This paper investigates the three-dimensional turbulent flow in a chimney used for venting flue gas from either a boiler or stove. The thermoelectric generator (TEG) modules are embedded in the chimney walls. To understand the power output performance of the TEG module, three-dimensional numerical simulations combining convection and radiation effects, including the chimney tunnel, TEG modules, plate-fin heat sinks and cold plates, based on water cooling are developed and solved simultaneously. The effects of operational parameters such as the flue gas velocity (V-in, = 3, 5 and 10 m/s) and flue gas temperatures (T-gas = 500, 600 and 700 K) on the flow and heat transfer are determined. The influences of the plate-fin height (H-fin) and number of fins (N), ranging from 0 mm < H-fin < 100 mm and 4 < N < 8 respectively, on the power output and pressure drop are also described in detail. It is worthy of note that the net electric power (P-net) of the TEG module was obtained using the ideal electric power (P-TEG) minus the extra pumping power (P-fan). The numerical results for the power vs. current (P-I) curve are in good agreement with the experimental data within an error of 9%. (C) 2013 Elsevier Ltd. All rights reserved.