ALTERNATIVE ENERGY SOURCES

SOLAR ENERGY
Solar power is energy from the sun and without its presence all life on earth would end. Solar energy has been looked upon as a serious source of energy for many years because of the vast amounts of energy that are made freely available, if harnessed by modern technology.A simple example of the power of the sun can be seen by using a magnifying glass to focus the suns rays on a piece of paper. Before long the paper ignites into flames.
This is one way of using the suns energy, but flames are dangerous and difficult to control. A much safer and practical way of harnessing the suns energy is to use the suns power to heat up water.
A magnifying glass can be used to heat up a small amount of water। A short piece of copper tube is sealed at one end and filled with water. A magnifying glass is then used to warm up the pipe. Using more than one magnifying glass will increase the temperature more rapidly. After a relatively short time the temperature of the water increases. Continuing to heat the water will cause water vapour to appear at the top of the tube. In theory, with enough patience, several magnifying glasses and very strong sun light enough heat should be generated to boil the water, producing steam. This is one way of harnessing solar power.

AIR MOVES FORMING WINDS
Wind power is generated by moving air. As the sun heats the land, the air above also warms and rises. Cold air then replaces the rising air. This creates the winds that we feel most days of the year. The diagram below shows how this ‘system’ works.Air tends to warm at a faster rate over land because the land retains its heat. Over the sea the air warms more slowly as heat by the sun is slowly cooled by the cold water. If you visit the seaside or coastal area you will probably find that the weather is more breezy or windy than inland. This is because the warm air rises over the land and cold air over the sea replaces it.

Throughout history people have taken advantage of the power of wind। Sail vessels have been used to travel along and across rivers, seas and lakes. For example, the Vikings used long ships with sail from Europe to England, Scotland, Wales and Ireland. It is also believed that they travelled even as far as North America, all through the use of wind power.It is also known that the Chinese over 1500 years ago had large sailing vessels and travelled as far as Africa.It is difficult to think of a time when people have not made great use of the power of the wind.

SEA POWER
The power of the tide can be seen in this photograph. It shows people running for their lives from a powerful tidal wave which has crashed over a coastal/river wall (China 2000). If tidal power can be harnessed electricity can be produced in large quantities.

The Earth is covered mainly by water। The seas as we call them, have currents and tides that circulate round the world. This vast amount of moving water produces immense amounts of energy. Countries like Britain that are surrounded by powerful seas and oceans are ideally placed to convert the energy of tides, sea currents and waves to produce electrical energy. The main problem in harnessing sea power is that it is not easy and usually means investment of large amounts of money. Also, quite advanced engineering and technology are required to convert sea power to electrical power.The power of the sea can be harnessed in three main ways; through the energy of waves, the energy of sea currents and tides.

DAMS / HYDRO ELECTRICITY
Water has been used to power industry for hundreds years. The example below shows a water wheel being driven round by a river / stream. As the water wheel turns, a shaft running through its centre would be used to power machines through a range of pulleys. This was the main form of power during the early years of the Industrial Revolution.
Water wheels were the fore-runner of our modern day water driven electrical turbines.
To increase the power provided by water a dam is added। This is seen in the diagram below. The dam allows a ‘head’ of water to build up. The water can be release when power is needed to drive machines inside the building/factory. This system provides more power because:1. A powerful ‘head’ of water is built up behind the dam.2. When the water is released, it is directed to the top of the water wheel. The wheel spins faster because gravity aids the falling water, pushing the wheel round at a higher speed.

NUCLEAR POWER GENERATION
Nuclear Power Stations use a fuel called uranium, a relatively common material. Energy is released from uranium when an atom is split by a neutron. The uranium atom is split into two and as this happens energy is released in the form of radiation and heat. This nuclear reaction is called the fission process
In a nuclear power station the uranium is first formed into pellets and then into long rods. The uranium rods are kept cool by submerging them in water. When they are removed from the water a nuclear reaction takes place causing heat. The amount of heat required is controlled by raising and lowering the rods. If more heat is required the rods are raised further out of the water and if less is needed they lower further into it.
GENERAL ADVANTAGES AND DISADVANTAGES OFNUCLEAR POWER GENERATION

DISADVANTAGES:1. Nuclear power is a controversial method of producing electricity. Many people and environmental organisations are very concerned about the radioactive fuel it needs. 2. There have been serious accidents with a small number of nuclear power stations. The accident at Chernobyl (Ukraine) in 1986, led to 30 people being killed and over 100,000 people being evacuated. In the preceding years another 200,00 people were resettled away from the radioactive area. Radiation was even detected over a thousand miles away in the UK as a result of the Chernobyl accident. It has been suggested that over time 2500 people died as a result of the accident. 3. There are serious questions to be answered regarding the storage of radioactive waste produced through the use of nuclear power. Some of the waste remains radioactive (dangerous) for thousands of years and is currently stored in places such as deep caves and mines.4. Storing and monitoring the radioactive waste material for thousands of years has a high cost.5. Nuclear powered ships and submarines pose a danger to marine life and the environment. Old vessels can leak radiation if they are not maintained properly or if they are dismantled carelessly at the end of their working lives.6. Many people living near to nuclear power stations or waste storage depots are concerned about nuclear accidents and radioactive leaks. Some fear that living in these areas can damage their health, especially the health of young children.7. Many Governments fear that unstable countries that develop nuclear power may also develop nuclear weapons and even use them.ADVANTAGES:1. The amount of electricity produced in a nuclear power station is equivalent to that produced by a fossil fuelled power station.2. Nuclear power stations do not burn fossil fuels to produce electricity and consequently they do not produce damaging, polluting gases. 3. Many supporters of nuclear power production say that this type of power is environmentally friendly and clean. In a world that faces global warming they suggest that increasing the use of nuclear power is the only way of protecting the environment and preventing catastrophic climate change. 4. Many developed countries such as the USA and the UK no longer want to rely on oil and gas imported from the Middle East, a politically unstable part of the world.5. Countries such as France produce approximately 90 percent of their electricity from nuclear power and lead the world in nuclear power generating technology - proving that nuclear power is an economic alternative to fossil fuel power stations. 6. Nuclear reactors can be manufactured small enough to power ships and submarines. If this was extended beyond military vessels, the number of oil burning vessels would be reduced and consequently pollution.