Carbon dioxide air capture
Encyclopedia
Carbon dioxide removal methods refers to a number of technologies which reduce the levels of carbon dioxide
in the atmosphere. Among such technologies are bio-energy with carbon capture and storage
, biochar
, direct air capture, ocean fertilization and enhanced weathering
.
CDR is a different approach to removing CO2 from the stack emissions
of large fossil fuel
point sources, such as power station
s, as this reduces emission to the atmosphere but cannot reduce the amount of carbon dioxide already in the atmosphere. It is by some regarded as a branch of geoengineering
, while other commentators regard CDR as a form of carbon capture and storage
.
CDR methods are supported by a range of individuals and organisations such as IPCC
chief Rajendra Pachauri, the UNFCCC executive secretary Christiana Figueres
, the World Watch Institute, the World Wide Fund for Nature WWF
and the Lenfest Center for Sustainable Energy at the Earth Institute, Columbia University.
As CDR removes carbon dioxide from the atmosphere, it creates negative emissions
, which is a cost effective way of dealing with small and dispersed point sources such as domestic heating systems, airplanes and vehicle exhausts.
The mitigation
effectiveness of air capture is limited by societal investment, land use, and availability of geologic reservoirs. These reservoirs are estimated to be sufficient to sequester all anthropogenically generated CO2.
project.
and science writer Robert Kunzig
, imagines huge numbers of artificial trees around the world to remove ambient CO2. The technology is now being pioneered by Klaus Lackner
, a researcher at the Earth Institute, Columbia University
, whose artificial tree technology can suck up to 1,000 times more CO2 from the air than real trees can, at a rate of about one ton of carbon per day if the artificial tree is approximately the size of an actual tree. The CO2 would be captured in a filter and then removed from the filter and stored.
The chemistry used is a variant of that described below, as it is based on sodium hydroxide. However, in a more recent design proposed by Klaus Lackner
, the process can be carried out at only 40 °C by using a polymer
-based ion exchange resin
, which takes advantage of changes in humidity
to prompt the release of captured CO2, instead of using a kiln. This reduces the energy required to operate the process.
covered the work of David Keith, of University of Calgary
, who built a tower, 4 feet wide and 20 feet tall, with a fan at the bottom that sucks air in, which comes out again at the top. In the process, about half the CO2 is removed from the air.
This device uses the chemical process described in detail below. The system demonstrated on the discovery channel was a 1/90,000th scale test system of the capture section, the reagents are regenerated in a separate facility. The main costs of a the full plant will be the cost to build it, and the energy input to regenerate the chemicals and produce a pure stream of CO2.
To put this into perspective, people in the U.S. emit about 20 tonnes of CO2 per person annually. In other words, each person in the U.S. would require a tower like the one featured on the discovery channel to remove this amount of CO2 from the air, requiring an annual 2 Megawatt-hours of electricity to operate it. By comparison, a refrigerator consumes about 1.2 Megawatt-hours annually (2001 figures). But by combining many small systems such as this into one large system the construction costs and energy use can be reduced.
It has been proposed that the Solar updraft tower
to generate electricity from thermal air currents also be used at the same time for amine gravity scrubbing of CO2. Some heat would be required to regenerate the amine.
mixed with steam
at 400 °C (forming calcium carbonate
) and release it at 1,000 °C. This process, proposed by Steinfeld
, can be performed using renewable energy
from thermal concentrated solar power.
estimates the costs for direct air capture to $600/tonne with optimistic assumptions. The IEA Greenhouse Gas R&D Programme
and Ecofys provides an estimate where 3.5 billion tonnes could be removed annually from the atmosphere with BECCS (Bio-Energy with Carbon Capture and Storage) at carbon prices as low as €50, whereas a report from Biorecro
and the Global Carbon Capture and Storage Institute estimates costs "below €100" per tonne for large scale BECCS deployment.
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the atmosphere. Among such technologies are bio-energy with carbon capture and storage
Bio-energy with carbon capture and storage
Bio-energy with carbon capture and storage is a greenhouse gas mitigation technology which produces negative carbon emissions by combining biomass use with geologic carbon capture and storage....
, biochar
Biochar
Biochar or terra preta is charcoal created by pyrolysis of biomass. Biochar is under investigation as an approach to carbon sequestration via bio-energy with carbon capture and storage. Biochar thus has the potential to help mitigate climate change, via carbon sequestration...
, direct air capture, ocean fertilization and enhanced weathering
Enhanced weathering
Enhanced weathering refers to chemical approach to geoengineering involving land or ocean based techniques. Examples of land based enhanced weathering techniques are in-situ carbonation of silicates. Ultramafic rocks, for example, have the potential to store 500 years worth of production according...
.
CDR is a different approach to removing CO2 from the stack emissions
Carbon capture and storage
Carbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...
of large fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
point sources, such as power station
Power station
A power station is an industrial facility for the generation of electric energy....
s, as this reduces emission to the atmosphere but cannot reduce the amount of carbon dioxide already in the atmosphere. It is by some regarded as a branch of geoengineering
Geoengineering
The concept of Geoengineering refers to the deliberate large-scale engineering and manipulation of the planetary environment to combat or counteract anthropogenic changes in atmospheric chemistry The Intergovernmental Panel on Climate Change concluded in 2007 that geoengineering options, such...
