India's Biomass Co-Firing Mandate: What the 7% Rule Requires

5% became 7%

The Ministry of Power revised its biomass co-firing policy in June 2023. It mandated 5% co-firing from FY 2024–25, rising to 7% from FY 2025–26. The requirement applies to all coal-based thermal power plants in India.

For a plant operator this is an obligation rather than a target, and it converts directly into demand for a fuel that behaves enough like coal to move through existing handling and milling equipment without modification.

Why ordinary pellets run out of road

Untreated agricultural-residue pellets can be co-fired at roughly 7 to 10 percent without changing existing plant equipment. NTPC has been doing this since 2017.

Above that band the physics gets in the way. Raw biomass carries more moisture, has lower energy density and grinds poorly, which causes handling and milling problems in equipment designed for coal. The mills were specified for a brittle, dry, dense fuel; fibrous damp material does not behave like one.

Torrefaction is a thermal treatment at 200–350 °C in a low-oxygen environment. It drives off moisture and volatiles, leaving a fuel that is drier, more brittle and closer to coal in handling behaviour. NTPC pilot work has demonstrated co-firing of up to 20 percent using torrefied biomass.

Calorific value by feedstock

Torrefied fuel is often quoted as a single figure, which is misleading — the energy content depends substantially on what went in. These are the ranges measured across Keystone Energy's plant configurations:

Woody biomass carries the widest range because feedstock moisture and species vary considerably. Sludge sits at the lower end: it arrives wet, and a larger share of the input energy goes into drying it.

Where the fuel comes from

Meeting the mandate at scale requires torrefaction capacity, and that capacity has to be built. Keystone Energy designs, engineers, procures and commissions continuous torrefaction plants using KeyTor, Keystone Energy's continuous torrefaction technology, which is the subject of Indian patent applications 202211023704 and 202211023710. Plant configurations run from 50 to 1,000 tonnes per day of input and are engineered for 6,000+ operating hours per year.

Delivered projects span four Indian states. The 100 TPD legacy waste and RDF plant in Warangal, Telangana is fully commissioned. A 500 TPD MSW plant for NTPC in Gorakhpur, Uttar Pradesh and a 200 TPD rice straw plant for TransPacific Engineers in Sangrur, Punjab are both in commissioning. A 50 TPD STP sludge pilot for Delhi Jal Board has been completed.

See the delivered plants  ·  How torrefaction works