New York Times
By C. CLAIBORNE RAY
Published: May 10, 2010

Q. I’ve heard that cow manure, but not human waste, can be used for energy production. Is it possible?

A. It is possible and has long been the subject of research and pilot projects. But with current technology, it often costs more than conventional fuels.

One project supported by NASA explored the use of human waste to supply astronauts with electrical power through a type of microbial fuel cell. Most projects, including the 19th-century British Webb Patent Sewer Gas Lampand an installation providing gaslight in Sheffield, England, rely instead on extracting gas from the waste.

In a project in 2005, a crowded prison in Cyangugu, Rwanda, turned a liability into an advantage by converting prisoners’ waste into burnable gas. The project used beehive-shaped converters to house bacteria to ferment the waste. One product, methane, was collected and burned to cook food. The solid residue was used as fertilizer.

The technology was developed by the Kigali Institute for Science, Technology and Management and won an Ashden Award for Sustainable Energy from a British nonprofit group.

The project was also praised as reducing pollution from waste disposal and preserving local wood supplies, which were previously used for fuel. The model was later used in a half-dozen other prisons.

Obstacles to the use of ordinary municipal sewage for power include its high initial moisture content, which requires potentially expensive drying; its relatively low fuel efficiency, even after drying and other treatments; and the possibility of pollution from burning other materials in sewer systems.

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