CarbonCalculator CarbonCalculator
[ (w/1000) * t ] * g = c
where
w = appliance wattage,
t = running time hrs,
g = CO2 per kWh
c = CO2 for running time
Firstly it is necessary to know what forms of fuel are used for energy generation and what proportion of the whole each represents.
|
Gas
|
38.54%
|
Using these numbers it is possible to imagine an average kWh of electricity which is generated by a combination of all types of fuel in the proportions listed.
|
|
Coal
|
33.93%
|
|
|
Nuclear
|
20.53%
|
|
|
Oil
|
1.36%
|
|
|
Hydro
|
1.25%
|
|
|
Wind
|
0.73%
|
|
|
Other Renewable's
|
3.66%
|
Thats the easy bit, most reputable sources agree on these figures for UK energy generation and the variations are very minor.
The amount of emitted carbon per generated kWh of electricity is a much more complex issue. Virtually every potential source of information has a vested interest in making one or more fuel types look better or worse than another. The way emissions are calculated can also have a significant effect on the results, for instance it is possible to claim that a solar panel generates zero emissions while in operation but taking into account the initial manufacture and disposal of the panel over a given life span can result in a figure of 13 - 731g/kWh.
The table below gives a minimum and maximum figure for grams per kilowatt hour based on life-cycle analysis, that is to say the figures include the carbon emitted as part of the production/construction process as well as emissions that result from disposal/destruction.
|
Fuel
|
CO2 emissions
g/kWh |
Average
|
|
Gas
|
389 - 511g
|
450 g/kWh
|
|
Coal
|
790 - 1182g
|
986 g/kWh
|
|
Nuclear
|
2 - 59g
|
30.5 g/kWh
|
|
Oil
|
744 - 1126g
|
935 g/kWh
|
|
Hydro
|
2 - 48g
|
25 g/kWh
|
|
Wind
|
7 - 124g
|
65 g/kWh
|
|
Other Renewable's
|
28 - 842g
|
435 g/kWh
|
For example:
Coal generation represents 33.93% of the total annual energy production [Table 1] therefore we assume that an average kWh is 33.93% Coal generated. Using the figures in Table 2 we can see that an average kWh of Coal generated energy creates 986g of CO2, 33.93% of 986g = 334.58g. Repeating this calculation and adding all the results gives the figures in Table 3.
|
Fuel
|
Average CO2 emissions g/kWh
|
Percentage of total enrgy production
|
Emissions by percentage.
|
|
Gas
|
450g
|
38.54%
|
173.42g
|
|
Coal
|
986g
|
33.93%
|
334.58g
|
|
Nuclear
|
30.5g
|
20.53%
|
6.26g
|
|
Oil
|
935g
|
1.36%
|
12.74g
|
|
Hydro
|
25g
|
1.25%
|
0.312g
|
|
Wind
|
65g
|
0.73%
|
0.48g
|
|
Other Renewable's
|
435g
|
3.66%
|
15.9g
|
By adding the "Emissions by percentage" from Table 3. we get a figure of 543g of CO2 for an average kWh of generated energy.
