The central regions of the earth is very hot and it is estimated that about 4000 miles underneath the surface of the earth, the temperature is about 7,000o F. This thermal energy is transferred to the surface of the earth and about 3-4 miles below the surface of the earth, the temperature is about 300-400o F. This thermal energy in this layer can be utilized as a source of heat and what is called geothermal energy.
2. Geothermal energy
Geothermal energy is considered as a renewable energy. This energy source is, in particular, one of the safest sources or energy. Sources of geothermal energy range from the shallow ground to hot water and also hot rocks found a few miles underground. In general, the Geothermal energy can be used for the production of electricity by using certain methods. Currently, Many countries have used these methods to generate electricity and have already reduced their dependency on fossil fuels to generate electricity. With the production of more than 3,300 MW in some states, the USA is a global leader in increasing its geothermal capacity.
3- Types of geothermal energy
Geothermal energy originates from two sustainable sources:
- The radioactive decay in the crust of the earth (the first layer of the earth’s surface),
- The heat coming from the earth’s core
Geothermal energy has a vital role in generating electricity in many countries especially in the USA. Some of its advantages can be mentioned as below,
- It’s one of the few renewable energy sources that are more sustainable, cleaner, continuous and base-load power.
- Unlike the nuclear energy, it is safe and clean.
- While the cost of its installation is relatively high, its running cost compared to the other sources of energy is very low.
5- Applications of geothermal energy
Before getting into the applications of the geothermal energy, it is essential to know more about how this power is extracted or generated from the earth’s heat.
The earth has a number of layers:
- The inner core
- The outer core of hot molten magma
- The mantle surrounding the core
- The crust of the earth.
The earth’s crust is broken into pieces called plates. The most widely used method for getting geothermal energy is called “Hydrothermal convection” method. In this method, cold water is run into the earth’s crust that has hot spots. This will create steam rising from the crust. This steam is then concentrated and used to drive generators.
There are three basic stages used in this method:
- The hot water and the steam are pulled out
- The very hot water is depressurized or “flashed” into steam which can then be used to drive a turbine.
- The hot water is passed through a heat exchanger, where it heats the second liquid like isobutene in a closed loop. Isobutene boils at a temperature lower than the water, so it is more easily converted into steam for running a turbine.
6- Other Applications:
- It can be used as a heating source for heating purposes in industries.
- The hot water can be also used for building heating especially in Iceland where every single house uses the hot water coming from geothermal.
- The heat energy is used for growing plants in greenhouses
- Improving oil recovery.
- At last as explained before, the geothermal is used to generate electricity.