Liquefied petroleum gas (or short LPG) is a mixture of propane and buthane and is commonly used for home heating and as an gasoline (petrol) alternative for internal combustion engines. It is made from crude oil or from natural gas, so by all means it is non-renewable fuel. It cannot be obtained easily at home and is very easy to use — the gas in pressure of 6 atmospheres is liquid in room temperature. So it doesn’t need large containers prepared for very high pressures to store it.

The following article gives a good intro about this fuel.