Electricity technologies

Coal

Image of Kriel power station

Producing electricity from coal starts when the coal is pulverised in huge mills into a fine powder before it is blown into huge kettles, called boilers. Due to the heat in the boiler, the coal particles combust and burn to generate heat to turn water into steam. The steam from the boilers is used to turn the blades of a giant fan or propeller, called a turbine. The turbine turns a coil made of copper wire (the rotor) inside a magnet (the stator). Together they make up the generator. The generator produces an electric current, which is sent to the homes and factories of consumers via power lines.

Conventional hydro power

In a hydroelectric scheme, water is stored in a dam and passed through a turbine and generator set before being released back into the river downstream. It is important to note that the power station does not consume any water in this process, it only uses the energy contained in running water to turn its turbines. 

Nuclear

Nuclear Animation

Nuclear power generation is the harnessing of the energy created by a nuclear reaction. To produce electricity an energy source is needed to drive the huge turbines in a power station. In a nuclear power station, that energy comes from the splitting of atoms of uranium – a process known as fission.

Pumped storage

In a pumped storage scheme, the power station is located between an upper and lower dam. In generating mode, water runs from the upper dam through the station’s turbines and into the lower dam where it is stored. During periods when there is sufficient electricity available, the machines are put into pump mode to pump water from the lower dam back into the upper dam where it is stored until the station needs to generate again.

Solar power

Image of Solar power station

Photovoltaic (PV) or solar modules are made up of solar cells that are connected in series. The most common commercial cells are made from purified Silicon (Si). The Silicon cell is essentially a p-n junction that utilises the energy from the sunlight to generate electron flow from the p-type Si (via an external resistance) to the n-type Si. A typical solar module comprises of 36 cells connected in series to produce an operating voltage of 12V.

There is also currently a research project underway to evaluate the potential energy savings and financial benefits of residential solar water heating. The technology is very successful in South Africa and Eskom is assisting the SABS to test a variety of different domestic solar hot water systems in order to determine which suppliers would be best suited in future solar installations.

Wind power

The principle involved in electricity generation is very much the same as what has been used during the centuries. The only difference is the introduction of an electricity generator. The movement of air is used to propel blades. These blades then turn in the wind and along with it an axle that is attached at the centre of the blades. The axle carries over the energy to a gearbox and finally to the generator where the electricity is generated.

Biomass power

Graphic of Biomass examples

Biomass is plant material, either raw or processed, and includes agricultural residues, wood waste, paper trash, municipal solid waste (MSW), energy crops and methane captured from landfill sites. Unlike fossil fuels, biomass is renewable in the sense that only a short period of time is needed to replace what is used as an energy source. This biomass can be used to generate electricity, heat or liquid fuels

Wave power

Waves are a free and sustainable energy resource created as wind blows over the ocean surface.

The technology involves two basic elements; a collector to capture the wave energy and a turbo generator to transform the wave power into electricity.