Geothermal energy is the heat derived from the earth's subsurface. The geothermal energy is carried to the Earth's surface via water and/or steam. Geothermal energy can be used for heating and cooling or for generating clean electricity, depending on its features. Geothermal energy can be found almost anywhere on the planet's surface. There are five geothermal provinces in India, as well as a number of geothermal springs. This article will explain to you about Geothermal Energy which will be helpful in preparing the Environment syllabus for the UPSC Civil Service exam.

How is Geothermal Energy Captured?

• Geothermal systems can be found in areas with a normal or slightly above normal geothermal gradient (the geothermal gradient, which reflects the increase in temperature with depth in the earth's crust, is a steady change in temperature).
• The normal geothermal gradient is about 2.5-3 °C/100 m. However, geothermal gradients near plate boundaries can be much higher.
• The most popular contemporary method of capturing geothermal energy is to use naturally occurring "hydrothermal convection" systems, in which cooler water penetrates into the earth's crust, is heated, and then rises to the surface.
• It's fairly simple to trap steam and use it to power electric generators when warm water is driven to the surface.

Basic Types of Geothermal Heat Resources Extraction

Hydrothermal Heat Source

• Water transfers heat to the surface, and water is recharged into the earth by rain or surface bodies (such as rivers, lakes, or glaciers), before being heated by underlying hot rock that is hot due to seismic or volcanic activity.
• This is demonstrated by the presence of hot springs in Iceland, the Himalayas, and the Alps.
• The lithology of the area must be porous to let water flow freely, both to replenish the system and to bring hot water to the surface.

Deep/ Enhanced Geothermal System

• Deep/Enhanced Geothermal systems, in which a deep borehole is dug to reach the hot basal rock, and then water is injected into the holes to get steam.
• This method is used to power a turbine and is the second form of resource extraction.
• Because accessing the deep basal rock bed is costly, this method isn't often used.

How is Power Generated from Geothermal Energy?

• Steam is used to generate electricity in geothermal power plants.
• The steam is produced by hot water reservoirs a few miles or more beneath the earth's surface.
• The steam spins a turbine, which turns a generator, which generates electricity.
• Dry steam, flash steam and binary steam geothermal power plants are the three types of geothermal power plants.
• Dry Steam - Dry steam power plants use underground steam resources. Steam is piped directly from underground wells to the power plant and fed into a turbine/generator unit.
• Flash Steam - The most common are flash steam power plants, which use geothermal reservoirs of water with temperatures above 360°F (182°C). Under its own pressure, this extremely hot water rises through wells in the ground.
  • The pressure decreases as it flows upward, and some of the hot water condenses into steam
  • After being separated from the water, the steam is used to power a turbine/generator.
  • Any leftover water and condensed steam are injected back into the reservoir, ensuring that this resource is sustainable.
• Binary Steam - Binary cycle power plants run on water at lower temperatures ranging from 225 to 360°F (107 to 182°C).
  • The heat from the hot water is used to boil a working fluid, which is usually an organic compound with a low boiling point.
  • In a heat exchanger, the working fluid is vaporized and used to turn a turbine.
  • After that, the water is injected back into the ground to be reheated.
  • Because the water and working fluid are kept separate throughout the process, there are few or no air emissions.

Potential of Geothermal Energy in India

• Exploration and study of geothermal fields began in India in 1970.
• Around 340 geothermal energy locations have been discovered in India by the Geological Survey of India.
• These have been classified as different geothermal provinces based on their occurrence in specific geotectonic, geological, and structural regions, such as orogenic belt regions, structural grabens, deep fault zones, active volcanic regions, and so on.
• The Puga valley in Ladakh is the most promising of these.
• According to the Ministry of New and Renewable Energy, geothermal resources in India have been mapped, and a broad estimate suggests that there could be a 10 gigawatt (GW) geothermal power potential (MNRE).
• The government of Chhattisgarh decided in 2013 to build the country's first geothermal power plant at Tattapani in the Balrampur district.
• An agreement to establish the first geothermal power project in Ladakh was signed in 2021.
• Satellites such as the IRS-1 have helped to locate geothermal areas by taking infrared photographs.

Government Initiatives

• The government has promised to provide a capital subsidy of up to 30% for industrial projects.
• NTPC and the Chhattisgarh Renewable Energy Development Agency (CREDA) have collaborated to bring the first geothermal power plant to Chhattisgarh.
• In India, the Ministry of New and Renewable Energy (MNRE) provides significant incentives and subsidies for geothermal energy research, design, development, and demonstration (RDD&D).
• By 2022, the Ministry of Renewable Energy plans to generate up to 1000 MW of geothermal energy.

