Solar ponds are salted water artificial lakes with salinity increasing with depth. Water is heated by mean of solar radiation which crosses the ponds. The high salinity of the lower layer inhibits natural convection, so a part of solar energy is trapped and stored as thermal energy. Besides being solar collectors, solar ponds are thermal energy storages up to 90°C available 24/7. The electricity generation is performed by an ORC (Organic Rankin Cycle) using the solar pond as hot sink. As we don’t want to affect drinkable water consumption, we propose to use seawater for solar ponds filling and rainwater recovered along the highway for the refilling required caused by evaporation. As all renewable energy plants, the main costs are construction costs, about 2.000.000 € for each solar pond (100 €/ m2) . Instead, as primary energy source is free, running costs are very low compared whit fossil fuel plants.