Overall, one could say that energy usage and consumption are linked to their prices. Energy prices are to a wide extent interconnected and as a result usually when one energy production source experiences price increases other energy sources also increase. This fact explains some kind of positive correlation between different energy sources, which can be observed while analyzing the historical data and complex interactions of the coal gas and oil markets. Energy prices are very volatile and do not necessarily only depend on demand and supply but also on political and economic decisions. As such, energy prices are complex and dependent on a wide variety of politico-economic determinants.