Roskilde Festival goers are donating their pee to make more beer in Denmark

Imagine the gallons of urine that collect at any of the world’s largest music festivals, flowing freely from beer-guzzling patrons. At Roskilde in Belgium this year, festival organizers decided to do something productive with all that pee, the Guardian reports: turn it back into beer.

Here’s an ad for the initiative from the Danish agriculture and food trade association:

They’re expecting to gather some 6,600 gallons of urine in what they’re calling their “from piss to pilsner” initiative. The urine will be used to fertilize barley eventually destined to turn into beer. Organizers hope that patrons will be drinking the beer they helped to grow by emptying their bladders by the time the 2017 festival comes around.