Geothermal energy

05 Sources of energy

GEOTHERMAL ENERGY

• Geothermal energy is the heat energy from hot rocks present inside the earth.

PRODUCTION OF GEOTHERMAL ENERGY:

 

Hotspots:

  • Due to geological changes, molten rocks formed in the deeper hot regions of earth’s crust are pushed upward and trapped in certain regions called ‘hot spots’.

 

Hotsprings:
  • When underground water comes in contact with the hot spot, steam is generated. Sometimes hot water from that region finds outlets at the surface.
  • Such outlets are known as hot springs.
WORKING

 

  • Hydrothermal convection system is used to harness geothermal energy.
  • A pipe is inserted through a hole which is drilled deep inside the earth.
  • The steam trapped in rocks is routed through a pipe to a turbine.
  • This high pressure steam turns the turbine of a generator to produce electricity which is used to generate electricity.
  • Steam may also be used to heat water from an external source which is then used to rotate the turbine.
Geothermal gradient

 

  • Geothermal gradient is defined as the difference in the temperature between the core and the crust of the planet which may exceed 4000 °C, in some places.
  • Geothermal gradient is the driving force for a continuous conduction of thermal energy in the form of heat from the core to the surface..
ADVANTAGES OF GEOTHERMAL ENERGY

 

  • Geothermal energy is free and abundant resource to an estimated time span of 4 billion years.
  • Geothermal energy is non-polluting and environment friendly and no residue or by-product is generated.
  • Geothermal power plants are highly sophisticated and involve large scale research before installation. This generates the employment for skilled and unskilled labors at a very large scale at each stage of production and management.
  • In cold countries, the geothermal energy is used directly for melting of ice on the roads, heating houses in winters, green houses, public baths etc.
  • Although the initial cost of installation is very high, the cost for maintenance and repair is negligible.
DISADVANTAGES OF GEOTHERMAL ENERGY

 

  • Geothermal energy cannot be transported easily and there are chances of emission of toxic gases getting released into the atmosphere during transmission.
  • The installation of geothermal power plants requires a huge investment in terms of material and human resource.
  • Extensive research is required, as the sites can run out of steam over a period of time due to a drop in the temperature as a result of excessive or irregular supply of inlet water.
  • The source of geothermal energy is available in limited regions, some of which are highly inaccessible, which makes the process economically infeasible.
  • The process of drilling may result in release of highly toxic gases into the environment near these sites, which sometimes prove fatal to the workforce involved in the process.
APPLICATIONS OF GEOTHERMAL ENERGY

 

  • The steam from the geothermal reserves is either directly used to rotate the turbines of an electrical generatoror is used to heat water which then produces steam for the process.
  • In cold countries, geothermal energy is used to heat greenhouses or to heat water that are used for irrigation.
  • Geothermal energy is used in industries for the purpose of food dehydration, milk pasteurizing, gold mining etc.
  • Geothermal energy is used to heat buildings through district heating systems in which hot water through springs is directly transported to the buildings though pipelines.

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