S1 Renewable Energy Summary Notes

Transcription

1 S1 Renewable Energy Summary Notes Energy Fossil Fuels and The Energy Crisis 1 We are learning to find out about fossil fuels and how they affect us and our environment. Fossil Fuels Our main sources of energy for hundreds of years have been fossil fuels. They are called fossil fuels because they are made from decaying fossils such as sea crustaceans or decaying vegetation. They take millions of years to create (under extreme pressure and temperatures), which is why we are running out of fossil fuels. For this reason they are often called non-renewable sources of energy. Coal, oil and natural gas are the three main fossil fuels we extract from the Earth. We are polluting our atmosphere with greenhouse gases. When fossil fuels are burned they release carbon dioxide which contributes to global warming. Other pollutants such as sulphur dioxide are also given off. Alternative and cleaner energy sources are needed!

2 Renewable Energy Forms of Energy 2 We are learning to find out about the different forms of energy 3 We are learning about the energy changes involved in different systems Energy cannot be created or destroyed; it can only be changed from one form to another. Forms of Energy Light energy Electrical energy Sound energy Kinetic energy Chemical energy Heat energy Potential energy

3 Some typical energy changes in different systems System Energy change Buzzer Electrical energy Sound energy Lamp Electrical energy Light energy Dynamo Kinetic energy Electrical energy Car Chemical energy Kinetic energy Solar cell Light energy Electrical energy Motor Electrical energy Kinetic energy Object falling Potential energy Kinetic energy Coal burning Chemical energy Heat energy Energy Generating Electrical Energy 4 We are learning to find out how electrical energy is generated Remember that we cannot simply create energy from nothing, so in order to power our homes and our electronic devices we need to change another form of energy into electrical energy. Fortunately this is quite easy to do. All we need is for a coil of wire to move through a magnetic field (produced by a magnet). This changes some of the kinetic energy of the wire into electrical energy. Either the wire or the magnet can move but if they are both stationary then electrical energy will NOT be generated. We can increase the electrical energy we get in three ways: Increasing the strength of the magnet Increasing the number of coils of wire Increasing the speed at which the wire moves

4 Energy Renewable Energy Generation 5 We are learning about the energy changes in a wind turbine, a wave generator, a hydroelectric power station and a solar cell. The Wind Turbine Wind turbines are able to harness the power of the wind to generate electrical energy. The wind pushes against the blades of the turbine which cause it to turn. Wind power will never run out, so it is a renewable source of energy. The generator contains a magnet and many coils of wire. Electrical energy is generated when the blades turn the coils of wire in the magnetic field. Factors that may affect the electrical energy generated from a wind turbine include: Wind speed (More wind = more electrical energy) Number of blades (Three blades are better than two!) Shape and surface area of blades (More surface area is generally better) Angle of turbine compared to direction of wind (Turbine should face directly into the wind) Wind turbines should be located in windy areas like Scotland. Although if it gets too windy, the turbines must be shutdown to avoid damaging them. Wind turbines do not give off any dangerous greenhouse gases so are considered clean forms of generating electrical energy.

5 Wave Power Wave power stations use the energy of the wave to move a piston or turbine which generates electrical energy. Wave power will never run out, so it is a renewable source of energy. In the same way that wind causes a turbine to turn, the waves move the turbine or piston, which is connected to a magnet surrounded by coils of wire. As the magnet moves through the coils electrical energy is generated. The electrical energy produced can be increased by faster movement of the magnet through the coils a stronger magnet more coils of wire. Wave power stations must be located in the sea or areas of water that get a lot of waves. Normally they are located close to the shore. Wave power stations do not give off any dangerous greenhouse gases so are considered clean forms of generating electrical energy. Hydroelectric Power Hydroelectric energy uses the kinetic energy of falling water to spin a turbine which generates electrical energy. Hydro electric energy will never run out, so it is a renewable source of energy. Rainwater collects in a raised reservoir with a dam to stop the water flowing downstream. This water is high up so has a lot of potential energy. When operational the water is allowed to flow down the dam through turbines that are connected to a magnet surrounded by coils of wire. The magnet moves through the coils and electrical energy is generated.

6 There are two main energy changes involved with hydroelectric power stations. 1. As the water flows down the dam the potential energy of the water turns into kinetic energy 2. Then the kinetic energy of the water turns the turbine changing kinetic energy into electrical energy. The location of hydroelectric power stations is very important. They must be built in hilly areas so that water can be stored in a raised reservoir. Normally they are built in areas that receive a lot of rain to fill the reservoir and in rural areas far away from cities and towns. Fortunately for us Scotland is perfect for hydroelectric power stations. Hydroelectric power stations do not give off any dangerous greenhouse gases so are considered clean forms of generating electrical energy. Solar Cell Solar panels are made up of 30 or more solar cells joined together. They generate electrical energy by using the energy found in sunlight to move electrons in the panel. Solar power will never run out, so it is a renewable source of energy. Solar power is very useful in areas that receive a lot of daylight and is normally sunny. The more sunlight that strikes the solar cells the greater the electrical energy generated. Solar cells do not give off any dangerous greenhouse gases so are considered clean forms of generating electrical energy.

7 Overview of advantages and disadvantages of renewable energy compared with fossil fuels. Energy Resource Advantages Disadvantages Fossil fuels Reliable Create pollution and will run out Wind turbines Clean and cheap to run Expensive to set up and wind does not always blow Wave generators Clean and cheap to run and Expensive to set up Scotland has a lot of coastline Hydroelectric power stations Clean and cheap to run Expensive to set up and output could be affected by drought Solar cells Clean and cheap to run Not always sunny and output does not always outweigh initial cost to set up