Electricity - Methods we use to Generate Electricity
An advantage of overhead electrical lines compared to underground lines is that they are cheap to repair.

Electricity - Methods we use to Generate Electricity

As part of their work on electricity in GCSE Physics, students will look at some of the methods used to generate electricity for homes and industry. In this quiz we take a look at the advantages and disadvantages of fossil fuels, nuclear energy and renewable sources of electricity.

Fossil fuels are still the main source of the world's energy. When they are burnt, they release pollutant gases into the atmosphere which are believed to contribute to both global warming and acid rain. The realisation that burning fossil fuels is probably harming the planet, which could ultimately harm the human race, has meant that many countries are attempting to use fewer fossil fuels. Instead they are using more renewable methods, such as the Sun, wind and water, in order to generate electricity. There are also an increasing number of electrically powered vehicles on the roads which is helping to reduce the emissions of polluting gases.

One alternative to fossil fuels is a non-renewable source - nuclear power. A nuclear power station generates electricity in the same way as a conventional fossil fuel power station: steam is used to turn turbines that turn generators to produce the electricity. Where it differs is that the heat comes from the radioactive decay of atoms in the fuel rods in the nuclear reactor. Since the heat does not come from the burning of fuels, no polluting gases are released. The pollution problem arises in different ways. If there is a leak from the power station, as has happened several times since nuclear power stations were developed, it is usually highly radioactive. When the nuclear fuel is spent it means that it cannot generate enough heat to make the steam. It has to be replaced and the spent fuel needs to be disposed of. The problem with that is that it is still radioactive and could remain radioactive for centuries. Storing it out of harm's way is the biggest problem for the industry. Despite this, many countries have nuclear power stations but more and more plans are being put in place to use cleaner and renewable methods of generating electricity.

One of the problems faced by the companies that supply electricity to homes and industry is the surges in demand at certain times of day, like at breakfast time when millions of homes around the UK switch on toasters and kettles or at peak television watching times. This is mainly solved by the National Grid, which connects power stations together and connects them to homes and businesses. Not all power stations operate at full capacity all of the time, some can be more or less switched off and on when required. Coal fired and nuclear power stations are difficult to switch on and off quickly so they are used to generate electricity all of the time. Gas fired power stations are cleaner than other fossil fuel fired power stations and also can be started and stopped relatively quickly. The fastest power stations to start up are hydroelectric, such as the Dinorwig pumped hydroelectric power station in North Wales. Water is pumped up to a storage reservoir high in the hills using cheap off-peak electricity overnight. When there is a surge in electricity demand, this station can be started immediately, ensuring that there is sufficient electrical energy in the National Grid to cover the surge demand. Dinorwig can go from off to full power in 16 seconds.

Why is decommissioning a nuclear power plant expensive?
The radioactive material has to be fired into space
Radioactive material needs to be disposed of
It is no more costly than decommissioning any other power plant
The material left over has to be used and this takes time and requires man power to ensure the material is safely burned
This requires specialist techniques and materials to ensure the nuclear hazard does not get into the environment
Which of the following fossil fuels has the shortest start-up time?
They all have the same start up time
Oil fired power stations have a shorter start up time than coal
What is an advantage of nuclear power?
Radioactive waste produced
No CO2 or SO2 produced
Costly decommissioning process
Long start-up time
The cost of fuel for nuclear plants is relatively low. They only require small amounts of fuel in order to be able to create large amounts of energy but building nuclear power stations is extremely expensive
What is an advantage of overhead electrical lines compared to underground lines?
Cheaper to repair
Affected by weather
There is no advantage to using overhead lines as opposed to underground
Overhead lines produce more electricity
They are also cheaper to set up. Buried power cables do have many advantages but in the end, the decision usually comes down to balancing the costs with convenience to consumers
Which of the following materials are used in nuclear reactors?
Uranium and plutonium
The most common nuclear fuels are the isotopes of these two elements - uranium-235 and plutonium-239. Kryptonite is a fictional material from the Superman stories, it doesn't exist in real life!!
What is an advantage of renewable sources of energy?
Produce small amounts of electricity
There is an unlimited supply
High maintenance
High initial capital outlay
There are limited supplies of fossil and nuclear fuels
How do solar cells create electricity?
Absorb light energy from the sun
Use turbines which are turned by the wind
Turbine turned by water flows through pipes
Uses steam produced in the Earth's crust to drive turbines
This is known as the photovoltaic effect. Be careful not to confuse solar cells with solar panels which reduce household electricity use by producing hot water by absorbing the Sun's heat
What is an advantage of burning coal?
Cheap and plentiful supplies
Produces more CO2 per unit of energy than oil or gas
Causes acid rain
Will never run out
Coal-fired power stations are flexible in meeting demand and have a quicker start-up time than nuclear plants. It is estimated that there may be over a century's worth of coal left
What is an advantage of using gas?
Risk of spillage during transport
Produce CO2 and SO2
Flexible in meeting demand and has a quick start-up time
Produce radioactive material
Gas fired power stations can be started up a lot quicker than coal, oil or nuclear stations
What is an advantage of using water pumped storage systems?
Uses less electricity
Increases cost of electricity at peak times
Creates electricity at peak times enabling demand to be met
It creates free electricity
Using water pumped storage systems allows power companies to pump water into a high lake using electricity obtained at low demand times, ensuring all power demands can be met during peak times. Its start up time is just a few seconds
Author:  Martin Moore

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