While several different types of biomass boilers are
described in this guide, their principle of operation
is the same. In many respects the technology used
to burn wood is similar to that used in coal boilers
which are still in use in some parts of the UK. Fuel
is fed to the grate mechanically where it undergoes
combustion to produce energy. Figure 2 outlines the
main stages and the temperature ranges associated
with them; however it is a simplification and several
stages can occur simultaneously.