By Kari Williamson

The steam turbine for geothermal applications combines the casing and turbine-generator package (gearbox, generator and base frame) of the Siemens SST-400 steam turbine with the steam path technologies developed, tested and applied by the steam turbine service provider TurboCare.

The SST-400 GEO steam turbine can be deployed in geothermal power plants that operate with superheated direct steam (dry steam) or with saturated steam produced on pressure reduction of the thermal fluid (flash principle).

The geothermal steam turbine can also be deployed in the direct or flash steam cycle of combined direct or flash steam/binary systems (flash/binary combined cycle).

The SST-400 GEO is suitable for live steam temperatures up to 250°C, with steam pressures up to 12 bar absolute, and includes resource- and turbine-stage-specific high-grade materials as well as special features for moisture removal at every stage.

"We've done intensive groundwork on the specific requirements of geothermal plants and are now going to market with a proven turbine concept," says Markus Tacke, CEO of the Industrial Power Business Unit of Siemens Energy.

"Worldwide a pronounced increase in the demand for geothermal steam turbines is evident. As a steam turbine manufacturer we are optimally set up with this machine to be well positioned in the marketplace over the long term."

At the end of 2010, the global installed power generating capacity of geothermal power plants was more than 11 GW. Based on a study conducted by IHS Emerging Energy Research, the installed capacity of geothermal power is predicted to nearly triple worldwide to approximately 31 GW by 2020.