Research: Reducing CO2 emissions from the use of coal
NSW Coal producers have joined in a voluntary commitment of $300 million towards the development and demonstration of technologies that can lower greenhouse gas emissions from coal-fired power stations.
Clean coal is the name given to a number of new technologies designed to lower the emissions of coal-fired power generation.
The technologies either increase the combustion efficiency of coal (burn less coal for the same amount of electricity produced); or capture carbon emissions before or after the coal is burned, then safely store it. This last process is called 'carbon capture and storage' (CCS) or geosequestration. Both of these technologies have the potential to significantly reduce the emissions produced from the burning of coal.
Increasing the efficiency of coal
When coal is burned to create energy (electricity), not all the energy contained within the coal can be converted to a form that is able to be used by the power station. This is called the coal's 'combustion efficiency'. Generally this efficiency is about 35%, but there are technologies becoming available that can increase this efficiency up to about 50%, meaning that less coal and fewer emissions are needed to produce a unit of energy.
Combustion efficiency
Oxy-fuel combustion
A power plant uses air to burn coal and converts this heat energy to mechanical energy to operate an electrical generator creating the power supply for our cities and towns.
New technology separates pure oxygen from nitrogen contained in air, so that when coal is combusted the gas contains more CO2 than waste nitrogen, and the CO2 can be captured and stored more easily. This technology is best suited to newly constructed power plants, yet will be able to be retrofitted to existing plants. A power station in central Queensland, in cooperation with Japan, will likely be the first large-scale demonstration. After this trial, there is potential for the technology to be rolled out in other places in Australia.
Find out more about oxy-fuel combustion at:
- http://www.csenergy.com.au/research_and_development/oxy_fuel.aspx
- http://www.csenergy.com.au/research_and_development/oxy_fuel_technical.aspx
- http://www.nedo.go.jp/sekitan/cct/eng_pdf/2_4c4.pdf
- Diagram of technological process
http://www.csenergy.com.au/_CMSImages/csenergy/pdfs/080822Oxyfuel_diagram%20.pdf
Ultra clean coal
In the Hunter Valley in NSW, a fully operational pilot project has been established producing Ultra Clean Coal (UCC). UCC has very low ash content and can be used as a substitute for natural gas in gas-fired power stations. Ash is the component of the coal left behind after the coal is burned. Ultra clean coal was developed by CSIRO, with financial support provided by an industry group.
The development of an ultra pure coal with less than 0.2% ash components allows coal efficiencies to be increased by 20 compared with conventional coal-fired power stations. Again, this represents a saving in carbon dioxide emissions, as less coal needs to be burned to produce the same amount of energy.
It is hoped that in the future, once this technology is installed, it has the potential to reduce up to 3.5 million tonnes of CO2 annually.
Find out more about this technology at:
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