Thermal energy can produce pollution. This pollution is often in the form of escaped chemicals or water released in thermal power plants or storage sights. Air and water pollution may also be linked to geothermal fields. For example, steam may emit heat waste that might affect cloud formations and weather patterns.

ORC is a closed cycle process like a conventional steam cycle process, in which waste heat is used to evaporate an organic fluid. Through an expander this drives a generator to produce clean energy.

The Organic Rankine Cycle's principle is based on a turbogenerator working as a conventional steam turbine to transform thermal energy into mechanical energy and finally into electric energy through an electrical generator.

”Waste heat recovery” is the process of “heat integration”, that is, reusing heat energy that would otherwise be disposed of or simply released into the atmosphere. By recovering waste heat, plants can reduce energy costs and CO₂ emissions, while simultaneously increasing energy efficiency.