Geothermal energy

Reykjanes power plant

Reykjanes - Iceland

Verkís services was project management and design supervision, detail design, tender documents and procurement: structural design, mechanical design, piping systems, ventilation, control and monitoring equipment. Supervision of construction work, testing and start-up activities.

 Sizes: 100 MWe and 850 GWh/year
 Project time:  2004 - 2006

Project overview:
Reykjanesvirkjun is among the most challenging geothermal power plants ever built in Iceland. The geothermal field is one of the hottest, with temperatures of the geothermal fluid in boreholes reaching up to 320°C. Scaling and corrosion, in combination with high salinity and high temperatures, was one of the main design challenges. In order to avoid silica scaling, a steam pressure of 18 bar was required, which is considered unusually high for a geothermal plant.

The production boreholes, 2.000-3.000 m deep, produce a mixture of steam and brine. The mix is collected and piped to a steam separator.  Before entering the turbine, the steam passes through a moisture separator. The turbine has been designed by Fuji for an 18 bar inlet pressure, which is unique. The turbine is of a single cylinder, double flow type. It is provided with special measures to allow cleaning of deposits, with units on line and several other features to increase tolerance against erosion/corrosion.

Once the energy has been harnessed, the steam flows to a shell and tube condenser where it is condensed at -0,90 bar using 4.000 l/s of 8°C seawater, pumped from boreholes located in proximity of the nearby coastline. The condensate, mixed with the brine coming from the steam separator, is piped to the brine injector where it is mixed with the seawater. The mix is then finally discharged via a 2 km water channel into the sea at 60°C.

The monitoring and control system is operated remotely from the Hitaveita Suðurnesja main control room and is composed of a redundant double industrial computer system and a redundant double fiber optic cable connection in order to maximize safety in case of failure in the control and supervisory system.