This paper describes the feasibility analysis of an innovative, extensible blade technology. The blade aims to significantly improve the energy production of a wind turbine, particularly at locations with unfavorable wind conditions. The innovative 'smart' blade will be extended at low wind speed to harvest more wind energy; on the other hand, it will be retracted to its original shape when the wind speed is above the rated wind speed to protect the blade from damages by high wind loads. An established aerodynamic model is implemented in this paper to evaluate and compare the power output of extensible blades versus a baseline conventional blade. The model was first validated with a monitored power production curve based on the wind energy production data of a conventional turbine blade, which is subsequently used to estimate the power production curve of extended blades. The load-on-blade structures are incorporated as the mechanical criteria to design the extension strategies. Wind speed monitoring data at three different onshore and offshore sites around Lake Erie are used to predict the annual wind energy output with different blades. The effects of extension on the dynamic characteristics of blade are analyzed. The results show that the extensive blade significantly increases the annual wind energy production (up to 20% to 30%) with different blade extension strategies. It, therefore, has the potential to significantly boost wind energy production for utility-scale wind turbines located at sites with low-class wind resource.Energies 2017, 10, 1295 2 of 24 away from cities [6,7]. However, more and more wind turbines named 'distributed energy resources' are installed at locations with lower-class wind resources [8-10] to take advantages of their close proximity to the existing electrical grid or manufacturing infrastructures. It helps to reduce the development and transportation cost, which offsets to a certain extent the disadvantages of the low-quality wind resource. In contrast to wind farms, which typically contain hundreds of wind turbines, distributed generators are mostly small-scale power generators located close to the service loads. There are a significant number of wind turbines built as distributed energy resources. According to the U.S. Department of Energy's Distributed Wind Turbine Market Report, 934 MW of distributed wind capacity was installed between 2013 and 2015, representing nearly 75,000 units across 36 states, Puerto Rico, and the U.S. Virgin Islands. Effective utilizing wind resources at sites with low and medium wind speed helps to make wind energy production to be more geographically dispersed; this also helps to reduce the inherent variabilities of wind energy production [11,12].Improving the energy production at sites with low-class wind bears an important practice value. One potential method is to increase the wind turbine hub height [4,[13][14][15][16], which utilizes the benefit that the near-ground wind speed increases with elevation. There are, however, significant cost factors...