Turbines in low-wind areas
Capacity factor is an indicator of how many hours a year a power generator runs. Today, guest author Bernard Chabot talks about how surprisingly high capacity factors are for wind turbines in areas with little wind.
At the end of April, I pointed out that the capacity factors of Germany's two current offshore wind farms is quite high – and what a commotion that article caused! (I would, however, ask those of you with my e-mail address to post comments in the box below instead of writing directly to me so we can have a discussion together.)
One person from the solar sector told me that capacity factors are a stupid indicator for wind power. For instance, he said, turbines being put up in areas with little wind have large swept areas but small generators. They are therefore, he concluded, turning too little of the kinetic wind energy into actual electricity.
But in fact, the same holds true for roofs that faced East and West – we would get more energy from sunlight if these panels were optimally oriented towards the south (or tracking the sun, for that matter). In reality, however, solar proponents in Germany have been pointing out for years that East/West-facing roof arrays help spread solar power production more evenly across the day, which facilitates grid integration.
The same roughly holds true for wind turbines in low-wind areas. They do not focus on the production at certain times to produce slightly more power over the year as a whole, but a more even level of power production across the year to improve reliability. Essentially, the comparison should be not between power from low-wind turbines and larger generators that run for fewer hours, but between wind power without storage (in the former case) and wind power plus storage (in the latter).
So what is the capacity factor of low-wind turbines? Check out Bernard Chabot's analysis in this PDF. (Craig Morris)