The Delhi government is currently working to set up a biogas plant inside Kesopur Sewage Treatment Plant (STP), with the end goal of producing enough compressed biogas (CBG) to fuel 120 of the city’s buses daily. India’s Union Ministry of New and Renewable Energy has collaborated with the Swedish government on this project. After the renovation of the plant, the biogas plant is expected to generate roughly 25,000 cubic metres of CBG per day.
Delhi currently has the largest number of vehicles running on compressed natural gas (CNG) in the world, with the government reporting nearly half a million vehicles and over 16,000 buses. Once the project is complete, Delhi will be the first city in India to have public transport that runs on two types of clean fuel, using both CBG and CNG.
The disposal of raw sewage is often seen as a costly problem, however the ability to use it to power cars actually turns it into an asset. Manure, rotten food from crops or markets and kitchen waste from restaurants and homes can also be used, resulting in a renewable energy source with a very small carbon footprint.
To produce biogas, the sewage must be heated so that anaerobic digestion will occur, creating a raw form of the gas. For the gas to be used for cooking or in vehicles, the upgrading plant is then used to filter and compress the biogas into CBG.
Earlier this year, CBG was tested on a regular CNG car in India. No modifications were required for the car, which was tested for over 15,000 km. Researchers found that emissions were actually lower using CBG than CNG. There was also little change in the mileage of the vehicle, with the vehicle fuelled with CBG operating at 24.11km/kg, while the vehicle fuelled with CNG operated at 24.38km/kg.
There is huge potential for the use of biogas in the country, with the Times of India reporting that the nation could potentially produce 48,382 million cubic metres a year. If the use was split evenly between transportation and cooking, biogas could fulfill 43.4% of demand in the transport sector, and 41.7% percent of demand for cooking requirements.