Capturing and converting CO2 from flue gas into useful materials.

    0
    55
    Cuycha, a Finnish company, has developed a process for capturing and converting CO2 from flue gas into useful materials by reacting it with naturally occuring minerals.
    By Ilkka Nurmia, CEO, Cuycha Innovation Oy


    There are three natural sinks for the CO2 in the atmosphere: oceans, green organisms, and rock weathering.
    The first sink, oceans, is problematic because increasing amounts of CO2 in the atmosphere will lead to the acidification of the oceans as this acidic gas dissolves into ocean water. This already endangers coral reefs, which are important to the whole ecosystem of oceans.
    Green organisms, such as trees on land, are beneficial as long as the carbon they remove from the atmosphere is not allowed to return to it through rotting vegetation or forest fires. Most secure are aquatic green organisms such as algae, which use carbon to build shells from calcium carbonate. These shells will eventually sink onto the sea bottom and become stable minerals such as limestone.
    The process of rock weathering starts with rain. Approximately 505,000 cubic kilometers (121,000 cu mi) of water falls as precipitation each year with 398, 000 cubic kilometers (95,000 cu mi) of it over oceans.
    Given the Earth’s surface area, that means the globally-averaged annual precipitation is 990 millimeters (39 in) (Wikipedia: Global climatology).
    This water is in equilibrium with the carbon dioxide content of the air at the temperature and atmospheric pressure prevailing in the location of the rainfall. The solubility of CO2 in water at 150 C is 2,1 g/liter per bar of CO2 pressure (www.engineeringtoolbox.com/gases-solubility-water).
    Assuming that the precipitation takes place at sea level at 150 C and the concentration of CO2 in the air is 390 parts per million in volume ( Wikipedia: Carbon dioxide in Earth’s atmosphere), this corresponds to a CO2 concentration of 0,82 g per ton of rainwater.
    The total amount of CO2 in the rainwater falling on the land is then 88 million tons per year. This CO2 does not end up in the ocean; it is converted into bicarbonate in the process of rock weathering. If all CO2 is converted into bicarbonate, the concentration of the latter in the water would be 120 mg/L. Comparing this with the measured amount of bicarbonate in the St. Lawrence River water, 110 mg/L (Kirk-Othmer, Encyclopedia of Chemical Technology 4th Ed., Vol. 25, p.374,Wiley & Sons), indicates that the CO2 in rainwater is indeed efficiently neutralized intobicarbonates. The bicarbonates formed in natural weathering flow in river water into the seas where coral polyps and other organisms use them as building material.
    This forms a CO2 sink, which together with the photosynthesis in green plants removes CO2 from the atmosphere.
    Cuchya’s process provides a simple way to direct our CO2 emissions into this sink. The bicarbonates end up in the oceans but they do not cause acidification; on the contrary, this process offers asolution to the CO2 problem through neutralizing the CO2 with feldspar minerals into harmless bicarbonates.


    Using feldspars to neutralize CO2



    Feldspars (KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8) are a group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth’s crust (Wikipedia: Feldspar). The above formulas are those of potassium-aluminum feldspar (orthoclase), sodium-aluminum feldspar (albite), and calcium-aluminum feldspar (anorthite). Pure anorthite is able to neutralize ca. 320 kg CO2 per ton while the neutralizing ability of other feldspars varies between 150 and 300 kg CO2 per ton depending on their anorthite content.
    The aluminum content of feldspars varies from approximately 10 % in orthoclase and albite to 19 % in anorthite. The most efficient feldspar in the neutralizing process is anorthite: its weathering follows the reaction CaAl2Si2O8 + 2CO2 + H2O Ca2+ + 2HCO3- + 2SiO2 + 2Al(OH)3 .The aluminum in anorthite is liberated as aluminum hydroxide, Al(OH)3 . This is easily converted into aluminum oxide (alumina), Al2O3 .
    The neutralization of one ton of carbon dioxide with anorthite produces about one ton of alumina plus 1,3 tons of quartz. Pure quartz sand sells for about US$ 70-300 per ton.
    Alumina is a major commodity. It is used in the ceramics industry and aluminium produc-tion and its price is about US$ 300 per ton.
    The logistics of this new way are determined by the amount of feldspar required. Taking a coal-fired power plant as an example, one ton of coal contains about 80 % of carbon and will produce 2,9 tons of CO2, which will require 9,2 tons of anorthite and theoretically produce about 3 tons of alumina.
    Using albite feldspar the neutralization of the CO2 from the combustion of one ton of coal will require 17,3 tons of feldspar and again produce 3 tons of alumina.
    Neutralizing the CO2 from a ton of coal requires about ten tons of anorthite to be mined and shipped to the neutralization process. However, even ignoring the value of the quartz sand and other byproducts, the alumina produced corresponds to ca. $3000 for each ton of coal and $ 300 for each ton of anorthite. Thermal coal costs about $100 per ton, yet coal is often transported by rail for hundreds of kilometers. It follows that the main economic aspect in the neutralization of CO2 with feldspar is the value of the alumina produced. In other words, we are discussing a revolutionary way of alumina production and not just a way to neutralize CO2 .
    New power plants, cement factories, etc., can be located close to feldspar formations, or a pipeline can be used to ship the CO2 from them to the feldspar mine for neutralization.

