Thermoelectric modules are usually sandwiched between hot-side and cold-side heat exchangers to generate electrical power. But the sandwiched structures are unsuitable for recuperators because large thermal resistance caused by the thermoelectric modules significantly reduces the heat transfer efficiency. In order to maintain heat transfer efficiency and generate more electrical power, a novel concept of a thermoelectric generator integrated recuperator is proposed, with fins made of thermoelectric materials rather than steel. A numerical model is developed using FLUENT software with User Defined Function codes. Compared with conventional plate-fin recuperators, the new recuperator has similar thermal-hydraulic performance and generates additional electrical power. The effects of Reynolds number on open circuit voltage, internal resistance, heat transfer, output power, and pumping power are studied. The optimum hot gas velocity is 1.5 m/s, which produces a temperature difference of 147.6 K, an open circuit voltage of 31.5 mV, and an output power of 0.23 mW. The Taguchi method is employed to design numerical cases for geometrical optimization. Results show that the effect order is: channel width > TE fin thickness > TE fin height. The optimum values of channel width, fin thickness, and height are 1 mm, 3 mm, and 1 mm, respectively. (C) 2019 Elsevier Ltd. All rights reserved.