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Glossary for the CCS web site
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| A | |
| Anthracite | Anthracite is a hard natural coal. It contains more than 91 % carbon. It has a very high energy availability. |
| C | |
| CO2 | Carbon dioxide |
| CCS (CO2 Capture and Storage) | Carbon dioxide Capture and Storage involves technologies for isolating carbon dioxide from flue gas (at combustion plants) and storing it. This means that a significantly lower amount of CO2 is emitted into the atmosphere. |
| Caprock | Caprock is a geological term for a harder or more resistant rock type overlying a weaker or less resistant rock type. |
| Capture efficiency | The technologies that are being developed today will capture around 90 % of the CO2. The goal is to come close to 100 % capture efficiency. |
| Climate change | When we talk about climate change today, we usually mean global warming. Global warming is a result of human activities that release greenhouse gases into the atmosphere. Carbon dioxide is emitted from combustion of fossil fuels and is the most common greenhouse gas. |
| Combustion of fossil fuels | Combustion of fossil fuels releases fossilised carbon into the atmosphere in the form of carbon dioxide, CO2 (carbon + oxygen). |
| D | |
| Demonstration plant | The demonstration plant (demo plant) is the scale-up between the pilot plant and the commercial concept that is to be developed. The main purpose of a demo plant is to validate the commercial ability of the technology |
| E | |
| Enhanced Gas Recovery (EGR) | EGR works by recirculating a portion of an engines’ exhaust gas. Intermixing the incoming air with recirculated exhaust gas dilutes the mix with inert gas, lowering the flame temperature.Because NOx formation progresses much faster at high temperatures, EGR serves to limit the generation of NOx. NOx is primarily formed when a mix of nitrogen and oxygen is subjected to high temperatures. |
| Emissions Trading Scheme | An administrative approach used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants. It is sometimes called cap and trade. The European Union Emissions Trading Scheme has been in operation since January 1 2005. |
| F | |
| Feasability study | Preliminary study (Feasible = likely, possible, viable) |
| Flue Gas | Flue gas is gas that exits via a flue, which is a pipe or channel for gases from a fireplace, oven, furnace, boiler or steam generator. It often refers to the combustion exhaust gas produced at power plants. Its composition depends on what is being burned, but it usually consists of carbon dioxide (CO2), water vapour and nitrogen (typically more than two thirds) derived from the combustion air as well as excess oxygen (also derived from the combustion air). It further contains a small percentage of pollutants such as particulate matter, carbon monoxide, nitrogen oxides and sulphur oxides. |
| Fossil fuels | Fossil fuels are hydrocarbons found within the top layer of the earth’s crust, formed from plant or animal remains. They range from volatile materials like methane, to liquid petroleum to nonvolatile materials composed of almost pure carbon, like anthracite coal. |
| G | |
| Geological Storage | Storing CO2 in deep geological formations as a way of mitigating CO2 emissions. |
| Geological formation | A geologic formation is a formally named rock stratum or geological unit. The concept of formally defined layers or strata is central to the geologic discipline of stratigraphy. Some geological formations are suitable for storing CO2. See Caprock |
| H | |
| Hard coal | Hard coal (or black coal / pit coal) is a black, sedimentary rock type with content of 84-91 % carbon. It has a high energy availability. Hard coal is the phase between lignite and anthracite. Anthracite is also classified as hard coal. It contains even more carbon, more than 91 %, and has an even higher energy availability. |
| L | |
| Lignite | Lignite is a sedimentary rock type, mostly used for electricity generation. Lignite’s energy availability is lower than hard coals’, around 65-84 %. Energy resources of lignite is about one third of that of hard coal and it contains more sulphur. |
| M | |
| Mineral trapping | During geological storage CO2may over the long-term react with minerals present in the reservoir and become immobilised in the form of carbonate minerals, similar to those found in natural limestone. |
| Mitigation | Reduction of emissions |
| N | |
| NOx | Nitrogen oxides (NO and NO2) |
| O | |
| Oxyfuel | The Oxyfuel combustion process eliminates nitrogen from the flue gas by combusting the fuel in a mixture of oxygen and recycled flue gases. After combustion, the flue gas is cleaned. The cleaned flue gas primarily consists of CO2 and water vapour. By cooling the flue gas, the water vapour condenses thereby creating an almost pure CO2 stream. The CO2 can be compressed, dried and further purified before being transported to a storage site. |
| P | |
| Physical trapping | CO2 remains trapped within the underground formation due to the presence of an impermeable caprock above the reservoir. This provides a natural seal that prevents the CO2from moving upwards. |
| Pilot plant | The pilot plant is the necessary link between initial engineering and the demo plant. The purpose of the the pilot plant is to validate the engineering work, to learn and better understand the technology and to demonstrate it. |
| Post-combustion | In Post-combustion capture, CO2 is captured from the flue gases in a "scrubber" using an absorption process based on chemical solvents, like amines. On leaving the "scrubber" the solvent can be reused. The captured CO2 can be transported to a storage site. |
| Pre-combustion | Pre-combustion CO2 capture involves removing all or part of the carbon content of a fuel before burning it. The fuel is processed to produce a gas stream that primarily consists of CO2 and hydrogen. The CO2 is then captured for storage and the hydrogen is combusted. |
| S | |
| Saline aquifers | Saline aquifers are underground rock formations that contain salty water. The CO2 partially dissolves in the formation water and in some cases the CO2 slowly reacts with minerals to form carbonates, thereby permanently trapping the CO2 underground. |
| Solubility trapping | The CO2 dissolves into the formation waters that fill the pore spaces in the reservoir rock. |
| Storage | Storing CO2 below ground in oil and gas fields, which are geological formations that have proven their capability to hold oil and gas over millions of years. Depleted fields therefore have great potential to serve as long-term storage sites for CO2. Storage of CO2is possible onshore as well as offshore. |
| T | |
| Test rig | A test rig is a smaller research device where new technologies are studied |
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