South Africa, as with the rest of the world, will one day receive almost all of its energy from renewable sources. All we need to decide is whether we assume the position available to us as leaders, or whether we dig in our heels and join the trend only when it calls for followers.
On Monday, the CSIR Energy Centre released results of a simulation model developed to test South Africa’s renewable energy potential. The hypothetical model builds a new power system from scratch where renewables are responsible for the bulk supply of South Africa’s base electricity load.
Initially this seems uncomfortable, as only the most reliable and consistent forms of power supply should provide the base load. But in an interview with Engineering News Online, energy scientist Dr Tobias Bischof-Niemz explained that the concept of base load was changing.
He emphasised that we should be concerned about energy production and not capacity. The CSIR simulation found that with a large enough renewable capacity distributed correctly across the country, renewables were not only capable of providing the base load but they were also the most cost effective method of new build options to do so.
The simulation started small and assumed a required base load of 8 gigawatts to supply a total annual demand of 70 terawatt-hours (about a third of South Africa’s demand). The 8GW base load would be met via a total generation capacity of 30GW: 6GW of solar PV, 16GW of wind generation and 8GW of flexible power.
Unlike traditional base load sources – such as coal and nuclear – the generation capacity of renewables far exceeds the base load demand. This is to allow for fluctuations in the actual power generated on any given day. When renewables cannot meet the total demand, the flexible power options kick in to make up the shortfall.
Flexible power generation includes natural gas, biogas, coal, pumped hydro, hydro, concentrated solar power or demand side interventions.
When the simulation was applied to wind and solar readings over three years from 2010 to 2012, the CSIR found that wind and solar could supply 83 percent of the base load and flexible capacity would supply the remaining 17 percent.
Despite the excess, renewable capacity installed and the use of expensive flexible capacity to make up supply shortages, the CSIR found that this model was more cost effective than existing models that relied on coal and nuclear for base load supply.
In the fourth bid window of the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP), competitive tenders brought the lifetime cost of wind generation down to 69c per kilowatt-hour and that of solar PV to 87c/kWh. The flexible capacity options carried a cost of 200c/kWh. The resulting blended cost of the energy mix investigated by the CSIR was estimated at 100c/kWh.
The lifetime cost (including capital expenditure) of base load coal production is between 85c/kWh and 120c/kWh and that of nuclear about 125c/kWh.
When the simulation was scaled up to meet a peak demand of 40GW – about 10 percent greater than South Africa’s current peak demand – the blended cost of 100c/kWh was sustained and the solution remained technically feasible. This does assume, however, that South Africa will have the resources necessary to build 35GW in flexible supply capacity.
The CSIR results show that if South Africa were to start from scratch using today’s technology, there would be no need for coal or nuclear generation of power. But South Africa is not starting from scratch and according to the Integrated Resource Plan, it will have 65 percent of its energy generated by coal in 2030.
The Medupi and Kusile power stations will be the last additions to coal capacity in that time period.
Improvements in renewable technologies will further increase the feasibility of the CSIR findings – the costs of solar and wind generation have more than halved since the first REIPPPP bid window in 2011 and continue to decline. Based on the CSIR results, there is therefore no need – cost, capacity or otherwise – for South Africa to add any new generation to its energy plan that is not based on wind or solar PV.