Geothermal Energy: Pros and Cons

Every type of energy has its own advantages and limitations. In this article I will discuss about the pros and cons of geothermal energy.

What is Geothermal Energy?

The earth is a heat reservoir of heat energy in the form of molten interior. Surface manifestation of this heat energy is indicated by hot water springs and geysers discovered at several places. Heat can be experienced from the temperature rise of the earth’s crust with increasing depth below the surface. Radial temperature gradient increases proportionally to depth at a rate of 30 degree Celsius per kilometer. At a rate of 3-4 kilometers water bubbles up; while at a depth of 10-15 kilometers the earth’s interior is as hot as 1000 to 1200 degrees. The core of the earth consists of a liquid rock known as Magma having a temperature about 4000 degrees.

The geothermal heat is transferred to the underground reservoir of water which also circulates under the earth’s crust. Its heat dissipates into the atmosphere as warm water and steam vents up through the fissures in the ground as hot springs and geysers. Limitless heat generation by the magma and by radioactive decay of unstable elements like K_40, Th₂₃₂and U₂₃₅which are abundant in the earth’s crust are forms of geothermal energy and considered as renewable energy resource.

Before analyzing geothermal energy pros and cons one must have knowledge about structure of the earth’s interior. The earth consists of a series of concentric shells. Its internal structure can be divided into three parts – Crust, Mantle and Core.

The crust

The solid crust of earth is 70-100km thick and can be divided into continental crust, 20-65 km under the continents and oceans crust 7 km under the ocean basins. The study of the seismic waves has indicated that the earth’s crust underneath continents is thicker than that of that underneath the oceans as seismic waves travels faster in oceanic crust than in continental. The oceanic crust consists of low density rocks (basalts) whereas the continental crusts largely contain the granite. Enormous amount of geothermal energy can be got from the cracks in the earth’s crust. Whenever a geothermal site is drilled. Steam, hot water gush out through the drilled hole and become a source of geothermal energy.

The mantle

 For the utilization of geothermal energy we must gain some basic knowledge about the layer underneath the crust. It is called the mantle. The upper rigid part of the mantle extends up to 100km below the separating crust and contains mainly iron and magnesium. The crust and upper mantle form ‘lithosphere’. The lower mantle extending up to 2900 km below the earth’s surface is less rigid and is hotter. This is known as ‘asthenosphere’ and is capable of being deformed. The phenomena of plate tectonics i.e. the movement of the earth’s crust is caused by the movement of the lithosphere over the asthenosphere.

The core

It forms about 35% of the earth’s mass and has a radius of 3500km. The outer core is molten or liquid while the inner core (radius 1170 km) is believed to contain nickel-iron alloy. The hot molten rock of the mantle is called magma. The outer core being in the molten state behaves like a liquid responsible for all the earthquakes and volcanic activities. A thermal gradient is created from core to mantle and earth crust. The outward of heat energy from molten hot interior of the earth to the cooler surface makes the earth to operate like a heat engine. That’s one of the advantages of geothermal energy.


Geothermal Energy Pros and Cons

Actually geothermal energy is a great source of heat found under the earth’s crust. It has its own advantages and disadvantages. Already fossil fuels have started to diminish. And in the future geothermal energy is expected to produce a great amount of power with a relatively cheap rate. Despite all this pros geothermal energy is not used widely because of this problems.

Geothermal energy disadvantages


 Geothermal energy is not wide spread source of energy because to utilize geothermal energy perfect equipment and infrastructure is needed. So world wide installation of geothermal plants is not possible. For a efficient geothermal plant thousands of skilled manpower is needed. 
The production of electricity from geothermal plant needs high installation cost because of setting up miles long pipe underneath the earth's crust. To get geothermal energy from a plant high skilled staff in needed which yields high cost. 
Initial research is needed to be done before a setting up a geothermal plant because the natural steam production can be reduced in course of time. Geothermal fields can die and can cause a great deal of loss to the company. 
All the countries cannot use geothermal energy because all countries fall in the geothermal field region. It is a great geothermal disadvantage. 
While digging a geothermal field poisonous gas can come out from the site. This can cause great harm to the life of people and animal. This can also pollute the atmosphere. 
geothermal disadvantages include the problem of transportation. It cannot be transported easily. Once the geothermal energy is extracted from the field it can only be used in the plants of its surroundings.

 This were the major geothermal energy disadvantages.

Geothermal energy advantages

The reliance on the fossil fuel will be drastically reduced if the proper utilization of geothermal energy is ensured. This will help the countries which have to bought a great amount of fossil fuel every year.
The less the use of the fossil fuels the less the pollution of the environment. It is the most important advantage of geothermal energy.
The running cost of geothermal energy is very low. The price is 80% less than the running cost of plant run by fossil fuels.
Geothermal energy can used directly. From an ancient time people are relying on the geothermal energy for heating, bathing and washing.
If geothermal energy is properly utilized it will create a great impact on the world economy and creat job opportunities for thousands of people.

Finally we can say that the world energy consumption is rising. The demand for different energy sources are also increasing. In this situation the use of renewable energy with innovation can solve all the problems. So all the scientists and engineers try to know about geothermal energy pros and cons and make the world a better place.

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Mechanical Engineering