BIOMASS ENERGY


The substances which compose vegetal and animal world represent the biomass.
Biomass energy can be used by direct combustion or transforming it into artificial fuels, such as charcoal, alcohol, biogas and diesel oil produced from vegetable oils, etc.
Biomass has been used for energy purposes ever since man discovered fire. Nowadays, biomass fuel may be used in various ways, from central heating to the production of the electrical energy and fuels for vehicles.
Biomass was used for the first time in Brazil to produce ethanol, which has been used as fuel for motors since 1903.
Figure 6.1 presents the structure of a sawdust-burning boiler, the sawdust being utilized for thermal power stations. The following notations have been used:

  1. sawdust container;
  2. fuel feeder;
  3. air supply chamber;
  4. combustion chamber;
  5. cooling chamber;
  6. smoke-outlet pipes.

Figure 6.1

Biomass can also be used as fuel in order to obtain heat and electricity, in the following forms:

  1. wood;
  2. forestry waste;
  3. light industry waste (textile, leather, etc);
  4. domestic waste;
  5. biogas;
  6. waste obtained by processing agricultural products;
  7. animal waste;
  8. agricultural waste;

Bioenergetics can be modernized due to the modern technologies of transforming the initial biomass into comfortable and modern energy carriers (electrical energy, liquid and gas fuels, finished solid fuel).


Figure 6.2

Figure 6.2 presents the structure of a chopped-waste combustion plant. The following notations have been used:

  1. air distributor;
  2. combustion air;
  3. secondary air;
  4. fuel insertion;
  5. tertiary air;
  6. flame;
  7. burner;
  8. postcombustion chamber;
  9. separator;
  10. wall;
  11. ascending flame tank;
  12. ash collecting container.

In contrast to other forms of renewable energy, biomass has two important advantages, namely,

  • it can be stored;
  • it can be found everywhere.

    • By biomass combustion, fewer noxious combustion products are given off than in the case of fossil fuels and natural gas. In general, biomass combustion temperature is low. Figure 6.3 presents the scheme of incorporated transformation of biomass into gas. The following notations have been used:

    • GG - gas generator;
    • Cc - cyclone,
    • DC - decarbonator;
    • CC - combustion chamber;
    • EG - electrogenerator;
    • T   - turbine;
    • WHB - waste-heat boiler;
    • Cs  - compressor.

    Figure 6.3

    The formation of fuel gases, by the decomposition of wet organic substances in media lacking molecular oxygen, is a natural process on Earth. Their main component is methane. This was the way in which natural gases were formed in the sediments from the Earth’s interior, by means of prehistoric plants and animals.

    Biogas is a mixture of fuel gases, which is formed by decomposing the organic substances in wet medium and lack of oxygen.

    Biogas needs processing before it can be used. It is usually passed through special separators, where methane is separated from the rest of gases. The use of raw biogas may end up in intoxication, because the rest of gases contains toxic gases.
    The chemical components of the organic material with the highest degree of conversion into biogas, are celluloses, hemicelluloses and fats.