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.

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.

Organic Rankine cycle (ORC) machines are used to convert low-temperature heat resources into power. Examples include systems making use of waste heat in a cogeneration system, low temperature geothermal electricity generation, solar ponds, and potentially OTEC.

ORC WHR system consists of four major components: pump, evaporator, expander and condenser, as shown in Figure 1.