustainable.

Indoor marijuana farms are energy hogs

Indoor marijuana cultivation is one of the most energy-intensive industries in the United States, generating nearly $6 billion in energy costs annually. According to the Northwest Power and Conservation Council, which carries out energy planning for the Columbia River Basin states (Montana, Idaho, Washington and Oregon), growing marijuana indoors consumes up to 5,000 kilowatt-hours of electricity per kilogram of output. For comparison, aluminum production requires about 16 kilowatt-hours per kilogram.


Colorado's experience demonstrates marijuana's large energy footprint. Since the state legalized recreational marijuana in 2014, the industry has expanded rapidly there. In 2015 legal marijuana businesses in Colorado made nearly $1 billion in sales, up 42 percent from the previous year. And as marijuana businesses become more competitive and specialized, growers are moving their farms indoors to get a more controlled product.

Indoor cultivation requires electricity to power high-intensity lights, frequent air exchanges and ventilation and to maintain consistent temperatures and humidity levels day and night. As a result, the state has numerous indoor warehouses that consume huge quantities of electricity.

Experts estimate that a 5,000-square-foot indoor marijuana facility in Colorado consumes six times more electricity per square foot than an average commercial business and 49 times more than an average residence. Last year Denver officials sought guidance from the Department of Energy on ways to curb the industry's power requirements. Electricity use in Denver is rising by 1.2 percent yearly, and marijuana farms account for nearly half of the increase.

Colorado has set a goal of generating 30 percent of its electricity from renewable sources by 2020. Currently, however, only 18 percent of its electricity comes from renewable sources. The rest is generated from coal and natural gas.

On-site generation systems, such as rooftop solar arrays, and community-scale energy projects cannot produce enough electricity to meet marijuana growers' energy needs. As a result, the marijuana industry is indirectly increasing Colorado's reliance on fossil fuel.

Legalization provides some energy benefits. For example, it allows indoor cultivators to connect to existing electricity grids instead of relying on carbon-intensive gasoline and diesel generators. However, these benefits are swamped by the industry's fast-growing electricity requirements.


Experts estimate that nationwide, indoor marijuana cultivation accounts for nearly 15 million metric tons of carbon emissions annually – more than the annual energy-related emissions of South Dakota, Delaware, Rhode Island and Vermont, or the District of Columbia. Public utility commissioners across the nation are discussing strategies for managing power demand from indoor pot growers.

Legalize and regulate

When states legalize marijuana cultivation, they establish detailed regulatory and licensing schemes governing who may sell, possess and cultivate the plant, where they may do so, and how much they must pay for licenses. Policymakers should also seize this opportunity to enact rules governing the industry's climate and energy impacts.

Since indoor growers consume such enormous amounts of electricity, policymakers should start by requiring indoor cultivators to consume only carbon-free energy sources or to pay a carbon fee until such measures can be implemented.

Boulder, Colo., is addressing this issue by implementing city and county licensing schemes that require indoor marijuana cultivators to use energy monitoring technology and routinely report their energy use. Growers must offset their energy use by utilizing 100 percent renewable energy, purchasing renewable energy credits or paying a carbon fee. However, few other states or localities have followed Boulder's lead.

Oregon has established a task force to study energy and water use for marijuana production. The group is scheduled to report its findings to the state legislature later this summer. Preliminary indications are that the task force will call on growers to follow energy best practices, but it is unclear whether it will recommend making this policy mandatory or merely a suggestion.


States that do not have enough renewable energy generation to meet the industry's electricity demands, such as in Colorado, should take a two-pronged approach. First, they should require indoor growers to pay escalating carbon fees based on their electricity consumption. These funds should be used to support development of more efficient technology and climate-friendly electricity facilities.

Second, legislators should also require an exponential increase in the percentage of energy consumed by indoor growers from renewable energy sources via on-site generation – such as rooftop solar – or community renewable energy facilities. This two-pronged approach would ensure growers do not become complacent just paying the fee.

The best time to address impacts of this magnitude is before they occur, not after a major industry is already established. Marijuana production is rapidly developing into an extremely lucrative industry that can afford to manage its impacts on the environment.

Gina Warren is an associate professor of law at the University of Houston This article was originally published on The Conversation. Read the original article.