I. Mpairaktaris, The issue of scale in hydroelectic energy: many small works or a large one?, Diploma thesis, 124 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, November 2020.
The rapid increase in world energy demand, combined with the ever-growing global environmental awareness, have contributed to the progressive departure from the conventional fossil fuels and the consequent shift to renewable sources. Hydroelectric power is the pillar of renewable energy sources (RES) with a 60% share in the worldwide RES energy production. Hydroelectric projects have a completely different way of construction and operating philosophy, depending on their size. In projects with high installed capacity, typically an upstream reservoir is formed which enables the controlled production of energy from the stored water, whenever required. On the other hand, hydroelectric projects with low installed capacity have negligible water storage capacity and thus energy production for the interconnected grid is not guaranteed. Of course, this configuration is perceived by modern societies as less invasive to the natural environment due to the absence of a reservoir. As a result, the global practice has shifted to the construction of small hydroelectric plants (SHPPs) and in fact large projects are no longer legally considered renewable energy sources. This diploma thesis compares the advantages and disadvantages of small projects in relation to large ones, to determine if the global trend towards them is reasonable. In order to achieve this objective, the study of the wider area of the Achelous river basin is chosen. The Kremasta dam, which is the largest hydroelectric plant in Greece, is being "replaced" with as many SHPPs as needed in order to achieve an equivalent installed capacity. Due to the large number of required stations, a standard design method is developed for their design, which aims to produce the most accurate energy and economic results possible for each of the installation sites, using as little input data as possible. Through this tool, 37 small stations are planned on the bed of the Achelous river, and its tributaries Agrafiotis and Tavropos. Thus, it becomes possible to compare the energy and the techno-economic current status of Kremasta with the hypothetical scheme of the 37 SHPPs.