The Callide Oxyfuel Project demonstrated the production of electricity from coal with almost no power station emissions to the atmosphere by capturing a major portion of the flue gas CO2 as liquefied gas, and other waste gases such as oxides of nitrogen (NOx), oxides of sulphur (SOx), and heavy metals in condensate form for dam storage together with the ash. The project involved the following key technologies and activities:
- Oxyfuel combustion of coal to achieve a 60 percent to 70 percent reduction in the actual volume of flue gas and a proportionate increase in the CO2 concentration.
- Cryogenic separation and recovery of industrial grade CO2 from the power station flue gas stream
- Assessment of CO2 storage capacity in Queensland, and injection testing of Callide Oxyfuel CO2.
The Callide Oxyfuel Project demonstrated that new technology could be applied to an old power station to produce cleaner electricity. Built in the 1960s, the Callide A Power Station near Biloela in Central Queensland was chosen as the project’s demonstration site. Retrofitting the Callide A Power Station with oxyfuel technology represented a low-risk and cost- and time-effective way to demonstrate clean coal technology on an industrial scale, and heralded an exciting new era in the station’s history.
Oxyfuel technology enables coal to be burned more efficiently in oxygen in a power station boiler to produce a significantly reduced stream of waste gas that contains carbon dioxide (CO2) in a concentrated form. More than 70 percent of the CO2 from the waste gas is then extracted in a downstream process using well-established cryogenic technology.Oxyfuel technology can therefore both technically and economically facilitate the capture of CO2 for subsequent geological storage.
Carbon capture and storage
In addition to extracting the CO2, the cryogenic technology removes other gaseous pollutants and normal coal-fired power station waste products such as fly ash from the waste gas stream. The industrial-grade CO2 product can be transported and stored securely and indefinitely in stable geological formations deep underground, or utilised for enhanced oil recovery from ageing reservoirs, or for other industrial uses. With further minor purification, it can be used in food and beverage applications.