Transcript Carbon Sequestration Methods: the State of the Art

Carbon Sequestration
Methods: the State of the Art
Daniel “J.” Leistra
GCCS Final Presentation
August 8, 2002
Strategies for Addressing
Climate Change
 For
many, the debate is polarized between
mitigation and adaptation
 Climate change policies don’t have to be
monolithic
 Carbon sequestration is the ‘third path’
 Sequestration shouldn’t be excluded from any
serious discussion of policy options
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 wouldn’t have entered before
 Possible sinks: plants and soils, carbonate minerals,
geologic formations, ocean

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 world’s 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)
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
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
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

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)

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 don’t 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 wouldn’t pose any danger

The Bad
 No
incentive to sequester
without a carbon tax or a
permit system
 Injection
well failure =
horrible, horrible death
…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
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 shouldn’t be all or nothing: while
carbon sequestration isn’t the answer, it is an answer


And they all lived happily ever after.
THE END
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

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
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

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