Page 3 - Energize March 2022

FROM THE EDITOR:

The importance of decarbonising

by Roger Lilley, Now Media the energy sector

ecarbonisation in the energy sector of electricity, and the environmental harm caused by the mining of coal cannot be ignored.
is essential, but how it is done is Neither can the detrimental effect of coal-fired power stations spewing noxious gases and
Dequally important. This is why it’s deadly particulates into the atmosphere. The Department of Environmental Affairs reports
referred to as a ‘just’ transition. that these gases and particulates cause life-threatening and life-shortening illness in both
South Africa’s electricity generating animals and people who live anywhere near where such emissions occur.
industry, dominated by the state-owned Eskom’s plan to repower older stations is a good one. It will help to make the power
power company Eskom, is no different network more reliable and reduce emissions.
to many other countries’ systems. Some At the same time a new technology is developing to make real decarbonisation – at
are further ahead on the decarbonisation an affordable cost – a reality. The falling cost of new wind and solar PV equipment, with
path, while others are behind us. associated energy storage systems, makes decarbonisation not just possible, but affordable.
South Africa’s transition is urgent – and It seems that some people view storage as an “add-on” to renewable energy systems.
becoming ever more so. Eskom’s coal-fired This is incorrect. Storage is, and should always be viewed as, an essential part of a renewable
power stations are getting older and more energy system.
unreliable every day. The number of units We need a reliable supply of power whether the wind is blowing or not, and whether
offline for unscheduled maintenance, the sun is shining or not. Therefore, we need a reservoir of power from which we can draw
as Eskom likes to describe repair after whenever we need to.
breakdown, gets higher every year. Eskom knows all about energy storage. The power utility owns a number of storage dams
These breakdowns add to the necessity into which water is pumped when demand is low, and which are emptied into canals, which
for load shedding and also add cost to the channel water to drive turbines to generate additional power when demand increases.
country’s generation of electricity. Similarly, the power utility also owns so-called peaking plants which have stores of diesel
Fortunately, the power utility has a fuel on hand to drive the modified gas turbines to produce the additional power required
plan to decommission five of its oldest during peak demand.
power stations by the end of 2029. On The concept of storing extra energy when its available for use when it is not, is not new.
paper, that would remove almost 8000 MW As one drives through rural parts of the country one may see numerous wind-powered
of capacity from the grid, but in reality, pumps spinning in the wind. These pumps draw water from a borehole to fill a dam or tank
these old stations don’t actually produce with water for use as and when needed.
anywhere near their rated outputs. Their Energy storage can be achieved in many different ways: pumped water storage, diesel
closure would result in a reduction of tons fuel next to peaking plant, battery storage, hydrogen gas storage, etc.
of CO 2, noxious gases and particulates from Some forms of renewable energy even produce their own storage as part of the
being emitted into the air. electricity generating process. One example is concentrated solar power (CSP) which uses
The youngest of these power stations, the sun to heat a fluid which heats water to produce steam to drive a turbine.
Hendrina, will turn 50 this year; while This fluid stores the sun’s heat for many hours after sunset and can be used to produce
Komati, the oldest is 58 years old. That’s power late into the night.
old for a coal-fired power plant. As Eskom’s coal-fired power stations become more expensive to operate, and less able
The utility has a plan to ‘repower’ to provide reliable power to the grid, the true cost of electricity continues to rise. This is
these, or possibly some of these power exacerbated by the rising cost of coal mining and the rising cost of transporting coal from
stations by replacing the coal-burning mines to power stations.
furnaces with gas burners. While gas is The Department of Mineral Resources and Energy’s integrated resource plan includes gas
also a fossil fuel, it is significantly cleaner and storage in the mix. But the amount of storage should be increased as it’s easier to add
to obtain, transport, store and burn than than new gas.
coal is now, and is ever likely to be. Decarbonisation – even partial decarbonisation by moving from coal to gas as a source of
There are many costs associated primary energy is essential. Eskom’s plan to repower some older power stations seems to be
with the use of coal for the generation a step in the right direction.

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