Sugarcane Byproduct ‘Pressmud’

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. 

More about the news:

• Feedstock for CBG:  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.

• 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 CBG valued at Rs 2,484 crore.

Advantages Of Using Press Mud As A Feedstock For CBG?

• 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.

• 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 CBG, 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).

Challenges 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 CBG 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.

Steps Needed 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