Does the need for flexibility spell the end for “baseloadism”?

March 9th, 2017, Published in Articles: EE Publishers, Articles: Energize


Electricity demand in South Africa has changed dramatically over the last eight years. New demand profiles call for more flexibility in electricity generation, while environmental concerns and new technologies make energy efficiency and renewable energy sources more popular.

Chris Yelland

Speaking at a meeting of the Society for Automation, Instrumentation, Measurement and Control (SAIMC) recently, Chris Yelland, the managing director of EE Publishers, said the fall in commodity prices on international markets has resulted in certain industries, which consumed enormous amounts of electricity, to no longer exist or to have changed considerably.

Click here to download Chris Yelland’s presentation slides

Large South African aluminium, steel, ferromanganese and ferrochrome smelters, which required enormous amounts of electricity are no longer in use in South Africa, he said. The mining sector is not as busy as it once was, particularly coal mining which has felt the reduction in coal demand from the country’s coal-fired power stations, acutely.

Yelland said that this change in electricity demand profile has resulted in a significant decrease in demand for baseload power, i.e. the minimum amount of electricity Eskom has to supply to the national grid on any given day. A lower demand profile has resulted in the power utility receiving less revenue while its costs have increased with inflation. This has resulted in higher electricity tariffs, which has made investing in energy efficiency measures more attractive.

Energy efficiency saves more than just money. By using less electricity, the country burns less coal (about 80% of South Africa’s electricity is generated in coal-fired power stations) resulting in fewer emissions of CO2 and particulates into the atmosphere, which is good for the environment. New technologies, which harness energy from the sun and wind for the generation of electricity, add to the reduction of demand for coal.

While coal-fired power stations provide a steady supply of electricity, wind and solar technologies have the disadvantage of not always providing electricity when it is needed, Yelland said. This creates “gaps” in generation which must be filled in some way. A number of options exist, including ramping smaller coal-fired power stations up and down; energy storage systems (batteries, water storage, heat storage, etc.); or flexible generation systems, such as gas- or diesel-fired generators.

To comply with the commitment the South African government made at the 21st Conference of Parties, known as COP21, which is aligned to the United Nations Framework on Climate Change, in December 2015, the country needs to reduce its carbon emissions significantly. To do so, Yelland said, South Africa should close a number of old coal-fired power stations as soon as possible. It should also reduce the number of fossil-fuel powered vehicles on South Africa’s roads.

Yelland said petrol and diesel vehicles should be replaced by electric vehicles; coal-fired power stations should be replaced by those which operate on clean fuels, such as nuclear, wind, hydro or solar. Even gas, which is a fossil fuel, is cleaner than coal and diesel, he added.

Nuclear power stations are extremely expensive to build, take many years to complete and do not offer flexible generation capability. Once complete, nuclear power stations are cheap and clean to run. But can South Africa wait for a decade or longer before electricity from a new nuclear power station becomes available?

Solar, either concentrated solar power or photovoltaic (PV), and wind are clean, quick but relatively expensive to build. Recent examples have shown that a 100 MW PV plant can be built in under a year. Once built, the fuel they use is free. The same is true for wind farms.

Gas-fired generation (closed cycle or open cycle types) are cheap and quick to build but require a fuel source we don’t have to hand: natural gas. Liquified petroleum gas (LPG) can be used, but that has to be imported and transported to the generator which adds to its cost, he said.

The results of a study undertaken by the Council for Scientific and Industrial Research (CSIR) show that South Africa has sufficient wind and solar to provide power to the country. However, to have the power when we want it, rather than when it’s available, we will need to supplement wind power and solar power with other generation technologies. The CSIR recently released a study which shows that 50% of South Africa’s landmass is suitable for wind turbines, as long as the turbines are 100 m or more above the ground, Yelland said.

South Africa needs to adopt a generation mix comprising solar (PV and CSP), wind, gas and coal to provide the country with a stable, relatively clean, source of electricity, Yelland said. The country should close all of its old coal-fired power stations immediately, abandon its new nuclear ambitions, cancel any agreements it may have entered into for new coal-fired plant (private or publically owned) and focus on building many more wind- and solar-powered stations.

Although nuclear power in South Africa has proven to be cost-effective and safe – the Koeberg nuclear power station in the Western Cape has been running for 30 years without accident – the cost of a large (9600 MW) plant is probably not affordable and may produce more electricity than the country needs, he added.

The electrical grid infrastructure, which transports electricity from generators to users, should be updated with modern “smart-grid” technology as this will enable it to manage multiple sources of generation distributed across the country.

The siting of these renewable energy power stations should be near to where the loads are, thereby improving efficiency by saving transmission losses.

Such a plan will achieve financial and environmental savings for the country and develop a new industry with new opportunities for employment and foreign investment, Yelland said.

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