The capacity factor or load factor of a wind turbine is the ratio of actual energy produced in a given time, compared with its full potential. Over a year, the output from a single turbine will vary depending on wind speeds. A typical turbine is expected to generate approximately 20 to 40 per cent of its theoretical maximum output over a year.
The average load factor for wind turbines in Scotland from 2000 to 2012 was 27.9 per cent. However, it is important to consider that this is the average output and that turbines will be active and producing power for around 6,000 to 7,500 hours each year, or about 70 to 85 per cent of the time.
No energy generation technology works at 100 per cent capacity 100 per cent of the time. For example, in 2012, the load factor for coal was 57.1 per cent; for gas, 30.4 per cent; and for nuclear, 70.1 per cent.