Geothermal energy is an inexhaustible energy source that can be put to a number of uses including generation of electricity. It is mainly heat energy trapped under the earth’s surface, which can be either used in its original form for heating enclosed spaces, or it can be converted to other energy forms for other requirements. It is more sustainable than fossil fuel because it produces much less greenhouse gas emissions. To tap into this energy source, these wells can be created using geothermal drilling.
The methods and equipment used for geothermal drilling vary from sonic rigs to truck-mounted drills – which were used for digging water wells previously. Sonic rigs are reportedly the quickest method for geothermal drilling. They use an advanced technique which can drill on any kind of ground, including sand and gravel. Other types of rigs include vertical rigs, rotary rigs and cable tools rigs. Geothermal drilling is also done under water, using marine rigs, but these require greater investments and are not used for drilling these wells. After the drilling is done, a well should be constructed without delay. A steel casing should be put around the pipe, to separate it from the rocks, and held in place by cement.
The heat energy acquired through geothermal drilling can be brought above the ground with very little effort, since heat rises upwards. The drilling just creates the path through which the energy should come up. To put this extracted energy to use, however, it needs to be processed. Not much processing is required for cases such as space heating, and these should be done near the extraction location; but for other cases like producing electricity, the well should be connected to power plants for the conversion to be carried out. This is generally done by producing steam, which is used to turn turbines. Sometimes, when geothermal drilling hits hot springs, this steam is also produced naturally.
Geothermal wells should be dug after comparing the estimated costs with the expected benefits. Generally, the temperature beneath the earth’s surface rises by 25- C for every kilometer, and the typical temperature needed to generate electricity is 135- C. So the geothermal wells need not be drilled deeper than 4km. But the temperature is not the same everywhere. This causes the depth requirement of geothermal wells to vary from place to place. Ideally, if a well needs to be deeper than 5km, then the cost of digging such a well will exceed its benefits. Making sure of the correct method, equipment and location is the key to profitable geothermal drilling.