Gaseous Fuels:- Fuels are the substances which undergo combustion or as a result of their burning, they produce heat energy. Most common fuels are:-
a)   Solid Fuels:- Wood, lignite, peat, coke, charcoal, etc.
b)   Liquid fuels:- Petroleum products such as petrol, kerosene, oils, spirits, etc.
c)   Gaseous fuels:- Water gas producer gas, coal gas, oil gas, natural gas, L.P.G. etc.
Characteristics of good fuel
i)             It should have high calorific value.
ii)           It should not give any offensive odour or any undesirable product during burning.
iii)          It should yield very little ash content.
iv)          The combustion should be of moderate speed.
v)           Its cost of production should be low and it should be easily available.
Superiority of Gaseous fuels over other fuels
Gaseous fuels are the best fuels. The advantages of gaseous fuels over solid and liquid fuels are given below.
i)             Gaseous fuels leave no ash and there is lesser loss of heat during their combustion.
ii)           They have high calorific value.
iii)          Gaseous fuels do not produce smoke.
iv)          No special devices are required for their combustion.
v)           Gaseous fuels can flow through pipes and can be ignited at the moment’s notice at any place where a burner is places.