Introduction

Beneath the hard shell of every rice grain lies a surprising secret—rice husk, the protective outer layer, is a potent source of renewable energy. This often discarded byproduct, generated in millions of tons annually, is a lightweight, silica-rich material with unique properties that make it perfect for bioenergy and industrial applications. 

Traditionally viewed as waste, rice husk is now being tapped for everything from biofuel production and electricity generation to high-grade silica extraction and eco-friendly building materials. Discover how this humble agricultural residue is sparking innovation and redefining waste-to-energy solutions.

Total Rice Husk Generation in India

India is one of the world’s largest producers of rice, and rice husk is a significant byproduct of rice milling. Annually, India produces around 23 million tonnes of rice husk, derived from approximately 130 million tonnes of paddy. The production is concentrated in major rice-producing states such as West Bengal, Uttar Pradesh, Punjab, and Bihar.

Biomass Characteristics

ParameterLoose FormBriquette Form
Gross Calorific Value (GCV)3200
Moisture Content10%6-8%
Ash Content19%19%
Silica Content15-20%
Volatile Matter73.5%14%
Fixed Carbon11.5%74.5%
Bulk Density150-200 Kg/m3650-700 Kg/m3
Price₹3-4/kg₹6-6.5/kg
Characteristics of Rice Husk in Loose Form and Briquette Form

Seasonality

Rice cultivation in India takes place under a wide range of altitudes and climatic conditions, leading to different rice growing seasons across the country. Factors like temperature, rainfall, soil type, and water availability significantly influence the cultivation calendar in various regions. In the eastern and southern parts of India, the temperatures are suitable for rice farming throughout the year, allowing farmers to grow two or even three crops annually. In contrast, in northern and western regions, where winters are cooler and rainfall is substantial, rice is typically grown once a year, from May to November.

Rice cultivation in India can be categorized into three main seasons—autumn, winter, and summer—based on the harvest period. Here’s a breakdown of these seasons:

Autumn Season (Pre-Kharif Rice)

Autumn rice, often referred to as pre-Kharif rice, is sown between May and August, with the harvest occurring in September and October. The specific timing of planting varies by state, depending on local weather and rainfall patterns. The crop goes by different names in different regions: Aus in West Bengal, Ahu in Assam, Beali in Odisha, Bhadai in Bihar, Virippu in Kerala, and Kuruvai/Kar/Sornavari in Tamil Nadu. This season accounts for about 7% of India’s total rice production, with most varieties being short-duration crops that mature in 90 to 110 days.

Winter Season (Kharif Rice)

The primary rice-growing season in India is the Kharif, also known as winter rice due to its harvest period. Sowing generally takes place in June and July, with harvesting from November to December. It goes by various local names, including Aman in West Bengal, Sali in Assam, Sarrad in Odisha, Agahani in Bihar and Uttar Pradesh, Sarava in Andhra Pradesh, Mundakan in Kerala, and Samba/Thaladi in Tamil Nadu. This season is responsible for around 84% of the country’s rice output, with farmers favoring medium to long-duration varieties.

Summer Season (Rabi Rice)

The summer rice crop, known as Rabi rice, is planted between November and February and harvested from March to June. Regional names include Boro in Assam and West Bengal, Dalua in Odisha, Dalwa in Andhra Pradesh, Punja in Kerala, Navarai in Tamil Nadu, and Garma in Bihar. This season covers about 9% of the rice-growing area, with early-maturing varieties being the norm.

Different states have specific planting and harvesting windows for these seasons, influenced by local climate conditions and rainfall.

