Starbucks announced today that customers will now be able to bring in their reusable cups whether they’re walking into a store or driving up in the US and Canada. The company claims it’s the first national coffee retailer to give customers this option for drive-thru and mobile orders.

For years, customers have been able to walk into select Starbucks locations to fill reusable cups (although the practice was put on hold between 2020 and 2021 due to the covid-19 pandemic). What’s changing is that now clean, refillable cups are acceptable in the drive-thru window at all company-operated and participating licensed stores in the US and Canada, expanding a policy that had been in place already at certain locations. Customers earn a $0.10 discount on their drink for bringing in a personal cup.

The move is supposed to reduce waste from disposable cups. But questions have swirled online over how much environmental impact it actually has. After all, there are tailpipe emissions to consider when sitting and waiting for a drive-thru order.

“This is part of a larger cultural movement the company is leading to shift toward reusables and away from single-use plastics, making it convenient for customers to use their own personal cup for every visit,” Starbucks says in a press release. The company goes through about 6 billion cups a year, about 1 percent of the 600 billion paper and plastic cups produced globally each year — most of which become garbage.

Environmental groups, including Greenpeace, have pushed Starbucks for years to abandon disposable cups altogether. Locations in South Korea pledged to do so by 2025. The chain has also committed to “providing easy access to personal or Starbucks provided reusable to-go cups in café, drive-thru and mobile order and pay” in the US and Canada by 2025. It also has global goals to reduce waste and planet-heating carbon dioxide emissions by 50 percent by 2030.

But over the years on Reddit, people have questioned whether encouraging people to drive through with their reusable cups might end up generating more tailpipe emissions. Baristas have to wait for customers to reach the pick-up window before collecting their personal cups. “We would have to wait for for you to get to the window in order to make the drink in it which would cause a lot of back up for us,” one Reddit user posted in 2022.

Starbucks is embroiled in bigger controversies at the moment — facing boycotts over labor conditions, alleged union-busting, and responses the company and union members have had to the Israel-Hamas war.