Enel - Visita alle Centrali

Steam turbine

The turbine is a mechanical component that allows the conversion of the steam (enthalpy) into mechanical energy. The steam, which has previously been separated by any dragged water, enters the turbine causing it to spin at 3000 revolutions per minute.

Alternator

The mechanical energy produced by the turbine is converted into electricity.

Transformer

The transformer has the task of raising the voltage of the current coming out of the alternator to the voltage level of the line.

Re-Injection well

The spill water from the geothermal plants is re-injected deep into the reservoir through dedicated injection wells, thus maintaining the reservoir pressure and preventing the pollution of groundwater or surface water courses. The re-injected water will be again heated by the rocks of the subsoil and then be subsequently extracted, such as liquid or vapor phase, with production wells.

Cooling tower

Cold water enters the capacitor at 25-30°C and, after it has caused the condensation of steam, hot water comes out at 35-40°C. In order to allow this water to cool down and restart the cycle, it is sent to the cooling tower, where it releases heat to the atmosphere and its temperature is lowered.

Pump

Sends the hot water of the condenser into the cooling tower, so that it can return, at a lower temperature, to the condenser.

Capacitor

The steam leaving the turbine is condensed by the cold water from the cooling tower and distributed by spray nozzles. The condensate is collected in an area called "heat sink", where it is extracted by means of a pump that sends it to the cooling tower.

Extraction wells

Production wells allow you to deliver geothermal fluids from underground.

Hydroelectric

Combined cycle

Photovoltaic

Wind


	Geothermal

	Steam turbine
	Alternator
	Transformer
	Pump
	Capacitor
	Cooling tower
	Extraction wells
	Re-injection well

Coal

Geothermal power plants use the heat of the deep Earth because the temperature of our planet increases as we descend toward the the earth core. This increase in temperature, which is called geothermal gradient, equal to about 3 degrees for every hundred meters of depth but in some areas, where there are geothermal systems, it is much higher, so to have temperatures of 250-350°C at a depth of about 2000-4000 m.
Through the fractures of rock strata, heated water and vapour rise to the surface and are intercepted and produced by geothermal wells.
The vapour delivered from the wells is then convoyed into ‘steam pipelines’ and sent to the turbine, where the energy is converted into mechanical rotation energy.
The axis of the turbine is connected to the alternator which, by spinning, converts the mechanical energy into electrical alternate current that is transmitted to the (AC) transformer. The latter raises the voltage rate to 132.000 volts and feeds it into the distribution network.
The steam leaving the turbine is taken back to a liquid status in a capacitor, while the uncondensable gases contained in the steam, are dispersed into the atmosphere.
A cooling tower can cool the water produced by steam condensation and can supply cold water to the capacitor.
The condensed water output from power plants is re-injected into deep rocks from which the steam has been extracted.
When the wells provide a liquid phase with a temperature below 180°C circa, the heat of the fluid is used to evaporate, in a special heat exchanger, another liquid at a low boiling point (usually isobutane or isopentane) which, once transformed into steam in turn, will be channelled into the turbine triggering the procedure described above.

Italy was the first country in the World to deploy geothermal energy, with the first generation plant constructed 1913 in Larderello. Since then the history of geothermal power has been a source of pride for the Italian energy industry and a feather in Enel’s cap.
Currently the installed geothermal capacity worldwide is 10,000 MW, and it is expected to double by 2016.
Italy, with about 700 MW, is one of the World's leading producers and by far the largest in Europe. Its geothermal generation is focused in Tuscany, which is therefore the Italian Region with the highest renewable production. Indeed, geothermal power covers one fourth of the Region’s energy needs and meets the electricity needs of approximately 2 million homes.
In the next few years this source is expected to undergo further development, also due to Enel’s increasing commitment towards developing and deploying innovative technologies and improving the integration of geothermal plants in their environment, landscape and social structure.
Concerning innovation, a significant development will come, at an international level, from the expanded construction of advanced binary cycle plants, allowing electricity to be generated also from geothermal power at medium temperature (80-180 °C), which up to now was used only for heating or hydrothermal purposes.