Advantages of Geothermal Energy

• It is thought that enough heat is radiated from the earth's core to meet human energy demand for the foreseeable future.
• People have been using this source of energy for bathing, heating homes, and preparing food since ancient times, and it is now also used for direct heating of homes and offices.
• One of the primary benefits of geothermal energy is that it produces no pollution and contributes to the creation of a clean environment.
• Geothermal energy, as a renewable source of energy, has aided in the reduction of global warming and pollution.
• As energy demand grows, additional units with modular designs can be quickly installed.
• The cost of producing electricity is nearly comparable to that of conventional energy sources.

Limitations of Geothermal Energy

• Not available in all areas: Geothermal hot spots are dispersed and located in far-flung areas from areas in need of energy.
• Pollution with H2S: Large amounts of H2S, also known as "rotten eggs" gas, can be released, and inhaling too much of it can be fatal.
• The use of geothermal energy results in some water pollution (somewhat similar to mining).

Challenges Associated with Geothermal Energy

Resource and Location

• Although there is geothermal energy beneath the entire surface of the earth, not all of it can be harnessed.
• The possibility of installing geothermal power plants is limited because only a small percentage of land lies above suitable pockets of water and steam that can heat homes or power electrical plants.
• Many of the locations that are ideal for supplying large amounts of geothermal energy that can be converted into electricity are also located in tectonically active areas.
• Corporations are hesitant to build large-scale electricity generating facilities when there is a constant risk of earthquakes or volcanic activity.

Infrastructure

• Aside from a lack of adequate resources, geothermal electricity is not widely used due to a lack of infrastructure.
• By definition, a geothermal energy source could only be used to provide baseline power for an electrical grid, which presents its own set of challenges.
• Drilling wells and setting up power plants require a lot of expensive equipment, and training people to work at a geothermal power plant is time-consuming and expensive.
• There is also a limit to where geothermal energy can be utilized.
• Once energy is extracted from underground wells, it cannot be transported to another facility whose grid is in greater need; it must be used immediately.

High Cost

• Geothermal energy is a costly resource to exploit.
• The upfront costs are high, however, they can be recouped over time as part of a long-term investment.

Drilling Cost

• Although the cost of producing geothermal electricity has dropped by 25% in the last two decades, exploration and drilling remain costly and risky.
• Because the rocks in geothermal areas are extremely hard and hot, developers must replace drilling equipment on a regular basis.

Renewable Doesn't Mean Endless

• Contrary to popular belief, the amount of water and steam extracted from the earth is limited.
• There is only so much water that can be extracted from each well, and without proper re-injection of used water, there isn't enough pressure to propel the steam and water upwards.
• If the pressure gradient is not properly restored, not only will the energy source dwindle, but there is also the risk of more serious geological consequences, such as the formation of sinkholes.

Transmission Barrier

• Because it is not practical to transport steam or hot water over distances greater than two miles, geothermal power plants must be located near specific areas like a reservoir.
• As many of the best geothermal resources are found in rural areas, developers' ability to supply electricity to the grid may be limited.
• New power lines are costly to build and difficult to install.

Environmental Side Effects

• Although geothermal energy does not typically emit greenhouse gases, many of these gases are trapped beneath the Earth's surface and released into the atmosphere during excavation.
• Although these glasses are naturally released into the atmosphere, they are released at a higher rate near geothermal plants.
• These emissions, however, are still significantly lower than those associated with fossil fuels.

Earthquakes

• Geothermal energy has the potential to cause earthquakes.
• This is due to changes in the structure of the Earth as a result of digging.
• This issue is more common with enhanced geothermal power plants, which force water into the Earth's crust to open fissures and allow for greater resource exploitation.
• However most geothermal plants are located far from population centers, and the effects of these earthquakes are minimal.

Sustainability

• To ensure the long-term viability of geothermal energy, the fluid must be pumped back into underground reservoirs at a faster rate than it is depleted.
• This implies that geothermal energy must be properly managed to ensure its long-term viability.
• This implies that geothermal energy must be properly managed to ensure its long-term viability.
• It is critical for the industry to weigh the benefits and drawbacks of geothermal energy in order to maximize the benefits while minimizing the risks.

Execution Challenges

• Through the holes drilled by the constructors, harmful radioactive gases can escape from within the earth.
• The plant must be capable of containing any leaking gases and disposing of them safely.

Conclusion

Many scientists believe that geothermal energy will play a significant role in the world's clean energy future, but that it will need to be combined with other technologies. Geothermal energy can assist developing nations by combating climate change while also raising living standards if there is strong international cooperation and support from wealthier countries. Geothermal energy comes from a clean source, is reliable, and is not affected by fuel price fluctuations, allowing more financial resources to be allocated to economic development.

FAQs

Question. What is geothermal energy and how is it generated?

Question. What are the advantages of geothermal energy?

