A growing problem: Lightening the carbon footprint of cannabis farms

Consider a typical cannabis farmer, growing an indoor crop.

In a protected, controlled environment, they can grow a profitable mix of high-potency, medicinal marijuana and any number of milder strains appealing to a new market.

But the venture comes with both a business and social overhead: high energy bills and a heavy, carbon footprint.

"It's a big problem," said Tim Hade, co-founder of microgrid company Scale.

A study estimated a single, indoor marijuana plant takes the equivalent of 70 gallons of oil to grow. Energy demand at Colorado's largest utility grew about 2 percent after marijuana was legalized.

Hade said the growing industry could wipe out gains the country made in the past decade that kept energy consumption stable even as the population and economy grew. As the legalized marijuana industry expands in California, it could challenge state goals to reduce greenhouse emissions.

The cannabis industry is starting to address the issue. Startups are hunting for ways to make growing more efficient. Farmers are innovating and experimenting.

Right now, the industry consolidation, leading to larger-scale indoor farms could prove "far more energy intensive" than the current growers', he said.

Scale, based in New York, combines solar, battery storage and natural gas generators in a system that can cut energy cost by as much as 35 percent.

With about 30 percent of a farmer's overhead spent on fuel and electricity, he said, "you have to be sophisticated about energy management."

While conceding that cannabis grown indoors can more easily produce high-quality crops, Cyril Guthridge in Mendocino County, Calif., is nonetheless trying to perfect outdoor farming.