Power Production
There are two distinct methods of using geothermal Energy to produce power; both are indirect applications, converting heat to mechanical energy which turns a turbine. Geothermal power is constant (base-load), has high operability, is sustainable due to re-injection of cool fluids and is environmentally sound.
- Steam from high enthalpy geothermal reservoirs (often associated with volcanism, such at Olkaria, Kenya) is used to drive a turbine, typically of 25+MWe capacity requiring a number of interconnected wells
- In lower enthalpy systems (such within the USA Basin and Range) a binary plant is used, in which the geothermal fluids heat a working fluid (either diluted ammonia or iso-butane) with a much lower flash boiling point than water – see schematic below
While less efficient that direct steam driven turbines, binary units are modular and suited to well-head generation that can be increased as a field is developed. Binary plants are closed circuit and emission free.