Large-scale electricity production using wind generators began attracting attention in the United States in the 1970s due to the energy crises initiated by oil embargoes. The first wind plants began to be installed in 1980, stimulated by aggressive policy provisions. Although some of these first installations were under-designed and did not survive the early years of operations, some of the best technology continues to operate, some 30 years later, producing electricity as part of profitable commercial businesses. As wind power facilities age, project owners are faced with plant end-of-life decisions. This book is intended to inform policymakers and the business community regarding the history, opportunities, and challenges associated with plant end of life actions, in particular, repowering. Specifically, the report details the history of repowering, examines the plant age at which repowering becomes financially attractive, and estimates the incremental market investment and supply chain demand that might result from future U.S. repowering activities.