Cow dung for CBG production: Opportunity and challenges in India

India is a country with a rich history and with a very special connection to agriculture in our hearts. Agriculture is one of the prominent pillars of the Indian economy over the centuries. As it evolved over the years, animal husbandry became an integral part of Indian farmer's income. As per data about 150 to 200 million animals actively contribute to the Indian farmer’s household income in various ways and provide them with a decent cash flow in times of uncertainties apart from value-added fertilizer to the farms.

Cattle dung is one of the readily available household items across the country and fulfilling the requirement of fuels and fertilizer over the years. The dung is basically a partially digested portion of relatively hard-to-digest components from food. The actual specification is highly dependent on the type of food they eat and the purpose of the animal milking or non-milking ones etc but not limited to. It is a privilege to come from a farming background with a close association with dairy at home and working in Biogas in the recent past developed a decent level of confidence to put some data on cow dung and its potential.

The chemical composition of cow dung is mainly cellulose, Hemicellulose and lignin portion of the food with rich flora of healthy ruminococcus micro-organisms. It is the perfect mix for generation of biogas and it might be the reason it energized millions of household over the years in india and across the globe at small, medium and large scale over the years. For a simplicity one can call cow dung a perfectly pretreated lignocellulosic feedstock for biogas production which generally gives really good digestion efficiency on ground. Typically dung has about 15-20% w/w dry matter with 50-60% volatile solid, balance lignin and Ash. Once can expect 50-60% digestion efficiency of the key constituent which result in the yield of 40-50 sm3/MT of as it cow dung.

A significant portion of cow dung stored in open undergoes rapid digestion to form very good manure which make it one of the most value-added fertilizer rich in NPK and soil conditioner. At the same time this also make it one of the prominent source of GHG emission in the world with a significant contribution and which is quite alarming. All the efforts world putting in toward 1.5 Degree target and dung can not be ignored. The common practice of using cow dung due to highly decentralized production is making Upla or Dry Fuel which serve as a source of heat to rural households apart from stocking at the place and using as fertilizer multiple times a year. This activity contributes to GHG emissions and demands more scientific ways of extracting energy from it via biogas generation. The government of India's policy for Biogas highly encourages this route at every scale of biogas generation.

Cow dung is seen one of the largest sources of compressed biogas in Indian and across the globe considering bioenergy production while protecting the environment and at the same time providing value-added organic fertilizer to boost farmer’s income. India over 25 MMT of recoverable dung can shoulder a responsibility to protect the environment while recovering the CBG and biofertilizers which will have significant forex saving. The CBG value chain and the government is providing all required assistance for the conversion of cow dung to CBG and fertilizer.

For any CBG project availability, access and affordability of the potential feedstock are key attribute which will make the project viable and sustainable. The project which are viable and sustainable will drive agricultural economy in a long term by actively contributing the farmer’s income while solving the environmental & energy issues of the country. As CBG is been pushed really hard by government in a very positive sense, most of the bulk generator looking at this as an opportunity for generating assured income in longer horizon. This actually pushed the feedstock prices at very challenging level at some cases where viability of a project is in jeopardy.

Here I would like to present a simple math for all the key stakholders of the value chain to think about the value of the dung w.r.t. product and given a choice I will not be surprised to hear the feedstock pricing roadmap from authorities in line with sugar policy which arrive a Fair price depending on the final output and its market value which make the feedstock a win-win proposition to all the stakeholders.  

Let’s take cow dung as a case but it equally applies to all the Feedstocks. A typical CBG potential of the cow dung is about 16-20 kg/ MT as per IS 16087:2016 Rev 1. The market price of the CBG/CNG at Delhi is about INR 80 per kg at some point of time (say) which estimated to result in revenue of about 1300 to 1600 Rs per MT of Cow dung. The avg cost of conversion on account of power, Operation and maintenance, transport, administrative and miscellaneous expense is about Rs. 15-20 translate to about 300 to 400 Rs/MT of cow dung. The above Number will left arrive at about 900 to 1200 per MT when gas sold by B2C method of product evacuation. If the product is sold at SATAT Base rate then 500 to 700 is left which suppose to suffice the cost of feedstock and pay for loan for capital investment ensuring a adequate profit which make this a viable business case for any developer.

For CBG business the total cost of production more than 55% of the Revenues from Gas and Fertilizers looking at present business value chain from feedstock sourcing to product evacuation make really tough call to take by any developer. The values could be here and there but the trend is worth to be noted which demands a logical rationale to arrive at a fair value for feedstock with long term visibility to make CBG a fuel of the future moving forward. Any addition to this is welcome from all of you so that we would be putting fact to the table which will empower developers to take informed decision on right mix of feedstock for their proposed business ventures.