As we move deeper from the surface of the earth to the core, we see an increase in temperature, called the geothermal gradient. Near the surface of the earth, the geothermal gradient has an average value of about 30 ° C per km depth. In some areas, either due to recent volcanic volcanoes or hot water rise from deep depths through cracks, the geothermal gradient is significantly above 30 ° C, resulting in relatively low depths of aquifers containing high water or steam. temperature. These areas are called geothermal fields and in these areas the exploitation of geothermal energy is extremely advantageous. When hot water or steam finds a way out through some opening of the Earth's crust to its surface then we have hot springs or hot springs.
Applications of geothermal energy vary with temperature and include power generation, space heating, cooling and air conditioning, greenhouse heating, etc. In addition to geothermal fields, current technology allows the use of constant temperature of the upper layers of soil for heating and air conditioning, using geothermal heat pumps. The main circuits used are the vertical type geo-alternator (closed circuit with a well) and horizontal type (horizontal circuits closed circuit). Tubes usually circulate hardened water that is heated or cooled by absorbing or rejecting heat to and from the ground.
During the winter, the geothermal heat pump removes heat from the ground and adds it to the building's heating system. This process is reversed during the summer to provide cooling. As the ground temperature at a few meters deep remains almost constant throughout the year, regardless of the weather, geothermal heat pumps provide efficient heating, cooling and hot water use, saving energy and reducing greenhouse gas emissions. Geothermal heat pumps utilize geothermal potentials below 25 ° C.
Heat pumps are machines that 'heat' (in the form of cooling or heating) from a heat tank (soil, ambient air, water tank, groundwater, lake, etc.) into a space through an exhaust cycle and condensation of a working medium by consuming electricity. The efficiency ratio of a heat pump (Coefficient of Performance) is given by the ratio: COP = (heat or cooling output) / (electricity consumed).
