The fuel is produced at a sewage treatment plant in Bristol, England, using a technique called anaerobic digestion. The technique uses microbes to break down organic waste such as feces and food scraps into methane and carbon dioxide in the absence of oxygen. The methane or natural gas produced by this method is called biomethane.
“The bus… clearly shows that human poo and our waste food are valuable resources,” said Charlotte Morton, chief executive of the Anaerobic Digestion and Bioresources Association, a non-profit group that advocates for the use of this technology.
The company says its Bristol plant generates 17 million cubic metres of biomethane a year from around 75 million cubic metres of sewage waste and 35,000 tonnes of food waste collected from homes, supermarkets and food manufacturers. That amount of biomethane is enough to power about 8,300 homes, it added.
Biomethane is already being used to fuel buses in Norway and Sweden.
In Canada, Quebec announced in 2012 that it would produce biomethane from compost and inject the fuel into the network of Gaz Métro, a company that distributes natural gas in Quebec and the northeastern U.S.
Another fuel produced from food waste, biodiesel, is more widely used in Canada and has been tested in buses in Montreal and Saskatoon.