CO 2 Sequestration Sequestration –To set off or apart; separate; segregate Why sequester CO 2 ? –Removal from atmosphere reduces the impact that anthropogenic CO 2 emissions has on global warming.

Concerns with CO 2 Projections: –Population: billion billion billion –Global Energy Consumption % based on electricity % based on electricity –CO 2 Emissions (in U.S.) 32% generated from utilities (1995)

Sequestration by Conservation Carbon Dioxide Sinks –Forests (terrestrial sequestration via photosynthesis) Carbon Dioxide Sources –Fossil fuel combustion –Deforestation Reallocation of agricultural land for residential uses

Non-carbon based energy Combustion based –Hydrogen as a fuel 2 H 2 (g) + O 2 (g)  2 H 2 O (g) –Photoelectric –Nuclear Power Costs:Time for research & development

Renewable Energy Solar Geothermal Hydroelectric Wind Ocean tides Cost:Altered ecology & biodiversity –Consider: Fossil fuels incur same costs

Iron Hypothesis Seed oceans with ferrous ion (Fe 2+ ) –Phytoplankton growth kept in check due to iron deficiency (iron needed for synthesis of electron transport proteins and pigments) –Iron promotes growth of phytoplankton –Increase oceans’ ability to serve as CO 2 sink Opposition over environmental tinkering –Excess growth may lead to decay of organisms in absence of oxygen (forms methane - 21 times more powerful than CO 2 as greenhouse gas)

REMOVAL OF CO 2 BY BIOLOGICAL PUMP Phytoplankton would incorporate CO 2 via photosynthesis Phytoplankton are consumed by other organisms and becomes part of organic carbon which sinks to ocean floor

Geological Sequestration Concentrate CO 2 from emission sources –Power plant CO 2 emissions absorbed in monoethanolamine (NH 2 CH 2 CH 2 OH) –Thermally strip CO 2 from absorbing solution –Compress CO 2 into a liquid –Store in geological repositories Depleted oil & gas reservoirs Porous strata (layers of sedimentary rock)

Carbon dioxide uptake by forests, biomass plantations, and degraded mine lands that are restored Carbon-based products(e.g. fuels, power, wood, plastics) Capture and Separation Soil Amendments Dispersed CO 2 Geological Formations

Geological Sequestration Problems –Costly to capture and separate CO 2 ($65/ton) –Difficult to predict CO 2 movement underground –Loss of CO 2 to atmosphere???

Marine Sequestration Injection of liquefied CO 2 deep into ocean –Below 800 m (need high pressure) Ocean is good for CO 2 sequestration –Has large capacity for CO 2 –Biological process may convert CO 2 to organic carbon compounds (such as alternative fuels)

Marine Sequestration Problems –Costly to separate and transport –Local increase in acidity may be fatal to marine life –Possible sudden release from oceans (blowouts)

Other Alternatives Sequestration of CO 2 by converting silicate based materials (quartz-bearing) to solid carbonates such as limestone (CaCO 3 ) as an industrial process Creation of a biomimetic process –the enzyme carbonic anhydrase can convert dissolved CO 2 to solid carbonates, analagous to marine life processes –can be performed on-site (no transport!)