Nuclear incompatible with renewables-heavy mix – Fraunhofer Institute

8th October 2015

By: Terence Creamer

Creamer Media Editor

  

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The technical and economic challenges associated with the large-scale deployment of renewable-energy had largely been solved, Professor Dr Clemens Hoffmann of Germany’s Fraunhofer Institute for Wind Energy and Energy System Technology argued during a presentation in Pretoria on Thursday. He, therefore, urged South Africa to take fuller advantage of its “excellent” wind and solar resources, which made the country’s renewable-energy projects highly cost competitive when compared with less well-endowed territories.

But Hoffmann also warned that it would not make sense to invest in nuclear plants should South Africa pursue a high concentration of renewables in its future electricity mix.

Speaking at the Council for Scientific and Industrial Research’s fifth conference, Hoffmann indicated that Germany had learned valuable and, at times, difficult lessons from its aggressive ramp-up of wind and solar photovoltaic (PV) to its current combined capacity of 80 GW. The European country had an average load of between 60 GW and 80 GW.

Increasing the role of renewables to such a dominant position had required changes to the technical architecture and market design, while the rapid deployment of solar PV, in particular, had created significant challenges for the operation and planning of the distribution grids. It had even resulted in a political and policy pushback, which had precipitated a rapid decline in installations in recent years, as support and subsidies reduced.

Nevertheless, the Fraunhofer Institute’s research showed that increasing the role of wind and solar levels above 200 GW each by 2050 would not undermine supply security, and was increasingly financially viable and environmentally desirable.

However, the technical architecture and market design would need to evolve further, with system operators facing the prospect of having to adapt to a situation where dispatchable load and supply followed non-dispatchable load and supply. Grids would also need to be made more intelligent, while the regulatory framework would need to adjust to ensure ongoing investment.

Countries that pursued generation systems dominated by renewables would also require complementary storage systems, as well as back-up generation capacity that was flexible enough to be ramped up and down rapidly.

In such a context gas-fired back-up generation was favoured, with Hoffmann raising serious compatibility issues between a renewables-heavy generation system and nuclear. “We do not see how, from a system point of view, nuclear and renewables fit together – it just does not fit,” he said.

But the back-up plants would need to be “future proofed” in a way that ensured they remained resilient in the context of being switched on and off at regular intervals.

Coal and nuclear plants were not designed, Hoffmann said, to ramp up and down on short notice, as they responded best to “shallow gradients”, rather than sharp adjustments. 

The pricing system for the back-up fleet would also have to take account of the fact that the plants would not earn much money on energy during a year. “So the pricing of the plants needs to be power based rather than energy based.”

Hoffmann said it would also make sense for South Africa to consider positioning renewables at the heart of its electricity system, owing to excellent wind and solar resources.

“South African has vast competitive advantages,” he argued, noting that the solar resource, in particular, was not subject to the seasonal variability experienced in countries such as Germany.

Edited by Creamer Media Reporter

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