Generating Electricity

Generating Electricity and Power Stations

In the BGE course, Power generation was discussed in the Energy topic. There are several Energy sources that are used on a commercial scale to generate Electricity:-


  1. Fossil Fuels (Coal / Oil / Natural Gas)

  2. Nuclear Power

  3. Hydroelectric Power

  4. Wind Power

  5. Solar Power

  6. Wave Power

  7. Tidal Power

  8. Geothermal Power

All of the above are used to generate Electricity in very different ways. Below is a more detailed look at the methods of generating Electricity.


Fossil Fuels

The main source of Energy since the Industrial Revolution has be the Fossil Fuels - Coal, Oil and Natural Gas. These are the remains of living organisms that died millions of years ago which were buried and the subject to huge temperature and pressure. The diagrams below show how the three Fossil Fuels were formed:-

The video below shows an in-depth look at the process of Coal Mining:-

Thermal Power Stations

All three Fossil Fuels generate Electricity in the same way, by acting as essentially a large kettle. The fuel is used to heat water, with the resulting steam being used to drive a turbine, which in turn drives a generator, generating Electricity.

The diagram below shows a simplified cross-section of a Thermal Power Station:-

The energy changes in a Thermal Power Station are:-

  1. Burning the fuel - Chemical Energy converted to Heat Energy

  2. Steam driven turbine - Heat Energy converted to Kinetic Energy

  3. Generator - Kinetic Energy converted to Electrical Energy

Note - A Nuclear Power Station works in the same way as a Thermal Power Station, except that the water is heated in a different way (see Nuclear Power - Unit 3)

The video below shows an animation showing the main parts of a Thermal Power Station, as well as some methods for reducing the pollution released by a Power Plant:-

Hydroelectric Power

Hydroelectric Power uses the Energy of water flowing rapidly downhill to generate Electricity. The diagram below shows a simplified cross-section of a Hydroelectric Power Station:-

As the water is at a high point above the dam, the water contains Gravitational Potential Energy. As the water flows down the penstock (tunnel through the dam), the Gravitational Potential Energy is converted to Kinetic Energy. This Kinetic Energy is used to turn a turbine and drive a generator, which generates Electricity.

The energy changes in a Hydroelectric Power Station are:-

  1. Stored in loch behind dam - Gravitational Potential Energy.

  2. Water flowing downhill - Gravitational Potential Energy converted to Kinetic Energy.

  3. Turbine and generator - Kinetic Energy converted to Electrical Energy.

Wind Power

Wind Power uses the Energy of moving air to generate Electricity. The diagram below shows a simplified cross-section of a wind turbine:-

When the wind blows, the moving air causes the blades of the wind turbine to rotate. These rotating blades are attached to a shaft which drives a generator, generating Electricity.

The energy changes in a wind turbine are:-

  1. Moving air (wind) - Kinetic Energy

  2. Turbine and Generator - Kinetic Energy converted to Electrical Energy

Solar Power

There are two main ways to generate Electricity using the Energy from the Sun.

These are:-

  1. Photovoltaic Cells (Solar Cells)

  2. Solar Thermal Power Stations


Photo-voltaic Cells

Photovoltaic Cells (more commonly known as Solar Cells) convert light energy directly into Electricity. The process of how this happens is covered in the Higher Physics course. The diagram below shows a simplified cross-section of a Photovoltaic Cell:-

The energy changes in a Photovoltaic Cell are:-

  1. Sunlight - Light Energy

  2. Photovoltaic Cell - Light Energy converted to Electrical Energy


Solar Thermal Power Station

A Solar Thermal Power Station uses focussed sunlight to generate Electricity. The diagram below shows a simplified diagram of a Solar Thermal Power Station:-

A Solar Thermal Power Station uses focussed sunlight to boil water into steam. This steam is then used to drive a turbine and generator in the same way that a Fossil Fuel Power Station does.

The energy changes in a Solar Thermal Power Station are:-

  1. Sunlight - Heat Energy

  2. Steam driven turbine - Heat Energy converted to Kinetic Energy

  3. Generator - Kinetic Energy converted to Electrical Energy

The video below shows a Solar Thermal Power Station in operation in Spain:-

Wave Power

A Wave Power Generator uses the motion of waves to generate Electricity. This motion is used to drive a hydraulic generator, which generates Electricity. The diagram below shows a simplified diagram of a prototype Wave Power Generator:-

In the above system, the yellow section of the device float on the water's surface. As the waves pass, the device opens and closes, forcing sea water into the flow line. This drives either a Hydraulic pump or a Hydroelectric system on the land, which generates Electricity.

The energy changes in a Wave Power Generator are:-

  1. Waves- Kinetic Energy

  2. Hydroelectric generator - Kinetic Energy converted to Electrical Energy

The video below shows an animation of how the above Wave Power Generator functions:-

Tidal Turbine

A Tidal Turbine uses the Energy of water flowing in tides to generate Electricity. The diagram below shows a simplified diagram of a tidal turbine:-

The Tidal Turbine works in a very similar way to a wind turbine, with the motion of the water causing the blades of the wind turbine to rotate. These rotating Blades are attached to a shaft which drives a generator, generating Electricity.

The energy changes in a Tidal Turbine are:-

  1. Moving water (Tides) - Kinetic Energy

  2. Turbine and generator - Kinetic Energy converted to Electrical Energy

Geothermal Power

Geothermal Power uses the Heat Energy contained within hot rocks deep underground to generate Electricity. The diagram below shows a simplified diagram of a Geothermal Power Station:-

A Geothermal Power Station uses heat from deep underground to boil water into steam. This steam is then used to drive a turbine and generator in the same way that a Fossil Fuel Power Station does.

The energy changes in a Geothermal Power Station are:-

  1. Geothermal Rocks - Heat Energy

  2. Steam driven Turbine - Heat Energy converted to Kinetic Energy

  3. Generator - Kinetic Energy converted to Electrical Energy

Future Energy Production

The video below shows some novel types of Electricity Generation, some in use commercially now, others that are only in the prototype stage:-