SLRegion/StateAutumn SowingAutumn HarvestingWinter SowingWinter HarvestingSummer SowingSummer Harvesting
1Northern Region
Haryana
PunjabMay-AugSep-Nov
West U.P.
Himachal PradeshJune-JulySep-Nov
Jammu & KashmirApr-JulySep-Dec
2Western Region
GujaratJun-AugOct-Dec
MaharashtraJun-JulyOct-Dec
RajasthanJuly-AugOct-Dec
3North-East Region
AssamMid Feb-AprJune-JulyJune-AugNov-DecDec-FebMay-June
4Eastern Region
BiharMay-JulySep-OctJuly-SepNov-DecJan-FebMay-June
East M.P.June-AugMid Sep – Mid Dec
OrissaMay-JuneSep-OctJune-AugDec-JanDec-JanMay-June
East U.P.May-JulySep-NovJuly-AugNov-DecJan-FebApr-June
West BengalMar-June (Broadcasting)May-June (Transplanting)July-NovApr-June (Broadcasting)July-Aug (Transplanting)Nov-DecOct-FebApr-May
5Southern Region
Andhra PradeshMar-AprilJuly-AugMay-JuneNov-DecDec-JanApril-May
KarnatakaMay-AugSep-DecJune-OctNov-MarchDec-FebApril-July
KeralaApril-JuneAug-OctSep-OctJan-FebDec-JanMarch-Apr
Tamil NaduEarly SambaLate Samba
SonavariApril-MayJuly-AugJune-JulyNov-DecOct-NovMarch-Apr
SambaNavarai
KarMay-JuneAug-SepJuly-AugDec-JanDec-JanApril-May
Thaladi/Pishanam
KuruvaiJune-JulySep-OctSep-OctDec-Jan
Seasonality of Rice in India

Regional Availability

The following are the top five states in India where rice is abundantly available, along with key regions within those states:

StateAnnual Rice Production (MTPA)Annual Rice Straw Generation (MTPA)Key Regions of State
West Bengal1623Midnapore, Bardhaman, Dinajpur, South 24 Parganas, Birbhum, Bankura, Murshidabad, Burdwan, Hooghly, Nadia
Uttar Pradesh1516Bijnor, Kushinagar, Pilibhit, Chandauli, Baghpat, Varanasi and Ambedkarnagar
Punjab1320Tehgarh, Sangrur, Ludhiana, Moga, Ferozepur, Bhatinda, Jalandhar, Kapurthala, Nawanshahar, Faridkot, Patiala, Mukatsar, Mansa, Ropar, Amritsar, Hoshiarpur, Gurudaspur
Telangana1217Nalgonda, Suryapet, Nizamabad, Siddipet, Karimnagar, Kamareddy, Yadadri, Khammam, Peddapalli, Rajanna Sircilla, Jangaon
Odisha912.5Baragarh, Mayurbhanj, Balasore, Bolangir, Ganjam, Kalahandi, Puri, Keonjhar, Bhadrak, Sundergarh
Top 5 Rice Producing States in India

Prices

  • Loose Biomass: The price of loose rice straw typically ranges from ₹3-4 per kg
  • Briquettes: If processed into briquettes, the price can go up to around ₹6-6.5 per kg, making it one of the more expensive biomass options​.

Uses of Rice Husk

Rice husk has several alternative uses apart from being a biomass feedstock for energy:

  • Silica extraction: Rice husk ash, produced from combustion, is rich in silica, which can be used in industries like rubber and cement.
  • Animal bedding and feed additive: Due to its absorbent properties.
  • Composting and soil amendment: When used in compost, rice husk improves soil structure.
  • Construction material: It is sometimes used in the production of lightweight bricks or as an insulating material.
  • Biochar production: As a carbon sequestration technique.
  • Activated carbon production: Used in filtration systems.

Storage of Rice Husk

  • Storage Space: One ton of rice husk occupies approximately 2.5-3 cubic meters of space due to its low bulk density (90-150 kg/m³).
  • Fire Hazard: Rice husk is highly flammable. Outdoor storage is common, with safety measures to reduce fire risks, such as 3-5 meters distance between stockpiles and use of fire breaks.
  • Compressed Storage: Briquetting or pelletizing can reduce storage volume by up to 80%, with densities increasing to 600-800 kg/m³.

Rice Husk as Feedstock – Key Challenges

  • Supply Chain Issues: India produces over 32 million tons of rice husk annually, but collection is inefficient, especially in smaller farms. Up to 30% of rice husk is wasted due to poor logistics.
  • Inconsistent Quality: Rice husk has varying moisture content (8-12%) and ash levels (15-20%), affecting its suitability as biomass feedstock, particularly for energy generation.
  • High Transport Costs: Being bulky and lightweight (density of around 100 kg/m³), transportation costs are high, often constituting up to 40% of total expenses.
  • Low Market Price: Rice husk’s low price (₹2-4 per kg) makes it less attractive for large-scale industrial use compared to other biomass alternatives like bagasse.

