Imagine turning waste into energy.
It sounds like the way to close the loop on waste and limited resources, allowing us to consume and return to the system - and ultimately help our planet.
South Korea is ahead of the game in this in that using the toilet can turn waste into usable resources.
Imagine that, all you need to do is complete a basic human function and voila, free coffee.
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The genius behind the technology is Cho Jae-weon, an urban and environmental engineering professor at the Ulsan National Institute of Science and Technology (UNIST).
Cho developed an eco-friendly and sustainable toilet that is connected to a laboratory to convert excrement into biogas and manure.
A vacuum and a small amount of water send the poop from the toilet into an underground tank and bioreactor.
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The name of the toilet is 'BeeVi', short for 'Toilet, like a Bee with a Vision,' and it can generate power for building appliances like a gas stove, hot-water boiler and a fuel cell that produces electricity.
'If we think out of the box, faeces has precious value to make energy and manure,' Cho said.
'I have put this value into ecological circulation,' Cho said.
A person defecates about 500g daily on average, which can be converted to 50 litres of methane gas, according to the environmental engineer.
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This would generate 0.5kWh of electricity or power a car for three-quarters of a mile.
Additionally, Cho has created a virtual currency called Ggool - meaning 'honey' in Korean.
So not only can users buy energy, but they can earn a bit of pocket money as well.
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Each person using the sustainable toilet earns 10 Ggool a day.
While the rate won't buy you any shares in Bitcoin, students can use the currency to buy things on campus, like stationary, fresh fruit, instant cup noodles, coffee and books.
The Ggool purchase is done by scanning a QR code.
Impressed by the tech, postgraduate student Heo Hui-jin said that instead of viewing faeces as 'dirty', he now appreciates it as a 'treasure of great value.'
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He added: 'I even talk about faeces during mealtimes to think about buying any book I want.'