    The CCN process


    The CCN process begins with the capture of CO2 from flue gases. In current technology this requires either energy-consuming separation technology or oxygen combustion with the expense and energy consumption of an air separation unit. In our technology the CO2 is captured from flue gas by washing the latter with water. The method has been patented (Finnish patent 121216 and WO 2010/000937). The neutralization process has been studied at the Chemistry Department, University of Jyvaskyla. It is illustrated in Fig. 1.
    Flue gas at normal pressure is cooled in a heat exchanger 21 and pressurized in turbo- compressor 22 (Fig. 1), preferably equipped with water injection, to ca. 5 bar.
    If the flue gas contains 16 % CO2 , the CO2 partial pressure at a total pressure of 5 bar is 0,8 bar. A ton of water at +50 will dissolve 2.4 kg of CO2 from the gas. The dissolution takes place in column 23 into which cold water is sprayed from connection 12. The flue gas exiting from column 23 is warmed in heat exchanger 21 and expanded in turbine 26 to recover part of the compression energy.
    The CO2 solution exiting from column 23 is passed into neutralization tank 24 filled with crushed feldspar. From there the neutralized solution passes into settling tank 25, where the insoluble aluminum compounds settle. The solution can then exit the process or it can be recycled into the CO2 dissolution process.
    In order to keep the amount of water needed for the dissolution within reasonable limits, the partial pressure of CO2 should be sufficiently high, in practice at or above 0.4 bar. The amount of water required in the process can be reduced by recycling a part of the bicarbonate solution formed back to the neutralization process. The dissolution and neutralization processes can also be combined to take place in one container filled with crushed rock. If air with an oxygen content of 40 % produced according to our patent 111187 is used in the combustion process, the flue gas will contain ca.30 % CO2 and its partial pressure at a total pressure of 5 bar will be 1.5 bar. One ton of water at +50 will now dissolve 4,5 kg of CO2 . Besides alumina and quartz sand, other possible byproducts in the neutralization include lithium. Instead of replacing other cations in feldspars it tends to form lithiumaluminum silicate, spodumene, LiAl(SiO3)2. One ton of spodumene can neutralize about 240 kg CO2 , and in addition to aluminum it would yield ca. 200 kg of lithium carbonate. The carbonate costs about US$ 10 /kg.
    Our process differs from so-called carbonization, where CO2 is neutralized with carbonate minerals such as limestone. Carbonates are much less plentiful than silicates in the Earth’s crust and they yield no valuable byproducts in the neutralization. Carbonization also mobilizes large quantities of carbon from the carbonate minerals.
    In summary, our method offers a double opportunity: we can simultaneously convert acidic CO2 into harmless bicarbonates and utilize the enormous quantities of aluminium in silicate minerals. This can be done without expensive chemicals or crippling amounts of energy.
    CCN project in South Africa

    Representatives from Cuycha Innovation will be travelled to the Republic of South Africa to start a massive CCNproject with CircleLink Holdings (circlelinkholdings.net) and other strategic partners. The consortium being formed is committed to producing the first low/zero-emission plant using Cuycha’s CCN-process.
    South Africa was selected for the government’s strong support of innovative new technologies with positive ecological impact.
    Discussions are underway and a meeting is planned with the Industrial Development Corporation (www.idc.co.za) in South Africa to provide the necessary funding for the project. The consortium will of course be totally BEE & BBBEE compliant.
    Besides building the first CCN pilot plant, the project will test many new ideas to minimize, or totally remove, other harmful by-products of industry and convert them to useful commodities for additional revenue.
    Interest in the CCN-process has already spread to neighboring Botswana and a similar project may soon be started there.


    More information:

    Cuyha Innovation Oy was founded in 2004 by renowned nuclear physicist Matti Nurmia to manage and develop his inventions. Most of Dr. Nurmia’s inventions relate to energy production and environmental issues.
    In February of 2010, Dr. Nurmia decided to concentrate his energy into inventing and passed the leadership of the company to his son. Ilkka Nurmia took over as CEO on Feb. 21, 2010.

    Comments

    comments