Solar chimney power plants are investigated numerically using ANSYS Fluent and an in-house developed Computational Fluid Dynamics (CFD) code. Analytical scaling laws are verified by considering a large range of scales with tower heights between 1 m (sub-scale laboratory model) and 1000 m (largest envisioned plant). A model with approximately 6 m tower height is currently under construction at the University of Arizona. Detailed time-dependent high-resolution simulations of the flow in the collector and chimney of the model provide detailed insight into the fluid dynamics and heat transfer mechanisms. Both transversal and longitudinal convection rolls are identified in the collector, indicating the presence of a Rayleigh-Benard-Poiseuille instability. Local separation is observed near the chimney inflow. The flow inside the chimney is fully turbulent. (C) 2013 Elsevier Ltd. All rights reserved.