“Wind farms do not reduce emissions.” A commonly used talking point by those opposed to wind farms. This talking point is evidently enjoyed so much by some that this week the Global Warming Policy Foundation reposted a story from Natural News on the subject. Natural News is at a level nutbaggery that one would have thought that even the GWPF would be sensible enough not to use it as a news source. But one thing is clear, most of the people who claim that wind farms don’t reduce emissions first don’t care about emissions in the first place, and second don’t care if wind farms don’t reduce emissions. They just don’t want them built.
So, do wind farms reduce emissions?
Let’s first get out of the way that some don’t. Building wind farms on certain types of peat bog is probably not a good idea. There are of course plenty of onshore sites without peat bogs, and offshore wind farms quite obviously don’t suffer from this problem at all. What we are looking at is something that can be solved through regulation, or carbon pricing. As an anti-wind talking point it is quite limited.
This tweet by the United Kingdom Independence Party’s MEP Roger Helmer leads me to the other claim: “wind farms increase emissions.”
The gist of this argument is that wind farms have an average capacity factor of 25%. So, if wind farms have a total capacity of say 10 GW, on average 2.5 GW will come from wind farms and 7.5 GW needs to come from something else. The problem for wind power proponents is that when the wind farms aren’t running it will be less efficient gas power that provides the electricity. A CCGT gas plant running efficiently will produce 0.4 tonnes of CO2 per MWh, whereas a less efficient OCGT plant, or CCGT plant running inefficiently, will produce 0.6 tonnes of CO2 per MWh. Add in 10 GW of wind to the electricity grid, and you go from 10 GW of electricity supply from efficient CCGT gas plants at 0.4 tonnes of CO2 per MWh being replaced by 7.5 GW of inefficient gas and 2.5 GW of wind, which comes to 0.75*0.6 = 0.45 tonnes of CO2 per MWh. An increase, not a decrease in emissions. A major blow for wind proponents, and total nonsense.
Consider electricity demand on a typical day. I’ll show Spain’s, but you can easily find it for other countries at the data sources page on my blog.
These swings in demand are far greater than anything that can be expected for wind power less than between 20 and 30% of electricity demand. The impacts of wind on the need to run less efficient gas plants is currently negligible, and likely will be for the next decade in the UK. Just ask the UK’s National Grid, who using actual grid data found that wind farms currently have a close to zero impact on how often inefficient gas plants are run.
I can also refute the argument in the “excellent” analysis linked to by Roger Helmer above with one simple graph: wind power output in Germany today.
The total wind capacity in Germany is about 33 GW, but I believe only about 30 GW is represented by the graph above. Let’s think about what the “wind farms don’t reduce emissions” claim requires. Essentially between 12 am and 12 pm this morning German wind farms must have forced about 17 GW of electricity to come from inefficient gas plants. But, wind farm output is essentially flat all morning. So, the claim that wind farms increase emissions is blatant nonsense, which requires us to assume wind farms have magical powers.