The repowering of vertical axis water mills preserving their cultural heritage: techno-economic analysis with water wheels and Turgo turbines

Emanuele Quaranta,Toni Pujol,Maria Carmela Grano

doi:10.1108/jchmsd-03-2021-0040

Abstract

PurposeThe paper presents a techno-economic analysis of the electromechanical equipment of traditional vertical axis water mills (VAWMs) to help investors, mill owners and engineers to preliminary estimate related benefits and costs of a VAWM repowering.Design/methodology/approachTwo sustainable repowering solutions were examined with the additional aim to preserve the original status and aesthetics of a VAWM: the use of a vertical axis water wheel (VAWW) and a vertical axis impulse turbine. The analysis was applied to a database of 714 VAWMs in Basilicata (Italy), with known head and flow.FindingsExpeditious equations were proposed for both solutions to determine: (1) a suitable diameter as a function of the flow rate; (2) the costs of the electromechanical equipment; (3) achievable power. The common operating hydraulic range of a VAWM (head and flow) was also identified. Reality checks on the obtained results are shown, in particular by examining two Spanish case studies and the available literature. The power generated by the impulse turbine (Turgo type) is twice that of a VAWW, but it is one order of magnitude more expensive. Therefore, the impulse turbine should be used for higher power requirements (>3 kW), or when the electricity is delivered to the grid, maximizing the long-term profit.Originality/valueSince there is not enough evidence about the achievable performance and cost of a VAWM repowering, this work provides expeditious tools for their evaluation.

Highlights

Water mills, by harnessing the energy of water, were developed for traditional production and works, e.g. grain grinding and wood sawing, with a central role in the shaping and evolution of the cultural landscape (Brykała and Podgorski, 2020)
The value of the maximum flow Qmax that can be generally exploited with a fixed head is Qmax 5 0.6–0.033 H, with Qmax expressed in m3/s (Figure 3). This equation can be used to verify the suitability of a certain site for a vertical axis water wheel (VAWW)
The research carried out to collect the database of vertical axis water mills (VAWMs) in Basilicata has highlighted the importance of archival cartographic sources for the census of historical mills, as the only source that can provide precise information of the mills location at a large scale

Summary

Introduction

By harnessing the energy of water, were developed for traditional production and works, e.g. grain grinding and wood sawing, with a central role in the shaping and evolution of the cultural landscape (Brykała and Podgorski, 2020). Water mills are part of the industrial and cultural heritage. Their preservation and management are challenging, due to the abandonment of these structures and the lack of knowledge about their value (Çorapçıoglu, 2016). In Germany, 58,000 mills operated in 1882 (Mu€ller, 1899) and 33,500 water wheels with power output ranging from 0.75 to 75 kW were licensed as late as 1925 (Kur and Wolf, 1985). In Poland, almost 10,500 water mills operated in the late 18th century (Fajer, 2018), while in Japan 56% of total power generation was provided by water wheels as late as 1886 (Minami, 1982)

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