, while other commentators regard CDR as a form of carbon capture and storage
Carbon capture and storage
Carbon capture and storage , alternatively referred to as carbon capture and sequestration, is a technology to prevent large quantities of from being released into the atmosphere from the use of fossil fuel in power generation and other industries. It is often regarded as a means of mitigating...
.
CDR methods are supported by a range of individuals and organisations such as IPCC
IPCC
IPCC may refer to:*Intergovernmental Panel on Climate Change, of the United Nations*Independent Police Complaints Commission, of England and Wales*Irish Peatland Conservation Council...
chief Rajendra Pachauri, the UNFCCC executive secretary Christiana Figueres
Christiana Figueres
Karen Christiana Figueres Olsen was appointed Executive Secretary of the UN Framework Convention on Climate Change on 17 May 2010, succeeding Yvo de Boer. She had been a member of the Costa Rican negotiating team since 1995, involved in both UNFCCC and Kyoto Protocol negotiations. She has...
, the World Watch Institute, the World Wide Fund for Nature WWF
World Wide Fund for Nature
The World Wide Fund for Nature is an international non-governmental organization working on issues regarding the conservation, research and restoration of the environment, formerly named the World Wildlife Fund, which remains its official name in Canada and the United States...
and the Lenfest Center for Sustainable Energy at the Earth Institute, Columbia University.
As CDR removes carbon dioxide from the atmosphere, it creates negative emissions
Negative carbon dioxide emission
A negative carbon dioxide emission or negative emission is a permanent removal of the greenhouse gas carbon dioxide from the atmosphere. It is considered the direct opposite of carbon dioxide emission, hence its name...
, which is a cost effective way of dealing with small and dispersed point sources such as domestic heating systems, airplanes and vehicle exhausts.
The mitigation
Mitigation of global warming
Climate change mitigation is action to decrease the intensity of radiative forcing in order to reduce the potential effects of global warming. Mitigation is distinguished from adaptation to global warming, which involves acting to tolerate the effects of global warming...
effectiveness of air capture is limited by societal investment, land use, and availability of geologic reservoirs. These reservoirs are estimated to be sufficient to sequester all anthropogenically generated CO2.
Enhanced Weathering
This is being attempted at the CarbFixCarbFix
CarbFix is a project in Iceland intended to lock away carbon dioxide by reacting it with basaltic rocks. Work on the project began in 2007. The CarbFix team involves American and Icelandic designers researchers including Iceland geologist Sigurdur Reynir Gislason serving as chief scientist, project...
project.
Artificial trees
A notable example of an atmospheric scrubbing process are the artificial trees. This concept, proposed by climate scientist Wallace S. BroeckerWallace S. Broecker
Wallace Smith Broecker is the Newberry Professor in the Department of Earth and Environmental Sciences at Columbia University and a scientist at Columbia's Lamont-Doherty Earth Observatory...
and science writer Robert Kunzig
Robert Kunzig
Robert Kunzig is an award-winning scientific journalist, specializing in the topic of oceans. He works at the European division of Discover magazine and is a regular contributor to National Geographic...
, imagines huge numbers of artificial trees around the world to remove ambient CO2. The technology is now being pioneered by Klaus Lackner
Klaus Lackner
Klaus Lackner is a professor in the Department of Earth and Environmental Engineering at Columbia University and co-founder of in Tucson, AZ. Lackner pioneered the concept of carbon dioxide air capture as a means for climate change mitigation, i.e. abating emissions of greenhouse gases into the...
, a researcher at the Earth Institute, Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
, whose artificial tree technology can suck up to 1,000 times more CO2 from the air than real trees can, at a rate of about one ton of carbon per day if the artificial tree is approximately the size of an actual tree. The CO2 would be captured in a filter and then removed from the filter and stored.
The chemistry used is a variant of that described below, as it is based on sodium hydroxide. However, in a more recent design proposed by Klaus Lackner
Klaus Lackner
Klaus Lackner is a professor in the Department of Earth and Environmental Engineering at Columbia University and co-founder of in Tucson, AZ. Lackner pioneered the concept of carbon dioxide air capture as a means for climate change mitigation, i.e. abating emissions of greenhouse gases into the...
, the process can be carried out at only 40 °C by using a polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
-based ion exchange resin
Ion exchange resin
An ion-exchange resin or ion-exchange polymer is an insoluble matrix normally in the form of small beads, usually white or yellowish, fabricated from an organic polymer substrate. The material has highly developed structure of pores on the surface of which are sites with easily trapped and...
, which takes advantage of changes in humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
to prompt the release of captured CO2, instead of using a kiln. This reduces the energy required to operate the process.
Scrubbing towers
In 2008, the Discovery ChannelDiscovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
covered the work of David Keith, of University of Calgary
University of Calgary
The University of Calgary is a public research university located in Calgary, Alberta, Canada. Founded in 1966 the U of C is composed of 14 faculties and more than 85 research institutes and centres.More than 25,000 undergraduate and 5,500 graduate students are currently...
