Carbon dioxide (CO2) from carbon capture and storage and direct air capture operations is often injected into deep geologic formations. These storage sites can be monitored for CO2 leakage. Monitoring can be done at both the surface and subsurface levels. [1] The dominant monitoring technique is seismic imaging, where vibrations are generated that propagate through the subsurface. The geologic structure can be imaged from the refracted/reflected waves. [1]
Subsurface monitoring can directly and/or indirectly track the reservoir's status. One direct method involves drilling deep enough to collect a sample. This drilling can be expensive due to the rock's physical properties. It also provides data only at a specific location.
One indirect method sends sound or electromagnetic waves into the reservoir which reflects back for interpretation. This approach provides data over a much larger region; although with less precision.
Both direct and indirect monitoring can be done intermittently or continuously. [2]
Seismic monitoring is a type of indirect monitoring. [3] [4]
Examples of seismic monitoring of geological sequestration are the Sleipner sequestration project, the Frio CO2 injection test and the CO2CRC Otway Project. [5] Seismic monitoring can confirm the presence of CO2 in a given region and map its lateral distribution, but is not sensitive to the concentration.
Organic chemical tracers, using no radioactive or Cadmium components, can be used during the injection phase in a CCS project where CO2 is injected into an existing oil or gas field, either for EOR, pressure support or storage. Tracers and methodologies are compatible with CO2 – and at the same time unique and distinguishable from the CO2 itself or other molecules present in the sub-surface. Using laboratory methodology with an extreme detectability for tracer, regular samples at the producing wells will detect if injected CO2 has migrated from the injection point to the producing well. Therefore, a small tracer amount is sufficient to monitor large scale subsurface flow patterns. For this reason, tracer methodology is well-suited to monitor the state and possible movements of CO2 in CCS projects. Tracers can therefore be an aid in CCS projects by acting as an assurance that CO2 is contained in the desired location sub-surface. In the past, this technology has been used to monitor and study movements in CCS projects in Algeria, [6] the Netherlands [7] and Norway (Snøhvit).
[8] This provides a measure of the vertical CO2 flux. Eddy covariance towers could potentially detect leaks, after accounting for the natural carbon cycle, such as photosynthesis and plant respiration. An example of eddy covariance techniques is the Shallow Release test. [9] Another similar approach is to use accumulation chambers for spot monitoring. These chambers are sealed to the ground with an inlet and outlet flow stream connected to a gas analyzer. [2] They also measure vertical flux. Monitoring a large site would require a network of chambers.
Interferometric synthetic aperture radar (InSAR), is a radar technique used in geodesy and remote sensing.
The Kansas Geological Survey (KGS) is a research and service division of the University of Kansas, charged by statute with studying and providing information on the geologic resources of Kansas. The KGS has no regulatory authority and does not take positions on natural resource issues.
Coal pollution mitigation, sometimes labeled as clean coal, is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment.
Carbon capture and storage (CCS) is a process by which carbon dioxide (CO2) from industrial installations is separated before it is released into the atmosphere, then transported to a long-term storage location. With CCS, the CO2 is captured from a large point source, such as a natural gas processing plant and typically is stored in a deep geological formation. Around 80% of the CO2 captured annually is used for enhanced oil recovery (EOR), a process by which CO2 is injected into partially-depleted oil reservoirs in order to extract more oil and then is largely left underground. Since EOR utilizes the CO2 in addition to storing it, CCS is also known as carbon capture, utilization, and storage (CCUS).
Enhanced oil recovery, also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. Whereas primary and secondary recovery techniques rely on the pressure differential between the surface and the underground well, enhanced oil recovery functions by altering the physical or chemical properties of the oil itself in order to make it easier to extract. When EOR is used, 30% to 60% or more of a reservoir's oil can be extracted, compared to 20% to 40% using only primary and secondary recovery.
Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in limiting climate change by reducing the amount of carbon dioxide in the atmosphere. There are two main types of carbon sequestration: biologic and geologic.
An integrated gasification combined cycle (IGCC) is a technology using a high pressure gasifier to turn coal and other carbon based fuels into pressurized gas—synthesis gas (syngas). It can then remove impurities from the syngas prior to the electricity generation cycle. Some of these pollutants, such as sulfur, can be turned into re-usable byproducts through the Claus process. This results in lower emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. With additional process equipment, a water-gas shift reaction can increase gasification efficiency and reduce carbon monoxide emissions by converting it to carbon dioxide. The resulting carbon dioxide from the shift reaction can be separated, compressed, and stored through sequestration. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, similar to a combined cycle gas turbine. This process results in improved thermodynamic efficiency, compared to conventional pulverized coal combustion.
