Slide 1: WELCOME Slide 2: PRESENTED BY Department: Forest Biology and Tree Improvement Carbon dioxide
Sequestration Department: Forest Biology and Tree Improvement Objectives : Objectives What is carbon dioxide sequestration?
Why should we be concerned with carbon dioxide in the atmosphere?
What are the different Carbon/CO2 Sequestration Pathways? CARBON DIOXIDE SEQUESTRATION : CARBON DIOXIDE SEQUESTRATION Sequestration is any means that prevents carbon dioxide from entering the atmosphere. Realistically, this is equivalent to the permanent storage of carbon dioxide, independent of the state of the CO2 or the location of the storage. Slide 5: Global Carbon Cycle Emissions from Fossil Fuels : Emissions from Fossil Fuels Millions of Metric tonnes of Carbon Per Year PRESENT TREND OF ATMOSPHERIC CO2 CONCENTRATION : PRESENT TREND OF ATMOSPHERIC CO2 CONCENTRATION Global WARmING OR Global WARnING : Global WARmING OR Global WARnING Slide 10: According to IPCC (1996), the atmospheric CO₂ has increased by 31%, methane by 151% and Nitrous oxides by 17% since 1750.
Over the 20th century the IPCC believes that global temperature increased close to 0.5⁰C, the largest increase of any century during the past one thousand years. PURPOSE OF CARBON SEQUESTRATION : PURPOSE OF CARBON SEQUESTRATION PATHWAYS : PATHWAYS Sequestration Methods : Sequestration Methods 1. Mineral Sequestration
2. Ocean Sequestration
3. Geological Sequestration 1.MINERAL SEQUESTRATION : 1.MINERAL SEQUESTRATION source: Lackner 10/7/2002 p.13 Principal metal oxides of Earth's Crust. : Principal metal oxides of Earth's Crust. ADVANTAGES : ADVANTAGES The carbonates formed are thermod- ynamically stable and the disposal is therefore permanent.
The mineral resources on earth far exceed need.
Carbonate is the lowest energy state of carbon, not carbon dioxide. Contd… : Contd… The minerals are readily accessible in locations near high-density power generation centers.
There is potential to produce value-added byproducts.
Implementation without an external supply of heat is possible because the reaction is exothermic. DISADVANTAGES : DISADVANTAGES Carbonation plant must be at the site of the mine due to the large volumes of material required.
Extensive mining operations necessary, which will have environmental impact.
There is the potential for asbestos to be present in the mineral deposit.
Must be able to deal with ore impuri-ties. 2.OCEAN SEQUESTRATION : 2.OCEAN SEQUESTRATION ADVANTAGES : ADVANTAGES It is vast, covering 70% of earth's surface with an average depth 3800 m.
The total carbon content of the ocean is 38,000 GtC versus the 750 GtC in the atmosphere.
The deep ocean is separated from atmosphere by thermocline. Contd.. : Contd.. Ecological perturbations should be limited to area of release.
Many fossil fuel plants on coast or along river waterway aiding transportation of the carbon dioxide to the disposal site via pipes, barges, or tankers. 3. Geological Storage : 3. Geological Storage Also known as geo-sequestration.
This method involves injecting carbon dioxide, generally in supercritical form, directly into underground geological formations. Oil fields, gas fields, saline formations, unminable coal seams, and saline-filled basalt formations have been suggested as storage sites. Aquifer : Aquifer This storage is considered the most promising storage possibility because of its tremendous magnitude.
A large-scale aquifer project has been underway in Norway since 1996. Depleted Oil and Gas reservoirs : Depleted Oil and Gas reservoirs These can store CO2 but not in high levels as aquifers.
Security is also not a major issue.
Oil/gas reservoir sequestration is considered a "value added" process; oil and small amounts of natural gas can be recovered with the aid of CO2. Coal Beds : Coal Beds Injection of carbon dioxide into coal beds causes methane desorption from the surface and pores of coal and carbon dioxide adsorption in its place. Coal bed sequestration can actually occur at a profit when natural gas prices are high. In addition, coal beds are usually located near high emissions sites, minimizing the cost of transportation. Slide 27: GLOBAL CARBON STORAGE Lal , 2008 Reuse of CO2 : Reuse of CO2 Conversion to Hydrocarbons:
CO2 -> CO -> Hydrocarbons.
Conversion to methanol:
CO2 + H2 -> Methanol FORESTS AS A CARBON SINK : FORESTS AS A CARBON SINK Forests are carbon stores, and they are carbon dioxide sinks when they are increasing in density or area, while dead forests are a major carbon source, the loss of such large areas of forest has a positive feedback on global warming. Slide 30: The Intergovernmental Panel on Climate Change concluded that "a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber fibre or energy from the forest, will generate the largest sustained mitigation benefit". Slide 31: In the United States in 2004, forests sequestered 10.6% of the CO2 released in the United States by the combustion of fossil fuels.
Urban trees sequestered another 1.5% (88 teragrams).
Carbon offset programs are planting millions of fast-growing trees per year to reforest tropical lands, for as little as $0.10 per tree; over their typical 40-year lifetime, one million of these trees will fix 0.9 teragrams of carbon dioxide. CONCLUSION : CONCLUSION References : References “Energy-Efficient Technologies and Climate Change Policies: Issues and Evidence.” Climate Issue Brief No. 19. Washington, DC. Resources for the Future.
http://en.wikipedia.org/wiki/carbon_sinks Contd… : Contd… http://en.wikipedia.org/wiki/global_warming
C. Chang, and B. McCarl. 1993. “Sequestering Carbon on Agricultural Land:Contemporary Policy Issues XI(1): 76-87. Slide 35: THANK YOU