DENVER (MainStreet) — Xcel Energy, Colorado's largest electric utility, is trying to figure out what marijuana will do to its grid.

Power demand has been spiking wildly as growers increasingly convert warehouses and industrial buildings into grow houses, said Xcel Energy spokesman Gabriel Romero.

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"We've never had an industry like this before that just sort of showed up," he said. "I couldn't begin to tell you how many grow houses there are. There are tons."

It's a moneymaker for Xcel for now, but it could become a money-loser if Xcel has to start upgrading substations or adding new ones to help growers satisfy Colorado's insatiable appetite for weed.

"They're high energy users," Romero said. "We know that. We're in the process of trying to determine how large."

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The company doesn't break out numbers for specific industries, but marijuana growers may have the potential to one day consume 1% to as much as 3% of Xcel's power.

"We're in the process of researching that exact figure," Romero said. "We're trying to get ahead of it before it becomes a problem."

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Marijuana growers, legal and otherwise, are already consuming 1% of the power generated in the U.S., according to a study by Evan Mills, an energy analyst with the Lawrence Berkeley National Laboratory. This amounts to about $6 billion worth of power every year, he estimates.

"The unchecked growth of electricity demand in this sector confounds energy forecasts and obscures savings from energy efficiency programs and policies," Mills wrote.

It also contributes mightily to mankind's carbon footprint. Mills calculated that the electricity used to grow one kilogram of weed dumps 4,600 kilograms of carbon dioxide into the atmosphere. Aggregated across all the growing operations nationwide, this results in carbon emissions equivalent to the pollution from 3 million automobiles, he estimates.

Xcel derives 56% of its power from coal, 22% from natural gas, 19% from wind, nearly 2% from hydro electric and more than 1% from solar. It is moving increasingly away from coal and more toward natural gas and renewables. But Colorado's tree-hugging weed smokers are contributing to global warming just like consumers of many other products.

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This may be just the beginning for an industry on a sharp growth trajectory. Colorado's Department of Revenue recently reported $19 million worth of recreational pot sales in March, up from about $14 million worth of recreational pot in February. That's a spike of nearly one-third and doesn't include medical marijuana sales.

Medical marijuana has been legal in the state since 2000, but Xcel started noticing increased power demand after 2010 with legislation that clarified matters for growers. Then came legalization of recreational use in January, and now warehouse space in Colorado is leasing and selling at a premium if you can find it at all.

Colorado's most notorious cash crop is typically grown indoors to ensure a year-round supply in a temperate climate with a short growing season. Indoor grow operations also provide needed security and allow for the tighter inventory controls that are mandated by state law.

Typically, growers must upgrade the electrical service of the buildings they occupy since their operations can consume as much as ten times the power that the previous occupants burned. This involves upgrading the panels for service coming into the building, as well as installing dedicated transformers on the utility poles outside.

These costs can run $25,000 to $35,000 and are paid by the growers. On top of that, growers often spend as much as $30,000 a month on the light bills, Romero said.

Anyone investing in the marijuana industry should consider this: as much as 50% of the wholesale price of marijuana is from electricity, according to Mills' research. If the boom in marijuana results in drastically lower prices, it could render indoor growing operations economically unviable, he writes.

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Energy-sucking grows are not a problem for Xcel as long as they are spread out evenly across many circuits, the load is easy to manage. But these operations tend to cluster in areas where their operations are tolerated by zoning ordinances and covenants. And this can put too much demand in one place.

Xcel now has account executives that work specifically with marijuana growers, offering advice on electrical systems and even tips on the right light bulbs to use.

"They're job is to make sure we are helping them the best way possible," Romero said. "We have to help them, just like any other customer."

They will have to help themselves. "If you're paying a $30,000 a month to power your building," Romero said, "you're going to find a way to get your utility bill down."

--Written by Al Lewis for MainStreet

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