Before twentieth century, geothermal’s fluid simply used for shower, wash, and cook. But nowadays the geothermal energy’s utilization are various, such as for electricity power either non-electricity as well as room heater, green house, farmland, to stove agricultural products and livestock, wood drying, etc.
The Geothermal System
Layer of earth and top section from earth sheath named Litosfer was about 80-200 kilometre. The section of earth sheath that is located under Litosfer known as soft rock but concentrated and much hotter. These section named Astenosfer was around 200-300 kilometre. The research explained that Listosfer was not intact surface, but consists of a number of thin and rigid plates. Virtually, those plates are thick rock expanse were about 64 to 145 kilometre which are floats on Astenosfer. The plates are move slowly and continuously. In some places those plates are move segregate whilst several places plates are encourage each other and one of them will crashing under another plate.
The high temperature’s effect from inside Astenosfer and high temperature sequence friction, that point section become melt and have high temperature (magmatic processes).
Because there are hot temperature’s materials in thousands kilometre in subsurface induce temperature change from bottom to surface, with average pressure gradient is 30 degree celcius per kilometre. In the subduction zone, the value of heat flow rate commonly much higher than average value. This case cause temperature gradient in that zone become higher than average gradien temperature which can achieve 70-80 degree per kilometre. Basically, geothermal system form as heat exchange from the heat resource into round which is happen in conduction and in convection. Conduction occur through rocks, whereas convection process happen by way of contact water between heat resource.
Geothermal Energy Types
Geothermal energy classified to 5 different categories. From all of that energy, hydrothermal energy system is most be used, because in hydrothermal system porous of rock contain water and steam or both, and reservoir ussually located shallow and much more economic.