A heat engine is provided. The heat engine includes a chassis, a work output member, and an operating mechanism for operating the work output member. The chassis supports one or more heat engine components, including the work output member. The work output member is adapted to generate and output mechanical power to an electric power generation system for generating electrical power. The operating mechanism includes a first actuator band array and a second actuator band array connected to displace the work output member in a first direction and a second direction, respectively, in response to heat exposure. A heat switching mechanism is operable to cyclically expose each of the first and second actuator band array to heat to cause cyclic displacement of the work output member in the first and second direction for generating the mechanical power.