Sources of Chemical Energy
As mentioned above, chemical energy is stored within the bonds of molecules and when these bonds break, heat is released or absorbed. These molecules are part of chemical compounds or fuels such as coal, oil, biomass, wood, animal waste, natural gas, food, etc. and they all constitute chemical energy sources that produce heat usually through combustion.
Chemical energy sources can be classified into two types, depending on whether they are naturally or artificially prepared and depending on their natural state (solid, liquid, or gaseous):
- Solid Fuel: wood, coal, lignite, etc.
- Liquid Fuel: petrol, diesel, alcohol, kerosene, etc.
- Gas Fuel: natural gas (coal gas, water gas, bio gas)
All these fuels contain hydrocarbons - organic compounds containing carbon and hydrogen - of various molecular weights. These hydrocarbons may be alkanes (methane, ethane, propane, etc.), alkenes (ethene, propene, etc), cycloalkanes, aromatic hydrocarbons and heterocyclic compounds.