Low Pressure Flash-Steam Cycle at Hellisheidi – Selection Based on Comparison Study of Power Cycles, Utilizing Geothermal Brine

Abstract

This paper describes a selection of power generation cycles, utilizing separated brine, at the Hellisheidi geothermal field.

Reykjavik Energy made the decision to construct a combined heat and power plant (CHP-plant) at Hellisheidi in 2001. Initially electrical power was supposed to be generated by high-pressure (HP) separated steam, followed by heat generation for district heating in the Reykjavik area, using separated brine.

Exploration of the geothermal field for the planned CHP-plant indicated a wet-steam reservoir with excess amounts of separated brine for heat generation.

The utilization of excess separated brine was examined and compared using three different cycles: Organic Rankine cycle (ORC), Kalina cycle and low-pressure (LP) flash-steam cycle. In the end the LP flash-steam cycle was selected as the most viable option for the Hellisheidi plant.

This paper also describes the operation of the selected power generation cycle and its planned future development.