Photo: Ulrik Eriksen

Grains and vegetables to be grown in festival pee

Innovation and product development
BEng students have found a green source of plant fertilizer: Nutrients from urine collected in balls of plant-based gel. 

Although phosphorus is a very common element, it is estimated that the phosphorus sources we use today will be exhausted within the next 100 years, so the search for alternative sources—and preferably some which are climate-friendly—has begun.

A group of BEng students have come up with a solution based on one of the original sources of phosphorus: urine. Via their urine, humans annually excrete the amount of nutrients needed to grow 250 kg of grains. The challenge is, however, to get the nutrients to where they are needed—and this is where the students’ idea, PeeBalls, comes into play.

"The feeling that anything is possible and that all doors are open when you study at DTU has been one of the greatest experiences of the project and of starting on the programme."
Liv Skovgaard, BEng student at DTU

PeeBalls are small balls of a plant-based biogel that can absorb 200 times their own weight in liquid. When the balls come into contact with urine, they absorb it, and subsequently the balls can be dehydrated, so that they only contain the nutrients. The concentrated nutrient balls can be used to fertilize fields instead of conventional fertilizers.

“Over the three weeks we worked on the project, a lot of ideas were on the table. The biogel solution actually occurred somewhere else, i.e. as a possible method for removing water after cloudbursts,” says Liv Skovgaard, who has just completed her second semester on the BEng programme in Process and Innovation.

It was a visit to the Distortion music festival which led the group in the direction of the parallel challenge of removing the large volumes of urine from festivals, and then they put two and two together.

“If you want to use urine as a fertilizer, you need to collect it, and that is often the tricky part,” says Liv. “But at the major festivals, no less that 3.7 million litres of urine are actually generated, which the organizers would really like to have removed in an eco-friendly manner.”

It means that festival-goers leave some 2.2 tonnes of phosphorus which PeeBalls can integrate in the agricultural sector if they decide to implement the solution.