# decc/numbers-for-decc

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 Pegs on which to hang your learning

Pegs on which to hang your learning

Four facts

1. Energy is bigger than electricity: Less than a fifth of the energy we consume is electricity.
Source: Dukes 2011 Chart 1.4: UK 2010 final energy consumption by fuel, electricity is 17.5%.
2. The UK uses about 2500 TWh of energy a year.
Source: Dukes 2011 Table 1.1: UK 2010 total primary demand. Exact figure is 2646 TWh.
3. The maximum speed at which energy is used by the UK is about 400 GW, the minimum speed is about 100 GW.
4. The UK spends 125 billion pounds on energy each year.
Source: Dukes 2011 paragraph 1.20: UK 2010 spend on energy by final consumers; does not include spend on energy using equipment like cars, boilers or kettles.

Four conversions

1. A TWh (tera-watt-hour) is a billion kWh (kilo-watt-hours). A kWh is the unit on your electricity bill.
In general: T means tera- which means trillion; G means giga- which means billion; M means mega- which means million; k means kilo- which means thousand.
2. A GW (giga-watt) is a million kW (kilo-watts). A kW is the rate at which a small fan heater produces heat.
3. A GW (giga-watt) of power, running non-stop for an hour, produces a GWh (giga-watt hour) of energy.
If a 1 kilo-watt solar panel ran flat out, non-stop, all year it would produce 1 kW x 24 hours x 365 days = 8760 kWh of electricty. It doesn't run non-stop, nor flat out. Darkness and clounds mean that, on average, it runs for 10% of the time, so it produces 1 kW x 24 hours x 365 days x 10% = 876 kWh of electricty. Almost nothing runs flat-out, non-stop, all year.
4. A billion pounds is £15 for each man, woman and child in the UK.
Exact figure: £d 16.06/person. Source: Office for National Statistics UK mid-2010 population of 62.3 million.

A caution

Don't trust claims that something is better because it is more efficient. You need to understand exactly what is meant. Get help.
For instance: the same device can be claimed to be more or less efficienct depending on whether its efficiency is 'gross' or 'net'; even though turning natural gas into heat is almost 100% efficient, while turning gas into electricity is only 60% efficient, turning gas into electricity isn't always wasteful; perpetual motion machines are impossible, but it is possible say a machine is more than 100% efficient.
This is version 0.1 written on 10 May 2012 by Thomas Counsell (tom.counsell@decc.gsi.gov.uk). The latest version is available from http:github.com/decc/numbers-for-decc/short.html.
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