EngineerLive.com sent me a routine newsletter and one topic caught my attention. The topic entitled
Capturing carbon for a cleaner future is not a new topic for me and for some of you. It is basically a new developed technology that can purify clean our environment. Before this I have only heard about Carbon Capture and Storage (CCS) but I wondered how the carbons in the air will be captured... After reading the interesting article below, I have better comprehension on the subject and how am I impressed with a compound called Alumina Silica (Al2O3 - SiO2). I have been working with Silica Alumina during my full time research few years ago and at my present work, SiO2 Al2O3 are the main compound in bleaching earth. Check out the article below which I adopted from
EngineerLive.com:
In what the two countries are describing as an important step towards a greener global future, Australia and China have signed a formal international agreement for clean coal research. The agreement, between the Australian Commonwealth Scientific Research Organisation (CSIRO) and China’s Thermal Power Research Institute (TPRI), will see TPRI install, commission and operate a post combustion capture pilot plant at the Huaneng Beijing co-generation power plant as part of CSIRO’s research programme (Fig.1).
Post combustion capture (PCC) is a process that uses a liquid to capture carbon dioxide (CO2) from power station flue gases and is a key technology that can potentially reduce carbon dioxide emissions from existing and future coal-fired power stations by more than 85percent.
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 10–15percent 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 85percent of the CO2 and the clean flue gas, virtually 100percent 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: deep saline aquifers; depleted gas or oil reservoirs; deep unmineable coal seams and adjacent strata; or other deep geological formations.
There are numerous benefits associated with PCC, including:
* It can be retrofitted to existing plants and is a very prospective means of substantially reducing their greenhouse gas intensity.
* It can be integrated into new plants to achieve a range of greenhouse gas intensity reductions down to near zero emissions.
* 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.
* It can be turned off and maximum power delivered to the market;
It 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.
m It 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.
For its part, the Beijing pilot plant is designed to capture 3000t/y of CO2 from the power station.
CSIRO’s involvement in this PCC project has been made possible through funding from the Australian government. The Australian government is supporting this work through a A$12million grant, A$4million of which supports this work in China.
Director of CSIRO’s Energy Transformed National Research Flagship, John Wright, said low emission energy generation was a key research area for the Flagship.
The installation of the PCC pilot plant in Beijing is a CSIRO Energy Transformed Flagship research project and forms part of the Asia Pacific Partnership on Clean Development and Climate initiative (APP). The APP programme for PCC also includes a pilot plant installation at Delta Electricity’s Munmorah power station on the NSW Central Coast, with an additional Australian site currently under negotiation. The Energy Transformed National Research Flagship is also undertaking PCC research outside the scope of the APP programme with a A$5.6million project in the Latrobe Valley, which focuses on brown coal.
New material to capture CO2
Meanwhile researchers in the US have developed a new, low-cost material for capturing CO2 from the smokestacks of coal-fired power plants and other generators of the greenhouse gas. Produced with a simple one-step chemical process, the new material has a high capacity for absorbing carbon dioxide – and can be reused many times.
Combined with improved heat management techniques, the new material could provide a cost-effective way to capture large quantities of carbon dioxide from coal-burning facilities. Existing CO2 capture techniques involve the use of solid materials that lack stability for repeated use – or liquid adsorbents that are expensive and require significant amounts of energy.
The new material is known as hyperbranched aluminosilica (HAS).
Growing concern over increased levels of atmospheric carbon dioxide has prompted new interest in techniques for removing the gas from the smokestacks of such large-scale sources as coal-fired electric power plants. But to minimise their economic impact, the cost of adding such controls must be minimised so they do not raise the price of electricity significantly.
Once removed from the stack gases, the CO2 might be sequestered in the deep ocean, in mined-out coal seams or in depleted petroleum reservoirs. If the CO2 capture and sequestration process can be made practical, America’s large resources of coal could be used with less impact on global climate change.
Working with Department of Energy scientists Daniel Fauth and McMahan Gray, Jones and graduate students Jason Hicks and Jeffrey Drese developed a way to add CO2-adsorbing amine polymer groups to a solid silica substrate using covalent bonding. The strong chemical bonds make the material robust enough to be reused many times (Fig.2).
Production of the HAS material is relatively simple, and requires only the mixing of the silica substrate with a precursor of the amine polymer in solution. The amine polymer is initiated on the silica surface, producing a solid material that can be filtered out and dried.
To test the effectiveness of the material, the Georgia Tech researchers passed simulated flue gases through tubes containing a mixture of sand and HAS. The CO2 was adsorbed at temperatures ranging from 50–75°C. Then the HAS was heated to between 100 and 120°C to drive off the gas so the adsorbent could be used again.
The researchers tested the material across 12 cycles of adsorption and desorption, and did not measure a significant loss of capacity. The HAS material can adsorb up to five times as much CO2 carbon dioxide as some of the best existing reusable materials. The HAS material works in the presence of moisture, an unavoidable by-product of the combustion process.
Because of their chemical structure, the amine groups provide three different classes of binding sites for carbon dioxide, each with a different binding energy. Optimising the production of binding sites is a goal for future research.
Beyond the material, other components of the separation and sequestration process must also be improved and optimised before it can become a practical technique for removing CO2 from flue gases. The best way to expose the flue gases to the adsorbent material is also key issue.
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