Innovation That Matters

Instead of water, the Beevi uses a vacuum pump to send faeces to an underground tank | Photo source UNIST

Toilet turns human waste into energy – and money

Agriculture & Energy

A university professor has devised a system that pays people to use a specially-designed toilet that funnels waste to a bio-digester

Spotted: A university in South Korea is letting students exchange their waste for money in a unique experiment. Professor Cho Jae-weon of Ulsan National Institute of Science and Technology (UNIST) designed the system, which is based around the BeeVi eco-friendly toilet and a biogas generator.  

The BeeVi uses a vacuum pump to send faeces to an underground tank. Microorganisms then break down the waste to produce methane, which in turn is used as an energy source to power a stove, hot-water boiler, and solid oxide fuel cell. What remains after the bacteria have done their job is turned into fertiliser. 

Underpinning the project is a virtual currency, called the Ggool (‘honey’). People using the toilet can earn up to 10 Ggool a day. The currency can then be exchanged for goods, such as coffee or books, by scanning a QR code on the products at an on-campus shop.

Each person defecates, on average, around 500g of material a day. This can be converted into 50 litres of methane gas – enough to produce 0.5kWh of power, or to drive a car for around 1.2 km. Cho explains that, “If we think [outside] the box, faeces has precious value to make energy and manure. I have put this value into ecological circulation.”

Biowaste is increasingly being seen as a way to turn waste into green energy, on both large and small scales. Innovations range from a city in Australia that is converting kitchen scraps into green energy and a bio-digester designed to produce cooking gas for home use.

Written By: Lisa Magloff

Email: jaeweoncho@unist.ac.kr

Website: unist.ac.kr

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