Many military systems produce thermal energy as a by-product. Generally, this so-called waste heat is lost to the surroundings. Capturing the waste heat and putting it to beneficial use could increase the efficiency of military systems, while having the added benefit of reducing thermal signatures. This paper outlines the application of modeling and simulation to estimate the usable electric power produced by a thermoelectric generator (TEG) array on the exhaust muffler of a small fossil fuel generator. The simulation results informed design, construction, and testing of an initial prototype. Key prototype test variables were temperature difference, load resistance, and electric current. The results of the experiment were compared to and used to update the initial model. This small-scale effort provides initial insight into the efficacy of applying thermoelectric generators to military systems. Future work will explore larger arrays, as well as detailed investigation of the tradespace to identify promising equipment or applications, and inform capability and acquisitions requirements.