An eco-friendly South Korean toilet transforms excrement into methane and fertiliser.
Called the Beevi toilet- a compound of the words ‘bee’ and ‘vision’-it uses a vacuum pump to send faeces to an underground tank. This eliminates the need for flushing, thereby saving water. Said toilet is attached to a laboratory, where the human waste is used to power a building. Methane created in this way also helps power a gas stove, a hot water boiler as well as a solid oxide fuel cell.
On average, a person defecates about 500g a day which can be converted to 50 litres of methane. Said amount can generate 0,5kWh of electricity or be used to drive a car for 1,2 km.
The excrement derived, renewable natural gas (RNG) produced in this way is also considered a low carbon biofuel and can fuel anything that runs on natural gas. The EU is the global market leader when it comes to the implementation of RNG, with Germany leading in terms of production. As of now, there are 282 RNG plants across Europe with a total production of 1.375bn cubic meters. Uses within a European context relate predominantly to heat and power though the transportation fuel market is on the rise.
On a global scale, using human waste for biogas generation represents an untapped opportunity. According to UN calculations, said waste would be enough to supply electricity to 138 million households-the equivalent of Indonesia, Brazil and Ethiopia combined.
Despite its economic and ecological potential, faeces as an energy source still hasn’t caught on. This is often on account of cultural barriers, leading to relevant stakeholders being unwilling to finance RNG facilities that make use of human waste.
Cho Jae-won, the urban and environmental engineering professor at the Ulsan National Institute of Science and Technology (UNIST) who designed the Beevi toilet, however, stresses the importance of ‘out of the box thinking’ when it comes to designing sustainable energy solutions.
"If we think out of the box, faeces has precious value to make energy and manure. I have put this value into ecological circulation," Cho said.
The way in which the scientist assigns value to human waste is through a merit-based system. As such, every time someone uses the toilet located at UNIST, they can earn 10 Ggool (a form of cryptocurrency).
Students trying the Beevi can use their digital currency to buy goods on campus, ranging from freshly brewed coffee and fruits to books.
"I had only ever thought that faeces are dirty, but now it is a treasure of great value to me," postgraduate student Heo Hui-jin said at the Ggool market. "I even talk about faeces during mealtimes to think about buying any book I want."