Energy generation of a small hydropower plant considering the ecological flow

Abstract

Because of an increased care for the environment, many related EU directives were issued on this subject. The Water Framework Directive is one of that and since it was published dramatically influenced the development of new SHPPs and the operation of the existing ones. The longitudinal connectivity of rivers and the available flow downstream SHPP weirs, due to the ecological flow and changes in the way to calculate it are reasons for operational and sometime even constructive changes of the SHPPs. This paper presents some methods for assessing the energy generation of a small hydropower plant considering the ecological flow. For that purpose, 3 different scenarios were considered to determine the ecological flow, and 4 methods were used to obtain the annual energy production: the classical method, a so-called simplified method and software packages dedicated to SHPPs, CASiMiR Hydropower and SMART Mini-Idro. The obtained results indicated that the simplified method and CASiMiR Hydropower performed very well, obtaining relative errors below 1%. The assessment of losses in energy production of a SHPP due to ecological flow for Romanian legislation case is also presented for a case study.