In line with South Africa’s commitment to reduce emissions, the promulgated IRP 2010–2030 imposed CO2 emission limits on the electricity generation plan. IRP 2010-2030 assumed that emissions would peak between 2020 and 2025 as Medupi and Kusile are brought on line, then plateau for approximately a decade and decline in absolute terms thereafter as old coal-fired power plants are decommissioned.

Figure 8 shows the emission reduction trajectory (referred to as the peak-plateau-decline (PPD)) for electricity generation adopted in the promulgated IRP 2010–2030.

While PPD was applied as the primary assumption, a scenario was tested as part of the draft IRP 2018 where the carbon budget approach was used for emission constraints. A carbon budget is defined as a tolerable quantity of carbon dioxide emissions that can be emitted in total over a specified time. The scenario was based on carbon budget targets divided into 10-year intervals which meant a total emission reduction budget for the entire electricity sector up to 2050 must be 5 470 Mt CO2 cumulatively.