processes Article Design Guideline for Hydropower Plants Using One or Multiple Archimedes Screws Arash YoosefDoost * and William David Lubitz   Citation: YoosefDoost, A.; Lubitz, W.D. Design Guideline for Hydropower Plants Using One or Multiple Archimedes Screws. Processes 2021, 9, 2128. https://doi.org/10.3390/pr9122128 Academic Editors: Santiago Lain and Omar Dario Lopez Mejia Received: 2 November 2021 Accepted: 24 November 2021 Published: 25 November 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). School of Engineering, University of Guelph, 50 Stone Rd E, Guelph, ON N1G 2W1, Canada; wlubitz@uoguelph.ca * Correspondence: YoosefDoost@Gmail.com Abstract: The Archimedes/Archimedean screw generator (ASG) is a fish-friendly hydropower technology that could operate under a wide range of flow heads and flow rates and generate power from almost any flow, even wastewater. The simplicity and low maintenance requirements and costs make ASGs suitable even for remote or developing areas. However, there are no general and easy-to-use guidelines for designing Archimedes screw power plants. Therefore, this study addresses this important concern by offering a simple method for quick rough estimations of the number and geometry of Archimedes screws in considering the installation site properties, river flow characteristics, and technical considerations. Moreover, it updates the newest analytical method of designing ASGs by introducing an easier graphical approach that not only covers standard designs but also simplifies custom designs. Besides, a list of currently installed and operating industrial multi-Archimedes screw hydropower plants are provided to review and explore the common design properties between different manufacturers. On top of that, this study helps to improve one of the biggest burdens of small projects, the unscalable initial investigation costs, by enabling everyone to evaluate the possibilities of a green and renewable Archimedes screw hydropower generation where a flow is available. Keywords: design Archimedes screw hydropower plant; quick estimation method; Archimedean screw; fish safe/friendly; multi-ASG; hydropower plant; hydro power plant; small/micro/pico/low head hydro power plant 1. Introduction Hydropower is among the most efficient and reliable renewable energy resources [1] and offers significant value for a sustainable future [2]. Hydropower plants can be classified as in Figure 1 [3] based on the electrical generating capacity. It is estimated that small hydropower plants generate about 10% of global hydropower [3]. Hydropower plants that utilize the natural flow of water in a run-of-river (ROR) configuration [4] usually have small or no reservoirs. The lack of a large, actively-controlled reservoir minimizes flooding land and soil destruction, greenhouse gas emissions, as well as environmental [5] and social impacts [6]. However, the resulting reduction in control of river flow can result in more variable or poorly timed power generation [6]. The Archimedes/Archimedean screw was one of the earliest hydraulic machines [7]. It is made of one or more helical arrays of blades wrapped around a central cylinder [8] and supported within a fixed trough with a small gap that allows the screw to rotate freely [6]. Using Archimedes screws as water pumps dates back many centuries. As a modern application, Archimedes screw pumps (ASP) have been regularly used in wastewater treatment plants. The earliest patent involving using a screw in hydro power plants dates back to 1922 [9], but examples of application of Archimedes screw generator (ASG) technology date back only to the 1990s [10]. The Archimedes screw is theoretically a reversible hydraulic, and there are examples of single installations where screws can be used alternately as pumps and generators [11]. The flexibility, mechanical simplicity, Processes 2021, 9, 2128. https://doi.org/10.3390/pr9122128 https://www.mdpi.com/journal/processes