Methods, apparatuses, and products passively generate electrical energy from waste heat. Electronic components in cabinets generate waste heat that is used to illuminate an interior of a cabinet. A thermovoltaic semiconductor detects a temperature differential between a pair of terminals installed in the cabinet. The thermovoltaic semiconductor generates a low voltage output in response to the temperature differential. A power supply receives the low voltage output and produces a higher voltage for low-wattage light sources installed in the cabinet.