„Direct Air Capture“ – Versionsunterschied
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Direct air capture of [[carbon dioxide]] requires [[water]] input. One estimate is that for Absorption, amine based technology, to capture 3.3 Gigatonnes of [[carbon dioxide]] a year, the water requirements would be 300km3 a year, or 4% of the water used for [[irrigation]].<ref name=":0" /> |
Direct air capture of [[carbon dioxide]] requires [[water]] input. One estimate is that for Absorption, amine based technology, to capture 3.3 Gigatonnes of [[carbon dioxide]] a year, the water requirements would be 300km3 a year, or 4% of the water used for [[irrigation]].<ref name=":0" /> |
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In addition to water consumption, direct air capture would require a large amount of energy. This is due to the low [[concentration]] of [[carbon dioxide]] in air, leading to more energy intensive capture.<ref>{{Cite journal|last=Ranjan|first=Manya|last2=Herzog|first2=Howard J.|date=2011|title=Feasibility of air capture|url= |
In addition to water consumption, direct air capture would require a large amount of energy. This is due to the low [[concentration]] of [[carbon dioxide]] in air, leading to more energy intensive capture.<ref>{{Cite journal|last=Ranjan|first=Manya|last2=Herzog|first2=Howard J.|date=2011|title=Feasibility of air capture|url=https://dx.doi.org/10.1016/j.egypro.2011.02.193|journal=Energy Procedia|volume=4|pages=2869–2876|doi=10.1016/j.egypro.2011.02.193|issn=1876-6102}}</ref> |
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===Energy estimates=== |
===Energy estimates=== |
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Version vom 28. Januar 2019, 00:31 Uhr
Direct air capture (DAC) is a capture method of carbon capture and storage that separates carbon dioxide from air. While still in the early stages, proponents of direct air capture argue that it is an essential component of climate change mitigation.[1]
Methods of capture
Like most forms of carbon capture and storage, direct air capture relies on three main technologies for separating the carbon dioxide from the air. Direct air capture of carbon dioxide (DAC) is a carbon capture technique which produces a concentrated Vorlage:Co2 gas stream from ambient air. Generally ambient air is flows through a filter where either adsorption, absorption or mineralization removes the Vorlage:Co2 from the air. This concentrated Vorlage:Co2 stream may be sequestered or reused for enhanced oil recovery to produce low carbon fuel. When DAC is combined with a carbon capture system, it can produce a negative emissions plant. DAC is one tool used to mitigate climate change and reach the Paris Climate Agreement goals. Direct air capture have larger energy and water requirements, because Vorlage:CO2 is removed from a very dilute stream. Current atmospheric Vorlage:CO2 levels are 410 parts per million (ppm). There are currently, seven DAC projects worldwide. Most projects are in infancy and do have not been scaled up to meet climate mitigation goals.Vorlage:Cn
Absorption
Absorption in the context of carbon capture refers to the use of a liquid solvent absorbing carbon dioxide from a gas. Amine solvents are most commonly used. This is currently the most common technology for carbon capture. [2]Absorption is the most common method of direct air capture. A fan blows air into a filter that is lined with a liquid solvent absorbent. Currently, the most common sorbents are caustic solution and amine based solvents. Absorption with a caustic solvent is an acid-base reaction in which Vorlage:CO2 reacts with sodium hydroxide and precipitates a stable sodium carbonate. This sodium carbonate is heated to produce a highly pure gaseous Vorlage:CO2 stream.[3]
Adsorption
Adsorption differs from absorption in that the carbon dioxide is removed via a solid.[2] Alternatively, a solid sorbent is used in adsorption. In adsorption, the Vorlage:CO2 binds to a gas-solid contact or. Amine based solid sorbents are often proposed for DAC. Vorlage:CO2 is removed from air by chemisorption, usually through primary amines. Through heat and vacuum the Vorlage:CO2 is then desorbed from the solid sorbent. This results in a gaseous Vorlage:CO2 stream that can be cooled and cycled back into the system.Vorlage:Cn
