There are environment-friendly interventions that will ensure that South Africa will have sufficient renewable power supply domestically as well as for export. (Dwayne Senior/Bloomberg via Getty Images)
South Africans are currently experiencing up to 10 hours of load-shedding a day and we are hovering between level five and level six and possibly higher. Maintenance of Eskom coal plants is being delayed due to “skills and liquidity challenges”, the Eskom gas power plants in the Cape and the private Avon and Dedisa gas power plants are running up billions in fuel and operating costs, and sometimes the diesel fuel logistics can’t keep up.
Koeberg appears to be hurtling towards a disaster with a dropped reactor, an expiring nuclear operating licence and delayed maintenance and upgrades, and there is an exodus of key technical and managerial skills. When both Koeberg units are off, transmission losses to the Cape amount to an entire unit of a typical Eskom “six-pack” power station – 500MW.
The energy crisis seems hopeless and our trust in our national leadership even more so. However, the energy problems are fixable, and in a shorter time than expected. In fact, with the correct interventions, South Africa could be exporting excess electricity to its neighbours.
The interventions and solutions are as follows:
- Install rooftop solar photovoltaic (PV) and battery energy storage systems (BESSs) on every structurally sound industrial, commercial, educational, medical and residential structure in the country.
- Install utility-scale solar PV generation together with BESSs around the country, even in areas with less-attractive solar irradiation levels, but only where transmission and distribution capacity is available. This will provide geographical diversity for natural weather patterns, dispersion of generation closer to load centres, and resilience for extreme weather events.
- Construct key strategic transmission lines in the Northern Cape and adequately compensate landowners for transmission line servitudes and power lines on their properties. This would unlock an immediate 5 to 10GW of shovel-ready utility-scale independent power producer (IPP) solar PV projects.
- Contract floating storage regasification units (FSRUs) and construct 1GW open cycle gas turbines (OCGTs) in conjunction with these FSRUs at key coastal cities such as Richards Bay, East London, Gqeberha (Port Elizabeth) and Saldanha Bay.
Rooftop Solar PV and battery energy storage systems
The South Africa housing market report 2020 states there are 16.9 million households in the country. If a 5kW PV system is installed on 16.9 million residential structures, this amounts to 84GW of electricity capacity, nearly three times the country’s maximum demand.
If only one-tenth of these households can support a 5kW PV system, this would imply 8.4GW of capacity and if only one-twentieth, this amounts to 4.2GW — the capacity of a large Eskom coal-fired “six-pack” power station and more than twice the capacity of the Koeberg nuclear power station in Cape Town.
Due to the diurnal characteristic of the sun and because of clouds and rain, this would not provide around-the-clock energy, but it would be an important addition to the energy supply and could be significantly improved by adding battery energy storage systems, to be charged when the sun shines and discharged at night. Add to the above 4.2GW capacity, capacity from office blocks, commercial buildings, schools, factories, hospitals, warehouses and millions of carports and car-parking areas, and the potential capacity from solar PV is significantly larger.
Legislation is urgently required to allow consumers to become prosumers, that is consumers who can also export their power to the grid and be compensated for it, albeit at differential tariffs. Time of use (ToU) tariffs should be implemented to encourage better electricity-use behaviour. Tax incentives and financial models from large financial institutions should be accelerated to assist customers who would find the capital outlay for solar PV and BESS systems prohibitive. Rooftop PV and BESS systems can be installed within weeks or months.
Geographically dispersed utility scale solar PV generation and battery energy storage systems
Over the past decade and as a result of the renewable independent power producer programme (REIPPP), variable renewable energy (VRE) developers (that is, solar PV and wind developers) have been identifying VRE sites with the best solar irradiation and wind resources. However, transmission line capacity is diminishing, and in the northern Cape, close to Upington, the transmission capacity is used up.
