Prof. Vilas Shamrao Patil

1. Biomass Energy
13.1 : Introduction:-
We saw in the previous chapters why alternate, non-
conventional resources of renewable energy are being
explored and how technologies are being developed to
harness maximum usable energy from them. Like solar
radiation, wind, biomass are also non-conventional
renewable cheap resources of energy. We are going to see
how usable energy is drawn from various types of biomass
(derived from plants, algae, animals etc.)
13.2: Origin of Biomass-
Organic matter derived from biological organisms like
plants, algae, animals is called Biomass. The energy
obtained from biomass is called Biomass energy. The raw
organic matter obtained from nature for extracting usable
energy is called Biomass Energy Resource. Biomass
resources can be classified into two categories :
(1) Biomass from cultivated fields, crops, forests.

2. (2) Biomass derived from waste which includes domestic
and municipal waste like spoiled food, vegetables, human
and animal excreta/dung, forest waste, agricultural waste,
bioprocess waste, butchery waste, fishery waste/fishery
processing waste etc. (Fossil fuels like coal, petroleum oil,
natural gas have ultimate origin in the above mentioned
two categories, but they are not included in the category
of Biomass. They are considered under conventional
resources of energy.)
But if carefully seen to the above two categories we find
that both have the same origin i.e. the photosynthesis
process taking place continuously in the nature.
Photosynthesis is the mother process in the formation of
all biomass.
Photosynthesis : Photosynthesis means synthesis with
light. In the process of photosynthesis green plants
consume atmospheric CO,, moisture, minerals and water
from underground and photo (light) energy from the

3. sunlight and by the interaction with chlorophyll produce
biomass and at the same time release oxygen in the
atmosphere. The biomass stored in the green plants
(trees, agricultural crops, algae, water plants) is in the
form of complex organic compounds of carbon, hydrogen,
nitrogen etc.
The formation of biomass by photosynthesis can be
shown as :
Carbondioxide gas from atmosphere+ Chlorophyll in
plants+ moisture + solar energy
6CO2+ 6H20 + 4.66 x 10-8
j of (solar Energy) C6H1206 + 602
The oxygen released into and absorbed from the help to
make the air more pure.
The green plants storing biomass are consumed as food by
animals, micro-organisms; even non-green plants derive
required organic matter from the biomass stored in green
plants. Then all these themselves become the sources of
biomass as spoiled food, decayed plants, human and

4. animal excreta, agricultural waste, butchery waste, fishery
waste etc.
Algae biomass is another important renewable source of
energy produced by photosynthesis. Algae is a kind of a
pack of a number of very small plants. It grows very fast
and the organic extracts from biogas plants is a good food
for it. The algae is kept on a special tank called algae pond.
It combines with some kind of bacteria in the pond and
the combination consumes the waste organic matter from
a biogas plant, in the presence of sunlight and by
photosynthesis and on absorbing CO2 and NH3 and
releasing 02, it grows and thus solar energy and chemical
energy are converted into biomass through it. (The solar
energy is fixed into biomass). The process can be shown
as in Fig. (13.1)

5. Fig. 13.1 : Growth of algae cell in algae pond
In the algae, in addition to carbon, nitrogen and hydrogen
some sulphur also is absorbed. Algae biomass is looked
upon as a prospective alternative rich source of renewable
cheap resource of energy. Therefore, technologies are
being developed to form algae farms to reap algae crops
on large scale.
Thus, biomass is obtainable from land based plants and
animals, aquatic. plants and animals, micro-organisms,
algae etc. and photosynthesis is the mother process in the
life cycle and is developed in green plants.

6. The biomass can be converted into secondary (useful)
energy forms as heat, solid fuels, gaseous fuels, organic
chemicals and liquid fuels.
Some biomass remains buried at high depths under
ground and under enormous pressure becomes fossil
fuels (coal, petroleum oil, natural gas) after several years.
However, fossil fuels are not included in the category of
biomass.
13.3 : Biomass Energy Resources -The biomass used for
producing usable (secondary) energy forms are called
biomass energy resources. They are classified as :
(1) Biomass from cultivated crops called energy farms
(2) Biomass from waste organic matter. Both are
renewable sources of energy (Waste to Biomass
resources),
1. Biomass from cultivated crops : For energy farming
special species are cultivated through genetic research.
The species include fast growing trees (super trees), fast

7. growing land-based or aquatic crops, algae etc. They have
high energy density and are renewable.
Such crops include :
(i) Sugar cane crops, sweet sorghum crops, sugar beets,
(ii) Non-woody (herbaceous) crops which yield biogas or
biochemical fuels,
(iii) Cereals, potatoes etc. which are rich in carbohydrates
and which by fermentation yield fuel gas, solid fertilizers
etc.,
(iv) Fast growing forest crops (silviculture),
(v) Aquatic crops in fresh water, sea water, sea-weeds,
algae, floating kelp, water hyacinth etc.
2. Waste to Biomass resources : Such type of resources
convert organic .wastes into intermediate and/or
secondary (usable) energy forms such as heat, biogas,
alcohol, fuels, chemicals etc.
The waste can be classified as —

8. (i) Urban waste : spoiled food, hospital waste, rubbish,
water, mud, skin, bones etc. from slaughtering houses.
(ii) Industrial waste : Baggase of sugar cane, chemicals etc.
(iii) Agricultural farm waste : Husk of rice, wheat, coconut,
groundnut shells, straw of rice etc.
(iv) Rural animal waste : Fodder, dung, skin, bones, flesh
etc. of dead animals.
(v) Forest waste.
(vi) Fishery, Poultry, Butchery waste.
(vii) Animal and human excreta.
(a) Most of the usable energy is obtained from the
intermediate sources of energy by incineration of the
biomass and the intermediate energy sources are steam,
electrical energy, heat.
(b) Urban waste is mostly decayed by bacterial decay and
mainly cooking gas (which contains more than 50% of
methane by volume) is extracted.

9. (c) Agricultural waste is converted into biogas (methane),
heat biochemicals (fertilizers) by various processes
including combustion.
(d) Industrial waste baggase is used for generating
electrical power and paper.
It is costly to transport solid biomass, therefore, it is first
converted in suitable form like liquid and gas and then
transported to distant places.