Introduction
The CO2 (carbon dioxide) while itself is not a pollutant, is a greenhouse gas, thus producing global warming. Although there are some voices who disagree with the theory of global warming due to greenhouse gases, the most widespread theory is that the average temperature rise on the planet due to absorption by greenhouse gases solar radiation.
In general, the CO2 is produced during combustion or decomposition of any organic matter. Currently the major source of CO2 is the burning of fossil fuels for energy production (78% approximately), whether derived from petroleum (gasoline, diesel, kerosene, benzene or any other fraction that can be used as fuel), gas natural or coal. To a lesser extent also help cement factories, refineries, steel and petrochemical industry (sectors over 1% contribution).
Among the different strategies that can lead towards the reduction of greenhouse gases is called CO2 capture, although I do not intend in this post explaining the process technically, it is interesting to know the different technologies used for capture.
The capture of carbon dioxide consists of three distinct phases of recruitment, transportation and storage thereof. [1]
In terms of recruitment, we can distinguish four technologies (each is subdivided into more, but I will not dwell) on the one hand is the most proven industrial separation, there are also pre and post combustion, and finally the so-called oxygen -gas is not yet operational.
As for transport by pipeline distinguish the carriage and transport tanks, mainly vessels.
However, the Gordian knot of the question is posed in storage, for that there are different technologies in different stages of development. On the one hand the storage sea (or ocean) by direct injection, this technology is still under investigation. We are also geological storage sites both saline (-in low-capacity general-) as coal or oil deposits. Another system would silicate mineral carbonation or waste materials. As a final way, and the one currently in use is so widespread industrial use of CO2.
A detailed description of the different processes can be found here. [2]
Although I consider the capture of carbon dioxide a good idea, consider also having problems currently intractable in most cases, what happened to reel.
a) Capture.
a.1) The industrial separation works relatively well, and can be performed by several mechanisms, but requires that the CO2 obtained is sufficiently pure for further reaction [See note [3]], it usually requires some expenditure of energy and also processes that can take advantage of the CO2 is not so large as to collect the proceeds of any central. There are also such technologies aimed at the production of H2 for fuel cells, but the fuel cell technology is still developing.
a.2) The pre and post combustion consist of removing the carbon before or after the oxidation / combustion, precombustion CO2 is removed prior to obtaining energy and the afterburner is deleted after the process of obtaining energy.
a.3) The technology of oxygen gas, fuel is burned only in the presence of oxygen, can more easily separate the CO2, but for that you have previously separated oxygen, so again we have an additional energy of around 10% apart from the problems generated by oxidation processes due to the oxygen concentration before combustion.
Courtesy of CO2CRC
Besides these there are other technologies that integrate several industrial processes such as integrated gasification combined cycle (IGCC usually called), which have good prospects for the separation of CO2. [4]
As you can see, so far the technology has advantages and disadvantages, but we must rely on science and technology, I am sure we will overcome the problems, we will do well in less time than estimated and also other techniques that let emerge these back. Training-research-technology should be the basis of the progress of a country. The technological problem is, overcome it.
b) Transportation.
b.1) ships, trucks and in general all forms of motor transport, polluting fossil fuel and generate CO2. Paradoxical truth. Emit CO2 to emit less CO2. That for now is not avoidable.
b.2) The pipeline may be well, but in general we talk about environmental impacts unassumable to paths that are not anywhere near the coast to the loading dock, or production areas that are not extremely close storage areas.
The problem is complex to overcome, given that current construction of power plants is liberalized and thus depends much more on the interests of production companies and facilities that put autonomous communities for the construction of these infrastructures that environmental criteria. [5] So both the motor vehicle transport, energy waste because they imply, as the construction of pipelines due to its environmental solutions are bad because they create a new environmental problem in trying to solve another.
c) Storage.
c.1) The ocean injection method involves injecting water sources, typically in oceans, carbon dioxide, until now the seas have been the main consumers of CO2, since most of it is removed does natural absorption by the oceans. This technology presents a difficult problem, most living in the oceans are very sensitive to changes in the acidity of water, CO2 injection significantly acidify the water, therefore has unpredictable consequences for aquatic ecosystems and currently are the main sink for CO2.
c.2) The geological storage is probably the most secure system that exists. Although several methods have mainly CO2 is injected in liquid or gas impermeable layers as possible or store in mines and oil wells.
Storage strata technically difficult drilling and sealing of the layers that store, but it has an even larger question what we can store gas volume without altering geological strata and how long it will stay there carbon dioxide?
