How does carbon capture and storage (CCS) work, and what are its key limitations?

• A. CO2 is captured after disposal from atmosphere.
• B. CO2 is captured from emission sources, compressed, transported, and stored underground; limitations include cost, energy penalty, long-term storage risk, and scalability.
• C. CCS converts CO2 into oxygen through chemical reactions in the atmosphere.
• D. CCS doubles energy efficiency without any penalty.

Answer: (B)

Carbon capture and storage works by removing CO2 from emission sources, then compressing, transporting, and injecting it underground for long-term storage. Capturing CO2 can happen at the smokestack or in the fuel gas before it’s burned, and the gas is separated from other gases. Once captured, the CO2 is pressurized into a dense fluid and moved through pipelines (or by ship) to a storage site, where it’s injected into deep geological formations such as saline aquifers or depleted oil and gas reservoirs, with dense rock layers above to help trap it. Ongoing monitoring and verification are used to ensure it stays stored.

There are several practical limits to how broadly CCS can be used. It adds substantial cost because capture equipment and the associated infrastructure are expensive. It also imposes an energy penalty: powering the capture, compression, and transportation steps means more fuel must be burned for the same output, reducing overall efficiency. Long-term storage carries a risk of gradual leakage or migration, so robust containment, well integrity, and long-term monitoring and regulation are essential. Finally, scalability is a major hurdle: widespread deployment requires extensive infrastructure, plentiful suitable geological storage sites, and socio-political acceptability, which take time and substantial investment to develop.