Wind energy plays a crucial role in clean energy generation. Currently, horizontal axis wind turbines dominate the wind energy sector. Nevertheless, vertical axis wind turbines (VAWTs) have some advantages over traditional horizontal axis wind turbines. However, their performance is difficult to predict and they are prone to failure over time. This is because the axis of rotation of a VAWT is perpendicular to the wind direction, which causes the individual blades to experience rapidly fluctuating airflows, even when the wind direction is constant. These fluctuations can lead to unsteady flow phenomena that are not well understood. In this talk, I will present new insights into the aerodynamics of VAWTs by elucidating the unsteady airflow over an individual turbine blade. I will discuss a flow phenomenon known as dynamic stall and its impact on VAWT performance. Because wind turbines are too large to study in a laboratory, most experimental wind turbine research is conducted on scaled-down models, but this typically changes the physics involved. The research I will present was conducted in a pressurized wind tunnel which allows for physically accurate downscaling of large-scale flows. The insights from this research can be used to design VAWTs with better durability and performance.