This Earth Day, April 22, Chipotle Mexican Grill will reward eco-friendly customers with a free burrito, bowl, salad or order of tacos if they purchase a Chipotle-branded repurposed billboard bag from Chipotle’s online store, store.chipotle.com, between now and April 14. Chipotle will donate all of its proceeds from the sale of the bags to the Chipotle Cultivate Foundation.

In keeping with Chipotle’s commitment to finding more sustainable solutions, the lunch bags are made through a unique process called “upcyling,” in which billboards sourced directly from Chipotle’s outdoor advertisements are given a second life by transforming would be waste into ultra-durable, one-of-a-kind, products using less energy than traditional recycling methods. Each lunch bag purchased through April 14 will include an eco-friendly card with a unique barcode that a customer can redeem for a free menu item on Earth Day. The cards are printed on tree-free stone paper that is made from limestone salvaged from construction sites and quarry waste.

“We are changing the way people think about and eat fast food,” said Steve Ells, founder, chairman and co-CEO of Chipotle. “For us, that starts with serving food made with better ingredients from more sustainable sources, but that same idea impacts all facets of our business. We are always pushing ourselves to find better, more sustainable practices for everything we do, and looking to educate our customers about these issues and why we think they are so important.”

Designed exclusively for Chipotle by Loomstate, a pioneer of sustainable apparel, and made in Denver by Billboard Ecology Partners, the lunch bags are available exclusively through Chipotle’s online store. The bag design features a classic top-roll adjustable strap closure, reinforced side seams and handle, and a convenient extra-large back pocket. The black back and front panels of the bags are the reverse side of the billboards while the side panels showcase unique front-facing billboard designs that differ by bag, meaning that each is truly one of a kind.

For every 20,000 lunch bags made from retired Chipotle signage, landfills are spared some 78,000 square feet of billboard vinyl — enough material to cover 2.7 Olympic swimming pools.

Lunch bag supplies are limited and customers must purchase their bag between Monday, March 26 and Saturday, April 14, 2012, in order to receive it in time for Earth Day. Each lunch bag purchased through April 14, 2012 will include a card containing a barcode, which customers must present to redeem their free Chipotle menu item. Each customer is limited to one free burrito, bowl, salad or tacos per barcode presented.

All proceeds from the lunch bag sales will go towards the Chipotle Cultivate Foundation, which launched in August 2011 with the debut of “Back to the Start,” an animated short film available at YouTube.com/Chipotle. The Chipotle Cultivate Foundation provides funding to support sustainable agriculture, family farming, and culinary education.