Science

Energy (Worksheet 3) Energy Resources Comprehension

Fossil Fuels

Coal, oil and gas are fossil fuels. They are concentrated sources of energy, formed from plants and animals that died over 100 million years ago. When they died, they were covered in mud and earth. Subsequently the huge pressures and hot temperatures changed them into the fossil fuels that we use today. Since it takes so many millions of years to create these fuels, we consider them to be non-renewable fuels. This means that once they have been used up, they cannot be replaced.

Apart from the fact that they are non-renewable, there are several other problems associated with fossil fuels. When fossil fuels are burned they produce carbon dioxide, which is released into the atmosphere. This causes an increase in the temperature of the earth and leads to a rise in the atmosphere. This is called The Greenhouse Effect. In addition when fossil fuels are burned gases are released that lead to acid rain. There are also environmental factors that are created by mining for fossil fuels or by oil spillage when oil is transported in tankers around the world.

Since it is a well-documented fact that fossil fuels will not last forever, we need to consider possible ways to overcome any future shortfalls. This line of research covers two basic concepts;

Firstly to reduce the amount of fossil fuels we use now in order that they may last as long as possible.
Secondly to discover and use other sources of energy, preferably renewable sources.
We can reduce the amount of fossil fuel consumed through a number of means. However the most important point regards educating the public to waste less energy through leaving lights on or not properly insulating their homes. In addition scientists are continually trying to develop better cars that use less petrol and are more efficient.

Renewable sources of energy include wind power, tidal power, wave power, solar power and others. All these sources of energy have some advantages and disadvantages as detailed further below.

Power Stations
The majority of electrical energy that we use at home is generated at power stations. There are different types of power station but most of them use coal or gas as their source of energy.

Alternative Energy Resources

GEOTHERMAL
In this process, water is pumped several kilometres below the ground to hot rocks. These hot rocks turn the water into steam, which then rises out of the ground and is used to drive turbines and hence create electricity. This is a renewable source of energy that has no associated environmental or pollution problems. However this source of energy is limited due to the very few suitable sites that are available and the high cost of set up.

TIDAL POWER
At high tide, water is trapped behind a dam. At low tide the water is released and flows through the dam back out to sea. The gravitational potential energy of the water converts into kinetic energy as it flows through the dam, driving the turbines within the dam and thus generating electricity. This is a renewable source of energy that is considered reliable. (After all there are two tides a day.) There are initially high costs involved in building the dam. However after any initial expense, the running costs are actually quite low.

SOLAR ENERGY
Solar Power is the process by which the energy carried in the sun's rays is converted into electricity using solar cells. An alternative method of solar power involves the sun heating water that is carried within dark coloured panels, which absorb the sun's heat more easily. There are absolutely no pollution implications with solar power. Solar Power does have a high initial cost but this is easily offset by the benefits thereafter. Obviously solar power has restrictions in countries where long hours of sunshine are limited.

BIOMASS
The chemical energy stored in 'things that grow' such as wood can be released by burning it.
This energy source can be maintained on an ongoing basis by growing successions of trees and using then when needed. You are probably thinking that burning wood is not very environmentally friendly and that this may add to the Greenhouse effect. However this is not strictly true since the carbon dioxide released on burning was taken from the atmosphere when the trees were still alive and growing. This is a renewable source of energy as well as being low-tech so that developing countries can use it easily. However large areas of land are needed in order to grow sufficient numbers of trees.

WIND POWER
Quite simply, the kinetic energy of the wind is used to drive turbines within wind farms. These particular turbines are very similar in shape to windmills although they are a lot sleeker. This is a renewable source of energy and is also considered quite low-tech and therefore can be used in developing countries.

HYDROELECTRICITY
This process uses the kinetic energy of water flowing downhill to drive turbines and generators. This is a renewable source of energy that can be stored until it is needed. However there is a high initial cost associated with this form of energy and the increased threat to the environment through flooding.

WAVE POWER
In this process, the rocking motion of the waves is used to generate electricity. The energy in the water waves allows a simple wave machine to rock back and forth. This motion is used to generate electricity. This is a renewable source of energy but it has very high initial costs with a very poor energy capture. i.e. It does not generate large amounts of electricity.

Energy Comprehension

1. Name three types of stored energy?

2. What kind of energy does water form as it falls down a waterfall?

3. Name three fossil fuels?

4. Why are fossil fuels called non-renewable sources of energy?

5. Suggest three ways in which we can make fossil fuels last longer.

6. Name three ways in which water can be used as an energy resource.

7. Name two energy resources that can be used in developing countries.

8. Give one example of an object that uses elastic potential energy.

9. Which fossil fuels when burned, cause acid rain?

10. Name two energy resources that may be limited by the ability to find a suitable site.

1.	Name three types of stored energy?
2.	What kind of energy does water form as it falls down a waterfall?
3.	Name three fossil fuels?
4.	Why are fossil fuels called non-renewable sources of energy?
5.	Suggest three ways in which we can make fossil fuels last longer.
6.	Name three ways in which water can be used as an energy resource.
7.	Name two energy resources that can be used in developing countries.
8.	Give one example of an object that uses elastic potential energy.
9.	Which fossil fuels when burned, cause acid rain?
10.	Name two energy resources that may be limited by the ability to find a suitable site.