- Purely electrical heat engines driven by the thermal noise voltage of resistors are introduced. In these engines, there is no steam, gas or combustion and the only mechanically moving elements are the piston and resonator (flywheel). Resistors, capacitors and electronically controlled switches are the other building elements. For the best performance, a large number of parallel engines must be integrated to run in a synchronized fashion. At room temperature, in the idealistic case, a two-dimensional ensemble of engines of 25 nanometer size integrated on a 1 square-inch silicon chip with 20 C temperature difference between the warm-source and the cold-sink would produce a power of about 1 Watt. Several standard and coherent (correlated-cylinder states) versions of these engines have been introduced and both of them can operate in either four-stroke or two-stroke modes. The correlated engines offer the same type of paradoxes as coherent quantum heat engines and they serve the solution of their paradox, too. 2011 IEEE.