Fuel from human waste

Windpower: One form of renewable energy

By Suzanne Mooney of BBC Science

A new process which turns human excrement into valuable fuel has been developed by scientists in Thailand.

They have produced a reactor which transforms unwanted waste materials into high quality fuel.

Although the process is expensive, the scientists believe it will become more economically viable as natural oil supplies dwindle.

Electricity from excrement?

Within the next 100 years, the world's supply of fuels like oil and gas is expected to disappear altogether.

Scientists have spent decades trying to invent ways of trapping so-called renewable energy, such as sunlight or windpower, that will last forever.

'Bio-oil'

In an attempt to find a new source of energy, engineers in Thailand turned to human faeces. They have been retrieving excrement and recycling it into what they are tastefully calling "bio-oil".

The Thai team make their oil partly by mimicking the process that creates natural oil under the Earth.

Nature's oil is formed after rotting animal and vegetable matter is buried under layers of sediment and rock. The resulting heat and pressure transform the organic matter into oil over hundreds of thousands of years.

Following similar principles but speeding up the process, the Thai engineers have developed a reactor which works by blasting very hot nitrogen gas over human waste.

The resulting product, they say, is a high quality fuel which can power car engines.

At present it costs twice as much to produce as diesel fuel. However the advantage is that, unlike the oil made in the Earth, the supply of ingredients for this people-derived fuel will never dry up.