The Rankine thermodynamic cycle is a concept wherby a set of processes involving a working fluid in a closed loop is such that thermal power is converted into mechanical power, and thereafter possibly into electricity. Traditionally, the working fluid is water (thus steam, when vaporized). In the Organic Rankine Cycle (ORC), the working fluid is an organic substance. Organic means that the molecules of the fluid contain a carbon atom. The implementation of the ORC concept is an engine or power plant. An examplary process flow diagram is shown in the figure on the right.