ELECTRICITY AND POWER GENERATION

POWER STATIONS

Power Stations
This section provides a brief description of the major types of power stations and their suitability for particular operational duties. Where possible, examples of actual power stations.

1. Steam Turbine
2. Hydro Electric
3. Tidal Fuel Cells
4. MHD
5. Open Cycle Gas Turbines
6. Pumped Storage Wave
7. Photovoltaic
8. Nuclear
9. Combined Cycle Gas Turbines
10. Reciprocating
11. Wind
12. Solar Thermal
13. Combinations

Power Station Operations
Modern coal fired power stations with generating units of approximately 200 MW or over, are generally used to generate continuous power for up to 24 hours a day. The abundance of cheap fuel makes these units the most economical generators to run, but due to their inability to change their output quickly, and follow demand, they are not suitable for use as a provider of 'peak demand' power. This is known as providing 'Base Load' power.

Smaller coal fired units are more likely to provide intermediate power, or power to 'top up' the base load providers to meet normal variations in daily power demand. These are normally run as a 2-shift station (2 x 8-hour shifts) which runs at high load during the morning and evening peak demand periods.

At times of very high or very low temperatures, demand for heating or air conditioning power becomes higher than normal. This presents an opportunity for the 'peaking' units to come 'on-line'. These units, usually gas or oil fired turbines, can respond rapidly to changes in demand. The cost of running these units is much higher than for the coal fired units, and so they are only used when absolutely necessary, and when the spot price of electricity is high enough for them to be run at a profit.

In the past, a conventional cycling unit (either an oil or a natural gas fired peaking unit) was described as one designed for rapid rates of load increase and a significantly large number of start-up and shutdown cycles compared to base load operation.

There is a growing number of small 'renewable energy' stations, fuelled by the wind, sun, landfill gas, bagasse, water, tide and waves. The power generated by these stations is generally used to supply energy to local users, or connected to the grid as 'green power'.