VRE IPPs should be encouraged to install geographically dispersed VRE plants close to transmission and distribution infrastructure and close to load centres. This would decrease electricity transport losses, provide geographical diversity for natural weather patterns and resilience to extreme-weather events. Utility-scale VRE power plants and BESSs can be installed within a year if the necessary environmental and social impact assessment (ESIA) approvals are in place.
Transmission lines in the Northern Cape
There are only two 400kV transmission lines from Aries substation in the Northern Cape (near Upington) to the key load centres of Gauteng, the Free State, KwaZulu-Natal and the Northern Province. Each 400kV line can transport roughly 500MW (0.5GW). There is an estimated 5GW to 10GW of planned and shovel-ready utility-scale IPP solar PV projects in the Northern Cape, where the solar irradiation levels are the best in the country.
This IPP capacity cannot be connected to the transmission system as the transmission lines from the Upington area are already running at full capacity. Additional transmission lines out of the Upington area have already been planned and designed, however, servitudes or wayleaves cannot be obtained from landowners on the routes of the 400kV transmission lines.
Servitudes for these transmission lines need to be secured for the national good, and some mechanism of attractive compensation needs to be offered to these landowners to secure these servitudes. It is possible to build 400kV lines and substations in two years with the correct procedures in place.
Floating storage regasification units and 1GW open cycle gas turbines
As the penetration of inverter-based VRE generation increases, the need for mitigating flexible power plants increases to counteract the intermittency and variability of the VRE. System flexibility can be obtained from BESSs, but another important source of flexibility comes from open cycle gas turbines (OCGTs) and internal combustion engines (ICEs).
Flexible thermal power plants also provide fault level and system inertia, and they can be called upon during extended bad-weather periods or as back-up generation when other conventional synchronous generation has unplanned and planned outages. The capital cost of OCGTs and ICEs is low, but the fuel costs are high. However, with the correct planning and operation, these thermal power plants should not operate for extended periods — not in excess of 5% of a calendar year, which is an environmentally acceptable compromise.
Global liquefied natural gas (LNG) prices are high due to the war in Ukraine; however, when the war ends, global prices should return to normal levels. When LNG arrives at a generating destination, it needs to be re-gasified — the liquid gas needs to be turned into gas, which has a much higher volume than LNG.
Re-gasification units can be built on land, close to ports (because of the sea-supply of the LNG). However, emergency FSRUs can be employed close to port, and the gas piped to OCGTs and ICEs on land. The thermal power stations would then be connected to grid substations close to the power plants. OCGTs and ICEs can be constructed in under two years if the necessary ESIA authorisations are in place.
Other medium-term and longer-term solutions
1) Very large natural gas volumes exist in the north of Mozambique (estimated at 100 trillion cubic feet). If gas pipelines could be built, similar to the Sasol Temane pipeline, natural gas thermal power plants could be built at non-port sites in South Africa.
2) The Mozambique north-south transmission system should be constructed which would unlock the 1 200MW Cahora Bassa lake’s hydro-generation capacity and the 1 500MW Mphanda Nkuwa hydro-power project which lies on the Zambezi River.
3) The large 40GW Grand Inga hydro-power plant on the Congo River in the DRC should be expedited together with the long and extremely high voltage (EHV) AC and DC transmission infrastructure to transport this clean energy to South Africa and the rest of Africa.
4) Transmission interconnectors between Tanzania and Zambia/Malawi should be expedited to access large quantities of low-cost hydro power from sources like the 6GW Grand Ethiopian Renaissance Dam’s hydro-power plant on the Nile River.
The above interventions will not provide an immediate remedy to South Africa’s power woes, but they can provide an environmentally friendly, best-cost, reliable and technically achievable direction for the energy sector in the short, medium and long term.
Paul Tuson (PrEng MSc MBL) is an electrical engineer with over 30 years of experience in the power industry in South Africa, Africa and globally.
The views expressed are those of the author and do not necessarily reflect the official policy or position of the Mail & Guardian.