Anyone imagine the kind of catastrophe that would occur if the injection disrupt the stratum in which it sits to the point of moving, either by injection volume as possible reactions with CO2. Would be talking about earthquakes, landslides to greater or lesser scale, change the paths of rivers, etc. On the other hand is almost impossible to predict whether the outputs of the stratum find gas once you reach a certain pressure.
The storage in mines, is a particularly complex since reached a certain pressure, the shift of their positions CO2 to methane, hard up again, however this methane would end up in the atmosphere has a net contribution to the greenhouse effect much greater than of CO2. Therefore we have not solved the problem at all (then comment on the other side of the problem) of climate change.
Storage in oil wells may be less problematic, because in principle could displace oil or natural gas to facilitate its removal.
c.3) The mineral carbonation, is reacting the CO2 with no carbonate minerals such as carbonates and silicates to produce silicon dioxide, silicates are abundant resources and would be quite likely to be found in areas near the sources of mass production CO2, just as the resulting product is stable (mainly calcite, magnesite, dolomite and siderite [6]) and therefore would be a form of permanent storage. This reaction occurs slowly in nature when carbon dioxide is carried by rainwater and it is these minerals. However, the two fundamental ways to generate these compounds undergo extract and make them react in a controlled manner, and therefore to mine ore with its environmental consequences or to achieve a reaction in the geologic strata themselves, but the increased volume of these substances around 75% -100%, which is again facing an enormous danger to the stability of geological strata. The carbonation of waste is still under investigation.
c.4) industrial reactivity is undoubtedly the best way, since it would take advantage of problematic waste as raw material, but the industrial need of CO2 is much lower than its production.
Courtesy CO2CRC
Author’s opinion.
I believe that CO2 capture and storage is a technique that should be further investigated, especially in the most unexplored and carbonation reactions, the reaction to waste, and new applications that can be achieved industral from carbon dioxide carbon. However, the fanfare of these initiatives comes from the research and it does not even concern about climate change. The CO2 capture and storage for large electricity producers is how to kick the problem for a good number of years (from 100 to 400 for example) and to continue with the production of electricity without having to pay the fees shall be imposed due to climate change. Of course there are ways to trap CO2 capture without the output of a power plant, is actually a little absurd (just a little) having to clean the air to the central entrance and do not clean the air. No more. Ie put CO2 purification [7], however this technology does not bring huge profits to utilities.
It is quite clear that this technology will not arrive in time to avert climate change, but utilities are terribly interested in that they are not displayed to them as guilty and pay the minimum possible for an increasing share of electricity production is funny how most governments, including the Spanish give priority to this type of research (as grants), compared to other energy developments more environmentally friendly (- go if installed in the right places-) such as solar or wind power.
Courtesy Greepeace.
Storing the CO2, with no guarantees that stays where you put forever is a way to continue consuming power irresponsibly, leaving the problem to our grandchildren.
If we think the challenge is to halt climate change, we must think about systems that harness the energy and produce no carbon dioxide, it is necessary that the 12.5 Tw consumed in the world (estimated at about 16.9 TW by 2030), obtained from renewable sources, mainly wind, solar and hydropower in their respective forms of the disease. (They are often referred to as VAS, Wind, Water and Sun.) And that is possible [8]. Of course there will be technical and scientific problems, but they will be met, for sure.
Conclusions
CO2 capture is a technique that should be improved, given that the future can have a high importance both to eliminate carbon dioxide and discharged to the atmosphere, to take advantage of the CO2 in reactions that generate environmental problems but should not be our main effort since the technique is not currently prepared or safe or for use, we must invest in my humble opinion on reducing emissions and using energy reasonably be produced from renewable energy sources.
Bibliography and notes.
[3] never cease to be amazed by some reports of power companies, they say that their plants do not emit NOx or drop or SO2 in environmental impact studies are those that recognize that it is expensive to clean up these substances CO2 final and so the technology is expensive to recover pure CO2 for industrial processes.
[5] La liberalización de los mercados energéticos; L. Martínez; 2006;Viento Sur; Nº 89; paxs 58-68
[6] http://www.igme.es/internet/divulgacion_didactica/Secuestro/06-Otros.htm
[7] Limpiar el carbono del aire; K.S. Lackner; Agostu 2010; Investigación y Ciencia; Núm 407; paxs 46-51
[8] Energía Sostenible, objetivo 2030; M. Z. Jacobson, M. A Delucchi;Xineru de 2010; Investigación y Ciencia; Núm 400; paxs 20-27.
