This waterless toilet could turn human excrement into renewable energy for 2.5 billion people


Cranfield University is developing a toilet that converts human waste into useable, renewable energy, which researchers claim could help bring sanitary facilities as well as renewable energy to 2.5 billion people in developing countries. The device uses no water, and is scheduled to be trialled this year.

The problem of sanitation in developing countries has received many propositions, but few real solutions. An estimated 2.5 billion people around the world continue to rely on outdated and deteriorating sanitary infrastructure. In many of these economically deprived locations, there is little practicality in large-scale infrastructure renewals, let alone the implementation of expensive solar-powered systems.

One promising solution could be a self-sustaining device that processes human waste without the use of water or external energy sources. Cranfield University in Bedfordshire, UK, is developing a ‘nano-membrane’ toilet that operates in this manner.

Upon closing the lid to the toilet, which accepts both faeces and urine, hollow-fibre membranes separate the solids through sedimentation – a process which collects the liquids as vapour. All of this occurs out of the user’s sight and is totally odourless.

A mechanical screw then transports the remaining solids to a chamber which converts them to energy, and ash – the only waste product of the entire process. This by-product is in fact rich in nutrients, free of pathogens, and therefore useable as plant fertiliser. The energy produced is fed back into the device to power the sedimentation process, allowing the toilet to continue functioning. Surplus energy can be used to charge mobile phones or other small devices.

The project is a response to the Bill & Melinda Gates Foundation’s ‘Reinvent the Toilet’ challenge. The Cranfield team is funded by them as well as by others third-party investors.

The toilet is intended for use by single households, and will be rented for 3p (5 cents) per day. It promises to be versatile, transportable, and able to operate in many different locations including yachts, construction sites, and outdoor festivals.

Photo Credit: Ironchefbalara on Flickr.