ORC: How it works In a typical ORC design, a thermal energy source feeds an evaporator to drive an expander or “reverse compressor”, which in turn generates the electricity. The provider of the heat can be natural, such as in the case of geothermal energy, or waste heat from any number of industrial waste heat sources.

A system that uses the Rankine cycle has four parts: a pump, a boiler, a turbine and a condenser. The pump's job is to deliver liquid to the boiler.

This process was developed in 1859 by Scottish engineer William J.M. Rankine. This is a thermodynamic cycle which converts heat into mechanical energy—which usually gets transformed into electricity by electrical generation.

An organic Rankine⁵ cycle turbine is a small turbine that is identical in design to a steam turbine but which uses a low boiling point organic fluid as its working fluid instead of water and steam. The turbine is packaged into a closed cycle system with a condenser and heat exchanger.