Capacity factor and specific power

Wind & Water
1

Hi,

How is Capacity factor and Specific power related. I read that that as specific power reduces capacity factor increases, I am trying to understand how.

Regards,
Karthik

2

Dear @Karthik.Prakash,

The capacity factor of a wind turbine is the average power produced divided by its maximum power. The specific power of a wind turbine is the maximum power divided by swept area. A turbine with a large swept area and a small generator will have a low rated wind speed, which means a large capacity factor and small specific power. A turbine with a small swept area and a large generator will have a high rated wind speed, which means a small capacity factor and large specific power.

Best regards,

3

Dear @Jason.Jonkman

Thanks a lot for getting back. Can you help me understand the importance of specific power while deciding a turbine for a site.

Best regards,
Karthik

4

Dear @Karthik.Prakash,

Typically you want to maximize cost of energy. A given site has a given wind speed probability distribution. From my post above, a large specific power has a high rated wind speed and low capacity factor and a small specific power has a low rated wind speed and high capacity factor, but the exact capacity factor will depend on the site-specific wind speed probability distribution. You’d have to set up a cost of energy optimization problem to choose the best turbine for a given site.

Best regards,

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