biomass (organic biomass)

Biomass is organic material derived from living or recently living organisms — plants, animals, and microorganisms — that can be used as a source of energy, chemicals, materials, or fertiliser. In the bioenergy context, biomass encompasses a vast range of feedstocks: woody biomass (forest residues, sawmill waste, short-rotation coppice), agricultural biomass (crop residues, energy crops, livestock manure), municipal biomass (food waste, garden waste, sewage sludge), and aquatic biomass (algae, water hyacinth). The defining trait is that biomass is part of the active carbon cycle — combustion releases recently captured atmospheric carbon, distinguishing it from fossil fuels that release ancient carbon.

Biomass is the largest source of renewable energy worldwide, providing about 10% of global primary energy supply, and is particularly significant in India where it accounts for roughly a quarter of total primary energy use. Major Indian biomass streams include agricultural residues — paddy straw (160 million tonnes per year), wheat straw (110 MT), sugarcane bagasse (100 MT), cotton stalks (30 MT) — and livestock manure — cattle dung at 1,200 MT per year fresh weight. Of these, an estimated 230 MT is surplus to existing fodder, mulch, and household fuel uses, and is therefore available for industrial bioenergy. Indian government estimates put the technical potential at 30,000 MW of biomass power and 60 MMT per year of biomethane production.

Biomass conversion pathways span four major routes. Combustion for power generation in dedicated biomass plants or co-firing with coal. Anaerobic digestion for biogas and CBG production, optimal for moist feedstocks. Thermochemical conversion — gasification, pyrolysis, hydrothermal liquefaction — produces syngas, bio-oil, or biochar. Biochemical processing for ethanol (sugarcane molasses, grain) and butanol. Each pathway has feedstock preferences: anaerobic digestion suits high-moisture biomass (>70% water content), while combustion and gasification need dry biomass (<20% moisture). Pre-treatment for densification (pelleting, briquetting) is often necessary to make biomass economically viable for transport beyond 50–100 km of source.