Seeing the Round Corners

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August 24, 2021

CARBON CAPTURE, USE AND STORAGE

Last week’s column introduced Carbon Capture, Use and Storage (CCUS), and this week, a closer overall of how carbon capture process works. The overall of carbon capture, transportation and storage is provided by the California Air Resources Board (presented verbatim).
Carbon Capture: Early commercial applications of carbon capture focused on certain industrial processes that remove carbon dioxide in concentrated streams as part of normal operations. For other industrial processes and electricity generation, current systems must be redesigned to capture and concentrate carbon dioxide usually using one of these methods:

Pre-Combustion Capture: Fuel is gasified (rather than combusted) to produce a synthesis gas or syngas. Consisting mainly of carbon monoxide (CO) and hydrogen (H2). A subsequent shift reaction converts the CO to Co2, and then a physical solvent reaction converts the Co2 from H2. For power generation, pre-combustion carbon capture can be combined with an integrated gasification cycle IGCC power plant that burns the H2 in a combustion turbine and uses the exhaust heat to power a steam turbine.
Post-combustion carbon capture: Post-combustion capture typically uses chemical solvents to separate carbon dioxide out of the flue gas from fossil fuel; combustion. Retrofits of existing power plants for carbon capture are likely to use this method.
Oxyfuel Carbon Capture: Oxyfuel capture requires fossil fuel combustion in pure oxygen (rather than air) so that the exhaust gas is carbon-rich which facilitates capture.

Transportation: Once captured, carbon dioxide just be transported from its source to a storage site. There are more than 4,500 miles of pipelines for transporting carbon dioxide in the United States for use in enhanced oil recovery, but more will be needed.

Storage: Carbon dioxide can be injected into geological formations and stored deep underground. U. S. geological formations could store carbon dioxide emissions from centuries of continued fossil fuel use. Options for carbon storage include:

Oil and gas gas reservoirs enhanced oil recovery with carbon dioxide, carbon dioxide – (EOR). Oil and gas reservoirs offer geologic storage potential as well as economic opportunity by injecting carbon dioxide to extract additional oil from developed sites. Oil and gas reservoirs are thought to be suitable candidates for the geologic storage of carbon dioxide given that they have held oil and gas in place for millions of years, and previous fossil fuel exploration has yielded valuable data on subsurface areas that could help ensure permanent Co2 geologic storage. Carbon dioxide-EOR operations have been operating in West Texas for over 30 years. Moreover, revenue from selling captured carbon dioxide to EOR operators could help defray the cost of capture technology at power plants and industrial facilities.
Deep Saline Formations: These porous rock formations infused with brine are located cross the United States but have been examined as extensively as oil and gas reservoirs.
Coal Beds: Coal beds that are too deep or too thin to be economically mined could offer carbon dioxide storage potential. Captured carbon dioxide can also be used in enhanced coal bed methane recovery (ECBM) to extract methane gas.
Basalt formations and shale basins: These are also considered potential future geologic storage locations.

Carbon Storage Regulation (as provided by the U. S. Department of Energy): The U. S. federal and state regulations already in place cover carbon dioxide storage site selection and injection for oil and gas. In addition, “systems for measurement, monitoring, verification, accounting and risk assessment can minimize or mitigate the potential of stored carbon dioxide to pose risks to humans and the environment.”

The U. S. Department of Energy (DOE) also stated, “Carbon Dioxide injection in EOR wells is commercially proven and has a history of safely storing carbon dioxide underground. For example, research by the University of Texas Bureau of Economic Geology found no evidence of leakage from the SACROC oil field where carbon dioxide-EOR has been performed since the 1970s.”

Readers must realize, CCUS is not a new idea, but has somewhat been shoved aside and overlooked in the zeal for renewable energy. Because of it proven record since the 1970s, Carbon Capture, Use and Storage should be recognized as part of the solution to greenhouse gas emissions. Renewable energy can only provide a portion of the electricity the world requires.

Here are some additional regulations that may serve to reassure readers:

In the United States, the Safe Drinking Water Act and the U. S. Environmental Protection Agency (EPA) Underground Injection Control Protection Program impose safety requirements on carbon dioxide injection.
In addition, the Clean Air Act and the EPA’s Greenhouse Gas Emissions Program requires project operators to report data on carbon dioxide injections and submit monitoring, reporting and verification (MRV) plans if carbon dioxide is injected for geologic storage.
The Underground Injection Control Program requires previous seismic history to be considered when selecting geologic carbon dioxide sequestration sites.
The risk of small earthquakes causing carbon dioxide leakage to the surface is mitigated by multiple layers of rock that prevent carbon dioxide from reaching the surface even if it mitigates from an injection zone.

Next week, a brief look at some of those unique innovative programs already in operation across America most ordinary Americans have never heard of.

The reader's comments or questions are always welcome. E-mail me at doris@dorisbeaver.com.