Estonia had set a target to increase the share of renewable energy sources in the energy production up to 5.1% of total consumption by the end of 2010. There are no large rivers and solar activity is also low in Estonia. Therefore one of the biggest possibilities to achieve that target is to use bio fuels and wind power. Approximately 90% of total electricity is generated from oil shale, hereby oil shale power plants have to cover wind energy deficits. Wind speed is very variable and therefore electric power production by wind turbines varies from zero to nominal power. This is a problem for the power grid. The current paper analyses whether wind turbines and wind farms need 100% balanced power. Wind data of four weather stations around Estonia were investigated. Wind speeds were calculated to 100 meters above the ground level and Weibull distributions were composed. Distribution and duration of zero energy periods were analysed. In 2008 zero wind production periods varied from 1 to 7 hours (63 times) and their sum was 137 hours. In these periods wind turbines need 100% balance power.