Combined Cycle Units (GCCU) Geothermal Power Plants
Ormat Geothermal Combined Cycle Units (GCCU) are designed to generate power from high-pressure geothermal steam resources. When there are non-condensable gases present in the geothermal steam, our GCCU technology provides higher efficiency, lower maintenance costs and higher electrical output in comparison to conventional condensing steam power plants. Ormat offers GCCU modules in a wide range of sizes in order to accurately match the power plant to the geothermal energy resource. The result is significant savings in well drilling and resource development. The GCCU can be air-cooled so that all steam condensate can be 100% re-injected. Total fluid re-injection sustains reservoir life and provides pressure support. Due to the low profile of the air-cooled condensers and the lack of any plum from the water cooling towers, the visual impact is minimized and the risk of acid rain is minimized as well.
How It WorksFor high-pressure steam-dominated resources, a geothermal combined cycle plant uses both a steam turbine and a binary cycle ORMAT® ENERGY CONVERTER
- The high-pressure steam from the separator drives a back pressure turbine, the most efficient use of steam at this stage in the cycle.
- The low-pressure steam exits the turbine at a positive pressure and flows into the vaporizer of a bottoming ORMAT® ENERGY CONVERTER (OEC).
- The heat of condensation of the low-pressure stream is used to vaporize the organic motive fluid and the expansion of these vapors drives the organic turbine.
- The organic vapors are then condensed and pumped back into the pre-heater and the geothermal fluid is re-injected.
- Since the steam pressure in the vaporizer remains positive, the non-condensable gases (NCG) can simply be vented without any loss of power.
- The steam condensed in the OEC heat exchangers is re-injected as condensate to the reservoir.