A transport refrigeration system for controlling temperature within a cargo box during transit, the transport refrigeration system comprising: a refrigerant vapor compression unit having a refrigerant compression device with a compressor motor, a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger arranged in a refrigerant flow circuit according to a refrigeration cycle; at least one fan associated with the refrigerant heat rejection heat exchanger and a fan motor configured to drive the fan; at least one fan associated with the refrigerant heat absorption heat exchanger and a fan motor configured to drive the fan; an electric resistance heater associated with the refrigerant heat absorption heat exchanger; and characterized by a power supply system including a fossil-fueled engine, an electric generator driven by the fossil-fueled engine and a thermoelectric generator operatively disposed in an exhaust gas flow from said engine, said thermoelectric generator operative to convert heat from the engine exhaust gas flow into electric current; and a storage battery comprising a low voltage pack and a high voltage pack; a controller configured to supply electric power from the electric generator to the compressor motor, to the fan motors (42, 46) and/or to the electric resistance heater, when the fossil-fueled engine is operating; and to supply electric power from the high voltage pack of the storage battery to the fan motors (42, 46) and the electric resistance heater and to supply electric power to the controller from the low voltage pack of the storage battery, when the fossil-fueled engine is not operating. a refrigerant vapor compression unit having a refrigerant compression device with a compressor motor, a refrigerant heat rejection heat exchanger and a refrigerant heat absorption heat exchanger arranged in a refrigerant flow circuit according to a refrigeration cycle; at least one fan associated with the refrigerant heat rejection heat exchanger and a fan motor configured to drive the fan; at least one fan associated with the refrigerant heat absorption heat exchanger and a fan motor configured to drive the fan; an electric resistance heater associated with the refrigerant heat absorption heat exchanger; and characterized by a power supply system including a fossil-fueled engine, an electric generator driven by the fossil-fueled engine and a thermoelectric generator operatively disposed in an exhaust gas flow from said engine, said thermoelectric generator operative to convert heat from the engine exhaust gas flow into electric current; and a storage battery comprising a low voltage pack and a high voltage pack; a controller configured to supply electric power from the electric generator to the compressor motor, to the fan motors (42, 46) and/or to the electric resistance heater, when the fossil-fueled engine is operating; and to supply electric power from the high voltage pack of the storage battery to the fan motors (42, 46) and the electric resistance heater and to supply electric power to the controller from the low voltage pack of the storage battery, when the fossil-fueled engine is not operating.