Claus Ballzus, Mannvit Engineering Iceland Geothermal Conference 2013 March 5-8, 2013, Harpa, Reykjavík

1. March 2013
Claus Ballzus
IGC 2013

2. • 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

3. • 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

4. • 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

5. • 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

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

7. Two 45 MW single pressure
units with independent steam
gathering systems

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

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

10. Thermal heating plant added:
133 MWt thermal output
utilizing geothermal water in
shell and tube heat exchangers

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

13. • 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.

14. 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

15. • 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.

16. • 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.

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

19. 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