Hydropower is one of the most efficient and confident sources of renewable energy
[12] and has considerable value for a sustainable future
[13]. By the end of 1999, around 2650 Terawatt hours (TWh) (19%) of the world’s total electricity relied on hydropower
[14]. It rose to about 3100 TWh until 2009, and it is estimated that it reaches to 3606 TWh in 2020
[15]. Dams are essential tools for controlling, storing, managing, and operating water for humankind. Large dams serve various specific purposes for our civilization, including water supply, flood control, navigation, sedimentation control, and hydropower
[16]. However, they also come with disadvantages, including flooding large areas of land, impeding fish migration, and affecting the physical characteristics of the dam’s downstream river
[17]. Construction of large dams needs significant capital, so many large dam projects are national (or even international) in scope. Currently, most new large dams are being constructed to provide combinations of energy, irrigation, and flood control in developing countries. At the same time, dam decommissioning is an increasing trend in developed countries because of environmental impacts and the economic costs of maintaining ageing structures
[11].
Hydropower plants can be classified based on their installed electrical generating capacity. Typical categories and associated capacities are: large hydro (>10 MW), small hydro (<10 MW), mini-hydro (<1 MW), micro-hydro (<100 kW), and pico-hydro (<5 kW)
[18]. It is estimated that about 10% of global hydropower is generated from powerplants with less than 10 MW of capacity
[18]. Micro-hydro plants often utilize the natural flow of water in a run-of-river (ROR) configuration
[19]. ROR plants include little or no controlled water storage, meaning that ROR typically has small or no reservoirs. The lack of a large reservoir formed by a dam, or significant control of river flow, avoids or minimizes the disadvantages associated with large reservoirs, at a cost of having to accept more variable or poorly timed power generation.
Micro hydropower plants can often be considered as a sustainable development option for generating electricity in both developing and developed countries. There is often no need to build expensive dams and flood massive areas for the reservoir. This minimizes land and soil destruction, threats to wildlife, climate change effects, and other environmental impacts, especially on ecosystems
[20] as well as the social impacts of ROR hydropower plants. New ROR hydropower technologies such as Archimedes Screws Turbines (ASTs) can be particularly advantageous in these regards.