The present invention discloses an expansion engine that, by means of a cycle similar to the
Carnot cycle, converts
thermal energy in general, and
solar energy in particular, so as to transform the heat from a hot source and a cold source into mechanical work and subsequently into electrical energy. There is no economically viable means in the prior art for converting heat resulting from small temperature differences into work. This applies both to systems based on the
Rankine cycle and to those based on the
Stirling cycle. The present invention generates useful energy from an inexhaustible source such as the sun, using an abundant resource such as water, in a
closed circuit. When applied to the utilization of
solar energy, the expansion engine has the notable
advantage of using virtually the entire spectrum of solar
radiation, from
infrared and visible light to
ultraviolet, and not just a fraction of the
visible spectrum, as is the case with photovoltaic panels. The invention is aimed at the production of energy from vast heat sources resulting from small temperature differences, such as those available in geothermal sources, from the
temperature difference between
surface water and deep-sea water, or from water heated by solar
thermal radiation. The present invention enables the production of energy at the required locations and in the required amounts, thereby eliminating the need for electrical
distribution networks. The present invention encompasses a
system for storing large amounts of energy.