Paddy Straw Torrefaction: Turning Stubble Into Coal-Replacing Fuel This Harvest Season

Every October and November, smoke from burning paddy fields in Punjab and Haryana adds to the smog over Delhi-NCR. Farmers burn the straw because there are only a few weeks between the rice harvest and wheat sowing, and clearing it any other way costs money.

The good news is that burning is falling. Punjab reported 5,085 farm fires in the 2025 season, about half of 2024's 10,443 (The Tribune). The harder question is what happens to the straw instead. Punjab alone expects over 20 million tonnes of it each season (The Tribune).

Why paddy straw needs a buyer, not just a ban

Fires drop when straw has somewhere to go. Punjab's off-field use of straw (industrial boilers, pellet plants, biogas, biomass power) grew from under 1 million tonnes in 2020-21 to about 7 million tonnes in 2025. The state also went from 18 to 37 working pellet plants in a year (The Tribune).

That demand is real, but raw rice straw is a difficult fuel. It is bulky, absorbs moisture, has high ash and silica, and burns unevenly. Most coal-fired plants and kilns cannot use much of it without problems.

What torrefaction does to paddy straw

Torrefaction is a mild roasting process. The straw is heated to roughly 250–300°C with very little oxygen, which drives off moisture and light volatile compounds. What remains is a dark, brittle material often called bio-coal or torrefied biomass.

Compared with raw straw pellets, torrefied straw:

• holds more energy per tonne

• repels water, so it can be stored outdoors and transported like coal

• grinds easily, so it can be fed alongside coal in existing mills and burners

• does not rot or degrade during storage between harvest seasons

Who can use torrefied straw

Torrefied biomass can replace part of the coal in:

• Thermal power plants, which are required by government policy to co-fire biomass with coal

• Cement kilns, which need large volumes of steady, dry fuel

• Steel plants, for heating and as a partial carbon source (read our post on greener steelmaking)

• Industrial boilers in Punjab and Haryana already switching to straw

Torrefied fuel vs biochar: what each does for the climate

These two products come from similar equipment but do different jobs.

• Torrefied fuel is burned. It cuts emissions by replacing coal and avoids open-field burning, but it does not remove carbon from the atmosphere.

• Biochar is made at higher temperatures (pyrolysis) and is not burned. It locks carbon into a stable form for centuries when added to soil or materials, and can earn carbon removal credits under recognised standards.

We build continuous rotary reactors for both torrefaction and pyrolysis, depending on whether the buyer needs fuel or carbon removal. See our pyrolysis and torrefaction technology.

Small plants near the fields

Straw is light and expensive to haul. Compact units placed near farm clusters cut transport costs, create local jobs, and give farmer producer organisations (FPOs) a product to sell instead of a waste to burn.

Frequently asked questions

What is paddy straw torrefaction? It is heating rice straw to about 250–300°C without much oxygen, turning it into a dry, energy-dense fuel that can replace some coal.

Is torrefied biomass the same as biochar? No. Torrefied biomass is a fuel and is burned. Biochar is made at higher temperatures and is kept out of the atmosphere, which is why it can earn carbon removal credits.

Can farmers earn money from paddy straw? Yes, when there is a nearby buyer. Pellet plants, boilers and torrefaction units buy baled straw, which turns a disposal cost into income.

Can torrefied straw be used in coal power plants? Yes. Because it grinds and burns like coal, it can be co-fired in existing plants in a blend with coal.

Work with us

Shaiva Green Carbon builds continuous torrefaction and pyrolysis reactors in Greater Noida, India. If you are an FPO, an industrial fuel buyer, a power or cement plant, or an investor in clean fuels, contact us or explore our project consultancy services.

About the author: Manoj Koshy is Co-Founder and Director of Shaiva Green Carbon.