Generating and Transmitting Electricity

S Thompson

Mr S Thompson

A renewable energy source is one that will not run out.

A non-renewable energy source is one that when it has been used it is gone forever.

Non-renewable energy sourcesNon-renewable energy sources

Coal, Oil, Gas and Nuclear

Advantages Disadvantages

Cheap fuel costs

Short start-up time for gas and oil

Good for “basic demand”

Fuel will run out

Costs a lot of money to

decommission a nuclear plant

Pollution – CO2 leads to global warming and SO2 leads to acid rain

Reliable

Nuclear produces little pollution

FuelsFuelsA “fuel” is something that can be burned to release heat and light energy. The main examples are:

Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.

Using non-renewable fuels in power Using non-renewable fuels in power stationsstations

1) A fossil fuel is burned in the boiler

2) Water turns to steam and the steam drives a turbine

3) The turbine turns a generator

4) The generator produces electricity

5) The steam is cooled down in a cooling tower and reused

Start up timesStart up timesDifferent power stations have different start up times:

Gas

Oil

Coal

Nuclear

Quick

Slow

PollutionPollution

When a fuel is burned the two main waste products are carbon dioxide and sulphur dioxide.

Carbon dioxide is a greenhouse gas and helps cause global warming. This is produced when any fossil fuels are burned.

PollutionPollution

Sulphur dioxide, when dissolved in rainwater, causes acid rain. This is mainly a problem for coal power stations.

Nuclear power stations do not produce these pollutants because they don’t burn fossil fuels.

Other ways of generating Other ways of generating electricityelectricity

Can we drive the turbine directly without burning any fossil fuels?

Renewable energy sources Renewable energy sources summarysummary

Wind,Wave,Tidal, Solar,Hydroelectric,

Geothermal and Biomass

Advantages Disadvantages

Zero fuel costs

Hydroelectric is good for a

“sudden” demand

Don’t produce pollution

Tidal barrages destroy the habitats of wading birds and hydroelectric

schemes involve flooding farmland

Unreliable (except for

hydroelectric)

Expensive to build

Solar is good for remote locations (e.g. satellites)

The National GridThe National GridElectricity reaches our homes from power stations through the National Grid:

If electricity companies transmitted electricity at 230 Volts through overhead power lines there would be too much power loss by the time electricity reaches our homes. This is because the current is high.

Power stationStep up

transformerStep down

transformerHomes

The National GridThe National Grid

To overcome this they use devices called transformers to “step up” the voltage onto the power lines.

They then “step-down” the voltage at the end of the power lines before it reaches our homes.

This way the voltage is high and the current and power loss are both low.

Power stationStep up

transformerStep down

transformerHomes

The Cost of ElectricityThe Cost of Electricity

Electricity is measured in units called “kilowatt hours” (kWh).

kWh = No. of kW (Power)

X No. of hours (Time)

Remember 1kW=1000W

The Cost of ElectricityThe Cost of ElectricityExamples:

A 3kW fire left on for 1 hour uses 3kWh of energy

A 1kW toaster left on for 2 hours uses 2kWh

A 0.5kW hoover left on for 4 hours uses 2kWh

A 200W TV left on for 5 hours uses 1kWh

A 2kW kettle left on for 15 minutes uses 0.5kWh

The Cost of ElectricityThe Cost of ElectricityTo work out how much a device costs we do the following:

Cost of electricity = Power (kW) x time (h) x cost per kWh (p)

For example, if electricity costs 8p then…

1) A 2kW fire left on for 3 hours 2X3X8 =

2) A 0.2kW TV left on for 5 hours 0.2X5X8=

3) A 0.1kW light bulb left on for 10 hours =

4) A 0.5kW hoover left on for 1 hour =

48p

8p

8p

4p