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.
A characteristic of hydroelectric power stations is their ability to react very quickly to changes in consumer demand.
Advantages: Water is a renewable source of energy. The process of electricity generation has no emissions.
Disadvantages: SA is a dry country with few rivers suitable for hydroelectric plants. The construction of dams in rivers always has an impact on the environment.
Micro-hydro power is a technically and economically feasible remote area power supply technology option at suitable sites. A typical micro-hydropower scheme diverts water from a river using a dam or weir. The intake is protected using a screen. The water is transported to the forebay using a canal or pipeline. From the forebay the water is taken to the turbine by the penstock. The turbines drive a generator either directly or by means of a mechanical transmission. Turbine speed regulation is achieved mechanically by regulating the flow to the turbine or by means of an electronic speed controller. Electricity can be transmitted by means of an underground cable or overhead line.
Micro-hydropower is highly site specific. The site needs to have a constant supply of water falling through a specific height. The amount of water and the height it falls through will determine the amount of power available. There are 9,8kW of power available from each cubic metre per second of water falling through one metre.
Maintenance on the turbine and generating plant is minimal, although civil works, such as the dam, require periodic maintenance.
- Power is continuous and available on demand
- The process is environmentally friendly
- Limited maintenance, low running costs
- The technology is long lasting and robust
Eskom has however concluded that microhydro is not a feasible option for South African circumstances. It is not economically viable at this stage.