Have you ever notice a change in temperature when you dig a hole on the ground? this is because of geothermal energy.you will learn everything related to geothermal energy in this article.
What’s in it for me?
- Overview on Geothermal Energy
- What is geothermal energy?
- Direct uses of geothermal energy
- A brief history of geothermal energy.
- Geothermal energy can capture through two methods
- Advantages of Geothermal Energy
- Disadvantages of Geothermal Energy
Overview on Geothermal Energy
Geothermal energy has been in use from a thousand years back when humans are using this energy for cooking and heating purposes. This energy is the result of the earth’s internal heat.
However, the earth is a combination of layers consist of the inner core, outer core, mantle, and crust. The mantle is consisting of magma.
Magma is nothing but the extremely hot molten rocks. Whenever this magma can flows through holes or cracks in the crust sometimes this can cause a volcanic explosion.
If you start digging a hole straight into the earth you will realize the temperature is getting warmer as you go deep inside that is because of earth’s internal heat.
Due to this earth’s, internal heat phenomena like lava flow, geysers, hot springs, and mud pots take place on the earth’s surface.
The main reasons that result in generating this heat inside the earth’s surface are radioactive decay (it is a process of spontaneous breakdown of an atomic nucleus resulting in the release of heat) of potassium, thorium, and uranium in Earth’s crust and also by friction generated along the margins of continental plates.
However, the amount of heat flow the earth can generate annually to the surface is average between 50-70 mill watt per square meter worldwide.
Which is huge compare to solar heat as solar can only generate 342 watts per square meter annually.
The estimated energy that can be generated using the earth’s internal heat on the surface is about 1.4 × 10^6 terawatt-years, which equates to roughly three times the world’s annual energy consumption.
However the amount of energy we can extract from inside the earth depends upon the depth and method of heat extraction we use.
The temperature increases with average 20-30 Degree Celsius with every kilometer depth we go, and this temperature can increase further if we drill at earth known geothermal areas. The use of fluid (or steam) is to bring energy to the surface.
Although there is a continuous source of heat within the earth, the rate of extraction can exceed the backfilling rate, therefore the use of this resource must be calculated.
What is geothermal energy?
So we can say that geothermal energy is the heat inside the earth.
Geo means earth in Greek and therme means heat from these two Greek words term geothermal is came.it is a type of renewable energy as heat within the earth is continuously produced.
Direct uses of geothermal energy
Firstly all direct application uses the low-temperature source of geothermal energy ranges between 50-150 Degree Celsius.
This low-temperature water and steam from the earth’s surface can bring directly into the use for warming small buildings, swimming pools, therapeutic facilities at spas, greenhouses and aquaculture ponds.
Other direct uses include cooking, drying fruit, vegetables, and timber, milk pasteurization, and large-scale snow melting.
In most of this activity, hot water is directly using for the heating system, or it may be used in conjunction with a heat exchanger.
A brief history of geothermal energy.
Geothermal energy has been since the Earth was formed about 4.6 billion years ago. There is some evidence that shows Native Americans used geothermal energy around 10,000 years ago.
In ancient times Greeks and Romans use to baths heated by spring hot water. Space heating with the use of geothermal energy was in the Roman city of Pompeii during the 1st century CE.
First known commercial use of the geothermal energy was in 1830 when Asa Thompson got one dollar to use of three spring-fed baths in a wooden tub in Arkansas, US.
In 1847 William Bell Elliot discovered geysers near San Francisco. The world’s first geothermal district heating system was in 1892 and after few years 200 homes and 40 businesses were using this system.
1904 was the year when Prince Piero Ginori Conti in Larderello, Italy invented the first geothermal power plant.
In 1970 exploration and study of geothermal field establish in India. By the early 21st century, 24 countries started using geothermal energy to generate electricity.
Geothermal energy can capture through two methods
- Power plants: They use heat from deep inside the Earth to generate steam to make electricity.
- Heat pumps: They tap into heat close to the Earth’s surface to heat water or provide heat for buildings.
Geothermal power plants
At geothermal power, plant holes are drilled into the surface of the earth to pump the steam or hot water available inside the earth’s surface. These holes can be as deep as 3 kilometers.
These power plants are mainly located near the area where a lot of hot springs, geysers, or volcanic activity happing as at such places you can find geothermal energy near to the surface. This is easy to extract with minimal efforts.
Working principle of the geothermal power plants.
- Hot water is pumped from underground through drilled well at high pressure.