The Sleipner gas field is a natural gas field in the block 15/9 of the North Sea, about 250 kilometres (160 mi) west of Stavanger, Norway. Two parts of the field are in production, Sleipner West, and Sleipner East (1981). The field produces natural gas and light oil condensates from sandstone structures about 2,500 metres (8,200 ft) below sea level. It is operated by Equinor. The field is named after the eight-legged steed Sleipnir of Odin a widely revered god in Norse mythology.
Carbon capture and storage (CCS) is a technology that can capture carbon dioxide CO2 emissions produced from fossil fuels in electricity, industrial processes which prevents CO2 from entering the atmosphere. Carbon capture and storage is also used to sequester CO2 filtered out of natural gas from certain natural gas fields. While typically the CO2 has no value after being stored, Enhanced Oil Recovery uses CO2 to increase yield from declining oil fields.
The milestones for carbon capture and storage show the lack of commercial scale development and implementation of CCS over the years since the first carbon tax was imposed.
Bioenergy with carbon capture and storage (BECCS) is the process of extracting bioenergy from biomass and capturing and storing the carbon dioxide (CO2) that is produced.
Post-combustion capture refers to the removal of carbon dioxide (CO2) from a power station flue gas prior to its compression, transportation and storage in suitable geological formations, as part of carbon capture and storage. A number of different techniques are applicable, almost all of which are adaptations of acid gas removal processes used in the chemical and petrochemical industries. Many of these techniques existed before World War II and, consequently, post-combustion capture is the most developed of the various carbon-capture methodologies.
The Weyburn-Midale Carbon Dioxide Project was, as of 2008, the world's largest carbon capture and storage project. It has since been overtaken in terms of carbon capture capacity by projects such as the Shute Creek project and the Century Plant. It is located in Midale, Saskatchewan, Canada.
Carbfix is an Icelandic company that has developed an approach to permanently store CO2 by dissolving it in water and injecting it into basaltic rocks. Once in the subsurface, the injected CO2 reacts with the host rock forming stable carbonate minerals, thus providing permanent storage of the injected CO2
The Gorgon Carbon Dioxide Injection Project is part of the Gorgon Project, one of the world's largest natural gas projects. The Gorgon Project, located on Barrow Island in Western Australia, includes a liquefied natural gas (LNG) plant, a domestic gas plant, and a Carbon Dioxide Injection Project.
Mexico highly depends on the burning of its fossil fuels, and for the same reason, it is in its interest to look into mitigation solutions for its corresponding emissions. In the General Law on Climate Change on 2012, Mexico promised to reduce 20% of its greenhouse gas (GHG) emissions by 2020 and 50% by 2050, as well as in the Paris Agreement. 19% of this new mitigation plan will be dedicated to carbon capture and storage and specifically 10% to the energy industry.
Direct deep-sea carbon dioxide injection was a (now abandoned) technology proposal with the aim to remove carbon dioxide from the atmosphere by direct injection into the deep ocean to store it there for centuries. At the ocean bottom, the pressures would be great enough for CO2 to be in its liquid phase. The idea behind ocean injection was to have stable, stationary pools of CO2 at the ocean floor. The ocean could potentially hold over a thousand billion tons of CO2. However, the interest in this avenue of carbon storage has much reduced since about 2001 because of concerns about the unknown impacts on marine life, high costs and concerns about its stability or permanence.
Direct air capture (DAC) is the use of chemical or physical processes to extract carbon dioxide directly from the ambient air. If the extracted CO2 is then sequestered in safe long-term storage (called direct air carbon capture and sequestration, the overall process will achieve carbon dioxide removal and be a "negative emissions technology".
Carbon storage in the North Sea includes programmes being run by several Northern European countries to capture carbon, and store it under the North Sea in either old oil and gas workings, or within saline aquifers. Whilst there have been some moves to international co-operation, most of the Carbon Capture and Storage (CCS) programmes are governed by the laws of the country that is running them. Because the governments have pledged net zero carbon emissions by 2050, they have to find ways to deal with any remaining CO2 produced, such as by heavy industry. Around 90% of the identified storage geologies for carbon dioxide in Europe are shared between Norway and the United Kingdom; all of the designated sites for storage are located in the North Sea.
The Carbon Connect Delta Program is a proposed carbon sequestration program to aid Belgium and the Netherlands in achieving carbon neutrality by 2030. It aims to capture, transport, and store 6.5 million tones of CO2 by 2030 using carbon capture and storage (CCS) in the transboundary area of the North Sea Port area of the Scheldt-Delta region connecting Belgium and the Netherlands.