by Clyde Mallinson –
The world will migrate to a virtually all-electric energy system by 2050. No more fossil fuel propelled vehicles, trains, busses, trucks, boats, and eventually aeroplanes. The same goes for many industrial processes which will be electrified or make use of “green” hydrogen as a feedstock.
In the South African context, my calculations show that we will require about four times our current quantum of electricity by 2050. According to the most recent integrated resource plan (IRP2019), we will consume about 1,4 times our current amount by 2050; but the IRP2019 only factors in demand growth from our current user base, not for the switch from fossil fuels to electricity in transportation and industry.
At present, our electricity demand profile calls the tune, and we must juggle our generation assets to dance to that tune. In the future, the generation profile will call the tune, and the new electricity demand sectors will adapt their patterns and user habits to fit in with the generation profile. The whole electricity supply industry will quite literally be turned on its head.
Figure 1 shows South Africa’s current electricity supply/demand curve. Nuclear and coal meet “baseload” and some of the mid-merit requirements, and Cahora Bassa (hydroelectric), wind, solar, pumped storage and diesel-fired open cycle “gas” turbines (OCGTs) supply the rest, including the peaks.
Night-time surpluses go into pumped storage and come out of pumped storage during the day. Pumped storage gets depleted during the week, so that by Thursday and especially Friday, extensive use of the OCGTs is required. Earlier in the week, OCGTs are only generally required in the evening peak period.
Figure 2 shows what a typical week in March 2050 will look like from a fleet dominated by solar PV, wind, and storage (240 GW PV, 150 GW wind, and 90 GW/360 GWh storage, including hydrogen storage). It shows an increased electricity demand profile (by 40%), to reflect the IRP2019 demand estimates for 2050. Notice that the “conventional” demand profile is easily met, even on days with much less wind and solar, by drawing on storage. There is no nuclear, no coal, and no gas. This then represents the new generation profile that will call the tune in 2050.
Figure 3 shows the 2050 residual demand curve, and highlights when surplus electricity is stored (brown), and when shortfalls are met by storage (green).
The newly electrified sectors would adapt and dovetail with the new generation profile, which would call the tune, and thus the actual demand curve for all of the electrified sectors would look as shown in Figure 4.
The demand profile would be dominated by the day/night solar pattern, with surpluses generally created during the daytime, stored, and released at night, when most of the shortfalls occur.
Figure 5 highlights the charging and discharging of energy storage systems. It is important to note that due to the scale of wind, solar and storage assets, there would never be a time when the existing (as at 2020) demand, scaled up by 40%, could not be met by the system.
So, in the end, in my opinion, South Africa does not require any more nuclear, coal, or natural gas for electricity generation. By 2050, we will all be dancing to the tune of the new generation.
Clyde Mallinson is a geologist who supports the use of renewable resources, in preference to those that deplete.
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