The current produced in the UK power stations is alternating current AC, the advantage of this is that AC power can be converted by passing it through electrical transformers and have its voltage increased and consequently its current reduced, this means that the cables required for the national grid system are relatively small for power they carry because they have the voltage stepped up to 400,000 volts, this is stepped down again at various stages of the distribution network until it reaches our homes and is at 240 volts or 415 volts in some large buildings or factories
Renewable resources and their advantages.
There are several factors I could use for this:
- the earths biomass, especially wood
- food supplies
- solar power
- hydro-electric
- tidal
- wave power
- wind powder
I have decided to use hydro electric power and wind power.
Hydro Electric Power
Hydro electric power is produced by the process of water flowing under the force of gravity from one level to a lower level and passing through a water turbine that in turn drives an electrical generator. This involves the construction of large dams to hold water back until it is required for powering the turbines, this is an advantage over other types of renewable energy because it can be controlled to produce power at times of peak demand and shut down as the demand falls. Another advantage is that the water can also be pumped back up into the reservoir at times when there is more electricity available on the distribution network than there is demand, this is comparable to a large battery to store power until it is required.
There are other advantages, the control of large amounts of water in a reservoir can prevent mass flooding and allow for the irrigation of dry agricultural land for farming. They can be used for leisure activity including water sport and fishing etc.
They do not contribute to global warming, acid rain or CO2 emissions
Hydro electric power station
Wind power
We have the best wind resource in Europe here in the UK and wind turbines are becoming more common along or coast and exposed areas of moor land. The principal of there operation is very simple, the wind pressure on the blades of the turbine force them to turn, this turns the electrical generator through a mechanical gear box. The blades of the turbine are adjustable so that they can change their angle to the wind, this allows them to keep a constant number of revolutions per minute at a range of wind speeds. The blades are also turned into the wind to match its direction.
The advantages of wind power are that it dose not produce any pollution, CO2 or other green house gasses. It also reduces our reliance on other forms of fossil fuel, our government has set a target of 10% of our power should be created from renewable sources by 2010 and it is estimated that at least half of this will come from the currently planed find farms. 7.2 GW of electricity will be created by these 15 wind farms the largest will be located off the Lincolnshire coast and will have 250 turbines.
As in common with all renewable energy it will not run out and
Wind turbine
Renewable resources and their disadvantages
Hydro Electric Power
The construction of large dams for reservoirs can be very destructive to the environment and there ecosystems, the location of these dams is often in remote areas that are damaged by the construction process. Often large areas of land have to be flooded under the waters of the reservoir these can in some cases include entire villages and destroy habitats. After the area is submerged the vegetation, plants trees etc. will start to decay and produce green house gasses like methane.
Dams can also prevent the migration patters of some fish, for example salmon, that travel up stream to spawn. Very large dams can cause geological damage and increase chance of earthquakes because of the weight on the earths crust. They can also create there own micro climate if they are very large.
Wind power
Wind power does have a number of disadvantages, because the wind turbines work best in exposed areas some are being sited in open high moor land this causes objections because they can spoil the areas by the way they look. They also produce a lot of noise from the blades and the turbine.
Other problems are that they can only work when there is wind and only then between a very limited wind speeds. In very strong winds they can become unsafe and blades can break. In icy conditions ice can form on the blades and then break off and cause damage.
Because of their height there are also problems with birds flying into them and low flying aircraft they can also affect radar equipment
Non-renewable resources and their advantages
Non-renewable recourse are limited to four factors:
- coal
- oil
- natural gas
- nuclear fuels
I have decided to use coal and nuclear fuels.
Coal
Coal is the most commonly used fuel for electrical power stations, the coal is ground into a dust and then blown into the combustion chamber of the large boilers, these heat water and creates steam that drives the turbines and generators,
The advantage that coal has over other types of fuel is that in the UK we have had large coal deposits and a big mining industry in the recent past. Because coal can be stock piled it can used to produce power at any time and is not weather dependant like wind and solar power.
Typical modern coal fired power station
Nuclear fuels
Nuclear power uses nuclear fission to produce heat energy, the atoms nucleus are spilt and this produces a chain reaction and creates large amounts of energy, the reaction is controlled to prevent it going too fast. The heat energy is used in the same way as in coal power stations, it is used to make steam to drive the turbines and generators
The advantage of nuclear power is that it only requires relatively small amounts of fuel, one kilo of Uranium-235 will produce the same amount of energy as 2,000,000 kilos of coal. This is an advantage if there are limited alternative resources.
Nuclear power stations do not emit any green house gas, or pollution that will create acid rain
Nuclear reactor
Non- renewable resources and their disadvantages
Coal
Coal is the largest contributor to acid rain in electrical power generation and other green house gasses, and is responsible the destruction of ecosystems because of this. The coal extraction in mining has also had a negative impact on the health of those employed in the industry, silicosis and other chronic lung disease have claimed the lives of many people.
Nuclear fuels
Nuclear power also has disadvantages, the ionising radiation emitted from the fuel is dangerous to all living cells this means that all the waste from the processing and reprocessing of the fuel must be keep away from human contact for many hundreds of years. Because of this risk the fuel is difficult to transport, and because the power station are have a limited life they are difficult and very expensive to decommission
Conclusion
Large modern thermal power stations ( coal, oil & gas) still generate over 90 % of all UK electricity and will do until the renewable energy generation improves its technology, a large thermal power station can generate the same amount of electricity as 300 (60 meter) wind turbines, 150 square kilometres of solar panels or 100 kilometres of wave energy converters. The UK government propose to generate 10% of its electricity by 2010 from renewable sources, this will involve a massive number of wind turbines being located on and off shore. However it is still important to remember that all non renewable resources will run out eventually and we most then rely on our renewable resources.
Bibliography
Electrical review - Jan 2004
Collins revision guide
CGP AQA Modular science
