The BeeVi toilet - a portmanteau of the words bee and vision - uses a vacuum pump to send faeces into an underground tank, reducing water use. There, microorganisms break down the waste to methane, which becomes a source of energy for the building, powering a gas stove, hot-water boiler and solid oxide fuel cell.

Cho has devised a virtual currency called Ggool, which means honey in Korean. Each person using the eco-friendly toilet earns 10 Ggool a day.