ALTERNATIVE ENERGY
SOURCES
Advantages and disadvantages
These are the different sources of energy available for our use instead of Fossil Fuels:
SOLAR ENERGY
The Sun is the main source of energy for our planet. By using the energy it gives us, we could use this to generate electricity to power in sunny countries. This can be achieved by the use of solar panels. The space ships in orbit have solar cells to power the stations.
One main disadvantage is that large scale construction of solar cells is very expensive. If solar panels were put in sunny deserts, they would create a lot of electricity, but it would be very expensive. And to equal the power that 1 power station generates, you would need 40 square kilometres of solar cells. Desert land is also becoming a source of income for estate agents, so no land can be considered cheap!
BIOMASS
This also derived from the sun. Some of its energy is trapped in plants and trees, as they grow. Burning wood and eating plants lets us use the BIOMASS. Methane is also given off by rotting plants and this can be used in the same way as natural gas. This saves on the amount of natural gas we need. Methane gas can be used for cooking, and is often used in China and India. The process of producing biomass is not instant , and a storage facility would be needed if we were to use biomass as a fuel for generating electrical power.
WIND ENERGY
Large numbers are needed to replace a power plant !
This energy also comes from the sun. Modern windmills are very efficient, although a very large number is needed to produce as much energy as a fossil-fuelled power station.
WAVE ENERGY
Waves are caused by winds moving across the surface of water. They have the potential for generating large amounts of electrical energy, if their energy could be harnessed efficiently on a large scale . One way in obtaining this energy is by putting large floats in the water, and as the waves move, the kinetic energy of the waves can be converted to electrical energy we can use. However, we would need 20 km of these floats to generate as much energy as 1 power station. There is also a problem of obstructing ships and boats by large-scale use of these floats, which will need to be joined together to generate a large amount of energy. Then there is a problem that the movement of the waves varies with time, and the demand for electrical energy might not be matched by the output of the wave generators.
HYDRO-ELECTRIC ENERGY
Falling water from rain, can be stored and used to generate electricity. An upper lake which collects the water, and this then drops a large vertical distance, and gathers speed. The high speed of the water gives a large amount of kinetic energy, which is then used to drive turbine, The kinetic energy of the turbine then drives a generator, which produces electrical energy . It is possible to pump water can be pumped back up to the reservoir, when the demand for electricity is low ( This is usually done at night )
TIDAL ENERGY
Tides are created by the moons gravitational attraction on the seas. As the Moon moves around Earth, the attraction force changes from high to low, on a regular cycle. This causes high and low tides. If a dam is built across an estuary, it could trap water at high tide, and let it flow back through at low tide. As it is allowed to flow back, it passes through turbines which generate electricity.
GEOTHERMAL ENERGY
The process of radioactivity within the inside of the Earth produces heat ! The Earth also becomes warmer towards its centre, and this can be very apparent in some parts of the world. In these regions hot water is heated from the hot rocks below, and gushes out of the ground, while in others it is pumped down very deep holes and steam comes back to the surface. This is used to produce the electricity. Not all regions of the world have hot rocks close to the surface. If we have to dig deeper to extract the heat, then the economics of the operation might not make it worthwhile. This is especially important if you have to pump water down first, since energy is needed to do this ! Of course, with time the rocks below the surface will cool, also making it more of a risky business for geothermal companies.