A simple method to evaluate the technical and economic feasibility of micro hydro power plants in existing irrigation systems

A simple method is proposed to site turbines and choose their power output, evaluate costs and incomes and provide useful indications for Micro Hydro Power (MHP) plant design in existing irrigation systems. This method, based on simple models available in literature and requiring a reduced number of input parameters easy to survey in preliminary design stages, has been applied and verified in an existing irrigation system located in Calabria (Italy). The results have highlighted that in the case study the smallest profitable turbine would produce 5 kW. A lower number of plants (with higher output) would produce no particular monetary savings compared to a greater number of smaller turbines. Furthermore, neither was the option of increasing pipeline diameter found to provide savings. In general, an appreciable potential from MHP operation has been shown in existing irrigation systems, providing a return on investment higher than that provided by the Italian financial market. Finally, MHP profitability noticeably increases with total annual operation time, being on average 55% higher in a wet year (eight months of electrical production/four month of irrigation) compared to a dry year (six months of electrical production/six months of irrigation).