The word Geothermal originates from Greek, wherein geo means earth and thérm means heat which implies that geothermal refers to heat on earth. There is excess heat present on earth which is conveniently used for our increasing fuel needs. Geothermal energy is a renewable source and measures you can take to make it more cost-effective. It is worthwhile to use geothermal well drilling.
In winters, due to cold atmospheric temperature, you will find that earth’s surface is cold but it becomes hotter after a certain level below the earth. It’s the reverse in summers. This difference in temperature generates thermal energy. Geothermal energy is directly harnessed from hot springs for space heating, food drying or some industrial purposes. The only disadvantage is that these applications are carried out near the resource only. Geothermal energy is a continuous source that is mainly used for electricity generation and so there is a need for drilling geothermal wells.
Geothermal well drilling applies the same approach as oil and gas industry, adapted for high temperature purposes and larger well diameters. A drill pipe, drill bit, drilling fluid, drill rig and power system comprises the usual geothermal drilling equipment. A drill pipe is typically used for transferring drilling fluid from mud pit to the ground below. It is also used to rotate the drill bit which does the real cutting of the surface. There are types of drill bits available. Selecting the right drill bit is an important part of geothermal well drilling which is usually documented for future references. The role of drill fluid, flowing through the pipe, is to promptly bring up the cuttings from the base so that the rocks don’t encumber the drilling process.
The power system powers the operation. All these tasks are efficiently manipulated by the drill rig to successfully keep up power, rotate the drill bit by hoisting the drill pipe and circulating the drill fluid. There are also tools that are used to avoid sudden high pressure fluid or steam from erupting through the opening. After you completed the drilling, you want to construct the well immediately. A steel pipe or casing lines in place by laying cement in the gap between the pipe and the rocks. Cementing is crucial to avoid expansion and shifting of the steel pipe.
The temperature below the earth’s crust increases at the rate of 25ºC/km. The temperature required for electricity generation is 135ºC, so the geothermal well depth seldom surpasses 4km. Expenditure for geothermal well drilling more than 5km actually exceeds the benefits. Research is productively being carried out to economize this renewable source. Although green house affect is one of its drawbacks, it’s considerably lesser than using fossil fuels with the added benefit of it being an inexhaustible source of energy.