1. What is Biomass?
Biomass refers to all organic materials that come from plants and animals. It is a renewable energy source because it can be replenished over a short period.
Examples include:
* Wood and wood waste
* Agricultural residues (like maize stalks, sugarcane bagasse, rice husks)
* Animal manure
* Organic waste from homes or industries
* Algae and other plant materials
2. Sources of Biomass
Biomass can come from:
| Source type | Examples | Renewable Feature |
| Forestry | Firewood, sawdust | Trees can be replanted |
| Agriculture | Crop residues, animal dung | Produced yearly with crops/livestock |
| Municipal Waste | Food scraps, paper | Continuously generated |
| Aquatic Plants | Algae, seaweed | Grows rapidly in water |
3. How Biomass Stores Energy
Plants capture solar energy during photosynthesis and store it as chemical energy in their tissues.
When we burn or convert biomass, this stored energy is released as heat, gas, or fuel.
Equation for Photosynthesis: 6CO_2 + 6H_2O + sunlight → C_6H_{12}O_6 + 6O_2
4. Methods of Converting Biomass to Energy
| Conversion Method | Process | Output |
| Direct Combustion | Burning biomass in air | Heat or electricity |
| Gasification | Partial burning with limited oxygen | Syngas (CO + H₂) |
| Anaerobic Digestion | Microbial breakdown without oxygen | Biogas (mainly CH₄) |
| Fermentation | Microbial conversion of sugars | Ethanol (biofuel) |
| Pyrolysis | Heating biomass without oxygen | Bio-oil, gas, and charcoal |
5. Uses of Biomass Energy
- Cooking and heating (firewood, charcoal, biogas)
- Electricity generation (in biomass power plants)
- Transportation fuels (bioethanol and biodiesel)
- Fertilizer production (from digested organic waste)
6. Advantages of Biomass
✅ Renewable and sustainable
✅ Reduces waste and pollution
✅ Can be produced locally
✅ Provides rural employment
✅ Carbon-neutral (if managed sustainably)
7. Disadvantages of Biomass
⚠️ Deforestation risk (if overused)
⚠️ Lower energy density than fossil fuels
⚠️ Can compete with food crops for land
⚠️ Requires good management to avoid air pollution
A simple biomass energy flow:
Sun → Plants (photosynthesis) → Biomass → Conversion → Bioenergy (heat, fuel, electricity)
10. Review Questions
1. Define biomass and give two examples.
2. Describe two ways biomass can be converted into useful energy.
3. State three advantages of using biomass as an energy source.
4. Why is biomass considered a renewable source of energy?
5. Mention one problem associated with large-scale use of biomass energy.