CO2 Sequestration

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CO2 Sequestration

• Sequestration
• To set off or apart separate segregate
• Why sequester CO2?
• Removal from atmosphere reduces the impact that
  anthropogenic CO2 emissions has on global warming.

2
Concerns with CO2

• Projections
• Population
• 1950 - 2 billion
• 2000 - 6 billion
• 2050 - 10 billion
• Global Energy Consumption
• 1950 - 15 based on electricity
• 2050 - 70 based on electricity
• CO2 Emissions (in U.S.)
• 32 generated from utilities (1995)

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Sequestration by Conservation

• Carbon Dioxide Sinks
• Forests (terrestrial sequestration via
  photosynthesis)
• Carbon Dioxide Sources
• Fossil fuel combustion
• Deforestation
• Reallocation of agricultural land for residential
  uses

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Non-carbon based energy

• Combustion based
• Hydrogen as a fuel
• 2 H2 (g) O2 (g) ? 2 H2O (g)
• Photoelectric
• Nuclear Power
• CostsTime for research development

5
Renewable Energy

• Solar
• Geothermal
• Hydroelectric
• Wind
• Ocean tides
• CostAltered ecology biodiversity
• Consider Fossil fuels incur same costs

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Iron Hypothesis

• Seed oceans with ferrous ion (Fe2)
• Phytoplankton growth kept in check due to iron
  deficiency (iron needed for synthesis of electron
  transport proteins and pigments)
• Iron promotes growth of phytoplankton
• Increase oceans ability to serve as CO2 sink
• Opposition over environmental tinkering
• Excess growth may lead to decay of organisms in
  absence of oxygen (forms methane - 21 times more
  powerful than CO2 as greenhouse gas)

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• REMOVAL OF CO2 BY BIOLOGICAL PUMP
• Phytoplankton would incorporate CO2 via
  photosynthesis
• Phytoplankton are consumed by other organisms and
  becomes part of organic carbon which sinks to
  ocean floor

http//www-personal.umich.edu/rstey/Site20files/
science.html
8
Geological Sequestration

• Concentrate CO2 from emission sources
• Power plant CO2 emissions absorbed in
  monoethanolamine (NH2CH2CH2OH)
• Thermally strip CO2 from absorbing solution
• Compress CO2 into a liquid
• Store in geological repositories
• Depleted oil gas reservoirs
• Porous strata (layers of sedimentary rock)

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http//www.ornl.gov/ORNLReview/v33_2_00/research.h
tm
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Geological Sequestration

• Problems
• Costly to capture and separate CO2 (65/ton)
• Difficult to predict CO2 movement underground
• Loss of CO2 to atmosphere???

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Marine Sequestration

• Injection of liquefied CO2 deep into ocean
• Below 800 m (need high pressure)
• Ocean is good for CO2 sequestration
• Has large capacity for CO2
• Biological process may convert CO2 to organic
  carbon compounds (such as alternative fuels)

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http//www-esd.lbl.gov/DOCS/index2.html
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Marine Sequestration

• Problems
• Costly to separate and transport
• Local increase in acidity may be fatal to marine
  life
• Possible sudden release from oceans (blowouts)

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Other Alternatives

• Sequestration of CO2 by converting silicate based
  materials (quartz-bearing) to solid carbonates
  such as limestone (CaCO3) as an industrial
  process
• Creation of a biomimetic process
• the enzyme carbonic anhydrase can convert
  dissolved CO2 to solid carbonates, analagous to
  marine life processes
• can be performed on-site (no transport!)