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CONTENT
1.INTRODUCTION:ALTERNATIVE SOURCES OF ENERGY.. 4
2. NUCLEAR POWER.. 5
3. HYDRO POWER.. 8
4. TIDAL POWER.. 10
5. Conclusion. The most used energy source in the XXI century. 13
1. INTRODUCTION: ALTERNATIVE SOURCES OF ENERGY
Everyone knows the effect that greenhouse gas production and global warming is having on our earth. We feel that it is vitally important for individuals, and especially governments, to start taking these problems seriously; before it is too late. Even though technology has greatly advanced in the last decade most countries around the world still use fossil fuel-based methods of energy production. The use of these fuels has two major problems; it depletes the natural supply and eventually we will run out; and the burning of the fuel (i.e. coal) creates vast pollution in the form of greenhouse gases (GHG's such as carbon monoxide and dioxide, and sulphur dioxide). It is these gases which lead to global warming and slowly destroy our planet. Only through the use of alternative sources of energy (which are virtually non-polluting) can we slow down this destruction and save our planet.
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NUCLEAR POWER
Nuclear power is an alternative power source that uses the nuclear fission of uranium to create heat and, thereby, through a heat transfer mechanism and turbines, create electricity.
For a nuclear reactor to create energy it is necessary for nuclear fission to take place. This occurs when an atom is split into smaller particles and an enormous amount of energy is released in the process. Uranium is used as the fuel for the reaction as it is radioactive, and is therefore unstable enough to be broken down into smaller parts. The uranium atom absorbs a neutron and splits into two equal parts and energy is created. This kinetic energy becomes heat energy as the particles slow down, and it is this heat energy, which is used to produce electricity. The heat is moved through a transfer medium, such as water, and is used to turn water into steam. This steam turns a turbine, which is connected to a generator. As the turbine turns the generator it creates electricity, which is then transferred to the consumers.
Nuclear power is renewable as it doesn't use fossil fuels or other non-renewable resources in the production of energy; however it isn't as renewable as some of the alternatives, such as wind or solar power, which rely solely on natural phenomena to create their power. In the short term it is unlikely that uranium will run out, but eventually it will. Therefore we can say that nuclear power is only renewable in the short term.
About 440 nuclear reactors are used around the world to produce about 17% of the world's electricity but in theory nuclear fission can be used for much more. At the end of the Second World War the Allies secured victory by dropping the atomic bomb on Japan. The bomb uses the same principles of splitting the atom as the nuclear reactors do in creating electricity. On a smaller, less destructive scale, the theories of nuclear fission are used daily in medicine. Scanning devices and the treatment of cancer both use the radiation from splitting an atom.
ADVANTAGES
As an alternative to normal coal-based electricity production nuclear power is favourable as it is much more efficient than coal (250g of uranium produces 20000 times more electricity than 250g of coal) and is far less polluting, especially to our atmosphere, as no harmful greenhouse gases are emitted. (ie. carbon monoxide, sulphur dioxide, nitrogen oxide etc.).
It is generally a reliable process that can be counted on to produce electricity for many years (average availability over three years is about 80%).
The amount of waste produced each year would cover only your dining room table!
The waste is stored in fire-, water-, and earthquake-proof capsules to ensure safety.
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DISADVANTAGES
There is pollution in the form of radioactive waste but with new technologies the process is becoming cleaner and safer each year.
The possibility of radiation leakage or plant meltdown. This is possible in theory and has happened in the past (Chernobyl in Russia) but nowadays there are procedures in place to ensure safety.
There are problems and dangers, which could lead to accidents. The power stations are all manually run and human error could lead to possible accidents.
The reactors also have a very expensive capital outlay in the beginning, although the costs are cheaper in the long run.
The plants do require downtime for maintenance.
HYDRO POWER
Hydro power is the process of changing the kinetic energy of flowing water in a river into electrical power that we can use.
