Carbon Sequestration: Engineering, Capturing, Storage, Trapping YouTube Lecture Handouts for NICL

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Ways to reduce atmospheric carbon

  • Reduce emissions

  • Store the carbon in terrestrial, oceanic and aquatic ecosystem

CO2 absorbs IR rays, as its concentration increases, average temperature of Earth’s lower atmosphere rises (global warming)

Sink:

Process that removes GHG from atmosphere

Carbon capture was first used in Texas in 1972 as a method to enhance oil recovery.

Sequestration

  • Carbon capture and long-term storage of carbon and CO2 to mitigate global warming

  • Can be natural or anthropogenic

Natural Carbon Sink

  • Forest

  • Growth of replacement vegetation on cleared land

  • Land-management practices that absorb carbon

Ocean

  • Iron fertilization encourage phytoplankton growth, which removes carbon from the atmosphere for at least a period of time

  • Fertilize ocean with urea, a nitrogen rich substance, to encourage phytoplankton growth

  • Seaweed grows very fast and can theoretically be harvested and processed to generate biomethane, via Anaerobic Digestion to generate electricity or as a replacement for natural gas.

Geoengineering

  • Carbon Capture & Storage (CCS) – 3-stage process - capture, transport and store - carbon dioxide is first separated from other gases contained in industrial emissions.

  • It is then compressed (dense, fluid, supercritical state) and transported to a location that is isolated from the atmosphere for long-term storage.

Three methods for capturing and separating CO2

  • Precombustion capture: Before the fuel is burnt, the fuel is converted to syngas, and then the syngas to hydrogen and CO2. Hydrogen is separated from CO2 so the hydrogen can be used as fuel.

  • Post-combustion: After the fuel is burnt, CO2 is separated from nitrogen using chemical sorbents such as monoethanolamine.

  • Oxyfuel combustion: Burning fuel in pure oxygen so no nitrogen is present in the captured gases

Suitable Storage Locations

  • Deep saline formations (sedimentary rocks whose pore spaces are saturated with water containing high concentrations of dissolved salts)

  • Depleted oil and gas reservoirs or deep, un-minable coal beds - Geological Sequestration

  • Deep ocean - Sub sea floor Sequestration

It can also include use of artificial trees and scrubbing towers

Geologic Sequestration Trapping Mechanisms

  • Hydrodynamic Trapping: CO2 can be trapped as a gas under low-permeability cap rock (as natural gas is stored in gas reservoirs).

  • Solubility Trapping: CO2 can be dissolved into a liquid like water or oil.

  • Mineral Carbonation: CO2 can react with minerals, fluids, and organic matter in a geologic formation to form stable compounds; largely calcium, iron, and magnesium carbonates.

Reuse

  • Paper Filler

  • House building material

  • Solar Gasoline

Concern: Leakage of carbon from reservoirs but properly managed geological storage is very likely (that is, 66–90 percent probability) to retain 99% of its sequestered CO2 for over 1,000 years along with high financial costs.

Carbon sequestration activities have been supported through CDM (Clean Development Mechanism) under Kyoto protocol with a focus on afforestation, reforestation, improved forestry or agricultural practices, and revegetation