Sales of aluminum are on the rise, and that’s in part because using it in products can have environmental benefits. But there’s a dirtier side to aluminum — producing it is energy intensive. So, now demand is growing for “greener” aluminum.

The move toward using aluminum in the U.S. auto industry started getting attention in 2015, when Ford used it in place of steel in the body of its iconic F-150 truck. “The only pickup with a high strength, military grade aluminum alloy body,” Ford TV ads boasted. Aluminum’s lighter weight shaved 700 pounds off the truck, which improved fuel efficiency, and that in turn reduced tailpipe emissions.

Soon other U.S. automakers followed suit. Industry analysts expect a continued upward trend in aluminum use. One reason is that California and 12 other states are moving forward with tougher fuel efficiency standards, as is Europe and other places. Christine Keener, vice president of sales at Alcoa, an aluminium producer, thinks aluminum will help these efforts. “It’s lightweight, it’s durable, it’s corrosion resistant,” she said.

This means the finished products can be friendlier to the climate. But making aluminum still has a heavy climate impact. Worldwide, producing one ton of it creates nearly 12 tons of carbon, almost six times the carbon emitted from producing a ton of steel. Automakers and other industries face increasing pressure to reduce carbon down the entire supply chain.

But Alcoa’s Keener said not all aluminum is equal. Chinese producers rely heavily on coal for power. U.S. manufacturer Alcoa said its carbon emissions are half the worldwide average because it uses hydroelectricity. Keener said demand for this lower impact aluminum is growing, “There is more interest out there from consumers, and we’re starting to see it in particular in European automotive and packaging. We also see it very heavily in North America building and construction.”

In fact, a group of producers and manufacturers, including Alcoa and Apple, are working together to create green manufacturing standards.

Fiona Solomon is director of that group, the Aluminum Stewardship Initiative, based in Australia. “Our aim is really to maximize the contribution of aluminum to a sustainable society,” she said. The group expects to start green aluminum certification by the end of the year.