Transitioning SA's Petrochemical Value Chain

The production of green fuels and carbon-based chemicals via the Fischer-Tropsch reactor requires carbon, in the form of carbon monoxide, that is classed as “sustainable”. There is no universal definition yet of what can be considered “sustainable carbon”. Potential candidate sources could include:

• Biomass feedstocks: which can be combusted, fermented or otherwise converted to release the required carbon (see discussion on first, second or third generation biomass feedstocks);

• Industrial emissions: carbon, emitted as CO2, is captured from point sources at high-emitting industrial plants, such as iron and steel and cement plants. The Intergovernmental Panel on Climate Change (IPCC) has identified that carbon capture, utilisation and storage (CCUS), will play a critical role globally in reaching a net-zero emissions target; and

• Ambient air: carbon is captured in the form of CO2 directly from the atmosphere via Direct Air Capture (DAC) technologies.

Carbon sources have different economic, geographical, and sustainability-related implications.

• Biomass can be supplied cost-effectively, but the availability of biomass is unevenly distributed, finite, and subject to competing uses. The Roundtable on Sustainable Biomaterials, which is highly regarded by industry, offers guidance on sustainability standards including potential trade-offs with agricultural production and food security, land degradation and community livelihood impacts.

• Use of industrial CO2 emissions has been critiqued for the potential to perversely extend ongoing fossil fuel-based production processes, although this could also represent an interim decarbonisation solution whilst alternative, low emissions production processes are developed.

• CO2 captured via DAC is expensive compared with other carbon capture methods due its technological nascency. This process is also energy intensive due to the low CO2 concentration in ambient air. However, DAC technologies can be situated anywhere, allowing a DAC plant to be situated adjacent to the demand for CO2, thereby reducing transport costs.