Biogas From Sewage converted to CNG

The Times of India, June 1st 2011

NEW DELHI: Soon, the city will be running on biogas. The Delhi government, in a joint venture with the Swedish government, plans to convert biogas from Keshopur sewage treatment plants to CNG.

The CNG will in turn be used in state-run buses. The project, a first for the city, will see biogas generated by the anaerobic digestion process at sewage treatment plants being converted into CNG. Delhi at present has the largest fleet of CNG-run buses in the world.

The biogas produced by the sewage treatment plants has a 60 per cent concentration of methane. For CNG, it has to be concentrated up to 90 per cent.

The project, set to begin by September this year, will be carried out as a joint venture between the Swedish and Delhi governments. The project has been granted an in-principle approval. The government will get 50 per cent funding for the project from Swedish Development Corporation Agency, and will pay for the rest. The project is being spearheaded by the Efficiency and Renewable Energy Management Centre. Sources in the government said that the Delhi government began talks with the Swedish government in December 2010, following which Swedish experts conducted a three-month study of four sewage treatment plants in Delhi — Dwarka, Keshopur, Coronation Park and Okhla.

The other plants were in disrepair or were too old. Based on the condition of the plant, the experts have finally zeroed in on the Keshopur plant. If successful, the government may replicate the project in all 17 STPs of the capital. This, say officials, will be able to meet the CNG requirement for a large part of the DTC fleet. One of the main criteria needed for setting up such plants is the presence of a CNG filling station within accessible distance of the plant. The organic waste produced at the Keshopur vegetable market will also be used to convert the biogas into a concentrated form of CNG.
South Africa
Do CNG not refer to "Concentrated Natural Gas"...a form of fossil fuel ?
I believe CBG (Concentrated Bio Gas) should be the acronym used in this article.

Alwyn Smith
Southern African Alternative Energy Association (SAAEA)
I would agree with you Alwyn. It seems as though the author is using the term "Concentrated Natural Gas" in the broadest sense but the article does refer specifically to Biogas.
This is indeed very interesting. I believe what is being referred to in the fist sentence is a similar process that being undergone in in Germany and Sweden where they are processing Biogas to produce an enriched form which is then fed into the Natural Gas grid. In this case in New Dehli this natural gas grade biogas will be used to fuel the cities buses.

This article http://www.indianexpress.com/news/cng-from-biogas-will-fuel-dtc-buses/791804/ explains that currently the biogas produced in New Dehli is at a 60% CH4 concentration and that this needs to be concentrated to reach 90% CH4 to be at a suitable grade for use as a transport.

Very interesting that Dehli has the largest fleet of CNG run buses as well - a lot to learn from this.
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