Human urine may soon be used to power homes.
Three teenagers came up with an apparatus that generates electricity with the help of human urine.
The Secondary 3 boys – Karan Bhatia, Prashasth Cheekoty and Sarthak Arora – displayed their device at the Amazing Science-X Challenge last Friday at the Science Centre Singapore.
The event, organised by the DSO National Laboratories, the National University of Singapore and the Science Centre Singapore, had 480 students working in teams to put up exhibits that explain physical science phenomena.
Prashasth, 14, said: “We watched documentaries where families in India and Africa lived without electricity and in darkness. We wanted to do something to help them.”
So the team from the NPS International School modified an existing science phenomenon to make it more cost-effective.
Currently, prototypes use expensive motors, but the team replicated it with cheaper alternatives like copper and aluminium.
Prashasth said urine contains salt (sodium chloride), and when placed with the water found in urine as well, the water molecules split the salt molecules into sodium and chloride ions.
When electrodes like a copper sheet and aluminium foil are placed in the solution, the ions move towards the two metals because of their charges.
This creates an electricity current.
Sarthak, 13, said: “Of course, for hygiene purposes we can’t use urine at our exhibit, so we used salt water instead.”
Taking a tablespoon of salt and putting it in a plastic bottle with 200ml of water, 300 millivolts was generated.
Sarthak said: “The inside of the bottle is lined with aluminium foil, and we attached a 2cm by 2cm piece of copper.
“This could light up a small LED light bulb after four hours of charging with a 10 volts capacitor.”
The team said a litre of urine contains 3.04g of sodium chloride, and electricity generated in volts depends on the amount of sodium chloride and the electrodes.
Though the team did not win an award at the challenge, Prashasth said: “We are proud of our experiment. We created a solution that is sustainable, eco-friendly and economical.”
Raffles Girls Secondary School won the gold in the category with a project on sound wave interference.