Approximately 27% of Australia’s industrial carbon emissions come from alumina refineries, in which fossil fuels are burned to heat the processes. But concentrated solar thermal (CST) could provide up to half of the heat needed. Australian researchers have for the first time demonstrated a novel solar reactor for calcining alumina, a process that typically occurs at approximately 950°C.

The researchers have shown at lab scale that good conversion – up to 96% – can be achieved in this high-temperature solar calciner for 3 seconds – without preheating. This shows that with preheating, the good conversion may be technically feasible on at large scale. In addition, the use of solar in itself has the potential to improve the quality of the alumina by avoiding contamination from combustion products from burning natural gas.

A group of companies and solar researchers at Australian universities is looking into how to make the solar calcining process work commercially; assessing the economics and technical specifics of potential solar calcination at commercial alumina facilities.Three programs within the project are focused on integrating solar thermal technologies to replace up to 50% of the fossil fuels presently used for the Bayer alumina refining process. The idea is to advance to commercial viability three related processes for reducing the carbon footprint of alumina production; solar trough or tower technology with thermal storage for the steam needed for the digestion process, solar reforming of natural gas and a novel solar calcining reactor.