Post combustion capture (PCC), a process that captures CO2 from power station flue gases, is a key technology with the potential to substantially reduce the greenhouse gas intensity of existing and future coal power stations.
When coupled with CO2 sequestration, post combustion capture (PCC) offers the potential for near-zero emissions from power stations.
CSIRO’s Energy Technology Division, as part of the Energy Transformed Flagship program, has committed significant resources towards PCC research and development.
How PCC works
In a traditional power station, coal is pulverised and burnt to produce high pressure steam. The steam is expanded in turbines, which turn generators to produce electricity. Flue gases leaving the boiler are filtered to remove dust and then vented to the atmosphere. These gases contain around 10 to 15 per cent CO2.
PCC enables the capture of most of the CO2 from power stations. Flue gas is cooled and cleaned then fed into the bottom section of a CO2 absorber where it passes through an absorbing solution, containing a chemical to capture the CO2. The absorber captures more than 85 per cent of the CO2 and the clean flue gas, virtually 100 per cent nitrogen, is released into the atmosphere.
The CO2 is then removed from the absorbing solution by steam heating, so the absorber can be reused. The CO2 is compressed and cooled to form a liquid. Using the technique of geosequestration this liquid can then be sequestered, or permanently buried, in:
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deep saline aquifers
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depleted gas or oil reservoirs
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deep unmineable coal seams and adjacent strata
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or other deep geological formations.
Benefits of PCC
Benefits of PCC include:
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PCC can be retrofitted to existing plants and is a very prospective means of substantially reducing their greenhouse gas intensity
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PCC can be integrated into new plants to achieve a range of greenhouse gas intensity reductions down to near zero emissions
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in contrast to competing technologies, PCC has high operational flexibility (partial retrofit, zero to full capture operation) and can match market conditions for both existing and new power stations- for instance, during periods of high power prices, PCC can be turned off and maximum power delivered to the market
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PCC offers a lower technology risk compared to competing technologies - this is further enhanced by the ability for staged implementation, which is not possible with competing technologies
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renewable technologies can be integrated in the PCC process - in particular, PCC allows low-cost solar thermal collectors to provide the necessary heat to separate CO2 from sorbents, effectively reducing the loss of electrical output due to capture
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PCC can be applied to capture CO2 from natural gas fired power stations and other large stationary sources of CO2, for instance, smelters, cement kilns and steelworks.
Find out more about Post-combustion capture: expertise and facilities.
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