Fossil fuel power plants, one of the main sources of power generation, are the major emitters of exhaust gases into the environment at relatively high temperature and significant energy. One way to utilize these hot gases is to use wind turbines in the path of fluid flow that created by buoyancy (like a solar chimney). In this paper, the power generation from the gas of the power plant's chimney based on the buoyancy phenomenon using the combination of the power plant's hot output with ambient air is modeled and investigated at different discharge rates and temperatures of the power plant's hot output on a pilot scale. An experimental model, at the same scale of modeling, is constructed and used to validate the modeling results. The obtained results showed that due to the buoyancy phenomenon the combination of the power plant's exhaust gases with the ambient air creates a higher volume of the fluid with a good velocity inside the chimney compared with the exhaust gases of the power plant only. At the temperature of 350 K and velocity of 1 m/s for the hot inlet, the velocity of the fluid resulting from the buoyancy would be greater than 1 m/s for the air which enters the chimney's foot and its gas.