What are the characteristics of good fuel?

A good fuel should:

1. Have a high calorific value, so it gives more heat per unit mass.
2. Have a moderate ignition temperature. If it is too low, the fuel is a fire hazard in storage. If it is too high, the fuel is hard to ignite.
3. Have low moisture content, because moisture lowers the heating value.
4. Have low non-combustible matter (ash), because ash lowers the calorific value, causes clinkers and needs disposal.
5. Burn at a moderate, controllable rate, with easy control of combustion.
6. Produce no harmful products (SO₂, CO, H₂S, smoke), which needs low sulphur and nitrogen content.
7. Be cheap and readily available.
8. Be easy and safe to store and transport at low cost.