Paper coffee cups are wasteful, taking decades to break down in a landfill after they're used for just a small part of someone's morning. But they're also irresistibly convenient to many. A new startup called Vessel Works is aiming to tackle the waste problem at coffee shops by applying the convenience of disposable to-go cups to reusable mugs, Fast Company reports.

The program, which is launching in four Boulder, Colorado cafes, takes the pressure off of customers to provide their own reusable cups. Instead, they can download an app and use it to check out an insulated, stainless steel mug free of charge. Throughout the day, the app updates them on ways their choice has made a difference, including how much waste they've prevented, how much water they've conserved, and how much they've reduced their carbon footprint. When they're done with the drink, users have five days to return their mug to a Vessel kiosk; from there it will be cleaned in one of the startup's facilities and returned to a cafe where the cycle will start all over again.

Vessel isn't the first company to attempt to bring reusable cups into the sharing economy. In 2016, coffee shops in Hamburg, Germany adopted a program where customers could acquire a mug for a small deposit and return it to a participating cafe to get their money back. Vessel Works's program differs in that users are never asked to pay unless they fail to return their cups on time (in that case, they'll be charged a fee).

Vessel is currently working with Boxcar Coffee Roasters and Trident Booksellers and Cafe in Boulder, and is coming soon to Seeds Library Cafe at the Boulder Public Library and the Pekoe Sip House at the University of Colorado. The startup hopes to eventually expand to more cafes and install dropoff kiosks at more convenient locations like transit stops.

[h/t Fast Company]