During the negotiations with EU, Estonia was set an indicative target to increase the share of renewable energy sources in the electricity, production to 5.1% by the year 2010. One of the main means to achieve this target is to install wind generators. This paper analyzes the capability of the existing power system to integrate large amounts of wind power and shows that involvement of large-scale oil shale power plants in the compensation of fluctuating production of wind turbines eliminates a substantial part of the expected positive effect of wind energy.