Membranes
Membrane separations of carbon dioxide rely on semi-permeable membranes to separate carbon dioxide from air. This method differs from the other two in that it requires little water and has a smaller footprint.[2]
Mineralization
In mineral carbonation cations from chemically weathered minerals reaction with atmospheric Vorlage:CO2. In the process mineral carbonates are formed that store the Vorlage:CO2. There are large reserves of magnesium silicate minerals useful for this process. This method is researched because it provides storage for a geological time scale. Current technology requires 1.6 to 3.7 tonnes of rock to fix a tonne of Vorlage:CO2.[3] Since the reaction is exothermic, it produces energy that can be recycled back to source the reactor. The kinetics of this process are slower than adsorption and absorption processes, and storage of carbonated solids must be done with low environmental impact.[3] There are currently no large scale implementation of mineral carbonation. One impedance to the implementation of mineralization is the large energetic costs of the preparation of the solid reactant and its additives.Vorlage:Cn
Energy and water use requirements for direct air capture
Direct air capture of carbon dioxide requires water input. One estimate is that for Absorption, amine based technology, to capture 3.3 Gigatonnes of carbon dioxide a year, the water requirements would be 300km3 a year, or 4% of the water used for irrigation.[1]
In addition to water consumption, direct air capture would require a large amount of energy. This is due to the low concentration of carbon dioxide in air, leading to more energy intensive capture.[4]
Energy estimates
Direct air capture requires more energy than carbon capture from a flue gas because the separation occurs from a highly dilute Vorlage:CO2 stream.[3]Estimates state that Vorlage:CO2 separation requires 1.8 to 3.6 times more energy than flue gas Vorlage:CO2 separation. A minimum of 20 kJ of energy is required to separate one mole of Vorlage:CO2 from an air stream. Energy estimates for contact, separation, release and compression of Vorlage:CO2 are 0.66 GJ/t Vorlage:CO2.Vorlage:Cn
Direct air capture projects and companies around the world
There are currentlyVorlage:When seven direct air capture projects worldwide. The stages of each project vary from in planning, operational and completed.Vorlage:Cn
Antecy
Antecyis a Dutch company that has developed non-amine technology for both DAC (CO2-From-Air) and CC (CO2-From-Point Source). Antecy was founded in 2010 and has a "first of its kind" pilot plant. It unique design allows to operate at large scale considering minimal use of energy, materials and footprint while maximising capacity. Apposed to amine sorbents, Antecy's inorganic solid sorbent provides high stability, robustness and long life. The materials used are non-toxic, disposable and fully recyclable. The Vorlage:CO2 produced does not contain any toxic contaminants, which makes this DAC technology environmentally friendly. Based on current achievements, the estimated cost of CO2 captured from air at large-scale is expected to be $80-100 USD/mt. Estimated costs for CO2 captured from point-sources with higher CO2 concentrations are lower.
Carbon Engineering
Carbon Engineering (CE) is a commercial direct air capture company located in Calgary, Canada and founded in 2009. They currently have a direct air capture pilot plant in British Columbia, Canada that has been in use since 2015. As of 2017, the plant converts a portion of its concentrated Vorlage:CO2 into fuel using enhanced oil recovery. By 2021, the project is expected to implement a full scale direct air capture to liquid fuel plant. The proposed scale of the project would be 2000 barrels a day of fuel that would be distributed to areas with Low Carbon Fuel Standards. Currently, the plant captures 1 ton of Vorlage:CO2 a day and produces 1 barrel of fuel a day using its AIR to FUELS technology.Vorlage:Cn
Climeworks
