Virkjanir 

HYDROELECTRIC POWER PLANT

 

Hydroelectric power is one of the three principal sources of energy used to generate electric power, the other two being fossil fuels and nuclear fuels. Hydroelectric power has certain advantages over these other sources: it is continually renewable owing to the recurring nature of the hydrologic cycle and produces neither atmospheric nor thermal pollution. Hydroelectric power is a preferred energy source in areas with heavy rainfall and with hilly or mountainous regions that are in reasonably close proximity to the main load centres.

 

Hydropower is the only renewable energy that produces a large part of the energy of humanity on competitive price. It produces about 17% of electricity in the world, thereof over 90% of renewable electricity in the world.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

They can be divided into two categories, power plants that utilize falling water and power plants that utilize streaming water. Power plants that utilize falling water utilize the carcass weight of water in the production of electricity and efficiency up to 90%. Power plants that utilize streaming water use part of the kinetic energy of the current to generate energy and the efficiency is 20-40%.

They are the most suitable in places where it is difficult to make dams, drop height is low, there is much water, stream speed is sufficient and flow is even. Most power plants in Iceland are hydroelectric power plants.

Hydropower, electricity is produced with generators which are driven by turbines that utilize the potential energy of falling water or kinetic energy of streaming water. During the generation of hydroelectric power, water is collected or stored at a higher elevation and led downward through large pipes or tunnels (penstocks) to a lower elevation; the difference in these two elevations is known as the head. At the end of its passage down the pipes, the falling water causes turbines to rotate. The turbines in turn drive generators, which convert the turbines’ mechanical energy into electricity.

That is how it works:

1. A lagoon behind the dam maintains the

water height and creates pressure.

2. The water flows down fall pipes and

drives a turbine.

3. Turbines drive a magnetic wheel inside

the generators. Copper windings surround

it and the movement of the magnet makes

electricity flow through the coils.

4. The generator produces the electricity 

which is led with transmission lines out to

the power system

5. Then the water flows from the powerhouse.

 

Hydroelectric power plants are usually located in dams that impound rivers, thereby raising the level of the water behind the dam and creating as high a head as is feasible. When hydroelectric power plants are designed is endeavoring to maximize the utilization of water a decision on the size and design of machines, waterways and reservoirs size. The operation of hydropower is seeking to maximize the use of the reservoir by controlling the flow of water and thus the production of individual plants in accordance with the need of electricity each time.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hydropower in the fall of water depends on the water flow and the collapse of the hill.

Usable water power (P) is recommended in

kiloWatts (kW) or megaWatts (MW). The power is a multiple of the fall height (H) and flow

(Q) through the turbine along factor takes into account the efficiency of the system and the acceleration.

Water power is calculated by the following formula:

P = η g ρ Q H

where

P is the waterpower measured in kiloWatts (kW)

Q is the flow through the turbine, measured in cubic meters per second (m3 / s)

H is the total fall height, measured in meters (m)

g is the acceleration by the earth, g = 9.81 (m / s2)

ρ is the density of the water (kg / liter)

η is the efficiency