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# The CarbonExpress  ### What are the facts? Does everyone agree about Carbon emissions?

#### Background:

• To calculate your Carbon footprint you have to know how much energy you are using and then convert that into the equivalent weight in Carbon Dioxide using a conversion figure.

For example 1 kWh of electricity is multiplied by a conversion figure of 0.52, indicating that 0.52kg of carbon dioxide is produced when that amount of electricity is generated.

In a week an average house uses about 75 kWh of electricity. If you use a conversion figure of 0.52, its carbon footprint is 75 x 0.52 = 39kg Carbon Dioxide.

• However, what is the "correct" conversion figure? Different "carbon calculators" vary considerably in their conversion figures, giving very different results when trying to work out your carbon footprint.

• Use the figures below to do some simple calculations to compare conversion figures for electricity production from three different sources.
• Your calculation is based on an average house using 3880 kWh electricity per year.
• To calculate, multiply this figure with the conversion factor.

Carbon Dioxide conversion figures for mains (grid) electricity:

Electricity type

Source

Conversion factor kg CO2

CO2 kg year (based on 3880 kWh per year use)

Grid Electricity

0.43

?

Grid Electricity from gas

CDIAC (USA)

0.56

?

Grid Electricity from coal

CDIAC (USA)

0.97

?

DEFRA is the Department for Environment, Food and Rural Affairs for the UK.
CDIAC is the Carbon Dioxide Information Analysis Center. USA Dept. of Energy

#### Discussion points:

• What is the % difference between the highest and lowest estimate?
• Do you think that these differences are significant?
• Discuss your ideas on why they might be so different with a classmate  Now travel on to the next station: MY EMISSIONS where you will find your data for your own personal emissions.