Tag Archives: Security

Capacity Credit

Capacity Credit is a measure of how much electricity any new plant can be depended upon to deliver. In the case of wind turbines, which really cannot be depended upon (in industry-speak, they cannot be “dispatched”), it is typically expressed as how much other generation wind can allow to be shut down. Wind energy proponents are eager to demonstrate as large a Capacity Credit as they can, and use traditional statistical techniques to do so.  But in the end their logic just doesn’t make much sense. Wind turbines over large geographical areas can all be becalmed at the same time for extended periods of time, telling me that, without massive storage, no traditional plants can be shut down at all. Capacity Credit must not be confused with Capacity Factor, which is what percentage of its “nameplate” capacity a plant actually generates. If the wind turbines were very reliable it would mean the utility wouldn’t have to maintain large reserves – which cost money and produce emissions. Unfortunately “reliability” in the context of wind turbines is not the same as “reliability” for traditional plants. Continue reading Capacity Credit