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February 20081
Carb-Fix (CO2 fixation into basalt)
Experiment at Hellisheiði Geothermal Plant, Iceland
by
Hólmfríður Sigurðardóttir
Project Manager
Reykjavik Energy
Contact: [email protected]
February 20082
The Beginning
• Jan 2006 Wally Broecker invited by President of Iceland to give a lecture on climate change”
• Workshop in Reykjavík January 16th -17th 2006
• Cooperation – University of Iceland - www.raunvis.hi.is– Columbia University - www.ldeo.columbia.edu– CNRS in France - www.cnrs.fr– Reykjavík Energy – www.or.is
The Future• CO2 strapped from the atmosphere
February 20084 Ingvar Sigurðsson
• Basalt is igneous rock formed during volcanic eruptions
• Can be glassy and/or crystalline• Basalt contains about 10 weight% CaO
which can be used for carbon fixation
Mineral name Potential CO2 fixed,kg/m³ mineral
Plagioclase 436
Olivine 2015-1896
Pyroxene 1404
Serpentine 1233
Mica group 62
Clay Minerals 161
February 20085
Why Iceland?
• Bedrock > 90% basaltic• Excellent infrastructure for experiment at Hellisheiði
plant• Ample supply of fresh water, CO2 gas and dissolvable
basalts• Group of scientist, engineers and craftsmen
– Fundamental equations describing rate of basalt dissolution – Study may prove the feasibility of CO2 fixation projects
elsewhere
Basalt
Sigfús Már Pétursson Guðmundur LárussonSigfús Már Pétursson
February 20086
Iceland - CO2 Emission
• Icelanders ~3.7 Mt CO2 /yr (figures from 2004)• Energy from fossil fuel 52%• Industrial processes 25%• Agriculture 14%• Waste 5%• Geothermal energy 4%
• Geothermal power plants (450 MW):• 20-40 g CO2/kWh
– Comparison of CO2 emission from different energy sources in the USA (Bloomfield et al. 2003)
• Natural gas: 599 g CO2/kWh
• Oil: 893 g CO2/kWh
• Coal: 955 g CO2/kWh
• Magma: ~ 2 Mt CO2 /yr Sigurður R Gíslason
Sigfús Már Pétursson
February 20087
Natural Processes
Recharge by cold ground-
water
Solidifying magma
Heat conductionand naturalCO2 release
Heat conductionand naturalCO2 release
Supercritical convection
Upflow zone280-320 °C
Deep inflow zone
FumarolesHot spring areas, fumaroles
350-400 °C
600-1000 °C
Outer boundary: 100 °C/km and constant pressure
Alteration cap
Lateral outflow zone, 220-280 °C
February 20088
CO2 Captured Naturally in
Hellisheiði
Dep
th (
met
ers
ab
ov
e s
ea l
eve
l)
February 20089
Solidifying magma
Heat conductionand natural
CO2 release
Heat conductionand natural
CO2 release
CO2 in geothermal steam from wells at Hellisheiði
Alteration cap
CO2 fully dissolved in fresh water and injected down to 400-800 m
Add calcite to the alteration cap
Gretar Ívarsson
February 200810
1 kg/s of CO2 fromcondensers
1 kg/s of CO2 fromcondensers
400 kg/s of steam, gas and water from deep and hot (>240 °C) geothermal wells400 kg/s of steam, gas and water from
deep and hot (>240 °C) geothermal wells Hellisheiði geothermal power plant
Hellisheiði geothermal power plant
Target zone for CO2 sequestration identified
at 400-800 m depth
Target zone for CO2 sequestration identified
at 400-800 m depth
Groundwater
Groundwater
Gas injected fullydissolved in water
into target zone
Gas injected fullydissolved in water
into target zone
Sigfús Már Pétursson
February 200812Sigfús Már Pétursson
The gas mixture: 0,5 % of the steam is geothermal gasGas mass%CO2 83 H2S 16CH4 N2 ~1 H2
~ 13 l/s of water to dissolve 1 kg/s CO2 at 25°C and 40 bar
~ 10 kg basalt to react with 1 kg/s CO2
February 200813
Tracer Tests
• An initial tracer test at the target zone for CO2-injection– Nature of the groundwater system– Flow-patterns and flow-rates
• Large dispersion• Matrix permeability – not through fractures• Large surface area for chemical reactions • Ensure that a potentially leaky site is not selected
Gretar ÍvarssonGuðmundur Lárusson
February 200814
CO2 Separated from the Gas Mixture
Compression, refrigeration and distillation: – 98% CO2 and 2% H2S as a liquid
– H2 ,possibly applicable as fuel
• Estimated cost:– 1MW/yr of electricity needed for
the process and injection– 1% of the electricity production
at Hellisheiði geothermal plant
Sigurður R Gíslason
February 200815
Bedrock and BoreholesHN-4
HK-31
Casing
Flow direction
Lavaflows
Hyaloclastite formations
Upper level of alteration minerals
Bedrock temperature
CO2 injection well - HN-2Fresh water - HN-1
February 200817
The ProcessInjection well: CO2 fully dissolved in fresh water
Low pH: 3-4
Dissolution of basalt release of Ca2+ and other ionsPrecipitation of calcite
pH increases
• Reservoir may gradually clog up with calcite scaling
• Natural process in high-temperature systems
February 200819
Regulatory Frameworks
• Law and regulations – Prevention of contaminating groundwater– Health and safety– Planning act, Nature conservation law – Operating permits
• Environmental impacts– Surface: Perturbation of pristine areas, visual impacts, suffocation
etc.– Subsurface: Metal mobilization, groundwater contamination etc.– Air: Leakage of CO2 back to the atmosphere
• Site monitoring and verification
Reykjavik Energy
February 200820
Site Monitoring
• Soil CO2 flux – before and after injection
• Tracers and chemical analysis• Geophysical signals
– Resistivity– Gravity
National Energy Authority
February 200821
Global Significance
• Extensive basalt shields worldwide
February 200822
Global Significance
• Extensive basalt shields worldwide
• Mineral stable for thousands or millions of years
• The experiment will address whether mineral storage of CO2 in basalts is a global alternative
• The project may demonstrate that “zero emission” geothermal power plants are possible
• New technology for strapping CO2 from the atmosphere – sequestration projects can be operated at “best” geological conditions
February 200823