Why Jaipur’s Hingonia biogas plant has emerged as a model for waste-to-energy facilities

The Sri Sri Krishna Balaram Seva trust, which has been operating a compressed biogas facility on its 900-acre dairy plant in Hingonia, Jaipur since 2016, can pave the way for sustainable waste-to-energy development in the country. 

The trust is a non-profit dedicated to serving the cattle in the region. Dairy plant that produces 25,000 litres a day also generates around 100 tonnes of cow dung daily. The cow dung is being utilised in the biogas plant. 

The compressed bio gas plant was set up by the Indian Oil Corporation Ltd under its corporate social responsibility initiative at a cost of Rs 38 crore. 

The capacity of bio-gas plant is 100 tonnes per day (TPD) and is supposed to produce 6 tonnes of gas. At present, however, it is under trial and running at a capacity of 30 TPD, producing 1.5 tonnes of gas. 

Pre-digester tanks 1 & 2 at the Hingonia compressed biogas plant. Source: Shreya Verma

Only fresh cowdung is used because straw mixed in it can choke the pipelines and pump.

The 1.5 tonnes of gas produced from the plant is being utilised for making meals for 150,000 students every day by the Akshaya Patra foundation, an independent organisation that runs kitchens at various locations to prepare mid-day meals. 

How the plant works

Biogas generation is an 8-day process. Cowdung and water is mixed in a 50:50 ratio in the mixing tank. The resultant cowdung slurry is pumped into the ‘pre-digester 1’ where it rests for three days and pumped into ‘pre-digester 2’. Anaerobic methanogens bacteria are added at these stages for the fermentation process.

Since the slurry is acidic in nature, it is transferred to a neutralisation tank. This step takes about a day.

From here, it is moved to a solid-liquid separator tank, where the solid settles down and liquid is transferred to a liquid recycle tank. Here, it is used again for mixing with cowdung. The water used for mixing has 80 per cent recycled liquid and 20 per cent fresh water. 

Each of the above tanks is connected with a pipeline for collection of biogas in two gas collector balloons (2,000 cubic metre each) where the gas is stored.

Compressed biogas is then produced by further processing of the biogas, during which other gases like carbon dioxide are reduced and methane is maintained at more than 90 per cent quantity. Compressed biogas primarily contains methane, a limited amount of carbon dioxide, nitrous oxide and traces of other compounds.

Solid settled in the solid-liquid separator tank is used for making around 20 tonnes of compost per day. 

Cowdung to compressed biogas process

The biogas plant is running at zero per cent loss.

The volume of disposable bio-waste in India is estimated to be around 600 million tonnes, according to an article in OkCredit, a digital ledger service provider. “If all of these are put into productive use, it will produce 25 times the CNG that we are using today, and replace more than 50 per cent of the total fuel imports.”

India is the second largest consumer of biogas in the world, the article noted. “As per Shri Dharmendra Pradhan, the minister for Oil and Natural Resources, India will receive an investment of Rs 2 lakh crore in setting up 5000 biogas plants, by 2023-24.” 

The infrastructure required for setting up a biogas plant is available in India. Financial assistance and strict waste segregation and management rules could help the industry to grow and meet the energy demand of the country.