- When this high-pressure hot water reaches the surface due to the pressure drop it converts into steam.
- This steam is used to spin a turbine which is connected to a generator that converts the mechanical energy of the turbine into electricity.
- This steam is then cooled inside the cooling water and due to the condensation turn back into the water.
- The cooled water is sent back into the earth to continue the same process.
There are three different types of geothermal power plants.
Direct dry steam
In this system steam extracted from the well is directly go to the turbine that drives the generator to produce electricity. This is the oldest type of power plant.
Flash and Double Flash Cycle
Fluids above 182 Degree Celsius can be used in flash type power plants.
In this system fluid coming from well is sprayed into the flash than which is a very low pressure than the fluid. It causes some amount of fluid to get vaporize (Flash) this vapor then drives the turbine to produce electricity.
If still, any liquid remains in the tank it can be flashed again in a second tank hence called Double Flash Cycle.
These systems using two fluids hence called binary cycle power plant. The secondary fluid has a boiling point lower than the water and it flows through the heat exchanger.
The heat of the fluid coming from well is helps to flash secondary fluid into vapor this vapor then runs a turbine to produce electricity.
This is a closed-looped system hence nothing is emitted into the atmosphere.in future power plant binary cycle will be preferred.
Geothermal heat pumps
A geothermal heat pump is so versatile that it is compatible with many things like heating and cooling buildings to warming up the swimming pools.
These systems transfer heat by pumping water or a refrigerant through pipes just underneath the surface of heat where the temperature varies between 10 to 15 Degree Celsius.
In winters water or refrigerant works like a heating element that takes warmth from the earth’s surface to heat the building and in summers same heat pumps works in reverse and act as a cooling element to cool down the temperature of the building.
Working principle of the geothermal heat pump
- Water or refrigerant is continuously flowing through a loop of pipes buried just below the earth where the temp is constant at 10-15 Degree Celsius throughout the year.
- In summer heat pump takes heat from the building or home and transfers it to the underground loop system. This radiates the heat away into the cool earth.
- In winter the same system is acting another way.
- In winter heat collected from the ground using the same loop system and the heat from the underground loop is compressed at a higher temperature and use for warming the air inside the building or house.
Advantages of Geothermal Energy
- Environmental friendly as pollution associate with it is very minimal than fossil fuels.
- A renewable resource of energy as it will last till the earth is there.
- Geothermal power plants have huge potential it can provide power between 0.0035 and 2 terawatts.
- Stable resource as compared to wind and solar energy.
- It is compatible with both heating & cooling purposes.
- No fuel required.
- Savings for Home and Building Owners as after installation they can save up to 30-60% on heating and 25-50% on cooling.
- Rapid Evolution happing in this field as new technologies are coming to improve the energy extraction process.
- Required low operating cost.
- The required small area in the heat pump type power plant.
- Small footprint on the ground as it can be partially underground.
- Highly Efficient as heat pump systems use 25% to 30% less electricity than conventional heating or cooling systems.
- Low maintenance required.
- Governments are investing hugely to promote geothermal power which creates more job opportunities.
Disadvantages of Geothermal Energy
- Geothermal energy is location-specific that’s why the restriction of location is there.
- Although geothermal energy releases any greenhouse gases while power generation but while drilling well trapped harmful gases inside the earth can be released in the atmosphere cause environmental side effects.
- Risk of triggering earthquakes.
- Upfront costs are high.
- To maintain the sustainability of geothermal energy used fluid needs to be pumped back into the underground reservoirs faster than it is depleted. This means geothermal energy needs to be used carefully to maintain its sustainability.
- Geothermal heat pumps need an external power source.
We can easily say that geothermal energy has grate advantageous over any other source of energy and has a huge potential as well.
But at the same time, we have to use it carefully as we have seen there are some issues as well that we have to face at the same time. So we have to use this energy with great care and responsibility.
Also Read :
In India geothermal energy found at Himalayas, Sohana, West coast, Cambay, Son-Narmada-Tapi (SONATA), Godavari, and Mahanadi.
As the source of geothermal energy is heat generated by the Earth’s core which is unlimited hence geothermal energy is renewable.
Geothermal energy is most economical in volcanic regions and where there are hot geysers. Most regions in India don’t have access to such regions therefore it is an expensive deal for India.
My name is Vivek Rawool. I am extremely motivated to constantly develop my skills and grow professionally. I have completed my BE Mechanical Degree from Mumbai University and currently working with Paramount India as a Sales and Marketing Engineer. I also do Share market trading and investment.