A Pilot Plant for Energy Harvesting from Falling Water in Drainpipes. Technical and Economic Analysis

Abstract

Renewable energy sources are currently object of great attention from the scientific community involved on the matter, in the general context of the ongoing climate change and related implications. In this work, we investigate the costs needed to implement a technical solution to harvest energy from drainpipes. To this aim, a pilot plant was built at the Laboratory of Environmental and Maritime Hydraulics (LIDAM), University of Salerno, Italy. The driving idea consists in the possibility of collecting rainwater at the roof of a building, storing it in tanks. In this way, the established hydraulic head can be converted into kinetic energy at the bottom of the building as can be easily explained by applying the Bernoulli’s principle. Here, a water jet of mean velocity of up to tens of m/s is formed at the pipe outlet as it is provided with a nozzle. The stream is directed against a Pelton turbine where the rotational kinetic energy is finally converted into electrical energy by means of a DC brushed motor turned as generator. The analysis of the investment and management costs of the pilot plant provides useful economic parameters for implementing the project in practice.