Water turbine like a true turbine. Fausto Veranzio in his book "Machinae Novae" (1595) described a vertical axis mill with a rotor similar to that of a Francis turbine. Johann Segner developed a reactive water turbine (Segner wheel) in the mid-18th century in Kingdom of Hungary. It had a horizontal axis and was a precursor to modern water turbines. It is a very simple machine that is still produced today for use in small hydro sites. Segner worked with Euler on some of the early mathematical theories of turbine design. In the 18th century, a Dr. Robert Barker invented a similar reaction
Water turbine applications. The power available in a stream of water is; formula_1 where: Some water turbines are designed for pumped-storage hydroelectricity. They can reverse flow and operate as a pump to fill a high reservoir during off-peak electrical hours, and then revert to a water turbine for power generation during peak electrical demand. This type of turbine is usually a Deriaz or Francis turbine in design. This type of system is used in El Hierro, one of the Canary Islands: "When wind production exceeds demand, excess energy will pump water from a reservoir at the bottom of a volcanic cone to