A dam is built where there is a natural lake or a big river in a valley. The dam is used to hold the water and create pressure so that the water can produce more electrical power. There is gravitational potential energy stored in the water and this energy is used to turn generators and create electricity. These turbines are within tunnels in the dam wall. Electrical generators are turned by these massive turbines and create electricity. Water flows through these tunnels with great pressure and is used to turn these turbines. The water has immense pressure due to the great height at which is kept in the dam. If there is a greater volume of water or there is a very large difference between the water level and where it flows out than you can get more power out of the water as it has greater potential energy. This difference in height of the water is called the head. The generator contains 2 main parts: the rotor and the stator. The rotator is the part which rotates and the wire has a huge magnet inside of it; and the stator is the part which is covered in copper. The electrical current is created when the rotor spins around the copper wire on the stator. This is the charge which is then used as electricity.
It is renewable because the process takes nothing away from the environment and therefore nothing needs to be replenished. The water stays in the water cycle and can keep producing energy endlessly.
Hydro power is also utilised by large scale companies as a private use. Many large mining companies or aluminium manufacturers use vast amounts of electrical so rather than buying from the state they can generate their own power by using hydro power generation.
ADVANTAGES
No pollution or waste produced
Renewable energy source
Very reliable energy source
Not expensive to maintain once the dam has been built
Can increase the plants production or decrease it whenever there is high or low demand
Water can be stored, waiting to be used in peak times
DISADVANTAGES
Building the dam is expensive and time taking
The dam will change the habitat and landscape upstream, as much more land will be submersed
The land below the dam is also affected as the flow of water is reduced
Silt can build up in the dam as the water slows down it does not have enough energy to carry the sand and silt which it was
TIDAL POWER
Tidal Power is the generation of electrical power through the harnessing of the ebb and flow of the tides.
A barrage, which is in fact a huge dam, is built across a river estuary or bay. This barrage has gates in it which allow the water to flow into the barrage with the incoming tide. These gates are then closed when the tide begins to go back out. This water which is now trapped inside the barrage is now called a hydrostatic head. The greater the head the more power can be generated from the outflowing water. There are other gates within the barrage which are now opened; these gates contain hydro-electric generators, very similar to the ones used in Hydropower. These generators are now turned by the outflowing water and power is generated.
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The tidal range has to be sufficient in order for this to be a practical means to generate power. This range should be in excess of 5 metres otherwise the power generated is not sufficient.
The main downfall of tidal power generation is the capital needed at the beginning of the project to construct the barrages and the effect on the environment by the change in the water levels. But once the barrages have been built there is a very low maintenance cost. The generators only need changing once every 30 or so years and there is very little work needed to be done.
Yes, the tides will continue to ebb and flow, thus there will always be power being generated. The water is not used up, it stays in the water cycle, and can therefore be used over and over again without the need for replenishment.
Small-scale tidal mills were used in the Middle Ages for grinding corn. The barrages which are built can be used as a means to cross the estuary with much greater ease. The main application of tidal power is as an additional means of generating renewable, sustainable energy which does not affect the environment in a negative way.
ADVANTAGES
It is very cheap to maintain
There is no waste or pollution
Very reliable
We can predict when tides will be in or out
The barrage can help to reduce the damage of very high tidal surges or storms on the land
DISADVANTAGES
It changes the coastline completely and the estuaries are flooded so any mud flats or habitats that birds or animals live on are destroyed
Initial building cost is very expensive
Water is not replenished, it cannot flow away so any dirt or pollution lingers around the coast much longer
Silt builds up behind the barrage
Disrupts creatures migration in the oceans
Needs a very big piece of sea to be cost effective
Not many sites suitable for this kind of power generation; building the barrage
Only produces power for about 10 hours of the day
Conclusion. The most used energy source in the XXI century.
In our opinion, the most popular source of energy in the 21st century will be hydro-energy. In confirmation of our theory, the following reasons were given:
- The source of energy requires minimal staff involvement;
- Hydroelectric power requires virtually no maintenance;
- This source of energy is practically inexhaustible;
- Renewable energy source;
- Ecological energy source.
Bibliography:
1. V. Volodin, AP Hazanovsky Energy, age twenty one - 2008
2. A. Goldin "Ocean of energy" - 2010
3. V. Lavrus Sources of Energy - 2009
4. L. Yudasin. Energy: Challenges and hopes - 2009.
