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The most plausible pathways are the replacement of coking coal, which is needed to reduce the ore, with hydrogen or bio-coke from wood (Hooey, 2018) plus carbon capture and storage/use (CCS/U). The major barrier is the development and demonstration of technologies that reduce production costs of these alternatives. An additional barrier is the need to develop ore-specific process modifications for each plant, since the details differ from plant to plant.

Since the low temperature stage of the alumina Bayer process is compatible with commercially-available CST technologies, there are no real technical barriers to its implementation. Direct use CST at higher temperatures could supply heat for the calcination process and/or the production of alternative fuels such as hydrogen and syngas generated from solar and natural gas or biomass in the mid term, and from only water in the longer term (McNaughton, 2018). Syngas has already been used commercially for calcination. Further research, development and demonstration is needed to de-risk the use of hydrogen, although no significant technical barriers are anticipated (Nathan, 2018).

In addition to already using 鈥渨aste鈥� to produce heat, the sector could benefit from stored, high temperature CST heat to reduce CO₂听for the energy-intensive calcination step of cement production. However, the pathway to net-zero CO₂听must also address the CO₂听released from the calcination process itself. While some substitute materials are being used as a blend to reduce net CO₂听emissions, an ongoing need for calcination is perceived for the foreseeable future (DeGaris, 2018). It is likely that CCS/U will also be needed to decarbonise this process.

Technologies are under development with a realistic expectation to supply heat at ~800 - 1000掳C for AUD$10/GJ, which is thought to be competitive with present prices of natural gas, although this is yet to be demonstrated. 听

New technologies are needed to produce solar hydrogen and/or syngas at costs competitive with fossil fuels. A series of new technologies, including photocatalysis, are under development seeking to meet this need.

These fuels are well established in industries such as cement and lime, where long residence time and potential to adsorb gas phase species enables potentially harmful products to be managed safely. They are also a potential feedstock for more valuable products, such as plastics and liquid fuels, via solar gasification and other processes.