Direct and indirect heat energy conversion into electricity

Conversion of heat energy into electricity is described. Energy conversion is the process of changing one form of energy to another. There are two methods of conversion: direct, when heat energy is converted directly into electricity and indirect, when heat energy is converted into mechanical energy first and afterwards into electricity. A principle of direct method is thermoelectric effect that includes three separately identified effects: the Seebeck effect, the Peltier effect and the Thomson effect. In case of heat energy conversion into electricity, we are talking about Seebeck effect. For indirect method, first heat energy is converted to mechanical energy. The principle is gas compression and expansion due to temperature change that is used i.e.: steam engine, Stirling heat engine or polish engine WASE2. The engine is based on the fundamental physical phenomena. The next step is to convert mechanical energy into electricity. The principle is electromagnetic induction that produces an electromotive force across a conductor when it is exposed to a time varying magnetic field. Electromagnetic induction is used in i.e.: generators, alternators or American type generators.