SWMBO has a work colleague, who apart from being an anti-vaxxer, was complaining to her about all these wind turbines which don't generate anything and are built with so much steel and concrete that they are making the climate change even worse.
We know from previous discussions on t’other forum that Solar PV becomes carbon neutral after about 3 years, but I had not heard how long a wind turbine takes to become carbon neutral. During the AGM it was quoted that an industry standard figure is around 6 months which quite surprised me as that’s 6 times faster than PV. I have this morning looked at some info online and 6 months does seem to be in the ball park, especially with a large 2MW+ size.
So I decided to do a back of fag packet calculation to see if that’s credible with the Ripple Wind Turbine 1.
We have heard from AGM that the structure is over 100 tonnes and of course its mainly in the steel tower so we will use 100 tonnes of steel. We also heard 60 concrete deliveries and we worked out its around 1000 tonnes. I did a rough estimate of volume from the photo using the people as a guide for dimensions and I came to a similar conclusion so we will take a figure of 1000 tonnes of reinforced concrete.
I found info on carbon per tonne of reinforced concrete, and of steel.
80kg of CO2 per tonne reinforced concrete (so incudes the steel in the foundation).
1.85 tonnes of CO2 per tonne of steel.
1000 tonnes of reinforced concrete = 80 tonnes CO2
100 tonnes of steel = 185 tonnes CO2
So that’s 265 tonnes of CO2, but then there’s the road, leccy cable, lots of FF vehicles, shipping of the turbine etc. I don’t know how much to add so I’m just going to say total carbon in the range of 300 to 400 tonnes of CO2. Lets take the pessimistic value of 400 tonnes of CO2.
Now the forecast annual generation (P75) is 6681 MWh for the 2.5MW wind turbine.
Now what grid CO2 value should we use, I think that generally wind displaces gas powered generation, so the best gas power stations are over 400g per kWh so let’s be generous to gas and say its 400g / kWh.
So that’s 0.4 tonnes of CO2 per MWh, therefore 6681 x 0.4 = 2672 tonnes of CO2 saved per year.
400 / 2672 = 0.15, so that’s only a little under 2 months, i.e. 12 months x 0.15 = 1.8 months
I guess you could use the grid average of about 233g (2020 figures from Bulb), in that case it would be 1557 tonnes of CO2 saved.
400 / 1557 = 0.26, so that’s still only just over 3 months.
NOTE - Ripples own figures use grid average of 255g and 1707 tonnes of CO2 saved.
And even if we used an even more pessimistic value of 500 tonnes of carbon for the whole build / installation.
500 / 1557 = 0.32, so that’s still just under 4 months.
Maybe you could argue if its really windy then the really big windfarms get curtailed and I believe this one does not, therefore you should use a lower generation figure because your displacing other wind farm generation, because the grid is crap and you need a minimum amount of gas generation to keep a minimum amount of asynchronous generation. So maybe lets knock off 30% of the generation and use 1090 tonnes of CO2 saved.
500 / 1090 = 0.46, so thats nearly 5.5 months.
Anyhow, unless I've missed a decimal point or something it looks pretty darn good. Even by being ultra pessimistic I cannot get the calculation to be above 6 months. And as most wind is in winter, if it manages to go operational by the end of this year, it could be carbon neutral by the time of the members Easter picnic.
Must remember to pack some truly zero carbon Budweiser from the South Wales Brewery powered by its bigger 3.5MW sister at Magnor. Cos that ones already been running since Dec 2020, so its guaranteed to have passed its carbon neutrality date.