, who built a tower, 4 feet wide and 20 feet tall, with a fan at the bottom that sucks air in, which comes out again at the top. In the process, about half the CO2 is removed from the air.
This device uses the chemical process described in detail below. The system demonstrated on the discovery channel was a 1/90,000th scale test system of the capture section, the reagents are regenerated in a separate facility. The main costs of a the full plant will be the cost to build it, and the energy input to regenerate the chemicals and produce a pure stream of CO2.
To put this into perspective, people in the U.S. emit about 20 tonnes of CO2 per person annually. In other words, each person in the U.S. would require a tower like the one featured on the discovery channel to remove this amount of CO2 from the air, requiring an annual 2 Megawatt-hours of electricity to operate it. By comparison, a refrigerator consumes about 1.2 Megawatt-hours annually (2001 figures). But by combining many small systems such as this into one large system the construction costs and energy use can be reduced.
It has been proposed that the Solar updraft tower
Solar updraft tower
The solar updraft tower is a renewable-energy power plant. It combines the chimney effect, the greenhouse effect and the wind turbine. Air is heated by sunshine and contained in a very large greenhouse-like structure around the base of a tall chimney, and the resulting convection causes air to...
to generate electricity from thermal air currents also be used at the same time for amine gravity scrubbing of CO2. Some heat would be required to regenerate the amine.
Quicklime process
Quicklime will absorb CO2 from atmospheric airAtmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
mixed with steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
at 400 °C (forming calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
) and release it at 1,000 °C. This process, proposed by Steinfeld
Steinfeld
-Germany:*Steinfeld, Bavaria, a town in the district of Main-Spessart, Bavaria*Steinfeld, Lower Saxony, a municipality in the district of Vechta, Lower Saxony*Steinfeld, Mecklenburg-Vorpommern, a municipality in the district of Bad Doberan, Mecklenburg-Vorpommern...
, can be performed using renewable energy
Renewable energy
Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...
from thermal concentrated solar power.
Economic factors
A crucial issue for CDR methods is their cost, which differs substantially among the different technologies, some which are not developed enough to perform cost assessments of. The American Physical SocietyAmerican Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...
estimates the costs for direct air capture to $600/tonne with optimistic assumptions. The IEA Greenhouse Gas R&D Programme
IEA Greenhouse Gas R&D Programme
The IEA Greenhouse Gas R&D Programme is an Implementing Agreement of the International Energy Agency, and was founded in 1991. IEA GHG is an international collaborative research programme focusing its efforts on studying technologies to reduce greenhouse gas emissions...
and Ecofys provides an estimate where 3.5 billion tonnes could be removed annually from the atmosphere with BECCS (Bio-Energy with Carbon Capture and Storage) at carbon prices as low as €50, whereas a report from Biorecro
Biorecro
Biorecro is a Swedish cleantech company deploying the BECCS technology through sales of negative emission carbon credits and carbon offsets. Founded in 2007, it is based in Stockholm, Sweden...
and the Global Carbon Capture and Storage Institute estimates costs "below €100" per tonne for large scale BECCS deployment.
See also
- BiorecroBiorecroBiorecro is a Swedish cleantech company deploying the BECCS technology through sales of negative emission carbon credits and carbon offsets. Founded in 2007, it is based in Stockholm, Sweden...
- Carbon negativeCarbon negativeCarbon negative is an adjectival phrase used to describe any process that removes carbon dioxide from the atmosphere, with the intent to avoid global warming.-Carbon dioxide sinks and carbon negativity:...
- Climate change mitigation scenariosClimate change mitigation scenariosClimate change mitigation scenarios are possible futures in which global warming is reduced by deliberate actions, such as a comprehensive switch to energy sources other than fossil fuels...
- GeoengineeringGeoengineeringThe concept of Geoengineering refers to the deliberate large-scale engineering and manipulation of the planetary environment to combat or counteract anthropogenic changes in atmospheric chemistry The Intergovernmental Panel on Climate Change concluded in 2007 that geoengineering options, such...
- Lithium peroxideLithium peroxideLithium peroxide is the inorganic compound with the formula Li2O2. This solid was deployed to remove CO2 from the atmosphere in the vehicles used in Apollo mission.-Preparation:...
- List of emerging technologies
- Low-carbon economyLow-carbon economyA Low-Carbon Economy or Low-Fossil-Fuel Economy is an economy that has a minimal output of greenhouse gas emissions into the environment biosphere, but specifically refers to the greenhouse gas carbon dioxide...
- Negative emissionNegative carbon dioxide emissionA negative carbon dioxide emission or negative emission is a permanent removal of the greenhouse gas carbon dioxide from the atmosphere. It is considered the direct opposite of carbon dioxide emission, hence its name...
- Virgin Earth ChallengeVirgin Earth ChallengeThe Virgin Earth Challenge is a competition offering a $25 million prize for whoever can demonstrate a commercially viable design which results in the permanent removal of greenhouse gases out of the Earth's atmosphere, so as to contribute materially to avoid global warming...
- Carbon dioxideCarbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
for chemical transformations