Actually, modern thermal plants have almost stopped using liquid fuels. The fuel most frequently used is methane and, to a smaller extent, liquid petroleum gas (LPG).

GASES INVOLVED

Methane CH4: Methane is a simple hydrocarbon and in nature it is in form of gas. Methane is the main component of natural gas and an excellent fuel.
LPG (C3H8): used as a fuel, LPG is a mixture of propane and butane, which is often odorized by ethantiol to make its detection easier in case of leaks.

EXPECTED RISKS

CH4: methane is a simple hydrocarbon and is in nature in form of gas. Methane is the main component of natural gas and is an excellent fuel, able to form easily in atmosphere resulting in a high risk of explosion.
C3H8: used as a fuel, LPG is a mixture of propane and butane, which is often odorized by ethantiol to make its detection easier in case of leaks. It can easily form an atmosphere with high risk of explosion