Context: Pressmud, a residual byproduct in the sugar industry commonly referred to as filter cake or press cake, has been recognized as a valuable resource for the production of green energy.
Compressed Biogas from Sugarcane Byproduct
- Feedstock for Compressed Biogas: Pressmud presents an opportunity for Indian sugar mills to generate additional revenue by using it as a feedstock for biogas production through anaerobic digestion and purification to produce compressed biogas (CBG).
- Surge in press mud prices: Earlier, viewed as a disposal concern for sugar mills, owners now acknowledge its potential for generating revenue.
- This recognition has led to a surge in pressmud prices over the past two years, escalating from Rs 100 per tonne to the current range of Rs 500-600 per tonne.
What is Compressed Biogas (CBG)?
- Production: Compressed Biogas is produced naturally through a process of anaerobic decomposition from waste / bio-mass sources like agriculture residue, cattle dung, sugarcane press mud, municipal solid waste, sewage treatment plant waste, etc.
- After purification, it is compressed and called Compressed Biogas, which has high methane content.
- Energy potential: Compressed Biogas is exactly similar to the commercially available natural gas in its composition and energy potential.
- Alternative, renewable automotive fuel: It has a similar calorific value to CNG. Thus it can be used as an alternative, renewable automotive fuel.
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- Yield: The yield of press-mud falls within the range of 3-4 percent weight by weight with the input sugarcane processed in a unit.
- Energy potential: India’s sugar production for the fiscal year 2022-23 amounted to 32.74 million tonnes, along with approximately 11.4 million tonnes of pressmud.
- This quantity has the potential to generate 460,000 tonnes of Compressed Biogas valued at Rs 2,484 crore.
Advantages Of Using Press Mud As A Feedstock For Compressed Biogas?
- Simplifying the feedstock supply chain: It avoids the complexities associated with agricultural residue, where biomass harvesting machinery is needed for harvesting and aggregation.
- Simplified Procurement: The feedstock is obtained from one or two producers or sugar mills, unlike agricultural residue, which involves multiple producers/farmers within a narrow 45-day window each year.
- Feedstock Quality: Pressmud has less inorganic material compared to Municipal solid Waste which can harm anaerobic digesters, leading to reduced gas output.
Sugar sector in India
- Regional Production: Uttar Pradesh and Maharashtra, the primary sugarcane-growing states, contribute to approximately 65 per cent of the total sugarcane cultivation area.
- Key sugarcane-producing states: Uttar Pradesh (225.2 million tonnes), Maharashtra (123.9 million tonnes), Karnataka (62.5 million tonnes), Tamil Nadu (16.9 million tonnes) and Bihar (12.1 million tonnes).
- Status of ownership of sugar mills: Among the 531 operational sugar mills in India, 330 were privately owned, 190 were cooperative and 11 were public during the year 2022-23.
- Export share: India stands as the second-largest sugar exporter worldwide.
By Product of Sugar Industry:
- The four main byproducts of the sugarcane industry are cane tops, bagasse, filter muds and molasses.
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- No Pretreatment cost: Due to lack of the organic polymer lignin in Pressmud compared to other Agri-residues.
- Higher conversion efficiency: It has higher conversion efficiency than agri residue.
- Approximately 25 tonnes of pressmud are required to produce a tonne of Compressed Biogas, while cattle dung requires 50 tonnes for the same gas output.
- Moreover, it is more economical than other feedstocks like agricultural residue (Rs 1.5-2/kg) and cattle dung (Rs 1-2/kg).
What challenges are associated with pressmud?
- Competition for usage: Pressmud encounters competition for its utilization as a fertilizer and in bio-composting, competing with spent wash and being employed as fuel in brick kilns.
- Absence of long-term agreements: The challenges are exacerbated by the absence of long-term agreements with sugar mills and the intermediaries involved in procurement.
- Concerns with storage: The necessity for Compressed Biogas plants to store feedstock throughout the entire year presents a challenge considering that sugar mills operate for a specific period.
- Storing pressmud presents challenges due to its gradual decomposition, leading to the breakdown of organic compounds.
- This complicates the feasibility of long-term storage and contributes to increased production costs.
What steps are required to unlock the potential of pressmud?
- Enacting bioenergy policies: States should enact bioenergy policies to streamline project approval processes.
- This can offer a unified solution and a range of monetary and non-monetary incentives.
- Uttar Pradesh and Bihar have already taken steps in this direction.
- Regulation of pressmud prices: The government should establish a mechanism to regulate pressmud prices, keeping them below a specified threshold.
- Sugar mills need to be encouraged for committing to extended agreements (10-15 years) with CBG plants with an annual rate increase of 5-10 per cent.
- Technology for pressmud storage: It needs conducting comprehensive research to develop technology for pressmud storage which prevents methane emissions into the environment and minimizes gas loss from the feedstock.
- Capacity building: Focus should be given to conduct regular training sessions to educate operators on the operation of CBG plants, the proper handling of scientific equipment, and the feedstock characterization.
News Source: DTE
1 Dec 2023
