How does carbon capture technology work to reduce greenhouse gas emissions?
Carbon capture technology, also known as carbon capture and storage (CCS), is a method used to reduce greenhouse gas emissions by capturing CO2 produced from industrial processes or power generation and storing it deep underground instead of releasing it into the atmosphere. The process involves three main steps: carbon capture, transportation, and storage. During carbon capture, CO2 is separated from flue gases in power plants or other industrial facilities using various methods such as absorption or adsorption. Once captured, the CO2 is compressed into a dense form suitable for transportation via pipelines or ships to a suitable storage location. The final step involves injecting the CO2 into geological formations beneath the Earth’s surface where it can be stored permanently.
Long answer
Carbon capture technology plays a crucial role in reducing greenhouse gas emissions, particularly from large industrial sources such as power plants and factories. These facilities produce significant amounts of carbon dioxide (CO2) during combustion processes. Carbon capture and storage (CCS) systems aim to prevent this CO2 from being released into the atmosphere where it contributes to climate change.
The first step in CCS is carbon capture, which involves separating CO2 from flue gases generated by industrial processes. There are different methods for capturing CO2, including post-combustion, pre-combustion, and oxy-fuel combustion approaches.
In post-combustion capturing, flue gases are treated after fossil fuels like coal or natural gas have been burned in power plants or other facilities. Various techniques like chemical absorption using solvents effectively remove the CO2 from the flue gases before they are emitted through smokestacks.
Pre-combustion capturing involves converting fossil fuels into synthetic gas before combustion takes place. In this process, known as gasification, coal or other hydrocarbon-based fuels are heated with steam to produce a mixture of hydrogen and carbon monoxide called syngas. The syngas can then be used for power generation or other industrial applications, while the CO2 is separated from it for storage.
The oxy-fuel combustion approach involves burning fuel in pure oxygen instead of air, resulting in a clean flue gas stream composed primarily of CO2 and water vapor. The CO2 can be readily captured and stored, leaving only water vapor as an emission.
Once the CO2 is captured, it goes through a compression process to reduce its volume and increase its density, making it easier to transport. CO2 can be transported via pipelines or by ships in liquid form to suitable storage locations. Pipelines are generally suitable for shorter distances, typically within regions or countries with infrastructure networks. For longer distances or international transport, liquid CO2 is shipped in specially designed vessels.
Finally, the last step of CCS involves the secure storage of captured CO2 deep underground to prevent its release into the atmosphere. This process is called geologic sequestration and involves injecting the CO2 into geological formations such as saline aquifers (underground porous rock formations filled with saltwater) or depleted oil and gas reservoirs that are no longer commercially viable. The injected CO2 is trapped by impermeable layers of caprock above these formations, where it remains securely stored over long periods of time.
Overall, carbon capture technology offers a significant opportunity to mitigate greenhouse gas emissions by preventing large quantities of CO2 from reaching the atmosphere. However, there are challenges associated with cost-effectiveness, regulatory frameworks, and public acceptance that need to be addressed for broader implementation of CCS on a global scale.