A mobile device for generating electrical power may include a combustion chamber and a heat sink. A TEC module is in thermal communication with the combustion chamber and the heat sink to transfer thermal energy from the combustion chamber to the heat sink. A heat flux across the TEC module causes electrical power to be generated. The mobile device may also include a fuel delivery system to feed fuel into the combustion chamber. A control system may be included to at least monitor and control delivery of fuel to the combustion chamber by the fuel delivery system and to control a temperature gradient across the TEC module to control the electrical power produced by the thermal-to-electric energy conversion device.