Carbon capture and storage (CCS) is a crucial method for mitigating global warming by reducing carbon emissions. This process comprises three steps: capturing carbon dioxide emissions from power generation or industrial processes like steel and cement manufacturing, transporting the captured CO2, and securely storing it underground.
How Does CCS Function?
The CCS process involves three key steps:
- Carbon Dioxide Capture: Carbon dioxide (CO2) is isolated from other gases generated in industrial operations, like those in coal, natural gas power plants, steelworks, or cement factories.
- Transportation: The captured CO2 is compressed and conveyed through pipelines, road transport, or ships to a designated storage site.
- Storage: Subsequently, the CO2 is injected deep underground into rock formations for long-term, secure storage.
Also See: What is Carbon Sequestration?
How Does CCS Contribute to Combating Global Warming?
To meet the Paris Agreement’s goal of limiting temperature rise to 1.5°C (2.7°F), the IPCC emphasizes the need for not only intensifying emission reduction efforts but also adopting technologies to extract carbon from the atmosphere. CCS is among these technologies and can play a significant role in addressing global warming.
Where are Carbon Emissions Stored in CCS?
Carbon emissions can be stored in various locations, with common sites being saline aquifers or depleted oil and gas reservoirs, typically located at depths of 0.62 miles (1km) or more underground.
For instance, in the UK’s proposed Zero Carbon Humber project, carbon emissions will be stored in a saline aquifer known as Endurance, situated in the southern North Sea, approximately 1 mile (1.6km) beneath the seabed, offering substantial storage capacity.
Similarly, the United States hosts multiple large-scale carbon storage sites like the Citronelle Project in Alabama, where carbon is injected into a saline reservoir at a depth of approximately 1.8 miles (2.9km).
How does Carbon Capture Work?
It is the process that prevents carbon emissions from entering the atmosphere by either reusing them or storing them underground in places like decommissioned oil and gas reservoirs, mines, or permeable rocks such as saline aquifers.
This process utilizes various methods to reduce carbon dioxide emissions, including natural ecosystems that convert atmospheric carbon into biomass, notably through tree planting. It also involves:
1. Post-Combustion Capture: It focuses on flue gas emissions from smokestacks of coal or natural gas power plants, as well as industrial sites that produce materials such as concrete and steel. It involves collecting emissions from a variety of sources, including ethanol factories in the Midwest. Post-combustion technologies use chemicals such as amines to recover carbon dioxide from flue gas efficiently. Amines bind with CO2 at low temperatures and release it when heated, resulting in practically pure carbon dioxide.
2. Direct Air Capture: Often conceptualized as a massive air filter, it is undeniably costly and energy-intensive due to its capacity to absorb significant amounts of carbon dioxide. Despite receiving funding for testing locations through the Infrastructure Investment and Jobs Act, there are prevailing limitations concerning cost and energy usage. Carbon capture proves most efficient when targeted at sources with elevated carbon dioxide concentrations, such as emissions from ethanol production or cement manufacturing.
3. Transportation and Storage: Once captured, isolated carbon dioxide is pressurized into a liquid state for transportation via pipelines to utilization or storage sites. Pipeline projects attempt to transport carbon dioxide from ethanol plants in the Midwest to North Dakota and Illinois. Nonetheless, concerns regarding pipeline safety and management persist.
4. Utilization and Sequestration: Carbon dioxide has commercial applications such as carbonating beverages and improving crude oil extraction by injecting it into aging oil wells. However, environmentalists are skeptical of technologies that use trapped carbon to extract more fossil fuels, which could increase carbon emissions.
Alternatively, carbon dioxide can be stored underground to prevent its release into the atmosphere. This involves injecting carbon dioxide deep underground into suitable rock formations, ensuring long-term storage by utilizing porous and permeable formations like sandstone or limestone, with a layer of dense rock above to prevent carbon dioxide seepage back to the surface.
Also, check out Advantages and Disadvantages of Carbon Capture
How Carbon Capture and Storage (CCS) is different from Carbon Capture, Utilisation and Storage (CCUS)?
In addition to CCS, there exists a related concept known as CCUS, which stands for Carbon Capture Utilisation and Storage. Unlike CCS, CCUS doesn’t solely focus on carbon storage but also explores the potential to repurpose captured carbon in industrial applications, such as the production of plastics, concrete, or biofuel.
Recommended: Carbon Sequestration Vs Carbon Capture: What’s the Difference?
