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Carbon dioxide is emitted in countless industrial and consumer applications. The sources of carbon dioxide are incredibly varied: from coal power plants to cement factories, from commuting to work in Los Angeles to farming practices in South America. For hundreds of years, these sources of carbon dioxide have been ignored. With modern data increasingly implicating carbon dioxide in climate change, environmental and political leaders have begun raising the call to do something about all these emissions. Up until recent times, efforts to lower carbon dioxide emissions have focused upon sequestration; that is, storage of carbon dioxide either in tanks or deep underground. However, several scientific advances are now leading to the possibility of using the carbon dioxide rather than hiding it away.
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What is CO2 Used For Now?
Carbon dioxide is already used in a wide array of technologies. According to Stephen K. Ritter, editor of Chemical & Engineering news, industrial uses of carbon dioxide exceed 115 million tons per year. Carbon dioxide is used in welding, industrial lasers, pneumatic systems, fertilizer manufacture, and as a solvent in the chemical industry. It also finds wide use in the petroleum and mining industries, where it is used to assist in oil recovery from wells.
Although carbon dioxide is already in demand, current uses are dwarfed by emissions: total worldwide emissions are approximately 24 billion tons annually, or over two hundred times as much as is used by industry. With such a large disparity between the amount carbon dioxide used and emitted, it is obvious that current technologies are inadequate for dealing with the issue.
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Use with Citrus Fruits to make Plastic
Luckily, a number of scientists have turned their focus towards finding more ways of using up carbon dioxide. Researchers at Cornell University in Ithaca, New York have discovered a method to turn citrus fruits and carbon dioxide into plastics. The polymer they created is called polylimonene carbonate, and has similar properties to polystyrene. Polystyrene is a petroleum-based polymer widely used in making inexpensive plastic products. If the Cornell researchers' invention gains use in industry, it may decrease the use of oil (and thus emissions of harmful greenhouse gases) as well as substantially increasing the use of carbon dioxide. Because the carbon dioxide is chemically altered to form polymer chains, this process semi-permanently removes the gas from the atmosphere.
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Use in Fuels
Another area of research is using carbon dioxide in fuels. Researchers in the United Kingdom have investigated methods for converting carbon dioxide to formic acid, chemical formula HCOOH. Once the reaction is complete, the formic acid may be used directly as a fuel to power fuel cells. Formic acid could also be further modified into other fuels.
Researchers at the University of California, San Diego hve invented a method along similar lines to the formic acid approach. In this novel approach, the chemists used a solar cell to convert CO2) to carbon monoxide (CO) and oxygen as well as generating electricity.
Though carbon monoxide is a poison to humans, it is extremely useful in industry. It finds use in both medicine and the chemical industry, and was approved for use in maintaining meat coloring by the FDA in 2004.
In the chemical industry, carbon monoxide is used in most production of acetic acid. It is also used in purifying nickel (in the Mond process). In medicine, recent research is pointing towards carbon monoxide's potential use as an antioxidant and anti-inflammatory agent.
Most intriguingly, however, carbon monoxide may be hydrogenated to form liquid fuels. Thus, this solar cell may be used to produce carbon monoxide, which may be further refined into a fuel which could be used in place of petroleum products or coal. Since the carbon monoxide would be obtained from carbon dioxide in the air, burning the fuel would be essentially carbon neutral.
These potential uses are just a few of the hundreds currently being researched. With any luck, these new uses will enter the marketplace within the next decade. In combination with current uses and some sequestration, it may be possible to largely mediate humanity's emissions of carbon dioxide in the foreseeable future.