I started working out my carbon footprint for next year to see if it could be reduced. It was an interesting exercise.
There are a lot of things I can’t change quickly – for example my electricity tariff lasts till middle of next year. But where I can’t change I can offset until I can make the change. So my goal for next year is to cut my carbon output by 60% by reducing use and offsetting a further 35% – a total reduction of 95%. But working things out was not just a case of plugging values in to the carbonfootprint or climatesteward calaculators.
I was interested in checking my electricity use. It used to be said that switching off equipment on standby would make a small difference in total consumption. So with my smartmeter I did a test. I placed everything in the house on standby – it was equal to 75% of my average electricity use. And that was without counting freezer and fridge. That tells me I will be hard pushed to reduce my use further, so I have set a reduction target of 5%. The other way to reduce is to look at whether I should change tariff when I can.
My electricity supplier provides the energy mix they used last year as their “disclosure”, so I have no idea what next year will be like. I started looking round at the so called green options. Take for example Green Energy – they claim to be 100% renewable non-nuclear giving 0g CO2e/kWh. Don’t bother trying to discover the carbon equivalent from the other green companies, you have trouble finding out what their energy mix is. A useful reference site seems to be Electricity Info, which will give the energy mix for your supplier. But the problem seems to be that most of the figures are operational carbon production, not lifetime carbon.
A useful pair of references are two documents (1 and 2)produced for parliament (yes they have some good information). This gives the total carbon output per kWh for different technologies. It can be hard to read so I tried my best to copy the values out below.
| Energy Type | Est g CO2/kWh | Low g CO2/kWh | High g CO2/kWh |
| Solar | 88 | 75 | 116 |
| Geo-thermal | 40 | 15 | 53 |
| Nuclear | 12 | 5.5 | 26 |
| Marine | 15 | 10 | 20 |
| Hydro River | 10 | 2 | 13 |
| Micro (local) Wind | 38 | 20 | 96 |
| Wind | 10 | 9 | 13 |
| Coal | 875 | 800 | 1000 |
| Gas | 500 | 400 | 650 |
| Coal with capture | 180 | 160 | 280 |
| Gas with capture | 170 | 140 | 200 |
Mixing this with the energy mix gives a less biased estimate to carbon output for your supplier. But unless you can tell which renewables they are using you end up with a big variation (somewhere between 10 and 100 g/kWh). The end result is that it is that a green tariff might not be so carbon neutral after all.
Seems to me that there are always people ready to sell us second hand cars with one previous old lady owner that took it to the shops once a week.