Energy / Climate Change

May 12, 2006


Bio-Methane from Sewage Sludge to Be Used as Bus Fuel

Keywords: Environmental Technology Local government Manufacturing industry Renewable Energy 

Kobe City in western Japan has decided during fiscal 2006 to prepare for the practical use of bio-methane gas as a fuel for natural gas vehicles. The gas is produced by purifying the gases generated from sewage sludge. This is the first attempt of its kind in Japan.

The new bio-gas was developed jointly by the city and Kobelco Eco-Solutions Co., a subsidiary of Kobe Steel. They started verification tests in October 2004 using a purification system installed at the Higashinada Sewage Treatment Plant. They successfully produced methane gas at 98 percent purity, the same level as city gas, by applying high pressure to the gas generated by microorganisms decomposing sewage sludge, and dissolving impurities such as CO2 and hydrogen sulfide, which make up 40 percent of the gas, in water. In 2005, they began to use this gas to run natural-gas-fueled city buses on a trial basis.

Bio-methane gas is a biomass energy source that does not result in any net CO2 increases in the atmosphere and discharges few atmospheric pollutants, such as nitrogen oxides or sulfur oxides, when burnt. The newly developed gas is seen as a promising clean energy source as it is 30 to 40 percent less expensive than gasoline. The gas is known as "Kobe Biogas", which was selected from among names proposed by the public.

A new purification plant is being built at the Higashinada Plant, with operations planned to begin in spring 2008. It will supply enough bio-methane gas for 40 city buses, each running 50 kilometers per day, or 700 passenger cars, each running 30 kilometers per day.

Posted: 2006/05/12 12:59:47 PM
Japanese version