Bagasse and black-liquor cogeneration

Sugar and paper mills burning their own residues for steam and power.

Recovery and reuse · Heat to power and cogeneration · No. 129

• Recovery and reuse
• Heat grade: Process heat

India's sugar mills burn their own crushed cane fibre to run about 9.8 GW of power plants.

Chart: Illustration: Bagasse and black-liquor cogeneration

Where it comes from

Chart: Map of where it comes from

Sugar and pulp mills burn their own residues, bagasse and black liquor, then pass the steam through turbines before using it in the process. Black liquor alone holds about 2 EJ of energy a year.

Three things to know

1. A 22 bar back-pressure sugar mill exports 0-10 kWh per tonne of cane, while a 67 bar condensing plant exports 90-120.
2. Recovery boilers also recover pulping chemicals as molten smelt, which can explode violently if it meets water.
3. Maharashtra (2,907 MW), Uttar Pradesh (1,986 MW) and Karnataka (1,869 MW) hold most of India's bagasse cogeneration.

The journey

1. 1 Mill residueBagasse fibre or black pulping liquor
2. 2 BoilerBurns residue to raise high-pressure steam
3. 3 Back-pressure turbineMakes power while lowering steam pressure
4. 4 Process steamFeeds evaporators, dryers and juice heaters
5. 5 Grid exportSurplus power sold to the utility

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