  Problem of utilization of the low-potential heat and its perspectives are
considered and one example from the author works is presented in detail.
Description of the project and the results obtained are presented by a
development of the Liquid Metal Magnetohydrodynamic (LMMHD) Gravitational Mini
Power Plant (GMPP) for utilization of the low-potential heat from any available
low-exergy sources, which are the huge sources of the wasted energy around the
globe. Project is based on the experience by the LMMHD energy transformation
with gravitational vapour/gas-lift driving principle. An example of the GMPP
was developed and designed for small local consumers (100kW-1MW) for the
application in the geothermal low-temperature sources 150-250C, big ferries
(unused hot waters from engine), hot waters and gases from metallurgical and
chemical factories, and many other similar customers. The drawings for the
construction have been made and the optimal parameters computed for some
potential liquid metal working media and two variants of the unit modules
assembling have been elaborated (parallel assembling for getting the desired
voltage or consecutive assembling for obtaining the desired current in the
electrical network). The optimal height of the liquid metal circulating loop
was obtained in the range 10-15 m, and the voltage in a unit 1-2 Volt.
