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1 [1] (November 16, 2021)

handle is hein.crs/govegvy0001 and id is 1 raw text is: Car Congressional Research Service nforrming Ih legislitive deba e since 1914 Carbon Capture Versus Direct Air Capture Carbon capture and direct air capture (DAC) have gained prominence in recent years as options to address climate change. The two technologies have similarities (beyond their names), but they also have differences. Key differences include how the technologies work, where the technology can be used, how the technology can address climate change, and levels of federal support. Congress affirmed its support for these technologies in Section 40301 of the Infrastructure Investment and Jobs Act (IIJA; P.L. 117-58): carbon capture and storage technologies are necessary for reducing hard-to-abate emissions from the industrial sector, which emits nearly 25 percent of carbon dioxide emissions in the United States ... carbon removal and storage technologies, including direct air capture, must be deployed at large-scale in the coming decades to remove carbon dioxide directly from the atmosphere ... large-scale deployment of carbon capture, removal, utilization, transport, and storage-is critical for achieving mid-century climate goals; and will drive regional economic development, technological innovation, and high-wage employment. The following analysis explains key differences between the two technologies to inform ongoing congressional deliberations regarding the merits of these technologies, rationale for federal support, and funding level considerations. Additional information, such as costs and other challenges, is provided in other CRS resources, listed below. How Do They Work? Carbon capture technologies prevent the release of carbon dioxide (CO2) to the atmosphere. In the most commonly used arrangement today, a chemical that can grab CO2 is placed in or near the stream of CO2 at a source. The captured CO2 is then released and compressed so that it can be transferred by pipeline. The CO2 can then be used, for example, as a feedstock to an industrial process or permanently stored (sequestered) underground. The chemical that does the capturing can be used repeatedly in the process. The full process is called carbon capture, utilization, and storage (CCUS), or sometimes carbon capture and storage (CCS). Direct air capture technologies remove CO2 from the atmosphere, even if that CO2 was released many years ago. In many technological approaches, air is forced over a chemical that can grab CO2. DAC and CCUS may use the same chemicals, but some chemicals are better suited for each application. Regardless, the supporting equipment must be optimized for the different CO2 concentrations involved in DAC and CCUS. After capture, the process for DAC is very similar to that used for CCUS and can use the Updated November 16, 2021 same equipment for compression, transfer, and storage. The chemical that does the capturing can also be used repeatedly. Both technologies are in early stages of development, with a few examples of operating projects worldwide. Of the two, CCUS is more mature, though researchers expect significant technology advancement can still be achieved. Although the capture technologies are different for CCUS and DAC, they face similar challenges. Both are typically capital-intensive and energy-intensive. Also, the demand for CO2 is small compared to its availability, resulting in low CO2 revenues. The low value of CO2 presents a hurdle to commercialization for both technologies. Where C an They Be Used. CCUS can be used at stationary sources of CO2 such as power plants or other industrial facilities. Existing facilities can be retrofitted to add CCUS equipment, or CCUS can be integrated into the design of new facilities. The type of source can affect the cost of a project because different sources emit CO2 in different concentrations (purities). All else being equal, carbon capture can be completed at lower cost per ton of CO2 captured for sources with higher-purity CO2 emissions (e.g., ethanol production plants). Sources of captured CO2 are often located far away from where CO2 may be used or stored, creating logistical and cost challenges related to the transport of CO2. DAC can be used anywhere. Many proposals envision building DAC projects close to either inexpensive electricity sources or locations where CO2 can be used or stored, reducing overall costs. How Can CCUS and DAC Address Cflmate Change? CCUS would reduce CO2 emissions released to the atmosphere. The extent of reduction is dependent upon the end use of the CO2. Currently, the main use of captured CO2 is for enhanced oil recovery (EOR). In EOR, compressed CO2 is injected into aging oil wells. This process increases oil production while also permanently sequestering some CO2. Many stakeholders see CCUS as a way to enable continued use of fossil fuels even if CO2 emissions were restricted in the United States and abroad. Fossil fuels have operational advantages over alternative fuels in many economic sectors. For example, cement, steel, and petrochemical manufacturing all require very high temperatures, currently provided almost exclusively by fossil fuel combustion. CCUS may allow continued use of fossil fuels in these and other sectors with lower CO2 emissions than today.