Distributed generation and water production: a study for a region in central Italy

This study examines the use of distributed power plants coupled to desalination systems to achieve combined production of electrical energy and of water for drinking and similar purposes in Marches, an Adriatic region in central Italy. To reduce Marches’ large electricity deficit, the regional government has drawn up an environmental and energy plan promoting distributed generation through power plants built right where the electricity is consumed. At the same time, the Region’s abundant water resources are increasingly threatened by aquifer pollution, due particularly to fertilizers and to the phenomenon of saltwater intrusion near the coast. Distributed electrical energy generation combined with water production can help meet the goal of reducing the electrical deficit while at the same time improving ground-water quality and reducing the hydrogeological risk. The solution is also efficient, since the more the useful heat recovered by the energy system, the higher its global efficiency. Furthermore, coupling power plants to desalination units is also an excellent application of cogeneration systems, allowing useful recovery of thermal energy in the summer. The study examines different sized plants for the distributed generation of water and power in Marches, from small units to thermal desalination systems that can be coupled to existing power plants. It shows that although endowing existing large power plants with MED (multiple effect distillation) units makes it possible to meet 58 % of the freshwater demand in Marches, it further increases the electricity deficit, whereas coupling small or medium-sized distributed power plants to reverse osmosis systems allows meeting 75 % of the demand for freshwater and reduces the electrical energy demand by up to 50 % in the more energy-intensive districts.