Geoengineering, Carbon Sequestration, and CCS Jerry Schnoor, Dept. Civil and Env. Engr. Center for Global Regional Env

3. Outline of the Class Introduction Geoengineering What is it? Defn.: Deliberate modification of the earth�s environment to meet human�s needs for habitability (e.g., avoiding dangerous climate change) Methods/proposals Carbon capture and storage (CCS); FutureGen Carbon sequestration

4. Summary Global Carbon Cycle (CO2 as C) (Accum in Atm. = Inputs � Outputs) 3.5 GtC/y = 6 GtC/y � 0.5 GtC/y land � 2 GtC/y ocean

14. Geoengineering: Space Mirrors to decrease solar insolation of earth (increase albedo of atmosphere) Solar insolation from sun is 1367 W/m2 Decrease the sun�s rays by one percent would decrease incoming solar radiation by 14 W/m2 which is several times the amount of warming experienced so far

15. Geoengineering: Sulfur injections into the stratosphere Like Mt. Pinatubo eruption in 1991 when more sulfur was put into the atmosphere than annual emissions from all sources: 40 x 1012 g/yr Some of the plume was elevated all the way to the stratosphere (>50,000 ft) There, sulfate aerosols are long lived and increase the albedo (i.e, the reflectance of the atm) S + O2 = SO2 SO2 + H2O = H2SO4 aerosol

16. Geoengineering: Nutrient pumps driven by wave action to increase algal growth removing CO2

18. Geoengineering by wind sailing ships making clouds by shooting marine water into atm. Thousands of sailing vessels would pump seawater from the surface and aerosolize it into the atmosphere making cloud condensation nuclei (CCN) from algal products like COS, CS2, C2H6S and then converted to methane sulfonic acid (CCN) Thus, clouds would be formed and cool the surface of the earth

19. By adding iron to the ocean, you could stimulate massive algal blooms to remove CO2 Iron (Fe) is an essential nutrient for phytoplankton and it is the limiting nutrient to phytoplankton (free floating algae) in the South Atlantic Ocean (there is plenty of excess nitrogen and phosphorus) Addition of Fe colloids to the ocean, like ground-up scrap iron, is hypothesized to exert a huge algal bloom taking CO2 out of the atmosphere However, recent reports indicate it won�t work because algae die and degrade before they sink to bottom, and/or the algae are eaten by zooplankton and their fecal pellets are biooxidized back to CO2 by bacteria before they sink to the bottom waters

21. Carbon Capture and Storage (CCS)Carbon Storage usually refers to chemical/physical storage; Carbon Sequestration is the most general term but generally refers to biological fixation of carbon in soils and woody biomass

22. Summary of Geoengineering Costs and Efficacy

24. Carbon Storage � to fix it �permanently� into geologic strata, e.g., dissolved in saline water, as a gas displacing CH4, as a supercritical liquid, or as part of solid precipitate

25. CO2 Storage into stable mineral forms Storage into mineral oxides like CaO (lime) or MgO to form stable carbonate minerals (exothermic rxns, natural occurring) CaO + CO2 = CaCO3 MgO + CO2 = MgCO3 Storage into magnesium silicates such as forsterite and serpentine (slow rxn but can perhaps be enhanced) Mg2SiO4 + 2 CO2 = 2 MgCO3 + SiO2 Mg3Si2O5(OH)4 + 3 CO2 = MgCO3 + 2 SiO2 + 2 H2O

26. CO2 can be scrubbed from the air, or carbonate rocks could be added to the ocean to decrease dissolved CO2 conc in ocean (increase ocean pH) Lackner (2008) proposes �artificial trees� to scrub carbon dioxide from the atmosphere (390 ppmv) K2CO3 (s) + CO2 (g) + H2O = 2 HCO3- + 2 K+ Ocean has become more acidified due to increased carbon dioxide concentration changing in the atmosphere from 280 ppm (pre-industrial) to 390 ppm now. Ocean pH has changed from approx. 8.2 in 1950 to 8.08 currently (32% increase in acidity). This is enough to cause coral reefs to �bleach� (die), and to decrease significantly the CO2 sink of the oceans. Adding calcium carbonate (ground-up limestone) could off-set the problem by increasing pH and increasing the carbon dioxide mass transfer rate from the atmosphere to the ocean CaCO3 (s) + H2O + CO2 = Ca 2+ + 2 HCO3-

