Answer: A good fuel has high calorific value, suitable ignition temperature, low moisture, ash and sulphur, burns at a controllable rate without harmful products, and is cheap, available and easy to store and transport.
- High calorific value: it should give a large amount of heat per unit mass or volume.
- Moderate ignition temperature: low enough to ignite easily, but not so low that it catches fire accidentally during storage.
- Low moisture content: moisture lowers the heating value because heat is wasted in evaporating water.
- Low non-combustible matter (ash): ash reduces the heating value and creates disposal problems.
- Low sulphur and nitrogen: they form SO₂ and NOₓ, which pollute air and corrode equipment.
- Controllable combustion: the rate of burning should be easy to start, stop and regulate.
- Harmless products: it should not produce smoke or poisonous gases such as CO in large amounts.
- Low cost, easy availability, easy storage and transport.
