Energy Conversion by Phase Transformation in the Small-Temperature-Difference Regime

The discovery of alternative methods of producing electrical energy that avoid the generation of greenhouse gases and do not contribute to global warming is a compelling problem of our time. Ubiquitous, but often highly distributed, sources of energy on earth exist in the small-temperature-difference regime, 10–250°C. In this review, we discuss a family of methods that can potentially recover this energy based on the use of first-order phase transformations in crystalline materials combined with ferromagnetism or ferroelectricity. The development of this technology will require a better understanding of these phase transformations, especially ferroelectric/ferromagnetic properties, hysteresis, and reversibility, as well as strategies for discovering improved materials.