A heat conversion device configured for generating electricity and converting thermal energy includes a heat engine configured for converting thermal energy to mechanical energy. The heat engine includes a pseudoplastically pre-strained shape-memory alloy having a crystallographic phase changeable between austenite and martensite in response to thermal energy from a temperature difference between fluids of less than or equal to about 300° C. The heat engine also includes a generator driven by the heat engine and configured for converting mechanical energy to electricity. A heat conversion system configured for generating electricity and converting thermal energy includes a source of thermal energy provided by a temperature difference of less than or equal to about 300° C. between a primary fluid having a first temperature and a secondary fluid having a second temperature that is different from the first temperature, and the heat conversion device.