Carbon sequestration

1. Carbon Sequestration
Presented by
Samuel Tope Trinity

2. Carbon sequestration = Carbon Storage

3. What Is It?
• Also known as “carbon capture and storage”
• A geoengineering technique for the long-term storage of
carbon dioxide (or other forms of carbon) for the
mitigation of global warming
• More than 33 billion tons of carbon emissions (annual
worldwide)
• Ways that carbon can be stored (sequestered):
– In plants and soil “terrestrial sequestration” (“carbon sinks”)
– Underground “geological sequestration” Deep in ocean “ocean
sequestration”
– As a solid material (still in development)

4. Terrestrial Carbon Sequestration

5. Terrestrial Carbon Sequestration
• The process through which CO2 from the
atmosphere is absorbed naturally through
photosynthesis & stored as carbon in biomass &
soils.
• Tropical deforestation is responsible for 20% of
world’s annual CO2 emissions

6. Terrestrial Carbon Sequestration
• Ways to reduce greenhouse gases:
–avoiding emissions by maintaining existing
carbon storage in trees and soils
–increasing carbon storage by tree planting or
conversion from conventional to conservation
tillage practices on agricultural lands

7. Terrestrial Carbon Sequestration
(continued)
• Carbon seq. rates differ based on the species of tree, type of
soil, regional climate, topography & management practice
– Pine plantations in SE United States can accumulate almost
100 metric tons of carbon per acre after 90 years (~ 1
metric ton : 1 year)
• Carbon accumulation eventually reaches saturation point where
additional sequestration is no longer possible (when trees
reach maturity, or when the organic matter in soils builds
back up to original levels before losses occurred)

8. • After saturation, the trees or agricultural practices
still need to be sustained to maintain the
accumulated carbon and prevent subsequent losses
of carbon back to the atmosphere

9. Geological Sequestration
Midwest Geological Sequestration Consortium (Illinois)

10. Geological Sequestration
• Involves collecting and
placing CO2 into suitable
underground formations
for storage. This is also
known as geo-
sequestration
–Held in small pore
spaces Layers shown: Coal, brine aquifer, gas bearing sandstone, gas bearing shale

12. Geological Sequestration
(continued)
• Oil fields, gas fields, saline formations,
unminable coal seams, and saline-filled basalt
formations have been suggested as storage
sites.
• Various physical (e.g., highly impermeable
caprock ) and geochemical trapping
mechanisms would prevent the CO2 from
escaping to the surface.

13. Geological Sequestration
(continued)
• CO2 is sometimes injected into declining
oil fields to increase oil recovery
(enhanced oil recovery).
• This option is attractive because the
storage costs are offset by the sale of
additional oil that is recovered.

14. Processes
• Capture
• Storage
• Transport
• Injection
CO2 is collected from fuels b4 they are
burned or from smokestack after fuels are
burned.
• Capture needs to happen at or near where
the energy is generated bcz that is where
combustion occurs.

15. CO2 Tech
Chemical or Physical means
Depends on the
• CONC.
• Temp. of emissions
• corrosiveness of the emissions.

16. Storage & Transport
• CO2 is stored prior to transport
• Under pressure=liquid form(Tanks,
Pipeline)
• Pumped underground to depths sufficient
to maintain critical temperature and
pressure

17. CO2 Transportation
After capture, the CO2 must be transported to suitable
storage sites. This is done by pipeline, which is generally
the cheapest form of transport, or by ship when no
pipelines are available

18. • Another example of an EOR project is the
Aneth Oil Field Project. Although not a
project used for geologic sequestration
only, the Aneth Oil Field Project which is
located in the Paradox Basin in Utah, is
injecting carbon dioxide into the ground to
enhance the oil recovery in an oil field

19. Ocean Sequestration

20. Ocean Sequestration
• Carbon sequestration by
direct injection into the
deep ocean involves the
capture, separation,
transport, and injection of
CO2 from land or tankers
• 1/3 of CO2 emitted a year
already enters the ocean
• Ocean has 50 times more
carbon than the atmosphere

21. Ocean Sequestration
Two main concepts exists;
• The 'dissolution' type injects CO2 by ship
or pipeline into the water column at depths
of 1000 m or more, and the CO2
subsequently dissolves.
• The 'lake' type deposits CO2 directly onto
the sea floor at depths greater than 3000
m, where CO2 is denser than water and is
expected to form a 'lake' that would delay
dissolution of CO2 into the environment.

22. b) Basalt formations. Basalts are of solidified lava. They have a unique
chemical makeup that could potentially convert all of the injected CO2 to a
solid mineral form, thus permanently isolating it from the atmosphere.
Research is currently being focused on enhancing and utilizing the
mineralisation reactions and increasing CO2 flow within a basalt formation.
Research is in its infancy, but these formations may, in the future, prove to
be optimal storage sites for stranded CO2 emissions.

23. More advanced research is being conducted to
develop fast-growing trees and grasses, in
deciphering the genomes of carbon-storing soil
microbes and in nutrient enrichment to enhance algal
growth in the oceans.
All of these are potential carbon stores of the future

24. How does CO2 affect oceans?
About half of the extra CO2 from the
atmosphere will dissolve in the oceans,
making the water more acidic.

25. Environmental effect
The environmental effects of ocean storage are
generally negative, but poorly understood.
Large concentrations of CO2 kills ocean
organisms, but another problem is that dissolved

26. Also, as part of the CO2 reacts with the water to form carbonic
acid, H2CO3, the acidity of the ocean water increases. The
resulting environmental effects on benthic life forms are poorly
understood. Even though life appears to be rather sparse in the
deep ocean basins, energy and chemical effects in these deep
basins could have far reaching implications.

27. THANKS!!!

28. CO2 Leakage (Greatest Concern)
A major concern with CCS is whether leakage of stored CO2 will compromise
CCS as a climate change mitigation option. For well-selected, designed and
managed geological storage sites, IPCC estimates that CO2 could be trapped
for millions of years, and are likely to retain over 99% of the injected CO2 over
1000 years. For ocean storage, the retention of CO2 would depend on the
depth; IPCC estimates 30-85% would be retained after 500 years for depths

29. The obvious worry is that leakage would lead to more global warming, defeating
the purpose of storage in the first place. But studies have shown that leakage, if
it happened at all, would be insignificant.
The IPCC reported that 99% retention of the carbon dioxide that is stored would
be ''very likely'' over 100 years and ''likely'' over 1,000 years. If done right,
selecting the site correctly and monitor, it can be near permanent.

30. CONCERNS
Of greater concern to the researchers are the potential risks of carbon
sequestration to human health, mainly through asphyxiation and groundwater
contamination. The threat of asphyxiation-or suffocation due to carbon dioxide
displacing oxygen-is very low, because of the unlikelihood of a rapid leakage,
which would have to occur to cause a problem.

31. Drinking water contamination is the more probable danger. For
example, if carbon dioxide enters the groundwater somehow, it can
increase the water's acidity, potentially leaching toxic chemicals, such
as lead, from rocks into the water. To address these risks, scientists
are studying reservoir geology to better understand what happens after
injecting carbon dioxide underground.