Power stations’ gain depends on the type of fuel used to the production of energy. Spreads in the energy markets are indicators that allow to estimate the future profit from the sale of energy. In analyses of energy production profitability, the most commonly used are two types of spreads: dark spread for coal-fired power stations and spark spread for gas-fired power stations. Paper presents calculationmethods of spreads in the energy markets in Western Europe, as well as factors influencing their level and relationships between. Spreads volatility depends mainly on changes in market prices of electricity and fuel burned in power plants. Significant influence on spreads level has also CO2 emission allowances price. Paper presents the hypothetical way in which the parties to the transactions in energy markets can adjust the volume of production having knowledge about the spreads formation. The essential elements of energy market, that determine the possibilities of using spreads in the future, have been pointed out. The most important is the diversity of fuels burned in power plants in the country. There are listed several European countries, in which spreads analysis is used to help optimizing energy production from different sources. Data presented in the article come from German energy market.