Changes

* '''Radioactive heat release''':It is 8x1012 J/seg .It comes from the Crust and it is produced by the fission of radiactive isotopes.

* '''Radioactive heat release''':It is 8x1012 J/seg .It comes from the Crust and it is produced by the fission of radiactive isotopes.

[[File:Figure 2|thumbnail|Figure 2: Igneos phenomena Strokkur Geyser,Iceland [http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/]. ]]

[[File:Strokkur Geyser,Iceland.png|thumbnail|Figure 2: Igneos phenomena Strokkur Geyser,Iceland [http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/]. ]]

# 2 Igneos phenomena

# 2 Igneos phenomena

In certain regions the geotermal gradient can be increased considerably due to magmatic  process (Figure 2).Most of the áreas of goethermal interest are situated in volcanic regions.In many places of our planet,hydrotermal evidence can be seen on the surface provided that geologial conditions are favourable.

In certain regions the geotermal gradient can be increased considerably due to magmatic  process (Figure 2).Most of the áreas of goethermal interest are situated in volcanic regions.In many places of our planet,hydrotermal evidence can be seen on the surface provided that geologial conditions are favourable.

[[File:Figure 3|thumbnail|[http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/].]]

[[File: Distribution of surface heat flow.png|thumbnail|[http://www.stewartsmithphotography.co.uk/shop/uncategorized/strokkur-geysir-national-park-iceland/].]]

# 3 Plate Tectonics and heat distribution

# 3 Plate Tectonics and heat distribution

# 1 Very low temperature deposits (T<30ºC) :It is generally considered that temperature seasonal variations are percived only over the first 10 meters f the soil. After that there is a interval where the temperature is almost constant and it is considered that below 20 meters, the temperature increases three grades every 100 meters.Therefore ,all the planet is a source of geotermal resources of low temperature.These resources have domestic use.

# 1 Very low temperature deposits (T<30ºC) :It is generally considered that temperature seasonal variations are percived only over the first 10 meters f the soil. After that there is a interval where the temperature is almost constant and it is considered that below 20 meters, the temperature increases three grades every 100 meters.Therefore ,all the planet is a source of geotermal resources of low temperature.These resources have domestic use.

[[File:Figure 4|thumbnail|Figure 4: Goethermal heating district. City of Boise. EEUU. [http://energy.ltgovernors.com/geothermal-resource-descriptions.html].]]

[[File:Goethermal heating district, City of Boise, EEUU.png|thumbnail|Figure 4: Goethermal heating district. City of Boise. EEUU. [http://energy.ltgovernors.com/geothermal-resource-descriptions.html].]]

# 2 Low temperature fields (30ºC<T<90ºC) :They are found in sedimentary basins with normal o hightly superior geotermal gradient.The sole condition is the existence of one or more aquifer horizons in adequate depths.Ej Paris Basin (France) ;Boise (EEUU) (Figure 4).

# 2 Low temperature fields (30ºC<T<90ºC) :They are found in sedimentary basins with normal o hightly superior geotermal gradient.The sole condition is the existence of one or more aquifer horizons in adequate depths.Ej Paris Basin (France) ;Boise (EEUU) (Figure 4).

# 3 Medium temperature deposits (90ºC<T<150ºC): They are foundin various places of our planet.They usually belong to áreas with specific geologic characteristics such as áreas of thin crust,higher concentration of radioactive isotopes or áreas close to or near igneous bodies.They can also be found over regions with higher gradient but a lower depth.They generally need an igneous intrusión and it is usual that,in this kind of field,water comes up to the surface forming hot springs.

# 3 Medium temperature deposits (90ºC<T<150ºC): They are foundin various places of our planet.They usually belong to áreas with specific geologic characteristics such as áreas of thin crust,higher concentration of radioactive isotopes or áreas close to or near igneous bodies.They can also be found over regions with higher gradient but a lower depth.They generally need an igneous intrusión and it is usual that,in this kind of field,water comes up to the surface forming hot springs.

[[File:Figure 5|thumbnail|Simplified diagram of a geotermal power plant. [http://www.bgs.ac.uk/research/energy/geothermal/].]]

[[File: Simplified diagram of a geotermal power plant.png|thumbnail|Simplified diagram of a geotermal power plant. [http://www.bgs.ac.uk/research/energy/geothermal/].]]

# 4 High temperature fields (T>150ºC): These deposits are found in áreas of higher igneous activity.They are related to extremely high gradients, corresponding to global tectonic process.They occur in plate borders, cortical thinnes áreas or Hot Spots. They need an igneous source an aquifer and a impermeable layer to keep up pressure. In many cases there is surface evidence suchs as geysers and fumaroles

# 4 High temperature fields (T>150ºC): These deposits are found in áreas of higher igneous activity.They are related to extremely high gradients, corresponding to global tectonic process.They occur in plate borders, cortical thinnes áreas or Hot Spots. They need an igneous source an aquifer and a impermeable layer to keep up pressure. In many cases there is surface evidence suchs as geysers and fumaroles

# 5 Hot dry Rock Deposits or Geotermal Stimulated Systems

# 5 Hot dry Rock Deposits or Geotermal Stimulated Systems

==Extraction and uses==

==Extraction and uses==

[[File:Figure 6|thumbnail|Figure 6. Simplified diagram of a geotermal plant [https://www.linkedin.com/pulse/smart-grid-energy-harvesting-martin-ma-mba-med-gdm-scpm-pmp].]]

[[File: Simplified diagram of a geotermal plant.png|thumbnail|Figure 6. Simplified diagram of a geotermal plant [https://www.linkedin.com/pulse/smart-grid-energy-harvesting-martin-ma-mba-med-gdm-scpm-pmp].]]

A geotermal central Works similarly to a thermic one :The only variation is the way to heat water.Water vapour at high temperaturas (up to 600ºC) is directed from the inside the earth to the central, allowing the evaporation of water present in different pipes surrounding the boiler. The water vapour reches higher pressure,thus it is used to move a turbine connected to the generator .When the turbine turns,electricity is produced, wich goes from the generator to the transformers. These increase the tensión of electricty, to transpor this energy along electrical network to home users.The refrigeration system allows to condenses the water vapour,so that can be used again.

A geotermal central Works similarly to a thermic one :The only variation is the way to heat water.Water vapour at high temperaturas (up to 600ºC) is directed from the inside the earth to the central, allowing the evaporation of water present in different pipes surrounding the boiler. The water vapour reches higher pressure,thus it is used to move a turbine connected to the generator .When the turbine turns,electricity is produced, wich goes from the generator to the transformers. These increase the tensión of electricty, to transpor this energy along electrical network to home users.The refrigeration system allows to condenses the water vapour,so that can be used again.