What is geothermal energy?
The energy that lies within the earth's crust is known as geothermal energy. The terms geothermal and geothermal energy are derived from the Greek words “geo” (earth) and “therme” (heat).
Geothermal energy is a renewable energy source since it is constantly created inside the ground. Bathing, heating, and generating electricity are all possible with geothermal heat. Geothermal heating is the instantaneous use of geothermal energy for some heating applications.
Humans have been taking advantage of geothermal heat in this way since the Palaeolithic era. A total of 270 PJ of geothermal energy was used directly by almost seventy countries. Around the world, 28 GW of geothermal heating capacity has been constructed, providing 0.07 percent of worldwide primary energy consumption. Since no energy conversion is required, thermal efficiency is good, but capacity factors are low (about 20%) because heat is used largely in the winter.
Where does geothermal energy come from?
Geothermal energy comes from the heat that has been trapped within the Earth since its formation, as well as radioactive decay of minerals and solar energy absorbed at the surface. The majority of high-temperature geothermal energy is gathered along tectonic plate borders, when volcanic activity rises near the Earth's surface. Ground and groundwater temperatures are greater in these places than the application's target temperature. Even frigid ground retains heat; below 6 metres (20 feet), the undisturbed ground temperature is consistently at the Mean Annual Air Temperature, and this heat can be retrieved using a ground source heat pump.
Is geothermal energy renewable or sustainable?
Since any anticipated heat extraction is modest in comparison to the Earth's heat content, geothermal electricity is considered renewable.
The Earth's interior heat content is 1031 joules (3.1015 TWh), or almost 100 billion times the annual energy usage of the entire planet. The remainder is due to past and current radioactive decay of naturally occurring isotopes. About 20% of this is due to residual heat from planetary accretion. In India, a geothermal power project discovered granite with a high thorium content, which is thought to be the source of the rock's high temperature.
On geologic timescales, natural heat flows are out of balance, and the globe is slowly cooling. Human extraction takes only a small portion of the normal outflow, and it is frequently not accelerated.Most official explanations of geothermal energy use term it renewable and sustainable since it returns an identical volume of water to the area where the heat extraction occurs, but at a slightly lower temperature. For example, if the temperature of the water leaving the ground is 300 degrees and the temperature of the water returning is 200 degrees, the energy obtained is equal to the difference in heat extracted. However, if domestic and industrial uses of this energy source were to increase dramatically in the coming years, owing to dwindling fossil fuel supplies and a rapidly industrialising world population necessitating new energy sources, the effect on the Earth's cooling rate would need to be re-evaluated.
Along with its ability to preserve the Earth's complex ecosystems, geothermal energy is also considered sustainable. By exploiting geothermal energy sources, current human generations will not jeopardise future generations' capacity to utilise their own resources to the very same extent that those energy sources are currently used. Furthermore, due to its low emissions, geothermal energy is viewed as having significant potential for reducing global warming.
Despite the fact that geothermal energy is globally sustainable, extraction must be closely managed to prevent local depletion. Individual wells reduce local temperatures and water levels over decades until a new equilibrium is formed with natural flows. Heat and water were taken quicker than they were restored, in varying degrees. These wells could theoretically restore their full capacity if production is decreased and water is reinjected. Some sites have already used such mitigation methods.