Important sources of biomass and their characteristics are given here.
A.
Crop residue and farm wastes
The straw of cereals and pulses, stalks and seed coats of oil seeds, stalks and sticks of fibre crops, pulp and wastes of plantation crops, peelings, pulp and stalks of fruits and vegetables and other wastes like sugarcane trash, rice husk, molasses, coconut shells etc. comes under this category.
Most of the crop residues have a higher ash content and mainly constitutes carbon, oxygen and hydrogen. Volatile matter content is 60-75%. The agricultural residues are hygroscopic in nature. Ash content varies from 0.5 to 2.8 per cent.
B.
Industrial wastes
These wastes include wastes from paper mills, chemical mills etc. for eg., paper wastes, plastic wastes, textile wastes, gas, oil, paraffins, cotton seeds and fibres, bagasse etc. Plastic and rubber wastes have good calorific value.
C.
Forest wastes
Logs, chips bark and leaves together constitute forest wastes. Sawdust is the forest based industry waste. Forest products are also used as a. domestic fuel in many developing countries.
D.
Logging residues
Tree tops, small stems and roots removed from a standard logging operation and broken debris generally considered as logging residues. It contains 40-50% moisture, 50% carbon, 40% oxygen and nitrogen 5%.
E.
Residues of wood product industries
Bark, knots, sawdust etc. are obtained from wood product industry. Moisture content of these residues is around 20% with 67% volatile matter and 11 % organic carbon.
F.
Residues from pulp and paper industries
The bark and black liquor produced in pulp and paper factories can be used as major source of energy in the paper industry. Moisture content varies from 5-10% with organic. carbon 8-11 per cent.
G.
Municipal solid wastes
Generally municipal solid wastes refer to a mixture of domestic, small construction and demolition wastes left out within a community. Composition of municipal solid wastes is given in a Table 1. It shows the heterogenic nature of these waste mixture.
Table 1 : Composition of municipal solid wastes
| Sl.No |
Component |
Percentage (weight) |
1 |
Paper |
41 |
2 |
Metals |
8.2 |
3 |
Glass, Stones, Ceramics |
11.2 |
4 |
Plastic, rubber |
4.9 |
5 |
Garbage, yard wastes |
24 |
6 |
Miscellaneous |
10.7 |
|
Total |
100% |
H.
Municipal sewage sludges
The sludges contain 95% water, and 5% organic matter and nutrients as the main constituents. These can be utilized for the production of methane through anaerobic digestion.
I.
Animal wastes
The moisture content of the manures ranges from 60 to 85 percent. The nitrogen varies from 0.3 to 0.9 %, phosphorus 0.05-0.1 % and potassium 0.12 to 0.8% Available statistics indicates production of 1300 million tonnes of dung annually from all types of animals. Of the total produced, 84% is of cow and buffalo dung and 13% goat and sheep droppings. Dung is used as a fuel in the form of cakes and biogas.
Availability of biomass resources in India along with their coal equivalent is shown in Table 2.
Table 2. Major biomass resources in India
| Sl.No |
Biomass |
Availability
(Tones/Yr.) |
Coal equivalent
(Tones/Yr.) |
| |
Agricultural residues |
| 1 |
Rice straw |
9 |
58.4 |
| 2 |
Rice husk |
19.9 |
15.7 |
| 3 |
Jute sticks |
2.5 |
2.3 |
| 4 |
Wheat straw |
50.5 |
37.5 |
| 5 |
Cattle dung |
1,335.00 |
128 |
|
Agro-industrial bi-products |
| 1 |
Bagasse |
28.1 |
22.4 |
| 2 |
Molasses |
2.1 |
0.8 |
| 3 |
Oil seed cakes |
6.7 |
0.9 |
| 4 |
Saw dust |
2 |
3.4 |
|
Forest products |
| 1 |
Mahua flowers |
1 |
0.4 |
| 2 |
Leaves, tops etc. |
3.3 |
3 |
The different processes that are followed in India to make these wastes into
a useful fuel are discussed in the next article.
Next :
Processes
for converting biomass to bio-fuel.
