This is a very small powerplant for smart grids application based on an ORC (Organic Rankine Cycle) adopting a mixture of ethanol and water as working fluid, to exploit thermal energy coming from renewable sources (such as solar, geothermal, etc.) or to improve the global efficiency of internal combustion engines. The system is based on a single stage alternative expander provided with an integrated feeding pump, completely designed and built at Istituto Motori of National Research Council of Italy, resulting a very low cost system. Also, even the working fluid results completely renewable, being a mixture of ethanol and water, exactly the same adopted for liquors and other alcoholic drinks (like wines and beers).
The adopted working fluid is completely renewable, it has a very competitive price and a reduced environmental impact. Moreover, especially for medium temperature sources (i.e. between 200°C and 300°C) it offers a clear thermodynamic advantage, because it can deliver a higher average temperature for the incoming heat entering in the system. The ethanol higher thermal capacity (if compared to other refrigeration fluids) also permits to reduce the amount of pumped flow, reducing very much the pumping work. The latter normally results very high (for the above mentioned fluids) because of their very low viscosity (this aspect being the cause of very high internal leakages which lead to a reduced efficiency).