Sustainable application of renewable sources in water pumping systems: Optimized energy system configuration

Eighteen years ago, in Portugal, the expenses in a water supply system associated with energy consumption were quite low. However, with the successive crises of energy fuel and the increase of the energy tariff as well as the water demand, the energy consumption is becoming a larger and a more important part of the total budget of water supply pumping systems. Also, new governmental policies, essentially in developed countries, are trying to implement renewable energies. For these reasons, a case-study in Portugal of a water pumping system was analysed to operate connected to solar and wind energy sources.A stand-alone and a grid-connected systems were tested. The stand alone was compared with the cost of extending the national electric grid. In the grid-connected system two solutions were analysed, one with a water turbine and another without. To be able to implement a water turbine, a larger water pump was needed to pump the necessary water as for consumption as for energy production. For the case analysed the system without a water turbine proved to be more cost-effective because the energy tariff is not yet so competitive as well as the cost of water turbines.