What are the different methods of carbon capture and storage currently in use?
The different methods of carbon capture and storage that are currently in use include post-combustion capture, pre-combustion capture, and oxy-fuel combustion. Post-combustion capture involves removing carbon dioxide (CO2) from the flue gases emitted by power plants or industrial facilities. Pre-combustion capture removes CO2 from fossil fuel feedstock before it is burned to generate electricity or heat. Oxy-fuel combustion involves burning fossil fuels with oxygen instead of air, resulting in a flue gas predominantly composed of CO2 which can be captured more easily. These methods offer potential solutions to reduce greenhouse gas emissions and combat climate change.
Long answer
-
Post-combustion capture: This method involves capturing CO2 from the flue gases produced during the combustion of fossil fuels in power plants or industrial facilities. Common post-combustion technologies include chemical absorption using solvents like amines or solid sorbents, adsorption using special materials like activated carbon, and membrane separation. Once captured, the CO2 can be compressed into a supercritical state for transportation and stored underground in geological formations such as deep saline aquifers or depleted oil and gas reservoirs.
-
Pre-combustion capture: In this method, CO2 is captured from fossil fuel feedstock before it is burned to produce energy. Hydrocarbon fuels are reacted with steam under high pressure to produce hydrogen gas (H2) and a stream of impurities containing CO2. The H2 can then be used as a clean-burning fuel while the impurities are removed via processes such as pressure swing absorption or solvent scrubbing. Pre-combustion capture is commonly used in applications like coal gasification for integrated gasification combined cycle (IGCC) power plants.
-
Oxy-fuel combustion: This technique involves burning fossil fuels in an atmosphere enriched with pure oxygen, resulting in a flue gas predominantly composed of CO2 and water vapor. By eliminating the presence of nitrogen from air, which usually makes up the majority of flue gas volume, the CO2 can be captured more easily. The captured CO2 can then be compressed and stored using similar methods as post-combustion capture. Oxy-fuel combustion also has the advantage of producing highly concentrated CO2 streams that require less energy for compression.
It’s worth noting that while these carbon capture and storage (CCS) methods show promise in reducing greenhouse gas emissions from various industries, there are still challenges to overcome. These include high energy and cost requirements, large-scale infrastructure development for transportation and storage, ensuring long-term storage integrity, and public acceptance concerns regarding potential environmental risks associated with storing CO2 underground. Nonetheless, ongoing research and development aim to improve current CCS techniques and explore new approaches for effective carbon mitigation strategies.