Biomass Energy •
1
B
IOMASS
E
NERGY
12.1
INTRODUCTION
Biomass refers to solid carbonaceous material derived from plants and animals. Biomass is
organic matter that can be used to provide heat, make fuel and generate electricity. Wood-fuel,
the largest source of biomass has been used to provide heat for thousands of years. Many other
types of biomass are also used as an energy source such as plant residue from agriculture or
forestry and the organic component of municipal and industrial wastes. Landfill gas is also
considered a biomass source. Biomass resources can be replenished through cultivation of
crops such as fast growing trees and grass.
Biomass fuels are the most important source of primary energy in Kenya with wood-fuel
(firewood and charcoal) accounting for over 68% of the total primary energy consumption.
About 55% of this is derived from farmlands in the form of woody biomass as well as crop
residue and animal waste and the remaining 45% is derived from forests.
Studies on biomass energy point to a widening gap between supply and demand for wood-fuel,
a challenge that requires dedicated policy interventions to redress. Wood-fuel supply does not
match demand over various parts of the country.
BIOMASS RESOURCES
Biomass resources for energy production are widely available in forest areas, rural farms,
urban refuse and organic waste from agro-industries. Biomass classification is illustrated below
Biomass
Energy crops(arid area
plantation aquatic crop)
Natural vegetable
growth
Organic wastes and
residues
Forest residue
Agricultural
crop residues
Animal
wastes
Urban
wastes
Industrial
wastes
Sewage liquid
wastes
Municipal solid
wastes
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India produces over 550 million tonnes of agricultural and agro-industrial residues every year.
Similarly, 290 million cattle population produces about 438 million tonnes of dung annually.
Prime biomass sources are discussed below:
Biomass Energy •
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Forests
Forests, natural or cultivated are a rich source of timber, fuel wood, charcoal and raw material
for paper mills and other industries. Fast growing trees like Eucalyptus, Neem, Kikar and
Gulmohar are grown along canals, railway tracks and on lands of marginal quality. Wood, saw
dust, and bark residue are generated in sawmills. Forests also provide foliage and logging
residues. An important characteristic of forest residue is its calorific value, which is 4399 to
4977 kcal/kg for softwood foliage and 3888 to 5219 kcal/kg for hard wood species.
Agricultural crop residues
Crop residues are available in abundance as natural resource, easily collected and stored.
jThese are, rice husk, wheat straw, com cobs, cotton sticks, sugarcane bagasse, groundnut and
coconut shells. These are converted into briquettes or pellets for use as clean fuel. These are
called ‘biofuels’ which are high efficiency solid fuels.
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- Spring '16
