Risks may arise directly from CO2Carbon dioxide (see 1.3.1 to 1.3.3) or from its associated incidental substances, saline formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name itUnderground rock where saline water occupies the tiny spaces between the grains of rock water, hydrocarbons, mobilised substances from rock or soil and indirectly from the geomechanical reaction of the storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) environment (see 1.3.5). For monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions purposes, rRisk assessments need to specify possible locations of leakage(in CO2Carbon dioxide storage) The escape of injected fluid from the storage formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) or water column, magnitudes and impacts of possible incidents. Though the discussion of risks initially often was restricted to CO2Carbon dioxide, all of the risks require adequate monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions.
Incidental associated substances
Depending on the captureThe separation of carbon dioxide from other gases before it is emitted to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) technology, the CO2Carbon dioxide phase may contain various incidental associated substances, such as SO2, NOx, COCarbon monoxide, H2S, He, N2, O2, Ar, Hg, As, Se, and other trace elements. These impurities pose potential risks or may affect the level of risks due to their various potential impacts on the storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) complex and on health, environmental and safety issues: Some species can be toxic, others form acids (SOx, NOx, H2S) that could cause corrosion problems, alteration of reservoirA subsurface body of rock with sufficient porosityMeasure for the amount of pore spaceSpace between rock or sediment grains that can contain fluids in a rock and permeabilityAbility to flow or transmit fluids through a porous solid such as rock to store and transmit fluids and caprocks, or the mobilisation of heavy metals from soils or aquiferAn underground layer of fluid-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) with significant permeability to allow flow rocks, which is of particular concern in freshwater aquifers.
Whether these minor components will cause risks in addition to effects caused by the CO2Carbon dioxide itself, depends on the concentration of these impurities and the subjects exposed to them. These risks need to be assessed individually for each separated CO2Carbon dioxide streamA flow of substances resulting from CO2Carbon dioxide captureThe separation of carbon dioxide from other gases before it is emitted to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) processes, or which consists of a sufficient fraction of CO2Carbon dioxide and sufficiently low concentrations of other substances to meet specifications of streams permitted for long term geological storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) and storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) project. For many risks, the monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions of one indicator or proxy may be sufficient as long as the impurities are in the CO2Carbon dioxide-bearing phase. Detection of CO2Carbon dioxide may be sufficient for early warning purposes.
FormationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it fluids
In an incident of leakage(in CO2Carbon dioxide storage) The escape of injected fluid from the storage formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) or water column, formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it fluids, phases naturally present in the storage(CO2Carbon dioxide) A process for retaining captured CO2Carbon dioxide, so that it does not reach the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it or the overburdenRocks and sediments above any particular stratum may migrate together with the CO2Carbon dioxide-rich phase to the surface and affect protected goods. Mobilised formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it brines, natural gasGas stored underground; It consists largely of methane, but can also contain other hydrocarbons, water, hydrogen sulphide and carbon dioxide, these other substances are separated before the methane is put into a pipeline or tanker or crude oil may be eco-toxic or pose risks to human health and safety. The displacement of formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it waterWater that occurs naturally within the pores of rock formations from saline aquifers is seen as a particular riskConcept that denotes the product of the probability of a hazard and the subsequent consequence of the associated event for freshwater aquifers. As water is almost incompressible, the injectionThe process of using pressure to force fluids down wells of pressurised CO2Carbon dioxide will push formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it brine away from the injectionThe process of using pressure to force fluids down wells wells. Displaced brine can potentially migrate or leak through fractures or wells into shallow aquifers and may thereby contaminate resources used for drinking water extraction.
Rock and/or soil constituents
Rock and/or soil constituents can be mobilised by various geochemical reactions. At depth, supercritical(CO2Carbon dioxide) Conditions where carbon dioxide has some characteristics of a gas and some of a liquid CO2Carbon dioxide is an excellent solvent for organic material that may be extracted from reservoirA subsurface body of rock with sufficient porosityMeasure for the amount of pore spaceSpace between rock or sediment grains that can contain fluids in a rock and permeabilityAbility to flow or transmit fluids through a porous solid such as rock to store and transmit fluids or caprocks. The solubility of organics will decrease during fluid ascent according to the pressure and temperature conditions along the flow path. Precipitation of higher hydrocarbons may lead to permeabilityAbility to flow or transmit fluids through a porous solid such as rock reductions in porous media. In open fractures such phases may be transported as mixtures with fluids of lower viscosity. Subsurface water and CO2Carbon dioxide can react with wall rocks, e.g. mobilising toxic heavy metals or just ubiquitous formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it waterWater that occurs naturally within the pores of rock formations constituents.
If impurities or mobilised substances pose additional risks to CO2Carbon dioxide leakage(in CO2Carbon dioxide storage) The escape of injected fluid from the storage formationA body of rock of considerable extent with distinctive characteristics that allow geologists to map, describe, and name it to the atmosphereThe layer of gases surrounding the earth; the gases are mainly nitrogen (78%) and oxygen (around 21%) or water column, than these risks have to be addressed by monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions as wellManmade hole drilled into the earth to produce liquids or gases, or to allow the injectionThe process of using pressure to force fluids down wells of fluids. For example at injectionThe process of using pressure to force fluids down wells facilities for H2S-bearing CO2Carbon dioxide both gaseous species should be monitored because of occupational safety, to avoid asphyxiation by CO2Carbon dioxide or poisoning by H2S. WellManmade hole drilled into the earth to produce liquids or gases, or to allow the injectionThe process of using pressure to force fluids down wells of fluids materials may need more intensive monitoringMeasurement and surveillance activities necessary for ensuring safe and reliable operation of a CGS project (storage integrity), and for estimating emission reductions when the concentrations of corrosion-enhancing substances (acidic gases, H2O, O2, Hg) exceed material-specific critical levels.