Utilities and grid operators worry about the impacts that energy-hogging marijuana will bring to their grids, and are excited about the profits they’ll bring to their bottom line.

The issue is pressing enough that it got its own session – “The Straight Dope on Energy & the Marijuana Industry” – at the Nov. 11 annual meeting of the National Association of Regulatory Utility Commissioners in Austin, Texas.

Attendees learned that Xcel Energy, which serves most of urban Colorado, sells some 300 gigawatt hours of electricity to pot growers per year, or enough to power some 35,000 homes. The U.S. marijuana-growing industry could soon buy as much as $11 billion per year in electricity.

One study estimates that it takes as much energy to produce 18 pints of beer as it does just one joint. The data are alarming, and will only get more so as legalization spreads. But legalization, if approached correctly, also opens doors of opportunity. The biggest guzzlers of electricity also hold the most potential for realizing gains via efficiency.

Back in 2011, a California energy and environmental systems analyst, Evan Mills, published a paper quantifying the carbon footprint of indoor cannabis production. That footprint, he discovered, was huge. His findings included:

While the U.S. pharmaceutical sector uses $1 billion/year in energy, indoor cannabis cultivation uses $6 billion.

Indoor cannabis production consumes 3 percent of California’s total electricity, 9 percent of its household electricity and 1 percent of total U.S. electricity (equivalent to 2 million U.S. homes per year).

U.S. cannabis production results in 15 million tons of greenhouse-gas emissions per year, or the same as emitted by 3 million cars.

Cannabis production uses eight times as much energy per square foot as other commercial buildings, and 18 times more than an average home.

Mills’ paper generated a flurry of media coverage, much of it sensationalist, which was then used to point out that pot smokers are hypocritical (based on the wrong assumption that pot smokers are environmentalists).

Some pundits even used the findings – along with some dubious math – to justify other carbon-intensive activities, such as mining Alberta’s tar sands.

But Mills wasn’t picking on pot, per se. He was focused only on indoor cultivation. And he made sure to point out that a lot of marijuana’s energy use is actually energy waste. Many growers, for example, use diesel generators to power their operations to avoid suspicious electric bills. They grow in places where there are no windows, without the benefit of sunlight, relying entirely on artificial lighting (which is extremely bright and energy intensive). When greenhouses are used, they tend to be of bad and inefficient design.

Most of this wastefulness occurs not because dope farmers are gluttonous slobs, but because they need to stay hidden in order to stay out of jail. So by simply legalizing and legitimizing the trade, some states have taken the first step in taking a bite out of cannabis’ energy footprint.

For one thing, legalization allows farmers to move their crops outdoors, where it takes no more energy to grow a pot plant than it does a carrot or tomato. It allows them to ditch the dirty, wasteful generators and hook up to the grid. (And to actually pay for the power they use: Electricity theft by pot producers is said to total as much as $100 million per year). And it allows utilities and farmers to work together on maximizing efficiency.

The Northwest Power and Conservation Council, for example, has found that huge savings could be realized if farmers switched to efficient greenhouses and to LED lighting, and their yields would increase.

In his paper, Mills suggests implementing energy-efficient incentives as well as energy-conscious construction codes for grow operations. There’s also tremendous potential for using all the pot growers on a single grid together as a demand response resource.

Demand response works like this: Demand on the grid spikes, perhaps because everyone turns on their energy-sucking flat screen televisions to watch the football game all at once. The utility needs to meet that demand by putting more power into the grid. The conventional way of doing this is to fire up a power plant, usually natural gas-fired, which is expensive and polluting.

But in demand response, the new power needs are met by curtailing the power use of a bunch of customers by, say, telling their hot water heaters to shut down for an hour or so, via smart meters. This has the same effect as injecting more power into the grid, to meet the increased demand. In other words, the consumers, collectively, become a sort of backup power plant.

A more rudimentary form of demand response is for the utilities to coordinate with the growers to shut down the power-sucking devices during peak load hours, such as when everyone else is cranking their air-conditioners, and turn them on during off-peak hours, like in the middle of the night. If the growers are on time-of-use electricity rates, that would be the most cost-effective way to go, anyway.

Unfortunately, many utilities are slow to seize the opportunities legalization presents. Xcel Energy’s representative at the Austin meeting said that the company has been wary of working with growers on efficiency because it might look like the firm is promoting drug production.

And the Bonneville Power Administration, the massive federal utility in the Pacific Northwest, doesn’t allow any of its efficiency incentives to go to cannabis cultivators, because growing marijuana is still against federal law.

This story originally published at High Country News (hcn.org).