After CNG, the national capital is all set to run its public transport fleet on biogas. Ambitious as it may sound, but Delhi plans to run its buses on biogas. In collaboration with the Swedish government, the Union Ministry of New and Renewable Energy plans to set up a biogas plant inside Kesopur Sewage Treatment Plant (STP) complex in West Delhi. The plant will receive raw gas emitted by the STP and upgrade it so that it can be used to propel vehicles.
The project, once completed, will earn the capital city the distinction of having the country’s first public transport fleet that runs on two types of clean fuel: biogas and compressed natural gas (CNG). Delhi already boasts running the world’s largest fleet of vehicles on CNG. Around 450,000 vehicles—this includes some 16,000 buses—in Delhi run on CNG, according to Indraprastha Gas Ltd, a Delhi government undertaking, which is the sole supplier of CNG in the capital.

for full text: http://www.downtoearth.org.in/content/delhi-go-greener