Australian researchers evaluate the commercial sustainability of Solar Alumina Calcining

Australia’s industrial carbon emissions released by the alumina refineries counted to be around 27%, where fossils fuels are burned to heat the procedure.

However, concentrated solar thermal (CST) could deliver up to half of the heat required. Australian researchers have for the first time demonstrated a novel solar reactor for calcined alumina, a process which 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, a good conversion may be technically feasible at large scale. Besides, 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.

Dr Woei Saw, the person leading the techno-economic assessment of the solar calcination project and is also managing the five-year research project, said: “Alcoa, CSIRO, ITP Thermal, University of New South Wales (UNSW) and Hatch are our collaboration partners.”

“It is quite a big team; around 30 staff and then another 10 PhD students. A lot of R&D has brought us to this point. We work very closely with these commercial partners who have contributed a lot to the development of potentially viable technology.”

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.

Professor Graham “Gus” Nathan who as the founding Director of The University of Adelaide’s Centre for Energy Technology is leading the project, said: “We anticipate hybridizing solar thermal with another low-carbon energy source. That’s because solar thermal becomes uneconomic during periods of extended cloud and low seasonal availability”.

The idea is to develop to commercial sustainability of 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.

Dr Woei Saw, the presenter of the paper; Technical feasibility of Integrating Concentrating Solar Thermal Energy in the Bayer Alumina Process at the most recent SolarPACES Conference in Korea, said: “Both trough and tower are already demonstrated commercially in the power sector but are yet to be integrated into a large industrial process such as the Bayer process. So our technology assessments are identifying commercially attractive pathways to integrate solar thermal into this new process.”