Water Energy for Turbine Generator

Water is a source of energy which is cheap and relatively easy to obtain. Because of water is stored potential energy (on the water falls) and kinetic energy (on water flow). Hydropower is the energy obtained from water flow.

Water energy can be utilized and used in the form of mechanical energy and electrical energy for turbine generator. Utilization of water energy is mostly done by using a water wheel or water turbine which utilizes the presence of a waterfall or water flow in rivers.

Since the early 18th century water turbine is widely used as the driving flour mills, sawmills and textile machinery. The amount of hydropower available from a water source depends on the size of head and debit water. In connection with the reservoir water, so head is the height difference between the water level in the reservoir and the water out of the waterwheel / water turbines. The total energy available from a water reservoir is a potential energy of water, namely:

E = m g h

Where:

E          = potential energy of water (Joule)

m         = mass of water (kg)

h          = head (m)

g          = acceleration of gravitation (m/s²)

Power is energy per unit time (E/t), so from the equation above can determine equation as follow:

E/t = m g h / t

By replace / doing substitution P to (E/t) and substitute (ρ Q) to (m/t), so can be taken the equation below:

P = ρ Q g h

Where:

P          = potential power of water (watt)

Q         = debit flow of water (m³/s)

ρ          = density of water (kg/m³)

In addition to utilizing hydropower falling water for water turbine generator, the power can be obtained from flat water flow. In this case the available energy is kinetic energy:

E = 0.5 m v²

Where:

v          = velocity of water (m/s)

Available power of water is expressed as the following equation:

P = 0.5 ρ Q v²

The other equation can be obtained with using continuity equation Q=Av, so:

P = 0.5 ρ A v³

Where:

A         = cross area of water flow (m²)