Understanding Geothermal Energy
Geothermal energy is the heat stored in rocks and fluids that fill their pores. Geothermal energy is the heat contained within the Earth’s inorganic matter as heat sensitive and produced most in the slow decay of natural radioactive substances existing in all types of rock. The heat energy comes from radially propagating from the center to the outside of the earth and is supplied continuously. The high temperature of the center of the Earth can be explained by the origin of the Earth, the existence of radioactive isotopes of uranium (U238, U235), thorium (Th232) and potassium (K40) in the Earth. The propagation is carried at all times and can say that geothermal energy is an inexhaustible source of energy. Geothermal energy is one of the alternatives that can satisfy the human need for energy while minimizing environmental impact.
In the area where, due to high temperature, molten rocks are found (magma), heat is transmitted mostly by convection due to the melt motion and conduction in lower proportion. In areas with lower temperatures, characterized by the fact that the matter is found in solid, heat is transmitted by conduction only.
Geothermal systems can be found in areas with normal or nearly normal geothermal gradient in the lower regions, where the geothermal gradient can be significantly higher than average. In the first case the systems are characterized by low temperatures, typically reaching up to 100 ° C to optimum depth in terms of economy. In the second case temperatures can range in a wide range,
from very low to very high, reaching 400 ° C.
A geothermal system can be described as a system in which water is used as the transport agent, whereby heat is taken up from the underground source to the surface and submitted to a consumer.
We distinguish 3 categories of geothermal sources:
A) hydrothermal sources
These sources are based on the circulation of rain water (surface) infiltrating the Earth’s surface to depth in the range of 100 m – 4,5 km. Natural circulation is ensured by the difference between the density of the cold water, hot water, or that water vapor.
B) Sources of pressure
Water in these tanks has low salinity and its composition is dissolved methane. Water and methane are held captive by impermeable rock layers in existing reservoirs at great depths (3-6miles) characterized by particularly high levels of pressure.
C) Hot Rocks
This source consists of layers of hot rocks in the earth crust. For sources in this case there are water underground reservoirs or potential infiltration of surface water. Exploitation is done by drilling. In the hot rocks, cold water is pumped in order to build a tank.
The water takes the heat from the rock and subsequently brought to the surface through a production well.
Considering these issues, this resource is virtually unlimited and is more accessible than hydrothermal resources.