Carbon capture and storage

Carbon capture and storage (CCS, or sometimes CCUS(...)( carbon capture, utilization and storage )) is an industrial process where CO₂ emissions are captured and stored deep in the Earth. This is a somewhat questionable approach to reducing climate change.

Capture - types

Direct air capture (DAC)

Not viable

Trying to take CO₂ out of the air uses almost as much energy as you got when you burned the equivalent amount of fossil fuels in the first place. (In other words, it's basically useless.) Any amount of green energy used in DAC, could have been used in any other industry (in place of fossil fuels) and done more to stop climate change.

Point source capture

Viability: Unknown ^{[RESEARCH needed]}

Capturing the emissions at the source:

• Suited for coal power plants, natural gas power plants, and some factories.
• Not suited for smaller sources like cars & trucks.

Storage - considerations

CO₂ is pumped into rocks deep in the ground. It reacts with minerals to become mineral carbonates, which are chemically stable. ^{[ELABORATION needed]}

Earthquakes

Possible problem

Sequestering of carbon deep underground, through multiple impermeable boundaries, can increase earthquakes, just as with waste water storage from fracking. ^[rw]

External links:

• Pumping carbon dioxide deep underground may trigger earthquakes, Science News, Jan 9, 2015

Sinkholes

Possible problem

Once carbon dioxide is pumped underground in large quantities (in this case, billions of tons), it displaces natural groundwater pools, causing groundwater to seep elsewhere underground, which greatly increases the risk of sink-holes and water seepage on the surface above. ^[rw]

Rejection

Carbon dioxide is naturally buoyant, and will thus spread around its initial injection point, and seep back out of the earth unless it is injected through one or more impermeable boundaries. ^[rw]

Storage capacity

Possible problem

This section needs info on how much carbon could really be stored in the ground - both globally and in terms of some local regions. ^{[RESEARCH needed]}

CO₂ transport

Unknown

CO₂ sources are not necessarily near geographic regions suitable for CO₂ storage. Pipelines would need to be built. ^{[RESEARCH needed - viability]}

Utilization

Not helpful in the big picture

The "utilization" part of CCUS: The CO₂ is sometimes "used" before being stored. In practice, the only usage is for mining more oil & gas.^{[ELABORATION needed]}

External links

This page contains some content copied from RationalWiki's page on "clean coal", which has some good info debunking carbon capture. [Footnote: ^[rw]]