Grid integration of variable wind power is confronted with many challenges. Challenges and issues associated with large scale wind integration into the existing power grid are discussed in this paper. Different wind turbine technologies and their technical features are presented. A review of the state of the art energy storage technologies, their characteristic features and comparison are presented. Finally, application of a hybrid battery-supercapacitor based energy storage systems with a direct drive variable speed wind turbine is investigated and simulation results are presented.