Energy

Energy

1. Wind power

   • The wind is produced as a result of large movements of air, driven by energy from the Sun. As long as the sun exists, wind will too.
   • Wind turbines
     • Wind turbines use the wind to drive turbines directly. They have huge blades mounted on a tall tower. The blades are connected to a 'nacelle', or housing, which contains gears linked to a generator. As the wind blows, it transfers some of its kinetic energy to the blades, which turn and drive the generator.
   • Advantages
     • Wind is a renewable energy resource. There are no fuel costs and no harmful polluting gases are produced.
   • Disadvantages
     • Wind farms are noisy and may spoil the view for people living near them.
     • The amount of electricity generated depends on the strength of the wind. If there is no wind, there is no electricity.

2. Water power

   • Like the wind, water can be used to drive turbines directly.
   • These include waves, tides, and falling water in hydroelectric power schemes.
   • Waves
     • The water in the sea rises and falls because of waves on the surface.
     • Wave machines use the kinetic energy in this movement to drive electricity generators.
   • Tides
     • Huge amounts of water move in and out of river mouths each day because of the tides. A tidal barrage is a barrier built over a river estuary to make use of the kinetic energy in the moving water.
     • Huge amounts of water move in and out of river mouths each day because of the tides. A tidal barrage is a barrier built over a river estuary to make use of the kinetic energy in the moving water.
   • Hydro electric power
     • Like tidal barrages, hydroelectric power stations use the kinetic energy in moving water. But the water usually comes from behind a dam built across a river valley.
     • The water high up behind the dam has a lot of gravitational potential energy. This is transferred to kinetic energy as the water rushes down through tubes inside the dam. The moving water drives electrical generators, which may be built inside the dam.
   • Advantages
     • Water power in its various forms is a renewable energy resource.
     • There are no fuel costs and no harmful polluting gases are produced.
     • Tidal barrages and hydroelectric power stations are very reliable and can be easily switched on.
   • Disadvantages
     • It has been difficult to scale up the designs for wave machines to produce large amounts of electricity.
     • Tidal barrages destroy the habitats of estuary species, including wading birds.
     • Dams flood farmland and push people from their homes.
     • The rotting vegetation underwater releases methane, which is a greenhouse gas.

3. Geothermal power

   • Hot water and steam from deep underground can be used to drive turbines. This is called geothermal energy.
   • Volcanic areas
     • Several types of rock contain radioactive substances such as uranium. These release energy, which warms up the rocks.
     • Here the steam can be used to drive turbines and electricity generators.
   • Hot rocks
     • In some places, the rocks are hot, but no hot water or steam rises to the surface. In this case, deep wells can be drilled down to the hot rocks and cold water pumped down.
     • The water runs through cracks in the rocks and is heated up. It returns to the surface as hot water and steam.
   • Advantages
     • Geothermal energy is a renewable energy resource.
     • There are no fuel costs and no harmful polluting gases are produced.
     • The hot water and steam can be used to heat buildings directly.
   • Disadvantages
     • Most parts of the world do not have suitable areas where geothermal energy can be exploited.

4. Solar energy

   • The Sun is a renewable energy resource. As long as it exists and continues to shine, it will release energy.
   • Solar cells
     • A solar cell is a device that converts light energy directly into electrical energy. Some pocket calculators use solar cells, and you may have seen large panels of solar cells on house roofs.
     • You may have seen solar cells powering road signs in remote areas. Very large arrays are used to power satellites in orbit around Earth.
   • Solar heating
     • Do not confuse solar cells with solar panels, which use energy from the Sun to heat up water. These may also be put onto house roofs so that they can absorb the Sun’s energy.
   • Advantages
     • Solar energy is a renewable energy resource.
     • There are no fuel costs and no harmful polluting gases are produced.
     • Solar cells can provide electricity in remote locations where there is no mains electricity.
   • Disadvantages
     • Solar cells are expensive and inefficient, so the cost of their electricity is high.
     • Solar cells do not work at night and not as well when it is cloudy.

5. What makes a good source of elctricity

   • Needs to be reliable
   • They shouldn't produce Co2
   • Low cost