27. Potential for Carbon Storage is Immense!

28. Advantages and Disadvantages of Carbon Storage

29. Carbon capture from diverse sources with concentrated CO2 (power plants, cement factories, fermentation facilities are likely candidates)

30. Geological carbon storage (sequestration)

33. Is there such a thing as �Clean Coal�?Clean Coal Technologies Clean coal technology is an umbrella term used to describe technologies being developed that aim to reduce the environmental impact of coal energy generation.[1] These include chemically washing minerals and impurities from the coal, gasification (see also IGCC), treating the flue gases with steam to remove sulfur dioxide, carbon capture and storage technologies to capture the carbon dioxide from the flue gas and dewatering lower rank coals (brown coals) to improve the calorific quality, and thus the efficiency of the conversion into electricity. Wikipedia definition 4/12/09

34. Carbon Capture at power plants and Storage is required if coal is to be used for electricity Coal-fired power plants emit almost twice the GHGs as other forms of electrical generation Integrated Gasification and Combined Cycle (IGCC) Gasification of the coal to make a gaseous fuel stream that burns cleaner than the coal itself Combined cycle is more efficient that normal coal-fired power plant (32% thermal efficiency) IGCC plants are considered to be �carbon capture ready�

36. Three types of Clean Coal Technologies (Wikipedia) Broadly, three different types of technologies exist: 1) post-combustion, 2) pre-combustion, and 3) oxyfuel combustion. 1. In ��post combustion capture, the CO2 is removed after combustion of the fossil fuel - this is the scheme that would be applied to fossil-fuel burning power plants. Here, carbon dioxide is captured from flue gases at power stations or other large point sources. The technology is well understood and is currently used in small industrial processes. 2. The technology for pre-combustion is widely applied in fertilizer, chemical, gaseous fuel (H2, CH4), and power production.[5] In these cases, the fossil fuel is partially oxidized, for instance in a gasifier. The resulting syngas (CO and H2) is shifted into CO2 and more H2. The resulting CO2 can be captured from a relatively pure exhaust stream. The H2 can now be used as fuel; the carbon dioxide is removed before combustion takes place. 3. Concentrated CO2 from the combustion of coal in oxygen is relatively pure, and could be directly processed. In other instances, especially with air capture, a scrubbing process would be needed.

37. Illinois FutureGen was designed to demonstrate CCS, but it has since been cancelled

40. Clean Coal Process Flow-Diagram

42. No new coal unless we master carbon sequestration; it�s already practiced for secondary recovery in oil fields Oil companies have been practicing carbon sequestration (or carbon storage) for decades Rich CO2 streams from petroleum fields are pumped back into the formation to recover more oil and gas Pipelines are already used to transport the gas and to sequester it below 3500 ft as supercritical CO2 (like a liquid at gas/liquid density) Illinois has deep coal beds that could be used for this purpose

44. Biochar is seen as one way to perform geoengineering Massive growth and harvesting of biomass (forests and crops) and burn them in the absence of oxygen to produce biochar Biochar is a carbon product that could be used as a soil conditioner and/or buried � it doesn�t oxidize easily, so it is viewed as a rather permanent way to remove carbon from the atmosphere

46. To form Biochar, you burn the waste biomass in the absence of oxygen (pyrolysis)

47. Biochar is very stable (doesn�t oxidize) and yet is a very good soil amendment and conditioner

48. Conclusions Geoengineering is an option that should be researched in the event that we fail to curtail our fossil fuel emissions, or if the consequences are much greater (faster) than we had predicted, but it should not distract from the main mission to decrease our dependence on fossil fuels and to stop emissions which is not sustainable (climate change) Carbon capture refers to the capture of concentrated CO2 gas streams from power and manufacturing facility emissions; technologies exist but are not considered economical at present Carbon sequestration usually refers to biological mechanisms to store carbon in soils and woody biomass, and carbon storage usually refers to physical/chemical methods (but the terms are used interchangeably, so be careful) CCS is largely in demonstration phase now and will need large scale testing before full scale implementation, but it offers some hope for large-scale reductions in greenhouse gases from coal-fired power plants (part of the solution)