Carbon%20Sequestration%20Methods:%20the%20State%20of%20the%20Art

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Carbon Sequestration Methods the State of the
Art

• Daniel J. Leistra
• GCCS Final Presentation
• August 8, 2002

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Strategies for Addressing Climate
Change

• For many, the debate is polarized between
  mitigation and adaptation
• Climate change policies dont have to be
  monolithic
• Carbon sequestration is the third path
• Sequestration shouldnt be excluded from any
  serious discussion of policy options

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Carbon Sequestration What It Is

• Stores CO2 removed from the atmosphere or
  captured from emissions and stores it in another
  form somewhere else (a carbon sink)
• Occurs naturally oceans and plants are already
  absorbing much of what we emit
• We can speed the process along or deposit CO2 in
  sinks that it wouldnt have entered before
• Possible sinks plants and soils, carbonate
  minerals, geologic formations, ocean

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Ocean Fertilization

• Plankton photosynthesis creates 45 Gt organic
  carbon per year
• Most carbon gets recycled to atmosphere, but some
  is drawn down into deep ocean
• Iron is the limiting factor for phytoplankton
  growth in 20 of the worlds oceans (HNLC zones)
• Fertilization with iron could enhance growth, fix
  more carbon

NOAA/NESDIS SeaWiFS satellite image of 1997
Bering Sea plankton bloom (http//www.sfos.uaf.edu
/npmr/projects)
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Studies Show

• Geologic record suggests phytoplankton growth may
  have substantially decreased atmospheric CO2 in
  the past
• Numerous experiments have shown huge (30-40x)
  increases in primary production, lower CO2 levels
• If it is successful, there will be virtually no
  limit on how much CO2 the oceans can hold

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Problems

• All of these studies were short-term unknown how
  much CO2 is being carried into the deep ocean
• Public perception, especially concerning
  Antarctic waters
• Fishing Industry???

• Fertilizing every HNLC zone would sequester
• 76 Gt C by 2100, but would require 300,000
• ships and 1.6 billion kg iron annually

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Injection into Deep Saline Aquifers

• Saline aquifers are underground layers of porous
  sediment filled with brackish water
• If they are deep enough and hydrologically
  separated from other aquifers, they can safely
  hold CO2

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The Future is Now

• U.S. is already dumping 75 million cubic meters
  of industrial waste into deep saline aquifers
  each year
• CO2 injection process is similar to EOR one
  commercial venture

• already in place and running smoothly
• Preliminary geologic data available, compiled by
  
• Hovorka et al. (2000)

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The Good

• Deep saline aquifers are widespread 2/3 of U.S.
  power plants and industrial centers could inject
  without constructing pipelines
• Unlike oil and gas fields, they dont need
  special geometries to sequester CO2 wide
  structures confined only by a horizontal layer of
  rock can hold it for thousands of years
• A large amount of CO2 would be incorporated into
  rocks and remain stable on a geologic time scale
• If there was a natural leak, it wouldnt pose any
  danger

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The Bad

• No incentive to sequester without a carbon tax or
  a permit system

• Injection well failure
• horrible, horrible death

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and the Unknown

• Estimates of worldwide sequestration potential
  range from 320 - 10,000 Gt CO2
• Environmentalists and the NIMBY effect
• More site-specific information needed before
  injection can begin

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Conclusions

• Though no single option is perfect, carbon
  sequestration has potential for great societal
  benefits
• Continuing research is sure to bring about
  further breakthroughs, particularly in the field
  of carbon capture
• Climate change policies shouldnt be all or
  nothing while carbon sequestration isnt the
  answer, it is an answer
• And they all lived happily ever after. THE END

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Cropland Retirement

• 20 50 of soil organic carbon (SOC) lost within
  first few decades of cultivation
• Worldwide estimates of loss 41 to 55 Gt C
• As farms face increasing ecological and economic
  challenges, many are being abandoned

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Cropland Retirement (cont.)

• Governments or NGOs can buy back failing farms
  and attempt to reestablish natural ecosystems
• This regeneration can be active or passive
• Temporary set-asides also a possibility

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Predictions

• Regenerating forests across eastern U.S.
  demonstrate that it can work, even without much
  effort
• Removing 15 of land in countries with surpluses
  would sequester 1.5 3 Gt C
• Conversion will increase biodiversity, provide
  habitat for endangered species, protect
  watersheds, reduce erosion and salinization
• Reestablishing grasslands more difficult than
  forests, but CRP is a well-proven alternative

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My Analysis

• Lower sequestration potential than other options,
  but simpler, more environmentally friendly
• Provides a good way out for struggling farmers,
  reduces need for government subsidies
• Lower food supply helps those farmers that stay
  in business, but could hurt the developing world
• Resulting ecosystems may not be natural, but a
  managed forest is better than a farm