Baseload electrical energy is, for the purpose of this article, energy that is readily dispatchable at a predictable energy availability factor level (EAF). The primary energy that enables dispatchability and predictable EAF are nuclear and fossil fuel.  The most compelling aspect of baseload that need consideration is that, power generation must be relatively continuous. Baseload therefore means electrical energy source that can be completely relied upon.

How about solar and hydroelectricity

Solar

Solar energy is used in two different forms as a source of primary energy, viz: (i) solar photovoltaic and rechargeable battery and inverter system; and (ii) concentrated solar and turbo-generator system. In these formats, Solar Energy does not meet baseload requirements as per the above-mentioned definition. During the period when the sun’s radiative intensity is lower than required, concentrated solar is unable to heat the working fluid to desired temperature levels or when the sun emits higher than required radiative intensity and photovoltaic cells lose their overall efficiency.

The intensive study on solar rays’ physical behaviour has yielded Improvements on these solar-oriented system.  Recent designs and application of heat storage systems have allowed for the storage of useful heat over an extended period of time and photovoltaic cells are now being designed and built to withstand beyond design-base heat intensity.  Photovoltaic is inefficient and require large space (agriculturally productive tracks of land could be lost to this technology) for small energy output, also then photovoltaic’s operational life is notoriously short. Soon solar will be engineered to meet the baseload requirements as defined above.

Hydroelectricity

A dam built across a river and a pumped-storage reservoirs with associated penstocks and turbo-generator arrangement can generate hydroelectricity.  In both cases, the amount of hydro-electric power generated is inversely proportional to the hydraulic head of the source. South African hydroelectric systems suffer low EAF as the seasons change from rainy to dry. The pumped storage system has an added disadvantage as its availability is already compromised due to necessary pauses between generating and pumping water back into reservoirs. Hydroelectric generation is therefore not a suitable baseload system (as per this article’s definition) for South Africa due to the fact that the South African river systems in unsteady and unreliable.

Grid stability issues

Even if PV solar, wind and battery energy technologies succeed at providing most of the energy required and they significantly surpass electrical energy generated by synchronous generating machines, a new problem would ensue. These inverters are not capable of keeping the grid stable, safe and efficient. The grid stability is defined as the grid’s ability to remain at the specific frequency and voltage levels.

The inverters in renewable energy generators mentioned above do not have capabilities to prevent the inertia shortfall, unless if further investment is made into equipment such as the synchronous condensers. The synchronous condensers emulate the synchronous turbo-generators in keeping the grid stable, safe and efficient.

Conclusion and necessary forward

A diverse baseload energy generating portfolio that includes renewables and aims to reduce adverse environmental impacts and associated externalities is essential for driving the country’s economy. As has been indicated herein, nuclear energy is an obvious choice for such a baseload portfolio. The other energy sources that must be explored and evaluated for the South African baseload is a geothermal energy source.