<P> In Australia, the state of South Australia generates around half of the nation's wind power capacity . By the end of 2011 wind power in South Australia, championed by Premier (and Climate Change Minister) Mike Rann, reached 26% of the State's electric power generation, edging out coal for the first time . At this stage South Australia, with only 7.2% of Australia's population, had 54% of Australia's installed capacity . </P> <P> Electric power generated from wind power can be highly variable at several different timescales: hourly, daily, or seasonally . Annual variation also exists, but is not as significant . Because instantaneous electrical generation and consumption must remain in balance to maintain grid stability, this variability can present substantial challenges to incorporating large amounts of wind power into a grid system . Intermittency and the non-dispatchable nature of wind energy production can raise costs for regulation, incremental operating reserve, and (at high penetration levels) could require an increase in the already existing energy demand management, load shedding, storage solutions or system interconnection with HVDC cables . The variability of wind is quite different from solar, wind may be producing power at night when other baseload plants are often overproducing . </P> <P> Fluctuations in load and allowance for failure of large fossil - fuel generating units requires operating reserve capacity, which can be increased to compensate for variability of wind generation . </P> <P> Wind power is variable, and during low wind periods it must be replaced by other power sources . Transmission networks presently cope with outages of other generation plants and daily changes in electrical demand, but the variability of intermittent power sources such as wind power, is more frequent than those of conventional power generation plants which, when scheduled to be operating, may be able to deliver their nameplate capacity around 95% of the time . </P>

1. how does a wind turbine generate power