Geothermal energy is the heat energy present inside the earth. The interior of the earth has a temperature in the range of around 6000 degrees Celsius. The main source of this heat is the gradual decay of certain radioactive isotopes which have longer half-life such as U238, U235, Th232, K40 etc. This heat is continuously transferred from the earth’s interiors towards the outer layers by conduction and convection. The upward movement of molten magma, which is the main source of heat transmission, results in a mean heat flux of approximately 80kW/sq.m at the earth’s surface.
What is Geo-Thermal Energy?
The movement of heat from the earth’s interiors is not uniform throughout the earth. It is concentrated near active plate boundaries where volcanic activity occurs regularly transmitting the molten magma near to the earth’s surface. A majority portion of this magma remains trapped at depths in the range of 5 to 20 km. The magma releases the heat to its surrounding rocks. In regions where water comes into contact with such rocks, high-temperature geothermal systems are formed such as hot water, water and steam mixture, or steam at depths in the range of 500 to 3000 m.
Characteristics of Geo-Thermal Energy
1. It’s a renewable form of energy which is clean (with minimal emission of greenhouse gases), reliable (with a very high availability of heat energy), and homegrown (reduces the dependence of energy imports such as coal, oil, natural gas etc.)
2. It has an extensive global distribution in both developed and developing countries, unlike fossil fuels.
3. It can be produced independent of weather or season, unlike renewables such as wind and solar power.
Geo-Thermal Energy Technologies
What is geothermal energy? technologies and challenges. Image Source: sciencefocus.com
Geothermal energy can be used for on-grid as well as off-grid power solutions. The main types of geothermal technologies include:
- Electricity production: Hot water and/or steam used to run turbines and generate electricity.
- Direct use: In direct use where heat energy is harnessed from the hot water and/or steam.
- Heat pump: heat energy from shallow sources is used to heat/cool buildings.
Challenges of Geo-Thermal Energy
1. Unlike other renewables such as wind and solar, geothermal energy is less known and less popular. Geothermal technologies are not fully developed.
2. Only a fraction of the potential geothermal energy sources/regions has been explored and mapped.
3. Many geothermal sources are located in inaccessible and harsh areas (polar regions, high mountains etc.) which makes them difficult to exploit.
4. Installation of geothermal technologies is highly capital intensive, though there is no cost of fuel use.
5. Safety issues arise from geothermal power plants since many harmful gases escape from the geothermal vents which can be difficult to contain and be disposed of properly.