sandersp |
Hi,
The updated carbon conversion data for 2008 is available from the Defra website (at http://www.defra.gov.uk/environment/business/envrp/conversion-factors.ht…) and contains some interesting stuff. It shows the annual conversion factors for electricity from 1990 to 2006 and this goes down from 0.77 Kg CO2 per KWh in 1990 to 0.49 in 1999, but is now on its way back up with 0.56 Kg CO2 per KWh in 2006. This is apparently due to electricity providers switching to coal as the gas prices rise. So much for them claiming to be green.
Defra suggests we use a rolling average over the last five years, which comes out as 0.53 Kg CO2 per KWh. This is to be used to calculate your electricity footprint. However, to calculate potential savings from efficiency measures the government use a figure of 0.43 Kg CO2 per KWh as any reduction in demand would result in the gas turbine power stations reducing their output first, and these more efficient types only emit 0.43 Kg CO2.
This possibly explains why Chris Goodhall in his book “How to live a low carbon life” and Mark Lynas in “Carbon Counter” both quote conversion factors of 0.43 Kg CO2 per KWh to calculate your footprint from electricity. Mayer Hillman in “How to save the planet” also quotes a similar 0.45 Kg CO2 per KWh but is not specific about his source. The difference between using conversion factors of 0.53 and 0.43 for the average British household electricity usage of 3300 KWh is 330 Kg CO2, so quite a sizable chunk.
According to Defra, the conversion factor for calculating gas from KWh of gas use is a bit more complicated as we need to know whether the gas was measured as net energy (factor of 0.206 Kg CO2 per KWh) or gross energy (factor of 0.185 Kg CO2 per KWh). Again, for the average British household gas usage of 19,000 KWh these 2 alternative factors make a carbon difference of 400 Kg CO2 which is again quite a large amount. Does anyone know which factor we should use – is our domestic gas usage net or gross? Any ideas?
Thanks,
Peter.