Sagebien and Zuppinger water wheels for very low head hydropower applications

In rivers and at old mill sites there is a substantial amount of very low-head hydropower with head differences from 0.3 to 1.5 m. Much of this potential is unused since in these conditions modern hydropower technology is not cost effective. In the mid-nineteenth century, the Sagebien and Zuppinger wheels were developed for such situations. Recent model tests showed the Zuppinger wheel has a maximum efficiency of 85%. No such data are however available for the Sagebien wheel. At Southampton University, 1: 10 scale model tests with Sagebien and Zuppinger wheels were conducted. Both wheels had maximum efficiency of 84%. The Sagebien wheel's performance curve was less affected by the flow rate. Contrary to the Zuppinger wheel, the Sagebien wheel's geometry avoids noise generation at the upstream blade entry. The results indicate that the Sagebien wheel is an attractive, although so far underestimated, hydropower converter for very low-head situations.