LETTER: Anti-nuclear, pro-renewable advocates mistake ‘intermittent’ supply for ‘variable’ supply
This is a response to the article, Need for base load power is a pro-Eskom fabrication, published on February 24 2017, by Dirk de Vos and Nicole Löser.
As the Nuclear Industry Association of SA (NIASA), we have noted with some concern some inaccuracies in the article, which cannot be left unchallenged for those interested in pursuing a balanced discussion on the future of energy generation in the country.
The electrical load of a power system consists of a portion that is fixed and a portion that varies according to the time of day and the activities in which a specific economy is engaged.
This load needs to be supplied by reliable and cheap power, such as from coal, nuclear or hydro, where available.
The authors choose to describe these conventional power plants as being inflexible. This is simply not accurate as all of them can be adjusted at will as the load changes.
However, from an economic point of view, it is best to run these flat out, as the cost of fuel is much lower compared with other fuels, such as gas and diesel.
The French grid has 58 reactors distributed throughout the country, some of which are used as load following (or variable). The authors use the term “variable” referring to renewable sources. The correct term is “intermittent”. Variability implies the power system operator can vary the output of the renewables at will. With renewables, we get what nature provides at any given time. I would argue that this is inflexibility.
The other argument put on the table is that base-load generation can result in overcapacity on the one hand and on the other hand cause load shedding if a large unit is on an unplanned outage.
This is the sort of work generation planners and system operators all over the world do very well by designing optimally sized units and commission them at appropriate time. A rule of thumb is to run these units with sufficient reserve margin to allow for unplanned outages, so that the units still connected to the grid can be ramped up to take up the load of the unit that has tripped.
It is incorrect to talk about overcapacity when about 20% of South Africans have no access to electricity. We still need to industrialise more and create the much-needed employment. Even if we were to have overcapacity, we are surrounded by neighbours with much less electricity penetration than us. France benefits from exporting its competitively priced nuclear-generated power to its neighbours in Europe, including Germany.
Scientists can provide accurate short-term forecasting of the weather and a desktop simulation assuming renewables spread all over the country (and closer to the loads) could show that renewables can supply all the power requirements.
These desktop models underestimate the need for an intricate network of transmission and distribution lines. If the entire region consisting of Limpopo, Mpumalanga and Gauteng is overcast, it means huge amounts of power need to be transmitted from the Northern, Eastern and Western Cape. This presupposes that the transmission infrastructure is in place to do so. The reality is that we would need massive gas or diesel plants as backup.
The cost of having a huge backup generation capacity has to be factored in to the consideration of the “cheap” renewables. Yes, if the grid were to be designed from scratch, maybe it would look different. The reality, however, is that we have an existing infrastructure and we should plan around what we have and make the best of it. The costs of having a green fields generation, transmission and distribution system is unfathomable at this stage.
Apart from the economics, there are technical issues that need to be resolved regarding operating an electrical system with only renewables. Renewables do no not have system inertia which is required to run a stable grid. These problems have not been solved anywhere in the world, ands that is why there is a limit on how much renewable generation can be connected to the grid without compromising its stability.
A country like Germany can make a political decision to eventually exit nuclear power generation because it is connected to the European grid, which is stabilised by many base-load plants in the system. To argue that advocating for base load generation is a pro-Eskom fabrication cannot be correct as base-load generation is used all over the world where there is no Eskom.
Our electrical system is similar to our transport system. We have trains (both Gautrain and Metro Rail) that move thousands of people in Gauteng. We also have bus services that play an important role in complementing the trains. We should not get excited and say, since we now have Uber, let us do away with trains and buses and have only Uber to provide all the transport we need. When travelling from Johannesburg to Durban, a combination of Uber, Gautrain and a flight is the way to go. The different modes of transport complement each other rather than compete.
Similarly, with our electrical power system, the different types of generation all have their strong and weak points and they are best deployed to compliment each other rather than compete to replace each other.
The energy mix approach adopted by the government is the right one. The only debate we should be having is how much of each should we go for in order to minimise cost and stimulate the economy by creating employment.
Knox Msebenzi, MD: Nuclear Industry Association of SA (NIASA)
Originally published at www.businesslive.co.za on March 6, 2017.