Which is a better fuel-biogas or wood? Why?

Explanation

To determine which is a better fuel between biogas and wood, we can analyze their properties, particularly their calorific values and environmental impacts.

### Step-by-Step Solution:

1. **Definition of Fuels**:
- Fuels are substances that can release energy when they undergo a chemical reaction, usually combustion.

2. **Calorific Value**:
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