This story was first published on June 20, 2015
WHO would have thought that poo could be a source of clean energy?
In Britain, there is a bus running between the city of Bath and Bristol Airport that operates on a very special type of biogas. Fuel is made from the excrement of the local population, which is collected after it has been treated at a water purification plant, along with food waste.
How can it be turned into energy? As the poo decomposes, it produces methane gas. This is then mixed with another gas called propane. Together, they create a fuel on which you can run an engine. The waste produced by a family of five over one year can run a bus carrying 40 people for 300km.
This new source of energy is far less polluting than petrol because it releases very few greenhouse gases, which are a cause of global warming.
For comparison, the fuel releases 80 per cent less nitrous oxide and 25 per cent less carbon dioxide than a diesel motor.
Passengers need not worry: the Bio Bus, or "Poo Bus" as it has been nicknamed, doesn't give off any nasty odours.
The vehicle underwent trials in November last year. Since the start of this year, it has been operating a regular service.
Elsewhere in Europe, the Norwegian capital Oslo has started running around 100 buses operating on human waste.
A. TARIEL/ L'ACTU - MON QUOTIDIEN (FRANCE)