Rice Husk for Industrial Heating and Power Generation

Uses of Rice Husk for Industrial Heating and Power Generation

  • Biomass Boilers: A primary use of rice husk in India is as fuel for biomass boilers. Industries, particularly in agro-processing, paper, textiles, and food processing, use rice husk to produce steam for heating processes.
  • Power Generation: Biomass power plants utilizing rice husk generate electricity, especially in rural regions. These plants convert husk into producer gas through gasification, then use it to run turbines, offering a reliable and renewable power source.
  • Cogeneration Systems: In large rice mills, husk is used for cogeneration, producing both steam for milling operations and electricity for local grids, optimizing energy use.

Form in Which Rice Husk is Used in Industries

Rice husk can be utilized in several forms based on the industry’s needs:

  • Raw Rice Husk: Directly used in biomass boilers, primarily for industries where cost efficiency is critical. Raw husk is inexpensive and readily available near rice mills.
  • Rice Husk Pellets: Compressed rice husk in pellet form, which offers a denser and more efficient fuel. Pellets are used for power generation in large-scale boilers due to their consistent combustion quality and easier handling.
  • Rice Husk Briquettes: Briquettes are another compact form, preferred for industrial applications requiring higher thermal efficiency.
  • Rice Husk Ash (RHA): After combustion, RHA is often used in cement, refractory material, and even in the production of advanced materials like silica. Some industries reuse the ash as an insulation material or additive.

The figure above displays bagasse pellets observed at the India Bioenergy & Tech Expo held in September 2024.

Boilers Using Rice Husk

The Indian industrial sector relies heavily on rice husk for boiler-based applications. Some prominent boilers designed for rice husk usage include:

  1. Fluidized Bed Combustion (FBC) Boilers: Widely adopted for their ability to burn a wide range of biomass, including rice husk. These boilers are popular due to their high efficiency, low emissions, and flexibility in fuel handling.
  2. Chain Grate Boilers: These are used extensively in agro-industries. They allow continuous fuel feeding and effective ash management, making them suitable for rice husk combustion.
  3. Stoker Boilers: Common in medium to large industries, stoker boilers use mechanical feeders and operate at moderate pressures. They are known for their durability and consistent heat generation using rice husk as fuel.

Amount of Rice Husk Being Used by Industries for Industrial Heating

In India, more than 15% of the rice husk produced annually is used for industrial heating and energy production. This equates to around 3.75 million tons per year. Some key statistics:

  • Power Generation: India’s biomass power plants, many of which use rice husk, have an installed capacity of around 10,000 MW.
  • Rice Husk Utilization Efficiency: Around 60% of rice mills in India use rice husk as a direct source of energy for their operations.
  • Boiler Fuel: Nearly 400,000 tons of rice husk are used annually by various industries as boiler fuel for generating steam.

Prominent Industries Using Rice Husk for Industrial Heating

Several industries in India utilize rice husk for heating and power, leveraging its low cost and eco-friendly attributes:

  1. Agro-Processing Industries:
    • The rice milling sector is the largest user of rice husk for direct combustion in boilers, generating steam for drying, parboiling, and power generation.
    • Large mills often employ cogeneration systems, optimizing their operational costs by utilizing waste husk.
  2. Textile and Garment Factories:
    • Use rice husk boilers for steam-based dyeing, finishing, and washing processes.
    • The shift from fossil fuels to rice husk has been prominent, especially in South India, where 40% of small and medium textile units have transitioned to biomass.
  3. Paper and Pulp Industries:
    • Rice husk boilers generate the required steam for the pulping and drying stages. Some leading paper companies use husk to lower operational costs and reduce carbon footprints.
    • Industry reports suggest that 20% of the biomass used in paper production in Northern India is rice husk.
  4. Food and Beverage Sector:
    • Breweries and dairy processing units employ rice husk boilers for steam production, enhancing the sustainability of their operations. A key example is the dairy cooperative Amul, which uses rice husk for steam generation in its Gujarat processing facilities.

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