Optimizing Carbon Capture

Carbon capture is the process of capturing carbon dioxide (CO2) emissions at the source, or directly from the air, preventing it from entering the atmosphere. Once captured, CO2 is then purified, liquefied and utilized in other marketable industrial and commercial products. Alternatively, it can be transported to a suitable storage location for long-term isolation from the atmosphere.

There are three main methods of extraction, which differ depending on the industrial process and the concentration of carbon in the source fuel or feedstock:

• Post-combustion capture – CO2 is removed after combustion of the fossil fuel, captured from the flue gases, especially at power stations, but also other point sources. This is used mainly for cleaner burning energy sources with lower carbon concentrations, like natural gas and biofuels.
• Pre-combustion capture – partial oxidization of the fossil fuel prior to combustion results in carbon monoxide. Steam added produces CO2, which is captured, and hydrogen that can be used as a fuel. This method is used for sources with average carbon concentration.
• “Oxyfuel” combustion – fossil fuel is burned in pure oxygen, creating a flu gas consisting almost entirely of CO2. This method is used for sources that have the highest concentration levels and are the most difficult to decarbonize.

The success of carbon capture depends largely on three factors:

• optimizing the efficiency and cost-effectiveness of the capture process.
• reducing the cost of transportation.
• ensuring reliable containment of gases and liquids.

Each of these items poses several key challenges. For the capture process itself, they include carefully managing energy consumption and controlling volatile chemical reactions under high temperature and extreme pressure with the goal of maximizing capture rates. Maintaining safe transportation operations depends on preventing compressor and pump failures, managing the liquefaction process, and preventing phase instability and loss of containment in cylinders, tanks and pipelines. Storing CO2 requires being able to accurately evaluate capacity, ensuring injection process efficiency, and maintaining the safety and integrity of underground storage sites, such as salt domes.