Johnson.ChemII.Fall2010

Steven Johnson

=CO2 Levels and Sequestration=

CO2 levels in our atmosphere have increased at a steady rate from 1800 starting at 280 parts per million to 2005 where it was measured at 380 part per million. This increase in CO2 gas has been attributed to global warming and other environmental issues.



Normal respiration of life forms and the decay of their bodies post mortem creates CO2 which is counter balanced by the consumption of CO2 by plants. Excess CO2 is created however due to the burning of fossil fuels and deforestation decreases the amount of plants available to chemically break down CO2 during photosynthesis.



Global warming occurs when radiation from the sun strikes the Earth. Normally this radiation is bounced off in all directions by the atmosphere but some travels deeper through the ozone layers but eventually shoots back off into space. Greenhouse gases such as CO2 prevent this radiation from escaping back into space. This trapped radiation increases the temperature in the upper atmosphere.

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Currently there is no system in operation being used to reduce the amount of CO2 currently in the atmosphere. There are however many plans in full swing designed to decrease the amount of CO2 emissions being produced. Some are as simple as increasing public transit in order to reduce the amount of fossil fuel burning vehicles on the road to making factories more energy efficient stretching the CO2 that is already created a little further.

There is however an effort being made by the University of Calgary to reverse the CO2 pollution through the use of a giant sized scrubber that uses air capture designs to strip the CO2 from the air where ever it is set up. These scrubbers would use Alkaline baths to create Calcium Carbonates that can be separated from the purified air. A major concern however is to make sure that the CO2 being removed from the atmosphere is significant enough to overcome the CO2 that is being created by the use of this machine itself. Another concern is what to do with the collected CO2 once it has been removed from the atmosphere.



[|Scrubber in action] In this video basic operation is shown and future plans of the scrubber are explained.

CO2 in ambient air is around 380 PPM. The CO2 levels are measured at the air inlet of the scrubber and again at the air outlet. As much as 80% of the CO2 within the air is filtered out dropping the CO2 levels to 72 PPM.

Once CO2 is removed from the atmosphere it is still in a gaseous form. Condensing the CO2 into its liquid or solid state makes it easier to transport and dispose of in a safer manner. Although many ideas have surfaced on what to do with emission CO2, two suggestions have been made that are gaining popularity. One involves forming solid CO2 into rocket shaped projectiles that can be dropped into the ocean where they will drill themselves into the ocean floor using their lower density as a form of propulsion. Another recomendation is to use liquid CO2 to aid off-shore natural gas platforms. Most natural gas platforms will drill to gas pockets and insert tubes to the gas in order to pump it to the surface. At times the gas level will drop and the pipe no longer reaches the low level of gas. This void that is created can sometimes even collapse on itself making further drilling more difficult. By using liquid CO2 pumped into the gas pocket, it will displace the gas driving the level up where it can reach the pipe and at the same time filling in the void within the pocket preventing a collapse.



Though these means and methods would indeed be successful in removing CO2 and safely keeping it out of the atmosphere, the debate continues on whether the devices themselves overcome their CO2 production and whether it is economically pheasible to produce these scrubbers and dispose of pollutants.

The process in which this scrubber isolates CO2 can be shown using the chemical equation NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl Concentrated Sodium Chloride and Ammonia in an aqueous solution trickle down the tower while air containing CO2 is pumped up through the tower. Other air components such as Oxygen and Nitrogen are left alone and continue upward while the CO2 bonds with the Sodium and Hydroxide. This Sodium Bicarbonate can be heated to release the captured CO2 and the now separated Sodium Chloride and Ammonia can be reused.

Further development of this system is being created that could possibly be attached to existing factories that are known to create excess CO2 emissions. By utilizing energy that is already being created at power plants these units could filter out CO2 gases before they had any chance to escape into the atmosphere and cause any harm. Also with this process being fairly new, new molecules with different structures can be discovered that lead to a higher percent yield of filtered CO2 along with needing less flow of air that would lessen the CO2 being created to run such a machine.

All in all this system in basic theory is extremely reliable but the efficiency must first rise before it can truly be accepted by an economy driven world.