Bio CNG technology can deal with air pollution at 3 levels by curtailing methane emissions, warding off waste burning and phasing out fossil fuel-powered vehicles. Bio CNG, also known as Compressed Biogas (CBG), is an upgraded version of the humble biogas compressed at high pressure in cylinders which is similar in chemical properties to CNG derived from petroleum sources. This is then sent off to filling stations to be used as fuel in vehicles. But despite economic and environmental promises, this industry is slow to pick up. Let us understand why, by studying the challenges faced by Asia’s largest Bio-CNG plant based on municipal solid waste/garbage (the biggest otherwise is in Punjab) in India’s cleanest city, Indore.

This is Devguradiya, earlier known as Indore’s dumping ground for almost 70 years. The particulate matter pollution was visibly high in the area not to forget the foul odour caused due to hydrogen sulphide (H2S) and ammonia. Although the trenching ground was replaced by a city forest and the Gobar Dhan Bio CNG plant. the putrefying odour of garbage still marks the area.

Gobar Dhan plant, built on 15 acres of land with an investment of Rs 150 crores, processes 550 tons of the 700 tons per day (TPD) of biodegradable waste in the city. The plant proposes to improve the city’s air quality by mitigating 130,000 tonnes of carbon dioxide annually. Gobar Dhan plant was set up by the Indore Municipal corporation (IMC) in partnership with the private company Ever Enviro Resource Management Pvt Ltd. IMC is supposed to supply 90% segregated waste to the plant for which the company has to pay them an annual royalty of Rs 2.5 crores. The Corporation buys bio-CNG from the plant at a rate that is Rs 5 less than the market price of CNG and uses it as a fuel to run its 146 buses. The Indore Municipal Corporation has already earned Rs 8.5 crores in carbon credits by replacing diesel buses with CNG. Also, half the gas produced is sold to Avantika Gas Ltd, the CNG and PNG supplier of the Indore region, at Rs 56/kg.

Besides bio-CNG, the plant generates 15 tons of carbon dioxide and 100 tons of organic manure as byproducts. While bottling of carbon dioxide for industrial use is still in the pipeline, the company sells their manure at a net rate of Rs 1,800 per ton. There is a plan to inject the compressed biogas produced in Gobar Dhan into Avantika’s city gas distribution network via a pipeline. This will not only cut gas compression costs but also reduce emissions through transportation and the 163 industries in the city

Gobar Dhan has its own share of challenges as it implements a technology that is still nascent in India. Indore is a pioneer in this technology and will have only its own experiences to learn from.

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Down to Earth is Science and Environment fortnightly published by the Society for Environmental Communication, New Delhi. We publish news and analysis on issues that deal with sustainable development, which we scan through the eyes of science and environment.

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