Method for burning fossil fuels and substitute fuels and burner for carrying out the said method

In the combustion of fossil fuels together with substitute fuels in a burner, the substitute fuels are supplied to the flame in the burner in a region that annularly surrounds the region in which the fossil fuel is supplied to the flame in the burner. A burner suitable for the joint combustion of fossil fuels and substitute fuels has a channel through which substitute fuel is supplied and which is bounded by two concentric tubes. This channel is arranged annularly around a channel through which fossil fuel is supplied.