Hydro power plants:Operating Equation:P = g..W.hwattswhere,g = 9.81m/s2 = 1000kg/m3 (density of water)W and h are discharge (m3/sec) and head (m), respectivelyP = 9.81. W.hkWatts

Another popular form of equation: P = g.w.Q.h.wattsWhere, g = 9.81 m/s2, w = 1000kg/m3 (density of water), Q is the discharge, h is the head, and is the efficiency.Types of these plants and the type of turbines used (also devise a way to remember)

Imp facts to note about hydro electric power plants:1. The oldest and the cheapest method of power generation.1. Energy obtained is free of running cost and pollution free.1. It involves high capital cost and civil construction.1. Requires a long gestation period of 5-8 yrs against 4-6 yrs of steam power plants.1. Types of hydro-power plants and turbines used:4. High Head or Storage (184 1840 m): Pelton 4. Medium Head or Pondage (37 490 m): Francis4. Run of River (up to 61 m): Kaplan1. Sometimes, cascaded hydro-power plants are also constructed. Here, the discharge from one plant becomes the inflow of the downstream plant.1. These plants start quickly (within 5 mins). The rate of taking up load on the machines is 20 MW/min. Thus, hydro power plants are ideal for meeting peak load occurring for a short duration of time.