Pot’s not green. The $3.5 billion U.S. cannabis market is emerging as one of the nation’s most power-hungry industries, with the 24-hour demands of thousands of indoor growing sites taxing aging electricity grids and unraveling hard-earned gains in energy conservation.

For the third time in three years, Fluence Bioengineering, an Austin company that makes lights for indoor plant growing, has moved into a yet-bigger manufacturing facility.

Electricity-intensive cannabis production has a big carbon footprint, but with legalization, some eco-conscious growers want to make pot a shining model of sustainability.

In Kentucky, the University of Louisville's Conn Center for Renewable Energy Research has started growing industrial hemp in an effort to spur its fuels and manufacturing research.

A task force in Oregon, studying energy and water use associated with marijuana production, is likely to recommend that the state do more to educate growers about existing agricultural rules and practices, as well as back a certification process that encourages Oregon's new industry to pay closer attention how it uses natural resources.

As legal marijuana markets continue to expand in the United States, some experts are arguing that growers have both the need and the opportunity to make their operations, well, greener.

As cannabis has increasingly gone legitimate, electric utilities have struggled to cope with the intensive energy demands of the proliferating industry.