Oil and Natural Gas Corporation (ONGC), a state-owned exploration company, recently has begun drilling its first well in Puga (Ladakh) to generate electricity using geothermal power, reducing Ladakh’s reliance on diesel generators. Read the article to know more about geothermal energy.
What actually is geothermal energy?
Is it a type of renewable energy?
Is it easy to harness it?
Geothermal energy is the heat that is generated within the Earth. (Geo means “earth,” and thermal means “heat” in Greek.) It is a renewable resource that can be harvested for human use.
Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal energy is derived from a clean source, is dependable, and is unaffected by swings in fuel prices, allowing more financial resources to be given to economic development
It is found in the rocks and fluids beneath the earth’s crust, down to the boiling molten rock, magma.
Wells are excavated a mile down into underground reservoirs to obtain the steam and hot water, which may then be used to operate turbines attached to electricity generators.
The global trend in geothermal energy
Geothermal energy, first employed in Italy in 1904, has been a stable and expanding source of energy in recent years.
Over 20 countries use geothermal energy.
The United States is the world’s greatest generator of geothermal energy and is home to the world’s largest geothermal field.
Indonesia has 40% of the world’s geothermal energy resources as the country has 130 active volcanoes and is a hub of tectonic plate movement.
India’s geothermal energy potential
India includes seven geothermal provinces and around 340 geothermal springs.
According to the Ministry of New and Renewable Energy, geothermal resources in India have been mapped, and a general estimate estimates that there could be a 10 gigatonne (GW) geothermal power potential (MNRE).
Tectonic factors mostly determine the occurrence of geothermal resources in India.
The primary zone of geothermal resources extends from Puga in Ladakh to Manikaran in Himachal Pradesh and Takshing in Arunachal Pradesh.
The development of geothermal resources in India was languishing due to a lack of appropriate machinery and a lack of incentives.
Extraction of Geothermal Heat Resources
Hydrothermal Heat source
Water conducts heat to the surface and is recharged into the earth by rain or surface bodies (such as rivers, lakes, or glaciers) before being heated by underlying hot rock caused by seismic or volcanic activity.
The presence of hot springs in Iceland, the Himalayas, and the Alps demonstrates this.
The area’s lithology must be porous in order for water to flow freely, both to replenish the system and to deliver hot water to the surface.
Deep Geothermal System
Deep Geothermal systems, in which a deep borehole is excavated to reach the hot basal rock, and water is injected into the holes to produce steam
This way of resource extraction is utilised to power a turbine.
This method is rarely utilised since accessing the deep basal rock substrate is expensive.
Power Produced by Geothermal Energy
In geothermal power plants, steam is used to generate electricity.
Hot water reservoirs a few miles or more beneath the earth’s surface produce steam.
The steam turns a turbine, which turns a generator, which produces electricity.
Geothermal power plants are classified into dry steam, flash steam, and binary steam.
- Dry Steam – Dry steam power plants extract subterranean steam. Steam is delivered directly into a turbine/generator unit from subterranean wells.
- Flash Steam – The most popular type of power plant uses geothermal reservoirs of water with temperatures above 360°F (182°C). This boiling water rises via wells in the ground under its own pressure. As it goes upward, the pressure falls, and some hot water condenses into steam. The steam is utilised to power a turbine/generator after it has been extracted from the water. Any remaining water and condensed steam are injected back into the reservoir, ensuring the resource’s long-term viability.
- Binary Steam – Binary cycle power plants operate at lower temperatures ranging from 225 to 360°F (107 to 182°C) and use water as fuel. The heat from the hot water is utilised to boil a working fluid, which is typically a low boiling point organic chemical. The working fluid of a heat exchanger is evaporated and used to turn a turbine. The water is then injected back into the earth to be warmed. There are minimal or no air emissions since the water and working fluid are maintained separate throughout the operation.
Benefits of geothermal energy
- It is cleaner fuel as it emits only one-sixth of the CO2 that a natural gas plant does.
- The ongoing flow of heat from the Earth makes it infinite and inexhaustible making it a renewable resource
- It is the only renewable energy available to mankind 24 hours a day, seven days a week that does not require storage and is unaffected by day-night or seasonal variations.
- Given the need to replace coal-based electricity with alternative energy sources, it is critical in creating new energy sources such as geothermal energy.
- Depending on geothermal properties and local geographical conditions, geothermal energy can be used as a primary power source as well as a substitute for electricity as a source of heat.
- It is a site-specific renewable energy source that is ideal for meeting the energy needs of remote/interior communities.
- Geothermal heat pump systems use 25% to 50% less electricity than conventional systems for heating or cooling and take up less space for gear.
- Mineral byproducts from hot springs, such as silica, borax, and caesium, could be used.
- Despite producing little CO2, geothermal has been linked to other pollutants such as sulphur dioxide and hydrogen sulphide.
- Influences the landscape. Geothermal generating facilities, influence the landscape and causes fractures and minor earthquakes in the areas where they operate.
- It has a high initial cost to build in a specific location.
- Because of its activity along the earth’s tectonic plates, it is also referred to as “the most location-specific energy source known to man.”
Draft Geothermal Energy National Policy
- The scheme’s objective is to establish India as a global leader in geothermal power by deploying 1000 MWth of geothermal energy capacity in the first phase until 2022.
- The initiative would examine the country’s geothermal resource potential and promote R&D projects for power generation and geo-exchange pumps.
India’s geothermal energy development framework
- It targets capturing 1,000 MW of geothermal energy by 2022 and 10,000 MW by 2030.
- It intends to significantly contribute to India’s long-term energy supply and reduce our national greenhouse gas emissions by building a socially and environmentally responsible geothermal energy business that is sustainable, safe, and secure.
- It aims to encourage international collaboration with world leaders in geothermal energy such as the United States, the Philippines, Indonesia, Mexico, and New Zealand in order to accelerate geothermal energy deployment through international investment promotion, customised capacity building, and technical assistance.
As geothermal discovery is capital-intensive, financial incentives may be announced to encourage geothermal resource exploration.
Exploration funding will encourage exploration agencies to pursue geothermal energy projects for power generation and direct heat usage. It will also attract private investors for geothermal energy development. Foreign financing and knowledge transfer, as well as appropriate financial incentives, may be promoted to attract private parties to develop geothermal energy in India.
So far, research in India has been primarily superficial, leaving a data void for power project design. It is critical in decoding the characteristics of deep reservoirs, which will be valuable in determining the feasibility of resources for power generation.
If there is strong international cooperation and support from wealthier countries, geothermal energy can help underdeveloped countries tackle climate change while simultaneously boosting living standards.
Article Written By: Atheena Fathima Riyas