Geothermal Energy

This energy comes from the earth and can be classify in two groups; the one that comes from the internal planet heat (This one is normally use through geothermal deposits, high deep areas with porous or impervious rocks layers that take and keep water and vapour at high pressure and temperature), and also the one that comes from the soil thermal inertia..

Therefore we can have the next classification because the way the energy is capture:

Energy capture through Geothermal deposits

• Direct use of geothermal water, the water temperature goes between 10º to 130ºC and are use on heat water, spa, greenhouse cultivation on winter, to reduce the growth rate on fish and seafood on farms, industrial use as milk pasteurisation or even a central heat system on complete city quarters or single family houses among others.
   
   
   
• Geothermal plants on geothermal deposits, here the produce vapour because the geothermal energy gives the power to move the turbines creating electricity. The subsequently condensed water is re-inject to the shaft to re-heat it keeping the pressure of the deposit. There are three types because the temperature they reach::
   
• Deposit with "dry" vapour, this one produce vapour with low water amount. The vapour is direct conducted through pipes to a "dry" vapour plant that gives the power to move the turbine generator.
   
• Deposit of hot water, mainly produce hot water that is use on a "flash" plant. The water, at 130º to 330ºC, is collect to surface through a well where, because the pressure of the deep deposit, part of it comes instantly into vapour that moves the turbines.
   
• Deposit between 110º to 160ºC, it has not enough heat to quickly produce vapour but can by use in a binary plant to produce electricity. In a binary system the geothermal water goes through a heat exchange, where the heat is transfer to a second liquid that boil at low temperatures. When heated, the binary liquid, converts into vapour moving the turbine. Afterwards this liquid returns to be re-heated in a enclosed cycle with no air emissions.

Energy capture through conduction

• Use of enclosed systems of high deep vertical pipes, to heat the fluid through the Earth heat. Afterwards this fluid will be use for direct heating or in a heat pump cycle. The advantage is that no geothermal deposit is needed. For its use in a single family house would be necessary a shaft of 150m because every each meter we get a media of 50w.
   
   
   
• Use of open and enclosed systems of low deep horizontal or spiral pipes,these systems mainly use the thermal inertia of the soil and can be use either to cool or heat because the constant temperature of the soil. It can be use either enclosed systems (heat pump cycle, heat exchangers,...) or open systems with air (for the air conditioning).  
   
   

 The advantage of these systems is the constant on the produce energy that let us to ensure a known energy creation with no season variations.