The main element of a CHP unit is a fuel-fired four-stroke engine, which converts the combustion energy of the fuel to thermal and mechanical energy; the latter is then converted to electricity by a generator. We therefore speak of Combined Heat and Power units.
The exhaust gases are not discharged directly into the environment; they flow through a flue gas/heat exchanger where heat is extracted from them. The heat exchanger is connected to the external (secondary) circuit of the transmission line.
The control unit takes full control over operation of the entire CHP unit system. The control system is of key importance for proper operation as well as for diagnostics and elimination of potential defects.
A CHP system effectively transforms 90% of the energy input, i.e. approximately 40% as electricity and 50% as thermal energy. Energy losses of a CHP unit amount to approximately 10%. | 
