A national record

For the first time in history, on Wednesday 7 June 2017, more energy was generated in the UK using the alternative sources of wind, solar and hydroelectricity than was generated using fossil fuels.

All types of energy resources are used to meet the demands of the UK consumers. It is not unusual for this demand to reach 30 GW at any time during the day.

curriculum-key-fact
1 GW = 1,000 MW = 1,000,000 kW = 1,000,000,000 W

30 GW is the equivalent of 15,000,000 electric kettles all being turned on at once!

The typical output of a power station may be:

Energy sourceApproximate output per station (GW)
Coal power station≈ 1.5
Gas power station≈ 0.5
Nuclear power station≈ 1.3
Wind turbine≈ 0.004
Tidal barrage≈ 2
Solar farm≈ 0.1

Renewable sources either produce much less energy than traditional power stations or require particular geography.

Question

How many wind turbines are needed to replace one average coal power station?

Coal power station = 1.5 GW

Wind turbine = 0.004 GW

1.5 ÷ 0.004 = 375

375 wind turbines provide the equivalent to one coal power station.

Using prefixes

The amount of power involved can be very different depending on where it is used. Power stations produce a lot of power whereas in comparison a light bulb uses much smaller amounts of power. Prefixes are used to make the numbers involved in different contexts more convenient.

1 kW = 1,000 W

1 MW = 1,000 kW or 1,000,000 W

1 GW = 1,000 MW or 1,000,000,000 W

1 TW = 1,000 GW or 1,000,000,000,000 W

A light bulb may only use 60 W so no prefix is needed. But a 15,000 W cooker maybe better expressed as 15 kW. A train may have a power of 1,500,000 W but it would be easier to say 1.5 MW.