March 2013 Claus Ballzus IGC 2013

Capacity 303 MW e and 133 MW t Largest geothermal power plant in Iceland Second largest power plant in Iceland Co-generates electricity and heat Commissioned in five stages between 2006 and 2011 State of the Art Design

Geothermal electricity generation since 1969 Experience from operating 5 geothermal fields Development of Icelandic key components in the steam gathering system Experience in producing electricity and hot water for district heating in a combined power plant

Svartsengi since 1976: Preheating of ground water with second flash steam, final heating with steam from back-pressure units Krafla since 1977: Only electricity generation in a double flash system with double pressure units

Nesjavellir since 1990: Preheating of ground water in turbine condensers, final heating with geothermal water Hellisheiði since 2006: Preheating of ground water in turbine condensers, final heating with geothermal water

Main requirements Independent heat and electricity production Optimal resource utilization Modular design Flexibility to meet changes in the geothermal field Fulfil environmental constrains

Two 45 MW single pressure units with independent steam gathering systems

Bottoming plant added: One 33 MW single pressure unit by flashing geothermal water

Two 45 MW single pressure units added, mostly independent steam gathering systems

Thermal heating plant added: 133 MW t thermal output utilizing geothermal water in shell and tube heat exchangers

Two 45 MW single pressure units added, mostly independent steam gathering systems

Flexibility: Mean enthalpy of the geothermal field has changed from 1200 kJ/kg at design start to the actual value of 1800 kJ/kg – steam/geothermal water portion is now 51/49% instead of 22/78% at design start. Flexibility and modular design: The size of the plant could be changed from 3x40 MW e and 400 MW t to 6x45 MW e + 33 MW e and 400 MW t. Flexibility and modular design: A bottoming plant could be added to the process increasing the overall efficiency. Modular design: Erection and commissioning of new modules of the plant was possible while operating the modules already commissioned. Modular design: Steam gathering system could be rearranged when well output of a certain part of the field turned out to be under expectations.

2002 Exploration wells 2002/03: Feasibility studies and environmental assessment 2003: Construction design starts 2005: Decision for the bottoming plant 2006: Commissioning of the first units 2006: Decision for the next 2 units 2007: Decision for heating power plant 2007: Decision for the next 2 units 2008: Financial breakdown in Iceland 2009: Slow down of stage 4 and 5, project delayed by appr. one year 2010: Commissioning of the heating plant 2011: Commissioning of units 5 & 6

First well location at Gráuhnúkar about 3 km from power plant. Turned out to be one of the hottest spots in the geothermal area and a site for make-up wells. New location about 1 km from power plant in a fissure zone. Good permeability but injection of the geothermal water triggered earthquakes. To avoid earthquakes a stable operation of the injection wells is preferred.

Development speed: If possible have about 3 to 5 years between stages; operation experience from the production wells can give you an important input for the next step in development of the geothermal field. Re-injection: During the exploration phase research of the re-injection areas is as important as for the steam fields. Have planes for an alternative sites or solution in your concept. Geothermal gas exhaust: In certain weather condition geothermal gas might not dissolve evenly in the air, numerical models may be misleading. Consider costs for an abetment system in the investment plan. Have in mind that a geothermal fields are a dynamic creature over the lifetime of the power plant. Leave space for future developments at the power plant site to keep flexibility. Think modular.

THANK YOU FOR YOUR ATTENTION Owner: Orkuveita Reykjavíkur Design team:

Production wells Steam separators Well head silencers Pressure regulation Turbines Generators Mist separators Condensers Emergency exhaust Hot water tank Cold water pump Heat exchangers De-aerators Condensers Hot water pups Re-injection wells Cooling towers 2x45 MW e +2x45MW e +1x33 MW e +2x45MW e +1x133MW t