Below the Earth’s surface lies an invaluable treasure, an inexhaustible energy source made up of huge reserves of heat that are just waiting to be exploited, geothermal energy. Geothermal energy has its origin in the depths of the earth’s crust where very high temperatures are reached, so much to melt the rocks and transform them into a river of fluid materials.
Features
Geothermal energy is a source of thermal energy that can be extracted from underground hot-water tanks of natural origin, considered one of the available sources of alternative or integrative energy.
The presence of hot water in the subsoil is caused by the combination of two effects: the natural increase in temperature, the so-called geothermal gradient, which is detected with increasing depth, equal to about 3°C every 100 m, merges with the possible presence, in the predisposed areas, of volcanic heat, bringing the gradient to 10°C every 100 m.
Electricity production
In areas whose geothermal gradient is very high. The temperature of groundwater reaches levels that allow the exploitation of geothermal energy for the production of electricity. These plants do not exploit any combustion process. They are extremely clean as they exploit a completely natural thermal heating without waste or atmospheric residues.
Geothermal plant
The geothermal system is a heat absorption system that provides vertical drilling of the soil up to a depth of 50-150 meters. Inside the excavations, closed-circuit pipes are provided, which bring the heat from the subsoil to the surface using a heat-transfer fluid, which consists of water mixed with antifreeze.
In this way, thermal energy is obtained at a temperature normally around 12-13 °C. Through a heat pump, the temperature of the fluid is further increased, making it usable for space heating and the production of domestic hot water.
Costs
The costs for a geothermal plant are significantly higher than conventional plants; the geothermal plant has the advantage of having a much longer life cycle. A traditional boiler must normally be replaced after 20-25 years, while in a geothermal system, it is sufficient to change the heat pump since the pipes are guaranteed by the manufacturers even up to 100 years. The purchase price of a heat pump for a system with a power of 15 kW, suitable for an average family unit, is approximately $100,000.
