To encourage a broad understanding of comparisons between nuclear and renewable energy generation options, it is important to review the basics.

The key difference between nuclear power and renewable energy options is that nuclear uses highly concentrated energy, the release of which must be extremely carefully managed. Renewable energy, on the other hand, is dispersed and requires infrastructure to collect. This has led to a widespread perception that renewable energy is insufficient to support industrialised society, regardless of the actual extent of the resource potential, which far exceeds what humans could use. A study of the availability of solar and wind resources in South Africa by the Council for Scientific and Industrial Research (CSIR) shows how the country could supply double its current electricity use from wind and solar power.

A difference that receives a lot of attention is that renewable resources are variable, with availability at any particular time depending on the weather, while a nuclear power plant is ‘inflexible’, being designed to run continuously.

System value

To understand the relative merits of generation options for grid-based supply one needs to consider the system value of the power supply. A key aspect of the system value of a new power plant is the extent to which it fills ‘gaps’ in the existing supply system, such as those that arise from peaks in demand – relatively short periods when total system use is highest. Since there are losses in electricity transmission (at least 10% within the South African system), plant location close to demand is also a factor in system value. In a system dominated by heavily polluting coal-fired plants, there is also system value, or national benefit, in reducing the negative impacts of the electricity supply system.

The South African electricity system already includes a large amount of pumped-storage capacity, which was developed as a way of using ‘baseload supply’ (continuous generation by large-scale nuclear or coal-fired plant) when it is surplus to system requirements. The subsequent hydropower generation can be scheduled to meet peak demand.

Optimal use of freely-available but variable solar and wind resources requires an electricity system that includes flexible generation and/or storage capacity to ensure supply meets demand. Research by the CSIR uses meteorological data of resource availability over a three-year period to model an electricity system with the same load profile (scale and timing of demand highs and lows) as today, but double the output, in which 75% of supply is from variable renewable resources with a broad geographical spread. The flexible generation providing the balance can be supplied from various sources –natural gas being the usual fall-back – that could be made up of concentrated solar power with thermal storage and OCGT burning biogas.

One characteristic of wind and solar PV technologies is that they can be deployed quickly, often within a year, and at any scale, while nuclear project lead times are upwards of eight years at best.


The cost of electricity generation depends not only on the costs of plant construction, maintenance and operation, including fuel where applicable, but also the project financing arrangements, including the terms of the power purchase agreement with the system operator, which may include local content and other requirements. The cheapest electricity on offer in South Africa is from solar PV and wind plant (costs vary somewhat as resources vary by location) and the second-cheapest is on offer from proposed independent coal-fired plant (when externalised costs such as pollution are ignored).

The cost of new nuclear power in SA remains speculative, but even accepting the industry’s own assumptions for costs levelised over a long plant life, they are expected to be almost double the cost of using the best renewable resources.

Environmental impacts

All electricity supply options involve some environmental impacts, even when best practice in materials handling and recycling is followed. Impacts are not borne equally by all of society – some are more systemic than technology-specific, such as from steel production, and some are quite subjective, such as visual impact.

Using controlled nuclear reactions involves a risk that even the most sophisticated control and back-up mechanisms may fail, either as a result of human error, as was the case at Chernobyl, or due to extreme natural events, as was the case with Fukushima. There are safety issues with nuclear power that have no parallel in renewables. The impacts of the increase in radiation from routine nuclear operations are highly contested, as is the cumulative extent of routine emissions and unintended releases (incidents, rather than accidents).

When the whole nuclear fuel cycle (not just the power plant) is considered, nuclear compares favourably only with fossil fuels in most environmental and worker health and safety assessments. Wind and solar at large scale are more spread out and conspicuous than uranium mines, fuel fabrication facilities, power plants and radioactive waste facilities, but the cumulative ecological impacts are more manageable and without calamitous accident risk. The life-cycle carbon footprint of wind and solar PV is considerably less than that of nuclear power (less than half in good resource conditions), while that of concentrated solar power looks similar to nuclear, though it is an immature technology.

Employment potential

In practice, employment impacts within the energy sector are a product of several factors, including project or programme design and the rate of return on capital required by investors, but particularly the degree of localisation of associated manufacturing, which is in part a product of the scale of national commitment to deployment of a particular technology.

Global trends show positive employment impacts of increasing the share of renewable energy in electricity supply, even when most projects are undertaken by the private sector.

The nuclear industry is promising a high level of localisation, largely conditional on procurement of multiple units, as well as trickle-down benefits from highly-skilled jobs, but does not offer the opportunities of decentralised development. Embedded solar PV generation – feeding into the distribution grid from rooftops – will create even more jobs than utility-scale deployment and avoided transmission losses will somewhat off-set the higher cost. The greatest employment potential is in the sustainable use of biomass, but this may be better applied to liquid fuel production.

The small units of renewable energy technologies make them most amenable to social ownership, such as through cooperatives, while the partial use of land can provide revenue in the most impoverished areas. Probably the greatest benefit of choosing renewable energy for grid-based supply would be in the knock-on benefits of developing local industries producing technologies with declining costs that can also be applied to extending access to electricity to the three million South African households that currently have none.

By Richard Worthington

See earthworks Issue 37, Apr-May 2017 for the full feature.