Climeworks has created a plant in Zurich, Switzerland that is capable of capturing 900 tonnes of CO2 in a year directly from the air. The $23 million plant with 18 capturing units traps enough CO2 to grow vegetables in a nearby greenhouse. Climeworks stated that it costs around $600 to capture one tonne of CO2 from the air.[5]
Climeworks received funding from the European Union to partner with Reykjavik energy to design a pilot plant using direct air capture and carbfix technology. The large-scale plant is expected to remove Vorlage:CO2 from air and sequester it in basalt in Hellisheidi, Iceland. The direct air capture project runs alongside a geothermal powerplant that currently injects and mineralizes Vorlage:CO2 into basalt bedrock. By combining both technologies, Climeworks hopes to produce the first carbon negative power plant. The project is currently testing direct air capture and Vorlage:CO2 injection 700 meters into the ground.Vorlage:Cn
Global Thermostat
Global Thermostat is privately funded carbon capture company located in Manhattan, New York and founded in 2010. Global Thermostat uses amine based sorbents bound to carbon sponges to remove Vorlage:CO2 from the atmosphere. The company has projects ranging from large scale capture at 50,000 tonne/year to small projects at 40 tonne/year.[6] The company claims to produce a 98% pure stream of Vorlage:CO2 from direct air capture.[6] Global Thermostat differentiates itself from other Vorlage:CO2 projects because produces its energy and utilities independently and can be transported to various locations. The company has no post-capture process and sells its Vorlage:CO2 from its remote capture locations.Vorlage:Cn
Center for Negative Emission
The Center for Negative Emission of Arizona State University is currently working on a DAC process using ion exchange resin. The estimated cost of capture is expected to be $30-200 USD/ton Vorlage:CO2. Water is used to desorb the carbon dioxide with an energy requirement of 50 MJ/mol.Vorlage:Cn
Coaway
USA based.
Kilimanjaro Energy
USA based.
Financial costs
Due to high energy consumption, direct air capture is expected to cost around $600 a ton of captured carbon dioxide.[7] A plant designed to capture 1 megatonne of carbon dioxide a year is estimated to cost $2.2 billion.[3]
Cost estimates
One of the largest hurdle to implementation of direct air carbon capture (DAC) are capital and energy costs required to separate Vorlage:CO2 and air.[3] Point source carbon dioxide levels (flue gas of a power plant) are 300 times more concentrated than air.[3] From the Sherwood's Rule the separation costs varies linearly with dilution of the feed stream. Vorlage:CO2 capture costs for hydroxide based solvents generally cost $150 USD/ tonne-CO2. Current liquid amine-based separation is $10-35 USD/ tonne Vorlage:CO2. Adsorption based Vorlage:CO2 capture costs are between $30-200 USD/ tonne Vorlage:CO2. It is difficult to find a specific cost for DAC because each method has wide variation in sorbent regeneration and capital costs.[3] These costs do not take into consideration future plans for the Vorlage:CO2 stream generated. Enhanced oil recovery, urea yield boosting, beverage carbonation and food processing are all economically viable Vorlage:CO2 demands.Vorlage:Cn
References
- ↑ a b Direct Air Capture (Technology Factsheet) In: Geoengineering Monitor, 24. Mai 2018. Abgerufen am 18. November 2018 (amerikanisches Englisch).
- ↑ a b c Smit, Berend, 1962-, Reimer, Jeffrey A. (Jeffrey Allen),, Oldenburg, Curtis M.,, Bourg, Ian C.,: Introduction to carbon capture and sequestration. London, ISBN 978-1-78326-329-5 (worldcat.org).
- ↑ a b c d e f g h Direct Air Capture of CO2 with Chemicals: A Technology Assessment for the APS Panel on Public Affairs. In: www.aps.org. 1. Juni 2011, abgerufen am 7. Dezember 2018.
- ↑ Manya Ranjan, Howard J. Herzog: Feasibility of air capture. In: Energy Procedia. 4. Jahrgang, 2011, ISSN 1876-6102, S. 2869–2876, doi:10.1016/j.egypro.2011.02.193 (doi.org).
- ↑ Jeff Tollefson: Sucking carbon dioxide from air is cheaper than scientists thought. In: Nature. Abgerufen am 7. Dezember 2018.
- ↑ a b Global Thermostat. In: Global Thermostat. Abgerufen am 7. Dezember 2018 (amerikanisches Englisch).
- ↑ Cost plunges for capturing carbon dioxide from the air In: Science | AAAS, 7. Juni 2018. Abgerufen am 19. November 2018 (englisch).