Scientists in the United States have found a way to convert human waste into renewable energy.
Sewage could go to electricity-producing cells instead
Researchers have developed a device which generates electricity from sewage and think it could become a green energy source of the future.
A report in the New Scientist magazine describes how the Microbial Fuel Cell uses bacteria to break down waste.
The process produces electrons which can then be used to power an electric circuit.
Normally the electrons would be used up by respiratory reactions in the bacterial cells and combine with oxygen molecules.
But researchers at Pennsylvania State University found the cell invention wrestles electrons away from the bacteria instead.
Then the electrons can be harnessed for use.
Environmental engineer Bruce Rittmann, told New Scientist magazine: "There are extraordinary benefits if this technology can be made to work."
The cell is 15 centimetres long and contains a special arrangement of electrodes.
Organic waste is pumped in and broken down by clusters of bacteria cells.
'Work to do'
Because the bacteria are deprived of oxygen, electrons are freed to set up a voltage.
There have been previous attempts to produce electricity in this way but using glucose solution as the raw material.
The energy output is not high so far and researchers think it could produce 10 times as much.
But the days when waste can produce a viable energy source could be decades away.
US microbiologist Derek Lovley said: "This technology is currently at the state of development that solar power was 20 to 30 years ago.
"The principle has been shown, but there is a lot of work to do before this is widely used."