March 2013 Claus Ballzus IGC 2013. Capacity 303 MW e and 133 MW t Largest geothermal power plant in...
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Transcript of March 2013 Claus Ballzus IGC 2013. Capacity 303 MW e and 133 MW t Largest geothermal power plant in...
March 2013Claus BallzusIGC 2013
The Development of the Hellisheiði Power Plant
ExpertiseSuccessValue
Key features
• Capacity 303 MWe and 133 MWt
• 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
Background• 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
Different approaches• 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
Different approaches• 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
Hellisheiði – requirements• Main requirements
• Independent heat and electricity production
• Optimal resource utilization• Modular design• Flexibility to meet changes in
the geothermal field• Fulfil environmental
constrains
Modular design – 1st stageTwo 45 MW single pressure units with independent steam gathering systems
Modular design – 2nd stageBottoming plant added: One 33 MW single pressure unit by flashing geothermal water
Modular design – 3rd stageTwo 45 MW single pressure units added, mostly independent steam gathering systems
Modular design – 4th stageThermal heating plant added: 133 MWt thermal output utilizing geothermal water in shell and tube heat exchangers
Modular design – 5th stageTwo 45 MW single pressure units added, mostly independent steam gathering systems
Learning process – expected and unexpected
• 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 MWe and 400 MWt to 6x45 MWe + 33 MWe and 400 MWt.
• 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.
Learning process – successes
Learning process – development speed2002 Exploration wells2002/03: Feasibility studies and environmental assessment2003: Construction design starts2005: Decision for the bottoming plant2006: Commissioning of the first units2006: Decision for the next 2 units2007: Decision for heating power plant2007: Decision for the next 2 units2008: Financial breakdown in Iceland2009: Slow down of stage 4 and 5, project
delayed by appr. one year2010: Commissioning of the heating plant2011: 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.
Learning process – re-injection
• 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.
Learning process – recommendation
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 MWe+2x45MWe
+1x33 MWe
+2x45MWe
+1x133MWt