Almost nothing happens in the Universe without there being a difference of temperature between two places. This suggests that most energy changes are associated with a temperature difference. Electric currents flow with associated Seebeck and Peltier effects. Chemical reactions are associated with exothermal and endothermal changes. Thermal energy itself “flows” from hot to cold places. Heat engines would not work without a temperature difference. Wind turbines require that temperature differences move masses of air. Hydroelectric dams require temperature differences to raise masses of water in the gravitational field.