Process
Process decarbonisation
The options for decarbonisation of Secunda and Sasolburg’s facilities are grouped into six categories, five of which are considered in Sasol’s 2030 or 2050 decarbonisation plans. The first two are reported by Sasol to be able to contribute to achieving a ‘turn-down’ – or reduction in use – of six coal-fired boilers, with the first boiler to be turned down by 2025.

- Energy efficiency and process changes: Energy efficiency interventions at Secunda will lead to a reduction in demand for electricity and steam and consequently a reduction in coal demand for coal fired boilers 1. At the same time, Sasol has included in their decarbonisation plans a reduction in coal gasifier utilisation, which will in turn reduce the demand for coal-based steam supply). Reduced gasification of coal will, however, result in a need for additional hydrogen to be produced for the FT process, which will need to be provided through steam reforming of additional natural gas over and above the current usage, which Sasol needs to source, or down the line green hydrogen. This is thus only an interim solution; whilst gas is a lower emissions-intensive feedstock than coal it still results in CO2 emissions. A final proposed process change which would reduce coal-related emissions is the briquetting of fine coal to use in the FT process rather than combustion in the coal boilers, which is understood to have a lower greenhouse gas emissions footprint in addition to local air quality benefits.
- Scaling up renewable energy to replace on site and grid-purchased fossil fuel energy.
- Moving away from coal as a feedstock through transitioning to using hydrogen combined with sustainable carbon as inputs to the process. The FT process is agnostic of the source of carbon and hydrogen inputs, and so this decarbonisation option is contingent on affordable, reliable and sufficient feedstock being available.
- Carbon Capture, Utilisation and Storage: Capturing the CO2 stream at source and utilising (in product) constitutes an emissions mitigation measure. If the captured CO2 stream is used for liquid fuels production, the emissions are released to the atmosphere only when the liquid fuel is burned rather than at the production site, thereby getting a “second use” out of the carbon – while at the same time reducing the emissions from combustion of fossil fuels.
As with natural gas, therefore, this is only a temporary transition solution. Sasol also has the option of permanently storing the CO2 emitted by its processes. This is a more mature technology than utilization, but still subject to high uncertainties around costs and permanence.
See here for a deep dive into carbon storage in South Africa
Carbon Capture and Storage (CCS)
CCS 1 involves capturing CO2 released at the source of large fossil fuel / industrial plants, and compressing the CO2 for transportation and injection into deep underground geological formations for permanent storage.
Although CCS is mostly nascent at commercial scale, the capture elements are well established, having been used commercially for the purification of hydrogen and a variety of gases in industrial settings since the 1930s 2. Up until 2021, there were 26 CCS facilities in operation internationally with a capacity to capture and permanently store approximately 40 Mt of CO2 per year 2. Most planned and active CCS projects are in industrial sectors, such as chemical, hydrogen and fertiliser production and natural gas processing, where high concentration CO2 is readily available and can be captured at relatively low cost compared to the low concentration streams from power plants 3.
The development of CCS technology in South Africa has been slow due to the high costs associated with the technology. However, there has been some progress in recent years, with a pilot project under development to test the feasibility of CCS in the local context and determine the most cost-effective way to deploy it. According to the Atlas on Geological Storage of Carbon Dioxide in South Africa 4, there is 150 Gt of theoretical storage capacity available to South Africa, of which 98% is offshore. Although there is significantly more offshore storage, the associated costs would most likely be more expensive than onshore storage, as captured CO2 would need to be transported from inland regions to geological injection sites offshore.
- Carbon removals: Removal of residual emissions from the atmosphere through either securing access to South Africa’s natural carbon sink, or the employment of Carbon Removal Credits. The latter could either be through international market purchases or Sasol constructing and operating DACC technology themselves. See here for a deep dive into carbon removal options.
See here for a deep dive into carbon removal options.
Carbon Removal Options
Paris-aligned decarbonisation target allows for ‘net zero’, meaning that at the end point any remaining emissions can be accommodated by carbon removals. In the context of this project, carbon removals must balance emissions into perpetuity for sustainable Paris-alignment. If the Secunda and Sasolburg processes (as with those of their value chains) still emit mid-century, then they will need access to negative carbon space by either a) relying on a portion of South Africa’s natural sink, b) undertaking carbon removal activities, or c) purchasing carbon removal credits on the international offset market. Here we briefly discuss these options.
A.South Africa’s natural carbon sink: International climate mitigation policy is developed under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), where nation states are parties to agreements to decarbonisation, and national greenhouse gas inventories are assessed for international policy progress. Under the current mitigation architecture, South Africa reports a natural carbon sink, which may be larger or smaller in 2050 depending on land use practices. According to current agreements a country can emit the same amount as its sink and remain in a ‘net zero state’ at the national level. Decisions regarding the allocation of this carbon sink to emitting activities within the country are a subject of domestic policy, which is still under development.
South Africa’s land sink is anticipated to increase and stabilize from 2014 figures of 21 Mt CO2 to 31 Mt CO2 in 2030 1. The ESRG modelling considers a natural sink range in 2050 of between 20 and 45 Mt.
- Reduce production at Secunda and Sasolburg, and ultimately terminate the processes. This final option is available should Sasol not be able to reduce its emissions to allow for alignment with international climate targets and/or its allocation in terms of the national emissions space.