According to one of the better-known Bible verses, Jesus once crashed a wedding in Cana and turned six jars of water into six jars of pretty decent wine. It's hard to beat Christianity's most famous party trick, but two Belgian scientists might have done it. Sebastiaan Derese and Arne Verliefde, both professors at Ghent University, have created a machine that uses solar energy to turn human urine into drinkable water and—probably because they're Belgian—they are using that pee water to brew beer.
Derese and Verliefde have spent the past two years researching how to recover potable water and nutrients from urine, in the hopes that farmers in developing countries could soon use these techniques to fertilize their own crops. But, in the meantime, they're testing the process by turning that piss into beer. They recently took their "installation," as Verliefde calls it, to a music and theatre festival in Ghent, collecting enough pee to yield more than 1,000 liters of water that have been delivered to a local microbrewery. The resulting beer will be bottled and sold under the name From Sewer to Brewer, which is a less disgusting name than Roskilde music festival's similar initiative called "From Piss to Pilsner" (yes, believe it or not, there are multiple groups trying to turn your pee into beer).
We had the chance to speak with Verliefde, who told us what made him pursue this field of study, what urine beer tastes like and why we should, um, give pee a chance.
MUNCHIES: You have co-authored several papers about recovering water and nutrients from human urine. How did this research get started? Arne Verliefde: It is part of a study that was started within my research group two years ago. Sebastiaan Derese and I both have an interest in working in developing countries and the recovery of resources, which is important because of the scarcity of certain nutrients. If you look at the amount that one person pees every year, if you look at the nutrient content in that, it's sufficient to fertilize about 135 kg (297 lb) of maize every year.
How much urine does one person produce in a year? Typically, a person produces about two liters a day, so that's about 700 liters per year.
That's a lot of maize. We thought 'If we can recover the nutrients, why can't we recover the water as well?' We started working on it in the lab, and our installation worked well, so we decided to give it a try-out in the real world. We thought we'd try it at the Ghent Festival because we need a location where we've got lots of urine. And then the idea came about to brew a beer with the clean water we produce. It's actually the third version of beer that we will brew. The first version was based on recovering wastewater from a brewery. The second one was a step up: it was actually filtered wastewater from a municipal wastewater treatment plant. The third version is going to be the urine version, From Sewer to Brewer. And you could actually buy the second version of the beer at the festival.
Was it a popular choice? There were a lot of people who were interested in buying it. A lot of people tried it. Even my family tried it, although they needed some persuasion.
How does it taste? Have you had it as well? It's actually quite good! It tastes a bit like a tripel beer, an amber beer. It's about 7% alcohol, so it's relatively high in alcohol percentage. It's one of the heavier beers.
So basically that beer became the source of your third beer, after everyone who tried it peed it out. Indeed, some traces of it might still be present in the urine that we collected.
Explain this to me like I'm a five-year-old: how do you turn urine into potable water? We collect the urine first. At the Ghent Festival, we only collected male urine, because we needed to collect the urine separate from the feces. We collected the male urine from urinals in our central collection tank, then we heated that using solar energy. We could then separate out the water and the nutrients. We recovered clean water, and (with) the stuff that remains we could make into a powder or crystal form which contains all of the nitrogen, phosphorus and potassium.
The beer aspect is interesting, but that's not ultimately how you hope to use this technology, is it? No, the beer is a bit of a gimmick and a bit of a social experiment as well. You know, how willing are people to try this type of beer made from urine? But the main market that we see is with farmers in developing countries.
Are you working with one particular brewery to make the beer? Yes, De Wilde Brouwers, a local brewer in Ghent. The guy who does the brewing is actually an ex-student of our [Ghent University] faculty. He brews all three versions of the Sewer to Brewer beers, and he does it in his own home, brewing about 2,000 liters per month.
When will the third batch be available? We have tested the water and we know that it's good, but it needs to be tested by the Flanders food agency. Those tests will probably run in September and, after that, we'll start brewing. It should be finished by the end of the year.
This interview has been edited for length and clarity.