Concept:
- The value of biogas becomes clear when it is compared with what a village would otherwise burn.
- Comparing it against firewood, dung cakes and kerosene on cost, efficiency, environment and health shows why it is the better choice on every count.
Step 1: Compare on cost of fuel.
Kerosene has to be bought, and collecting firewood costs hours of labour every day. Biogas is made from shrubs, farm waste, animal waste and human waste that the village already produces and mostly throws away.
After the plant is built, the fuel itself is free.
Step 2: Compare on how much heat is obtained.
Biogas has higher thermal efficiency than kerosene, dung cake and charcoal. The same effort therefore yields more cooking heat, and a meal is ready faster.
Step 3: Compare on what is left behind.
Burning dung cakes destroys the dung completely. A biogas plant takes the gas and leaves a slurry that is a better manure than the original dung, so the farmer gets energy and fertiliser from one input.
This is why the cattle dung plants are called Gobar gas plants and are described as giving twin benefits.
Step 4: Compare on damage to the environment.
Firewood collection strips the forest near a village, and burning dung takes nutrients away from the soil. Biogas prevents both losses at once, which is why it is called the most efficient use of cattle dung.
Step 5: Compare on health inside the house.
A smoky chulha harms the eyes and lungs of whoever cooks on it, usually the women of the household. A gas flame is smokeless, so the kitchen becomes safer and cleaner.
Final Answer: On every comparison with firewood, dung cakes and kerosene, biogas comes out ahead. It is cheaper, more efficient, leaves better manure, protects forests and soil, and gives rural families a smokeless kitchen.