Carbon Sources & Sequestration

Carbon Sources & Sequestration

Carbon sink & source

A carbon sink is anything that absorbs more carbon that it releases, while a carbon source is anything that releases more carbon than is absorb

• Forests, soils, oceans and the atmosphere all store carbon and this carbon moves between them in a continuous cycle. This constant movement of carbon means that forests act as sources or sinks at different times. 

• Natural sinks    ? Oceans (Largest on earth) + Photosynthesis by plants
• Artificial sinks ? Landfills + Carbon capture and storage proposals

• Oceans are the largest active carbon sink on Earth, absorbing more than a quarter of the carbon dioxide that humans put into the air

Carbon Sequestration

• long-term storage of carbon dioxide to mitigate global warming & avoid dangerous climate change
• proposed as a way to slow the atmospheric and marine accumulation of greenhouse gases
• includes carbon capture and storage, which refers to large-scale, permanent artificial capture & sequestration of industrially produced CO2 using

• Subsurface saline aquifers
• Reservoirs
• Ocean water
• Aging oil fields or other carbon sinks

Geological sequestration / storage (Carbon Sink)

The method of geo-sequestration or geological storage involves injecting carbon dioxide directly into underground geological formations for ex :

• Declining oil fields
• Saline aquifers
• Unminable coal seams

• CO₂ has been injected into declining oil fields for more than 40 years, to increase oil recovery
• CO₂ is soluble in oil hence lowers viscosity of the oil & reduces its interfacial tension which increases the oils mobility.
• Salty water contained in deep saline aquifers is not suitable for drinking or agriculture, making saline aquifers an ideal large-scale storage solution for large stationary industrial CO2 emitters.
• Unminable coal seams can be used to store CO₂, because CO₂ absorbs to the coal surface, ensuring safe long-term storage.
• In this process it releases methane that was previously adsorbed to the coal surface and that may be recovered, & Again the sale of the methane can be used to offset the cost of the CO₂ storage

Carbon credit

• Any trad-able certificate representing the right to emit one tonne of carbon dioxide or the mass of another greenhouse gas equivalent to one tonne of carbon dioxide
• Carbon credits and carbon markets are a component of national and international attempts to mitigate the growth in concentrations of greenhouse gases (GHGs)
• One carbon credit is equal to one tonne of carbon dioxide, or in some markets, carbon dioxide equivalent gases.
• Carbon off setters purchase the credits from an investment fund or a carbon development company that has aggregated the credits from individual projects
• Buyers and sellers can also use an exchange platform to trade, such as the Carbon Trade Exchange, which is like a stock exchange for carbon credits
• China is currently the largest seller of carbon credits controlling about 70% of the market share with India at second place with 20% market share
• MCX has become the first exchange in Asia to trade carbon credits

Carbon offset

• A carbon offset is a reduction in emissions of carbon dioxide or greenhouse gases made in order to compensate for or to offset an emission made elsewhere
• Carbon offsets are measured in metric tons of carbon dioxide-equivalent (CO₂) and may represent six primary categories of GHGs: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF₆)
• One carbon offset represents reduction of one metric ton of carbon dioxide or its equivalent in other greenhouse gases

Carbon tax

• a tax based on greenhouse gas emissions (GHG) generated from burning fuels
• Basically a tax on fossil fuels, especially those used by motor vehicles, intended to reduce the emission of carbon dioxide
• puts a price on each tonne of GHG emitted, sending a price signal
• India Doesn’t like it & is against carbon tax from goods imported from India to other countries