Question. What are the main uses of geothermal energy?

Question. What are the environmental benefits of using geothermal energy?

Question. What are the challenges of using geothermal energy?

MCQs

1. Which of the following is a major advantage of geothermal energy?

A) High operational costs

B) It is dependent on weather conditions

C) It is a renewable energy source

D) It leads to high greenhouse gas emissions

2. What is one of the main uses of geothermal energy?

A) To generate electricity

B) To produce coal

C) To manufacture natural gas

D) To create biofuels

3. Which of the following is a challenge associated with geothermal energy?

A) It requires a large amount of land

B) It is available only in certain regions

C) It generates a lot of waste

D) It is dependent on sunlight

4. Geothermal energy can be used directly for which of the following purposes?

A) Wind energy production

B) Space heating and hot water supply

C) Solar energy generation

D) Bioenergy production

5. Which of the following is a key environmental benefit of geothermal energy?

A) It produces large amounts of waste

B) It reduces greenhouse gas emissions

C) It leads to land degradation

D) It is highly polluting

GS Mains Questions and Model Answers

Q1: Discuss the role of geothermal energy in promoting sustainable development and mitigating climate change.

Answer: Geothermal energy plays a critical role in promoting sustainable development and combating climate change due to its renewable nature and minimal environmental impact. As a clean energy source, geothermal energy produces significantly lower greenhouse gas emissions compared to fossil fuels. Its ability to provide a reliable and continuous supply of energy, independent of weather conditions, makes it an ideal solution for reducing dependency on non-renewable sources of energy. Moreover, geothermal energy supports the decarbonization of energy systems, contributing to climate change mitigation by reducing carbon footprints. By shifting to geothermal energy for electricity generation, heating, and cooling, countries can reduce the reliance on polluting energy sources, enhance energy security, and promote economic resilience in the long term. Furthermore, the use of geothermal energy in various sectors such as agriculture and industry fosters economic sustainability while minimizing environmental degradation.

Q2: Evaluate the challenges and opportunities of geothermal energy in India, focusing on its potential as a clean energy source.

Answer: India has significant potential for utilizing geothermal energy, especially in regions with substantial geothermal activity such as the Himalayan belt and parts of Rajasthan. However, there are several challenges in harnessing geothermal energy effectively in India:

• Geographical limitations: The potential for geothermal energy is largely concentrated in specific regions, which limits its widespread application across the country.
• High initial investment: The cost of setting up geothermal power plants and the infrastructure needed for drilling wells is relatively high, making it challenging for small-scale investments.
• Technical expertise: The lack of sufficient technical expertise in geothermal exploration and the need for advanced drilling technologies can hinder the growth of this sector in India. Despite these challenges, geothermal energy presents numerous opportunities:
• It can provide stable, renewable energy to complement other renewable sources like solar and wind, especially in areas where they may be intermittent.
• It can support energy independence and economic development in rural and underserved areas by providing decentralized heating solutions and supporting agricultural activities.
• Geothermal energy can be a key player in reducing India's carbon footprint and contributing to the nation’s climate action targets under the Paris Agreement.

Q3: Analyze the global potential of geothermal energy and its role in the future energy mix.

Answer: Geothermal energy holds immense global potential as a sustainable and low-carbon energy source. As the world transitions to a cleaner energy mix, geothermal energy plays a significant role in reducing reliance on fossil fuels and mitigating the impacts of climate change. Countries like Iceland, Kenya, and the Philippines have successfully harnessed geothermal energy to meet a significant portion of their energy demands, demonstrating its potential in both developed and developing nations. Geothermal energy is particularly attractive due to its ability to provide baseload power—continuous energy supply regardless of weather conditions, making it a reliable and stable energy source in comparison to intermittent sources like solar and wind. As technological advancements reduce costs and improve efficiency, the global use of geothermal energy is expected to grow significantly in the coming decades. Its role in the future energy mix will be crucial in achieving net-zero emissions targets and ensuring energy security in many parts of the world, especially in regions with accessible geothermal resources.

Previous Year Questions on  Geothermal Energy

1. UPSC 2020

Question: Discuss the potential of geothermal energy in India and evaluate its role in meeting the country’s energy needs.

Answer: This question required candidates to evaluate India’s potential for harnessing geothermal energy, assessing its capacity to meet energy demands, and the challenges in implementing geothermal projects within the country. The response also needed to highlight the role of geothermal energy in India’s clean energy transition.

2. UPSC 2019

Question: Evaluate the environmental and economic advantages of geothermal energy as a renewable energy source.

Answer: The question focused on evaluating the environmental and economic advantages of geothermal energy, discussing how it contributes to sustainability, reduces greenhouse gas emissions, and offers cost-effective solutions for long-term energy needs.