Tuesday 12 May 2015

New energy technology to address the issue of atmospheric carbon dioxide

Cryogenic carbon capture





Cryogenic Carbon Capture

Cryogenic Carbon Capture™ (CCC) is a post-combustion technology that has the potential to reduce carbon emissions from fossil-fueled power plants by 95–99%, at half the cost and energy of current state-of-the-art carbon capture processes. In addition, CCC also removes other pollutants, such as SOX, NOX, and mercury.
  • Up to 99% CO2 capture
  • Less than $30 per ton of captured CO2
  • Less than 15% parasitic load
  • Additional cost and energy savings when retrofitted to existing plants
  • Demonstated on-site at coal-fired power plants
  • Uses scalable equipment familiar to the power industry
  • Allows for high-efficiency energy storage
Cryogenic Carbon Capture can be implemented as a retrofit or greenfield installation in one of three ways:
Compressed Flue Gas™ (CCC-CFG)External Cooling Loop™ (CCC-ECL)Energy Storing™ (CCC-ES)

How CCC Works

Click to expand
CCC uses phase change to separate CO2 and other pollutants from exhaust or process gases. In CCC the CO2 is cooled to such a low temperature (about -140 °C) that it desublimates, or changes from a gas to a solid. The solid CO2 is separated from the remaining gas, pressurized, melted, and delivered at pipeline pressure. The captured CO2 can be used in many applications, including enhanced oil recovery (EOR) and biofuels production. The gas that remains after the CO2 and other pollutants have been removed is nearly pure nitrogen, and can be safely released to the atmosphere.

Additional Benefits

Pollutant Capture

In addition to capturing 95–99% of carbon, CCC also captures other pollutants such as NOX, SOX, and mercury (Hg). In greenfield installations, the pollutant capture capability of CCC can offset the cost of traditional pollutant removal systems.
The pollutants are captured using desublimation—the same mechanism used to capture CO2. At lower temperatures, higher quantities of the pollutants are captured. At low enough temperatures, the exhaust exiting the stack actually has less CO2 content than the surrounding air.
Temperature (°C)What's Captured
-48100% of the mercury in coal
-77All of the above, plus 99% of the mercury from the atmosphere
-117All of the above, plus 90% of the CO2 from coal; SO2 EPA standard met
-132All of the above, plus 99% of the CO2 from coal
-143All of the above, plus 100% of the CO2 from coal. Below this point, the exhaust exiting the stack is cleaner than the surrounding air.
-150All of the above, plus 80% of the CO2 from the atmosphere
-162All of the above, plus 99.5% of the CO2 from the atmosphere

Steam Cycle Integration

In greenfield installations, the warm exhaust gas entering the CCC process can first be used to heat the feed water to the boiler. This boosts the steam cycle efficiency and power output of the plant. The plant can provide more power for the same initial investment.

Energy and Economics

CCC can capture carbon for a fraction of the cost and energy of current methods. When considering the additional benefits of pollutant capture and steam cycle integration, the cost is even lower.

Projected first year costs and parasitic load of CCC with varous integration options in a greenfield installation
Existing carbon capture technologies aren't cheap. According to the National Energy Technology Laboratory (NETL), a current state-of-the-art amine absorption process would cost $69/tonne of avoided CO2. The same reduction of carbon emissions can be acheived using CCC at a cost of $35/tonne avoided. When considering the cumulative effects of CCC's additional benefits, the cost drops to only $14/tonne avoided.
CCC also requires only half the energy as a current state-of-the-art amine absorption process. Energy requirements for carbon capture technologies are often reported as parasitic load, which is the fraction of power generated by the plant that is used by the carbon capture system. The parasitic load of the base CCC process with no plant integration is about 14%, compared to 28% for the amine absorption process.
CCC's energy efficiency and low parasitic load are mainly due to effective heat integration. The cold products, including solid CO2, are used to cool the flue gas entering the process. The Energy Storing (CCC-ES) implementation also allows for very efficient grid-scale energy storage—enabling better use of renewable energy sources and virtually eliminating CCC's parasitic load during peak demand times.

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